Create Small Business Inventory Management System with FastAPI and SQLite

- Set up project structure and FastAPI application
- Create database models with SQLAlchemy
- Implement authentication with JWT
- Add CRUD operations for products, inventory, categories
- Implement purchase order and sales functionality
- Create reporting endpoints
- Set up Alembic for database migrations
- Add comprehensive documentation in README.md

README.md

@@ -1,3 +1,116 @@
-# FastAPI Application
+# Small Business Inventory Management System
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A comprehensive inventory management system for small businesses built with FastAPI and SQLite.
+
+## Features
+
+- **Product Management**: Create, update, delete, and search products with SKU, barcode support
+- **Inventory Tracking**: Track inventory levels across multiple locations
+- **Purchase Order Management**: Create purchase orders and receive inventory
+- **Sales Tracking**: Record sales and automatically update inventory
+- **User Authentication**: Secure API with JWT authentication
+- **Role-Based Access Control**: Admin and regular user roles
+- **Reporting**: Several reports including inventory value, low stock, sales summary, and purchase summary
+
+## Technologies
+
+- **Backend**: FastAPI (Python 3.9+)
+- **Database**: SQLite with SQLAlchemy ORM
+- **Authentication**: JWT tokens with OAuth2
+- **Migration**: Alembic for database migrations
+- **Validation**: Pydantic for data validation
+- **Linting**: Ruff for code quality
+
+## Setup and Installation
+
+1. Clone the repository
+2. Install dependencies:
+   ```
+   pip install -r requirements.txt
+   ```
+3. Run the database migrations:
+   ```
+   alembic upgrade head
+   ```
+4. Start the application:
+   ```
+   python run.py
+   ```
+
+The API will be available at http://localhost:8000
+
+## API Documentation
+
+Once the application is running, you can access:
+- Interactive API documentation: http://localhost:8000/docs
+- Alternative API documentation: http://localhost:8000/redoc
+
+## Default Admin User
+
+The system comes with a default admin user:
+- Email: admin@example.com
+- Password: admin123
+
+**Important**: Change the default password after first login!
+
+## Directory Structure
+
+```
+├── app                 # Application source code
+│   ├── api             # API endpoints
+│   ├── core            # Core functionality
+│   ├── crud            # CRUD operations
+│   ├── db              # Database setup
+│   ├── models          # SQLAlchemy models
+│   └── schemas         # Pydantic schemas
+├── migrations          # Alembic migrations
+├── alembic.ini         # Alembic configuration
+├── main.py             # Application entry point
+├── pyproject.toml      # Project configuration
+├── README.md           # Project documentation
+├── requirements.txt    # Dependencies
+└── run.py              # Script to run the application
+```
+
+## API Endpoints
+
+The API provides the following main endpoints:
+
+### Authentication
+- `POST /api/v1/login/access-token` - Login and get access token
+- `POST /api/v1/login/test-token` - Test access token validity
+
+### Users
+- `GET /api/v1/users/` - List users (admin only)
+- `POST /api/v1/users/` - Create user (admin only)
+- `GET /api/v1/users/me` - Get current user
+- `PUT /api/v1/users/me` - Update current user
+
+### Products
+- `GET /api/v1/products/` - List products
+- `POST /api/v1/products/` - Create product
+- `GET /api/v1/products/{id}` - Get product
+- `PUT /api/v1/products/{id}` - Update product
+- `DELETE /api/v1/products/{id}` - Delete product
+
+### Inventory
+- `GET /api/v1/inventory/` - List inventory
+- `POST /api/v1/inventory/` - Create inventory
+- `POST /api/v1/inventory/adjust` - Adjust inventory
+
+### Purchase Orders
+- `GET /api/v1/purchase-orders/` - List purchase orders
+- `POST /api/v1/purchase-orders/` - Create purchase order
+- `POST /api/v1/purchase-orders/{id}/receive` - Receive purchase order
+
+### Sales
+- `GET /api/v1/sales/` - List sales
+- `POST /api/v1/sales/` - Create sale
+- `POST /api/v1/sales/{id}/cancel` - Cancel sale
+
+### Reports
+- `GET /api/v1/reports/inventory-value` - Inventory value report
+- `GET /api/v1/reports/low-stock` - Low stock report
+- `GET /api/v1/reports/sales-summary` - Sales summary report
+- `GET /api/v1/reports/purchases-summary` - Purchases summary report
+- `GET /api/v1/reports/inventory-movements` - Inventory movements report

alembic.ini

@@ -0,0 +1,74 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts
+script_location = migrations
+
+# template used to generate migration files
+# file_template = %%(rev)s_%%(slug)s
+
+# timezone to use when rendering the date
+# within the migration file as well as the filename.
+# string value is passed to dateutil.tz.gettz()
+# leave blank for localtime
+# timezone =
+
+# max length of characters to apply to the
+# "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; this defaults
+# to migrations/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path
+# version_locations = %(here)s/bar %(here)s/bat migrations/versions
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+# SQLite database URL - Use absolute path
+sqlalchemy.url = sqlite:////app/storage/db/db.sqlite
+
+# Logging configuration
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

app/api/api_v1/api.py

@@ -0,0 +1,13 @@
+from fastapi import APIRouter
+
+from app.api.api_v1.endpoints import users, login, products, categories, inventory, purchase_orders, sales, reports
+
+api_router = APIRouter()
+api_router.include_router(login.router, tags=["login"])
+api_router.include_router(users.router, prefix="/users", tags=["users"])
+api_router.include_router(categories.router, prefix="/categories", tags=["categories"])
+api_router.include_router(products.router, prefix="/products", tags=["products"])
+api_router.include_router(inventory.router, prefix="/inventory", tags=["inventory"])
+api_router.include_router(purchase_orders.router, prefix="/purchase-orders", tags=["purchase-orders"])
+api_router.include_router(sales.router, prefix="/sales", tags=["sales"])
+api_router.include_router(reports.router, prefix="/reports", tags=["reports"])

app/api/api_v1/endpoints/categories.py

@@ -0,0 +1,109 @@
+from typing import Any, List
+
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_db, get_current_active_user, get_current_admin_user
+from app.crud.crud_category import category
+from app.models.user import User as UserModel
+from app.schemas.category import Category, CategoryCreate, CategoryUpdate
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[Category])
+def read_categories(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Retrieve categories.
+    """
+    categories = category.get_multi(db, skip=skip, limit=limit)
+    return categories
+
+
+@router.post("/", response_model=Category)
+def create_category(
+    *,
+    db: Session = Depends(get_db),
+    category_in: CategoryCreate,
+    current_user: UserModel = Depends(get_current_admin_user),
+) -> Any:
+    """
+    Create new category. Admin only.
+    """
+    db_category = category.get_by_name(db, name=category_in.name)
+    if db_category:
+        raise HTTPException(
+            status_code=400,
+            detail="A category with this name already exists",
+        )
+    new_category = category.create(db, obj_in=category_in)
+    return new_category
+
+
+@router.get("/{id}", response_model=Category)
+def read_category(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get category by ID.
+    """
+    db_category = category.get(db, id=id)
+    if not db_category:
+        raise HTTPException(status_code=404, detail="Category not found")
+    return db_category
+
+
+@router.put("/{id}", response_model=Category)
+def update_category(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    category_in: CategoryUpdate,
+    current_user: UserModel = Depends(get_current_admin_user),
+) -> Any:
+    """
+    Update a category. Admin only.
+    """
+    db_category = category.get(db, id=id)
+    if not db_category:
+        raise HTTPException(status_code=404, detail="Category not found")
+    
+    # Check if updated name conflicts with existing category
+    if category_in.name and category_in.name != db_category.name:
+        existing = category.get_by_name(db, name=category_in.name)
+        if existing:
+            raise HTTPException(
+                status_code=400,
+                detail="A category with this name already exists",
+            )
+    
+    updated_category = category.update(db, db_obj=db_category, obj_in=category_in)
+    return updated_category
+
+
+@router.delete("/{id}", response_model=Category)
+def delete_category(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: UserModel = Depends(get_current_admin_user),
+) -> Any:
+    """
+    Delete a category. Admin only.
+    """
+    db_category = category.get(db, id=id)
+    if not db_category:
+        raise HTTPException(status_code=404, detail="Category not found")
+    
+    # TODO: Check if category has products, and prevent deletion if it does
+    
+    deleted_category = category.remove(db, id=id)
+    return deleted_category

app/api/api_v1/endpoints/inventory.py

@@ -0,0 +1,162 @@
+from typing import Any, List, Optional
+
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_db, get_current_active_user, get_current_admin_user
+from app.crud.crud_inventory import inventory
+from app.crud.crud_product import product
+from app.models.user import User as UserModel
+from app.schemas.inventory import Inventory, InventoryCreate, InventoryUpdate, InventoryAdjustment
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[Inventory])
+def read_inventory(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    product_id: Optional[int] = None,
+    location: Optional[str] = None,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Retrieve inventory items.
+    Filter by product_id or location if provided.
+    """
+    items = inventory.get_multi(db, skip=skip, limit=limit)
+    
+    # Apply filters
+    if product_id is not None:
+        items = [item for item in items if item.product_id == product_id]
+    
+    if location is not None:
+        items = [item for item in items if item.location == location]
+        
+    return items
+
+
+@router.post("/", response_model=Inventory)
+def create_inventory(
+    *,
+    db: Session = Depends(get_db),
+    inventory_in: InventoryCreate,
+    current_user: UserModel = Depends(get_current_admin_user),
+) -> Any:
+    """
+    Create new inventory record. Admin only.
+    """
+    # Verify product exists
+    prod = product.get(db, id=inventory_in.product_id)
+    if not prod:
+        raise HTTPException(status_code=404, detail="Product not found")
+    
+    # Check if inventory already exists for this product and location
+    existing = inventory.get_by_product_and_location(
+        db, product_id=inventory_in.product_id, location=inventory_in.location
+    )
+    
+    if existing:
+        raise HTTPException(
+            status_code=400,
+            detail="Inventory record for this product and location already exists. Use adjustment endpoint to modify quantity.",
+        )
+    
+    new_inventory = inventory.create(db, obj_in=inventory_in)
+    return new_inventory
+
+
+@router.post("/adjust", response_model=Inventory)
+def adjust_inventory_quantity(
+    *,
+    db: Session = Depends(get_db),
+    adjustment: InventoryAdjustment,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Adjust inventory quantity for a product.
+    Use positive quantity to add, negative to remove.
+    """
+    # Verify product exists
+    prod = product.get(db, id=adjustment.product_id)
+    if not prod:
+        raise HTTPException(status_code=404, detail="Product not found")
+    
+    # Adjust inventory and record transaction
+    result = inventory.adjust_inventory(db, adjustment=adjustment)
+    
+    return result["inventory"]
+
+
+@router.get("/{id}", response_model=Inventory)
+def read_inventory_item(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get inventory item by ID.
+    """
+    item = inventory.get(db, id=id)
+    if not item:
+        raise HTTPException(status_code=404, detail="Inventory item not found")
+    return item
+
+
+@router.put("/{id}", response_model=Inventory)
+def update_inventory(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    inventory_in: InventoryUpdate,
+    current_user: UserModel = Depends(get_current_admin_user),
+) -> Any:
+    """
+    Update an inventory item. Admin only.
+    Note: For regular quantity adjustments, use the /adjust endpoint instead.
+    """
+    item = inventory.get(db, id=id)
+    if not item:
+        raise HTTPException(status_code=404, detail="Inventory item not found")
+    
+    # If changing product_id, verify product exists
+    if inventory_in.product_id is not None and inventory_in.product_id != item.product_id:
+        prod = product.get(db, id=inventory_in.product_id)
+        if not prod:
+            raise HTTPException(status_code=404, detail="Product not found")
+        
+        # Check if inventory already exists for new product and location
+        existing = inventory.get_by_product_and_location(
+            db, 
+            product_id=inventory_in.product_id, 
+            location=inventory_in.location or item.location
+        )
+        
+        if existing and existing.id != id:
+            raise HTTPException(
+                status_code=400,
+                detail="Inventory record for this product and location already exists",
+            )
+    
+    updated_inventory = inventory.update(db, db_obj=item, obj_in=inventory_in)
+    return updated_inventory
+
+
+@router.delete("/{id}", response_model=Inventory)
+def delete_inventory(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: UserModel = Depends(get_current_admin_user),
+) -> Any:
+    """
+    Delete an inventory item. Admin only.
+    """
+    item = inventory.get(db, id=id)
+    if not item:
+        raise HTTPException(status_code=404, detail="Inventory item not found")
+    
+    deleted_inventory = inventory.remove(db, id=id)
+    return deleted_inventory

app/api/api_v1/endpoints/login.py

@@ -0,0 +1,48 @@
+from datetime import timedelta
+from typing import Any
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi.security import OAuth2PasswordRequestForm
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_db, get_current_user
+from app.core.config import settings
+from app.core.security.jwt import create_access_token
+from app.core.security.password import verify_password
+from app.crud.crud_user import user
+from app.schemas.token import Token
+from app.schemas.user import User
+
+router = APIRouter()
+
+
+@router.post("/login/access-token", response_model=Token)
+def login_access_token(
+    db: Session = Depends(get_db), form_data: OAuth2PasswordRequestForm = Depends()
+) -> Any:
+    """
+    OAuth2 compatible token login, get an access token for future requests
+    """
+    db_user = user.get_by_email(db, email=form_data.username)
+    if not db_user:
+        raise HTTPException(status_code=400, detail="Incorrect email or password")
+    if not verify_password(form_data.password, db_user.hashed_password):
+        raise HTTPException(status_code=400, detail="Incorrect email or password")
+    if not db_user.is_active:
+        raise HTTPException(status_code=400, detail="Inactive user")
+    
+    access_token_expires = timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
+    return {
+        "access_token": create_access_token(
+            db_user.id, expires_delta=access_token_expires
+        ),
+        "token_type": "bearer",
+    }
+
+
+@router.post("/login/test-token", response_model=User)
+def test_token(current_user: User = Depends(get_current_user)) -> Any:
+    """
+    Test access token
+    """
+    return current_user

app/api/api_v1/endpoints/products.py

@@ -0,0 +1,170 @@
+from typing import Any, List, Optional
+
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_db, get_current_active_user, get_current_admin_user
+from app.crud.crud_product import product
+from app.models.user import User as UserModel
+from app.schemas.product import Product, ProductCreate, ProductUpdate, ProductWithInventory
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[ProductWithInventory])
+def read_products(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    category_id: Optional[int] = None,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Retrieve products with inventory information.
+    """
+    products = product.get_multi_with_inventory(db, skip=skip, limit=limit)
+    
+    # Filter by category if provided
+    if category_id is not None:
+        products = [p for p in products if p["category_id"] == category_id]
+        
+    return products
+
+
+@router.post("/", response_model=Product)
+def create_product(
+    *,
+    db: Session = Depends(get_db),
+    product_in: ProductCreate,
+    current_user: UserModel = Depends(get_current_admin_user),
+) -> Any:
+    """
+    Create new product. Admin only.
+    """
+    # Check for duplicate SKU
+    if product_in.sku:
+        db_product = product.get_by_sku(db, sku=product_in.sku)
+        if db_product:
+            raise HTTPException(
+                status_code=400,
+                detail="A product with this SKU already exists",
+            )
+    
+    # Check for duplicate barcode
+    if product_in.barcode:
+        db_product = product.get_by_barcode(db, barcode=product_in.barcode)
+        if db_product:
+            raise HTTPException(
+                status_code=400,
+                detail="A product with this barcode already exists",
+            )
+    
+    new_product = product.create(db, obj_in=product_in)
+    return new_product
+
+
+@router.get("/{id}", response_model=ProductWithInventory)
+def read_product(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get product by ID with inventory information.
+    """
+    db_product = product.get_with_inventory(db, id=id)
+    if not db_product:
+        raise HTTPException(status_code=404, detail="Product not found")
+    return db_product
+
+
+@router.put("/{id}", response_model=Product)
+def update_product(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    product_in: ProductUpdate,
+    current_user: UserModel = Depends(get_current_admin_user),
+) -> Any:
+    """
+    Update a product. Admin only.
+    """
+    db_product = product.get(db, id=id)
+    if not db_product:
+        raise HTTPException(status_code=404, detail="Product not found")
+    
+    # Check for duplicate SKU
+    if product_in.sku and product_in.sku != db_product.sku:
+        existing = product.get_by_sku(db, sku=product_in.sku)
+        if existing:
+            raise HTTPException(
+                status_code=400,
+                detail="A product with this SKU already exists",
+            )
+    
+    # Check for duplicate barcode
+    if product_in.barcode and product_in.barcode != db_product.barcode:
+        existing = product.get_by_barcode(db, barcode=product_in.barcode)
+        if existing:
+            raise HTTPException(
+                status_code=400,
+                detail="A product with this barcode already exists",
+            )
+    
+    updated_product = product.update(db, db_obj=db_product, obj_in=product_in)
+    return updated_product
+
+
+@router.delete("/{id}", response_model=Product)
+def delete_product(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: UserModel = Depends(get_current_admin_user),
+) -> Any:
+    """
+    Delete a product. Admin only.
+    """
+    db_product = product.get(db, id=id)
+    if not db_product:
+        raise HTTPException(status_code=404, detail="Product not found")
+    
+    # TODO: Consider checking if product has inventory or is referenced by other entities
+    
+    deleted_product = product.remove(db, id=id)
+    return deleted_product
+
+
+@router.get("/by-sku/{sku}", response_model=ProductWithInventory)
+def read_product_by_sku(
+    *,
+    db: Session = Depends(get_db),
+    sku: str,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get product by SKU with inventory information.
+    """
+    db_product = product.get_by_sku(db, sku=sku)
+    if not db_product:
+        raise HTTPException(status_code=404, detail="Product not found")
+    
+    return product.get_with_inventory(db, id=db_product.id)
+
+
+@router.get("/by-barcode/{barcode}", response_model=ProductWithInventory)
+def read_product_by_barcode(
+    *,
+    db: Session = Depends(get_db),
+    barcode: str,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get product by barcode with inventory information.
+    """
+    db_product = product.get_by_barcode(db, barcode=barcode)
+    if not db_product:
+        raise HTTPException(status_code=404, detail="Product not found")
+    
+    return product.get_with_inventory(db, id=db_product.id)

app/api/api_v1/endpoints/purchase_orders.py

@@ -0,0 +1,185 @@
+from typing import Any, List, Optional
+from decimal import Decimal
+
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_db, get_current_active_user, get_current_admin_user
+from app.crud.crud_purchase_order import purchase_order
+from app.crud.crud_product import product
+from app.models.user import User as UserModel
+from app.schemas.purchase_order import PurchaseOrder, PurchaseOrderCreate, PurchaseOrderUpdate
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[PurchaseOrder])
+def read_purchase_orders(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    status: Optional[str] = None,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Retrieve purchase orders with their items.
+    Filter by status if provided.
+    """
+    orders = purchase_order.get_multi_with_items(db, skip=skip, limit=limit)
+    
+    # Apply status filter
+    if status:
+        orders = [order for order in orders if order.status == status]
+    
+    # Calculate total amount for each order
+    for order in orders:
+        order.total_amount = purchase_order.get_total_amount(db, id=order.id)
+        
+    return orders
+
+
+@router.post("/", response_model=PurchaseOrder)
+def create_purchase_order(
+    *,
+    db: Session = Depends(get_db),
+    order_in: PurchaseOrderCreate,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Create new purchase order with items.
+    """
+    # Verify all products exist
+    for item in order_in.items:
+        prod = product.get(db, id=item.product_id)
+        if not prod:
+            raise HTTPException(
+                status_code=404, 
+                detail=f"Product with id {item.product_id} not found"
+            )
+    
+    # Create purchase order with items
+    new_order = purchase_order.create_with_items(
+        db, obj_in=order_in, user_id=current_user.id
+    )
+    
+    # Calculate total amount
+    new_order.total_amount = purchase_order.get_total_amount(db, id=new_order.id)
+    
+    return new_order
+
+
+@router.get("/{id}", response_model=PurchaseOrder)
+def read_purchase_order(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get purchase order by ID with its items.
+    """
+    order = purchase_order.get_with_items(db, id=id)
+    if not order:
+        raise HTTPException(status_code=404, detail="Purchase order not found")
+    
+    # Calculate total amount
+    order.total_amount = purchase_order.get_total_amount(db, id=order.id)
+    
+    return order
+
+
+@router.put("/{id}", response_model=PurchaseOrder)
+def update_purchase_order(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    order_in: PurchaseOrderUpdate,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Update a purchase order (but not its items).
+    Can only update pending orders.
+    """
+    order = purchase_order.get(db, id=id)
+    if not order:
+        raise HTTPException(status_code=404, detail="Purchase order not found")
+    
+    # Only allow updates to pending orders
+    if order.status != "pending":
+        raise HTTPException(
+            status_code=400,
+            detail=f"Cannot update purchase order with status {order.status}. Only pending orders can be updated."
+        )
+    
+    updated_order = purchase_order.update(db, db_obj=order, obj_in=order_in)
+    
+    # Get full order with items for response
+    result = purchase_order.get_with_items(db, id=updated_order.id)
+    
+    # Calculate total amount
+    result.total_amount = purchase_order.get_total_amount(db, id=result.id)
+    
+    return result
+
+
+@router.post("/{id}/receive", response_model=PurchaseOrder)
+def receive_purchase_order(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Mark a purchase order as received and update inventory.
+    """
+    order = purchase_order.get(db, id=id)
+    if not order:
+        raise HTTPException(status_code=404, detail="Purchase order not found")
+    
+    # Only allow receiving pending orders
+    if order.status != "pending":
+        raise HTTPException(
+            status_code=400,
+            detail=f"Cannot receive purchase order with status {order.status}. Only pending orders can be received."
+        )
+    
+    # Update status and inventory
+    received_order = purchase_order.receive_order(db, id=id)
+    
+    # Calculate total amount
+    received_order.total_amount = purchase_order.get_total_amount(db, id=received_order.id)
+    
+    return received_order
+
+
+@router.post("/{id}/cancel", response_model=PurchaseOrder)
+def cancel_purchase_order(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Cancel a purchase order.
+    """
+    order = purchase_order.get(db, id=id)
+    if not order:
+        raise HTTPException(status_code=404, detail="Purchase order not found")
+    
+    # Only allow cancelling pending orders
+    if order.status != "pending":
+        raise HTTPException(
+            status_code=400,
+            detail=f"Cannot cancel purchase order with status {order.status}. Only pending orders can be cancelled."
+        )
+    
+    # Update status
+    cancelled_order = purchase_order.cancel_order(db, id=id)
+    
+    # Get full order with items for response
+    result = purchase_order.get_with_items(db, id=cancelled_order.id)
+    
+    # Calculate total amount
+    result.total_amount = purchase_order.get_total_amount(db, id=result.id)
+    
+    return result

app/api/api_v1/endpoints/reports.py

@@ -0,0 +1,341 @@
+from typing import Any, Dict, List, Optional
+from datetime import datetime, timedelta
+from decimal import Decimal
+
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy import func, and_, desc
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_db, get_current_active_user, get_current_admin_user
+from app.models.user import User as UserModel
+from app.models.product import Product
+from app.models.inventory import Inventory, InventoryTransaction
+from app.models.purchase_order import PurchaseOrder, PurchaseOrderItem
+from app.models.sale import Sale, SaleItem
+
+router = APIRouter()
+
+
+@router.get("/inventory-value")
+def inventory_value_report(
+    db: Session = Depends(get_db),
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get current inventory value report.
+    Calculates total inventory value (quantity * cost price).
+    """
+    # Join Product and Inventory to calculate value
+    inventory_value = db.query(
+        func.sum(Product.cost_price * Inventory.quantity).label("total_value"),
+        func.count(Inventory.id).label("items_count"),
+        func.sum(Inventory.quantity).label("total_quantity")
+    ).join(
+        Product, Product.id == Inventory.product_id
+    ).filter(
+        Inventory.quantity > 0
+    ).first()
+    
+    # Get top products by value
+    top_products = db.query(
+        Product.id,
+        Product.name,
+        Product.sku,
+        Product.cost_price,
+        Inventory.quantity,
+        (Product.cost_price * Inventory.quantity).label("value")
+    ).join(
+        Inventory, Product.id == Inventory.product_id
+    ).filter(
+        Inventory.quantity > 0
+    ).order_by(
+        desc("value")
+    ).limit(10).all()
+    
+    top_products_result = []
+    for p in top_products:
+        top_products_result.append({
+            "id": p.id,
+            "name": p.name,
+            "sku": p.sku,
+            "cost_price": float(p.cost_price) if p.cost_price else 0,
+            "quantity": p.quantity,
+            "value": float(p.value) if p.value else 0
+        })
+    
+    return {
+        "total_value": float(inventory_value.total_value) if inventory_value.total_value else 0,
+        "items_count": inventory_value.items_count or 0,
+        "total_quantity": inventory_value.total_quantity or 0,
+        "top_products_by_value": top_products_result,
+        "report_date": datetime.now()
+    }
+
+
+@router.get("/low-stock")
+def low_stock_report(
+    db: Session = Depends(get_db),
+    threshold: int = 5,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get low stock report.
+    Shows products with inventory below specified threshold.
+    """
+    # Get products with low stock
+    low_stock_products = db.query(
+        Product.id,
+        Product.name,
+        Product.sku,
+        Product.barcode,
+        func.sum(Inventory.quantity).label("total_quantity")
+    ).outerjoin(
+        Inventory, Product.id == Inventory.product_id
+    ).group_by(
+        Product.id
+    ).having(
+        func.coalesce(func.sum(Inventory.quantity), 0) < threshold
+    ).all()
+    
+    result = []
+    for p in low_stock_products:
+        result.append({
+            "id": p.id,
+            "name": p.name,
+            "sku": p.sku,
+            "barcode": p.barcode,
+            "quantity": p.total_quantity or 0
+        })
+    
+    return {
+        "threshold": threshold,
+        "count": len(result),
+        "products": result,
+        "report_date": datetime.now()
+    }
+
+
+@router.get("/sales-summary")
+def sales_summary_report(
+    db: Session = Depends(get_db),
+    start_date: Optional[datetime] = None,
+    end_date: Optional[datetime] = None,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get sales summary report for a specified date range.
+    If no dates provided, defaults to the last 30 days.
+    """
+    # Set default date range if not provided
+    if not end_date:
+        end_date = datetime.now()
+    if not start_date:
+        start_date = end_date - timedelta(days=30)
+    
+    # Get summary of all sales in date range
+    sales_summary = db.query(
+        func.count(Sale.id).label("total_sales"),
+        func.sum(SaleItem.quantity * SaleItem.unit_price).label("total_revenue"),
+        func.sum(SaleItem.quantity).label("total_items_sold")
+    ).join(
+        SaleItem, Sale.id == SaleItem.sale_id
+    ).filter(
+        Sale.status == "completed",
+        Sale.created_at >= start_date,
+        Sale.created_at <= end_date
+    ).first()
+    
+    # Get top selling products
+    top_products = db.query(
+        Product.id,
+        Product.name,
+        Product.sku,
+        func.sum(SaleItem.quantity).label("quantity_sold"),
+        func.sum(SaleItem.quantity * SaleItem.unit_price).label("revenue")
+    ).join(
+        SaleItem, Product.id == SaleItem.product_id
+    ).join(
+        Sale, SaleItem.sale_id == Sale.id
+    ).filter(
+        Sale.status == "completed",
+        Sale.created_at >= start_date,
+        Sale.created_at <= end_date
+    ).group_by(
+        Product.id
+    ).order_by(
+        desc("quantity_sold")
+    ).limit(10).all()
+    
+    top_products_result = []
+    for p in top_products:
+        top_products_result.append({
+            "id": p.id,
+            "name": p.name,
+            "sku": p.sku,
+            "quantity_sold": p.quantity_sold,
+            "revenue": float(p.revenue) if p.revenue else 0
+        })
+    
+    return {
+        "start_date": start_date,
+        "end_date": end_date,
+        "total_sales": sales_summary.total_sales or 0,
+        "total_revenue": float(sales_summary.total_revenue) if sales_summary.total_revenue else 0,
+        "total_items_sold": sales_summary.total_items_sold or 0,
+        "top_selling_products": top_products_result,
+        "report_date": datetime.now()
+    }
+
+
+@router.get("/purchases-summary")
+def purchases_summary_report(
+    db: Session = Depends(get_db),
+    start_date: Optional[datetime] = None,
+    end_date: Optional[datetime] = None,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get purchases summary report for a specified date range.
+    If no dates provided, defaults to the last 30 days.
+    """
+    # Set default date range if not provided
+    if not end_date:
+        end_date = datetime.now()
+    if not start_date:
+        start_date = end_date - timedelta(days=30)
+    
+    # Get summary of all received purchase orders in date range
+    purchases_summary = db.query(
+        func.count(PurchaseOrder.id).label("total_purchase_orders"),
+        func.sum(PurchaseOrderItem.quantity * PurchaseOrderItem.unit_price).label("total_cost"),
+        func.sum(PurchaseOrderItem.quantity).label("total_items_purchased")
+    ).join(
+        PurchaseOrderItem, PurchaseOrder.id == PurchaseOrderItem.purchase_order_id
+    ).filter(
+        PurchaseOrder.status == "received",
+        PurchaseOrder.created_at >= start_date,
+        PurchaseOrder.created_at <= end_date
+    ).first()
+    
+    # Get top suppliers
+    top_suppliers = db.query(
+        PurchaseOrder.supplier_name,
+        func.count(PurchaseOrder.id).label("order_count"),
+        func.sum(PurchaseOrderItem.quantity * PurchaseOrderItem.unit_price).label("total_spend")
+    ).join(
+        PurchaseOrderItem, PurchaseOrder.id == PurchaseOrderItem.purchase_order_id
+    ).filter(
+        PurchaseOrder.status == "received",
+        PurchaseOrder.created_at >= start_date,
+        PurchaseOrder.created_at <= end_date
+    ).group_by(
+        PurchaseOrder.supplier_name
+    ).order_by(
+        desc("total_spend")
+    ).limit(5).all()
+    
+    top_suppliers_result = []
+    for s in top_suppliers:
+        top_suppliers_result.append({
+            "supplier_name": s.supplier_name,
+            "order_count": s.order_count,
+            "total_spend": float(s.total_spend) if s.total_spend else 0
+        })
+    
+    return {
+        "start_date": start_date,
+        "end_date": end_date,
+        "total_purchase_orders": purchases_summary.total_purchase_orders or 0,
+        "total_cost": float(purchases_summary.total_cost) if purchases_summary.total_cost else 0,
+        "total_items_purchased": purchases_summary.total_items_purchased or 0,
+        "top_suppliers": top_suppliers_result,
+        "report_date": datetime.now()
+    }
+
+
+@router.get("/inventory-movements")
+def inventory_movements_report(
+    db: Session = Depends(get_db),
+    product_id: Optional[int] = None,
+    start_date: Optional[datetime] = None,
+    end_date: Optional[datetime] = None,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get inventory movements report for a specified date range and product.
+    If no dates provided, defaults to the last 30 days.
+    """
+    # Set default date range if not provided
+    if not end_date:
+        end_date = datetime.now()
+    if not start_date:
+        start_date = end_date - timedelta(days=30)
+    
+    # Build query for inventory transactions
+    query = db.query(
+        InventoryTransaction.id,
+        InventoryTransaction.product_id,
+        Product.name.label("product_name"),
+        Product.sku,
+        InventoryTransaction.quantity,
+        InventoryTransaction.transaction_type,
+        InventoryTransaction.reference_id,
+        InventoryTransaction.reason,
+        InventoryTransaction.timestamp,
+        InventoryTransaction.location
+    ).join(
+        Product, InventoryTransaction.product_id == Product.id
+    ).filter(
+        InventoryTransaction.timestamp >= start_date,
+        InventoryTransaction.timestamp <= end_date
+    )
+    
+    # Filter by product if specified
+    if product_id:
+        query = query.filter(InventoryTransaction.product_id == product_id)
+    
+    # Execute query
+    transactions = query.order_by(InventoryTransaction.timestamp.desc()).all()
+    
+    result = []
+    for t in transactions:
+        result.append({
+            "id": t.id,
+            "product_id": t.product_id,
+            "product_name": t.product_name,
+            "sku": t.sku,
+            "quantity": t.quantity,
+            "transaction_type": t.transaction_type,
+            "reference_id": t.reference_id,
+            "reason": t.reason,
+            "timestamp": t.timestamp,
+            "location": t.location
+        })
+    
+    # Get summary by transaction type
+    summary = db.query(
+        InventoryTransaction.transaction_type,
+        func.sum(InventoryTransaction.quantity).label("total_quantity")
+    ).filter(
+        InventoryTransaction.timestamp >= start_date,
+        InventoryTransaction.timestamp <= end_date
+    )
+    
+    if product_id:
+        summary = summary.filter(InventoryTransaction.product_id == product_id)
+    
+    summary = summary.group_by(InventoryTransaction.transaction_type).all()
+    
+    summary_result = {}
+    for s in summary:
+        summary_result[s.transaction_type] = s.total_quantity
+    
+    return {
+        "start_date": start_date,
+        "end_date": end_date,
+        "product_id": product_id,
+        "transaction_count": len(result),
+        "summary_by_type": summary_result,
+        "transactions": result,
+        "report_date": datetime.now()
+    }

app/api/api_v1/endpoints/sales.py

@@ -0,0 +1,168 @@
+from typing import Any, List, Optional
+from decimal import Decimal
+
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_db, get_current_active_user, get_current_admin_user
+from app.crud.crud_sale import sale
+from app.crud.crud_product import product
+from app.crud.crud_inventory import inventory
+from app.models.user import User as UserModel
+from app.schemas.sale import Sale, SaleCreate, SaleUpdate
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[Sale])
+def read_sales(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    status: Optional[str] = None,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Retrieve sales with their items.
+    Filter by status if provided.
+    """
+    sales = sale.get_multi_with_items(db, skip=skip, limit=limit)
+    
+    # Apply status filter
+    if status:
+        sales = [s for s in sales if s.status == status]
+    
+    # Calculate total amount for each sale
+    for s in sales:
+        s.total_amount = sale.get_total_amount(db, id=s.id)
+        
+    return sales
+
+
+@router.post("/", response_model=Sale)
+def create_sale(
+    *,
+    db: Session = Depends(get_db),
+    sale_in: SaleCreate,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Create new sale with items and update inventory.
+    """
+    # Verify all products exist and have enough inventory
+    for item in sale_in.items:
+        # Check if product exists
+        prod = product.get(db, id=item.product_id)
+        if not prod:
+            raise HTTPException(
+                status_code=404, 
+                detail=f"Product with id {item.product_id} not found"
+            )
+        
+        # Check if enough inventory is available
+        available = inventory.get_total_product_quantity(db, product_id=item.product_id)
+        if available < item.quantity:
+            raise HTTPException(
+                status_code=400,
+                detail=f"Not enough inventory for product {prod.name}. Available: {available}, Requested: {item.quantity}"
+            )
+    
+    # Create sale with items
+    new_sale = sale.create_with_items(
+        db, obj_in=sale_in, user_id=current_user.id
+    )
+    
+    if not new_sale:
+        raise HTTPException(
+            status_code=400,
+            detail="Failed to create sale, likely due to insufficient inventory"
+        )
+    
+    # Calculate total amount
+    new_sale.total_amount = sale.get_total_amount(db, id=new_sale.id)
+    
+    return new_sale
+
+
+@router.get("/{id}", response_model=Sale)
+def read_sale(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get sale by ID with its items.
+    """
+    sale_item = sale.get_with_items(db, id=id)
+    if not sale_item:
+        raise HTTPException(status_code=404, detail="Sale not found")
+    
+    # Calculate total amount
+    sale_item.total_amount = sale.get_total_amount(db, id=sale_item.id)
+    
+    return sale_item
+
+
+@router.put("/{id}", response_model=Sale)
+def update_sale(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    sale_in: SaleUpdate,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Update a sale (but not its items).
+    Can only update completed sales that haven't been cancelled or returned.
+    """
+    sale_item = sale.get(db, id=id)
+    if not sale_item:
+        raise HTTPException(status_code=404, detail="Sale not found")
+    
+    # Only allow updates to completed sales
+    if sale_item.status != "completed":
+        raise HTTPException(
+            status_code=400,
+            detail=f"Cannot update sale with status {sale_item.status}. Only completed sales can be updated."
+        )
+    
+    updated_sale = sale.update(db, db_obj=sale_item, obj_in=sale_in)
+    
+    # Get full sale with items for response
+    result = sale.get_with_items(db, id=updated_sale.id)
+    
+    # Calculate total amount
+    result.total_amount = sale.get_total_amount(db, id=result.id)
+    
+    return result
+
+
+@router.post("/{id}/cancel", response_model=Sale)
+def cancel_sale(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Cancel a sale and return items to inventory.
+    """
+    sale_item = sale.get(db, id=id)
+    if not sale_item:
+        raise HTTPException(status_code=404, detail="Sale not found")
+    
+    # Only allow cancelling completed sales
+    if sale_item.status != "completed":
+        raise HTTPException(
+            status_code=400,
+            detail=f"Cannot cancel sale with status {sale_item.status}. Only completed sales can be cancelled."
+        )
+    
+    # Update status and return to inventory
+    cancelled_sale = sale.cancel_sale(db, id=id)
+    
+    # Calculate total amount
+    cancelled_sale.total_amount = sale.get_total_amount(db, id=cancelled_sale.id)
+    
+    return cancelled_sale

app/api/api_v1/endpoints/users.py

@@ -0,0 +1,116 @@
+from typing import Any, List
+
+from fastapi import APIRouter, Body, Depends, HTTPException
+from fastapi.encoders import jsonable_encoder
+from pydantic import EmailStr
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_db, get_current_active_user, get_current_admin_user
+from app.crud.crud_user import user
+from app.models.user import User as UserModel
+from app.schemas.user import User, UserCreate, UserUpdate
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[User])
+def read_users(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    current_user: UserModel = Depends(get_current_admin_user),
+) -> Any:
+    """
+    Retrieve users. Admin only.
+    """
+    users = user.get_multi(db, skip=skip, limit=limit)
+    return users
+
+
+@router.post("/", response_model=User)
+def create_user(
+    *,
+    db: Session = Depends(get_db),
+    user_in: UserCreate,
+    current_user: UserModel = Depends(get_current_admin_user),
+) -> Any:
+    """
+    Create new user. Admin only.
+    """
+    db_user = user.get_by_email(db, email=user_in.email)
+    if db_user:
+        raise HTTPException(
+            status_code=400,
+            detail="A user with this email already exists",
+        )
+    new_user = user.create(db, obj_in=user_in)
+    return new_user
+
+
+@router.put("/me", response_model=User)
+def update_user_me(
+    *,
+    db: Session = Depends(get_db),
+    password: str = Body(None),
+    full_name: str = Body(None),
+    email: EmailStr = Body(None),
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Update own user.
+    """
+    current_user_data = jsonable_encoder(current_user)
+    user_in = UserUpdate(**current_user_data)
+    if password is not None:
+        user_in.password = password
+    if full_name is not None:
+        user_in.full_name = full_name
+    if email is not None:
+        user_in.email = email
+    updated_user = user.update(db, db_obj=current_user, obj_in=user_in)
+    return updated_user
+
+
+@router.get("/me", response_model=User)
+def read_user_me(
+    current_user: UserModel = Depends(get_current_active_user),
+) -> Any:
+    """
+    Get current user.
+    """
+    return current_user
+
+
+@router.get("/{user_id}", response_model=User)
+def read_user_by_id(
+    user_id: int,
+    current_user: UserModel = Depends(get_current_active_user),
+    db: Session = Depends(get_db),
+) -> Any:
+    """
+    Get a specific user by id.
+    """
+    db_user = user.get(db, id=user_id)
+    if not db_user:
+        raise HTTPException(status_code=404, detail="User not found")
+    if user_id != current_user.id and not current_user.is_admin:
+        raise HTTPException(status_code=400, detail="Not enough permissions")
+    return db_user
+
+
+@router.put("/{user_id}", response_model=User)
+def update_user(
+    *,
+    db: Session = Depends(get_db),
+    user_id: int,
+    user_in: UserUpdate,
+    current_user: UserModel = Depends(get_current_admin_user),
+) -> Any:
+    """
+    Update a user. Admin only.
+    """
+    db_user = user.get(db, id=user_id)
+    if not db_user:
+        raise HTTPException(status_code=404, detail="User not found")
+    updated_user = user.update(db, db_obj=db_user, obj_in=user_in)
+    return updated_user

app/api/deps.py

@@ -0,0 +1,60 @@
+from typing import Generator
+
+from fastapi import Depends, HTTPException, status
+from fastapi.security import OAuth2PasswordBearer
+from sqlalchemy.orm import Session
+
+from app.core.config import settings
+from app.db.session import get_db
+from app.core.security.jwt import decode_token
+from app.crud.crud_user import user
+from app.models.user import User as UserModel
+
+oauth2_scheme = OAuth2PasswordBearer(
+    tokenUrl=f"{settings.API_V1_STR}/login/access-token"
+)
+
+
+def get_current_user(
+    db: Session = Depends(get_db), token: str = Depends(oauth2_scheme)
+) -> UserModel:
+    """
+    Get current user based on JWT token
+    """
+    token_data = decode_token(token)
+    if not token_data:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Could not validate credentials",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    
+    db_user = user.get(db, id=token_data.sub)
+    if not db_user:
+        raise HTTPException(status_code=404, detail="User not found")
+    return db_user
+
+
+def get_current_active_user(
+    current_user: UserModel = Depends(get_current_user),
+) -> UserModel:
+    """
+    Get current active user
+    """
+    if not current_user.is_active:
+        raise HTTPException(status_code=400, detail="Inactive user")
+    return current_user
+
+
+def get_current_admin_user(
+    current_user: UserModel = Depends(get_current_user),
+) -> UserModel:
+    """
+    Get current admin user
+    """
+    if not current_user.is_admin:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN, 
+            detail="The user doesn't have enough privileges"
+        )
+    return current_user

app/core/config.py

@@ -0,0 +1,42 @@
+import secrets
+from typing import Any, Dict, List, Optional, Union
+from pathlib import Path
+
+from pydantic import AnyHttpUrl, validator
+from pydantic_settings import BaseSettings
+
+
+class Settings(BaseSettings):
+    API_V1_STR: str = "/api/v1"
+    SECRET_KEY: str = secrets.token_urlsafe(32)
+    # 60 minutes * 24 hours * 8 days = 8 days
+    ACCESS_TOKEN_EXPIRE_MINUTES: int = 60 * 24 * 8
+    # BACKEND_CORS_ORIGINS is a JSON-formatted list of origins
+    # e.g: '["http://localhost", "http://localhost:4200", "http://localhost:3000", \
+    # "http://localhost:8080", "http://local.dockertoolbox.tiangolo.com"]'
+    BACKEND_CORS_ORIGINS: List[AnyHttpUrl] = []
+
+    @validator("BACKEND_CORS_ORIGINS", pre=True)
+    def assemble_cors_origins(cls, v: Union[str, List[str]]) -> Union[List[str], str]:
+        if isinstance(v, str) and not v.startswith("["):
+            return [i.strip() for i in v.split(",")]
+        elif isinstance(v, (list, str)):
+            return v
+        raise ValueError(v)
+
+    PROJECT_NAME: str = "Small Business Inventory Management System"
+    
+    # Database configuration
+    DB_DIR: Path = Path("/app") / "storage" / "db"
+    
+    # Make sure DB directory exists
+    DB_DIR.mkdir(parents=True, exist_ok=True)
+    
+    SQLALCHEMY_DATABASE_URL: str = f"sqlite:///{DB_DIR}/db.sqlite"
+
+    class Config:
+        case_sensitive = True
+        env_file = ".env"
+
+
+settings = Settings()

app/core/health.py

@@ -0,0 +1,39 @@
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+from app.db.session import get_db
+import time
+
+health_router = APIRouter()
+
+
+@health_router.get("/health", tags=["health"])
+async def health_check(db: Session = Depends(get_db)):
+    """
+    Check service health
+    
+    Checks:
+    - API is responsive
+    - Database connection is established
+    """
+    
+    # Basic health check
+    health_data = {
+        "status": "healthy",
+        "timestamp": time.time(),
+        "version": "0.1.0",
+        "checks": {
+            "api": "ok",
+            "database": "ok"
+        }
+    }
+    
+    # Verify database connection
+    try:
+        # Run simple query to verify connection
+        db.execute("SELECT 1")
+    except Exception as e:
+        health_data["status"] = "unhealthy"
+        health_data["checks"]["database"] = "failed"
+        return health_data
+    
+    return health_data

app/core/security/dependencies.py

@@ -0,0 +1,64 @@
+from typing import Generator, Optional
+
+from fastapi import Depends, HTTPException, status
+from fastapi.security import OAuth2PasswordBearer
+from jose import jwt
+from pydantic import ValidationError
+from sqlalchemy.orm import Session
+
+from app.core.config import settings
+from app.core.security.jwt import ALGORITHM, decode_token
+from app.db.session import get_db
+from app.models.user import User
+from app.schemas.token import TokenPayload
+from app.crud.crud_user import user
+
+
+oauth2_scheme = OAuth2PasswordBearer(
+    tokenUrl=f"{settings.API_V1_STR}/login/access-token"
+)
+
+
+def get_current_user(
+    db: Session = Depends(get_db), token: str = Depends(oauth2_scheme)
+) -> User:
+    """
+    Get current user based on JWT token
+    """
+    token_data = decode_token(token)
+    if not token_data:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Could not validate credentials",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    
+    db_user = user.get(db, id=token_data.sub)
+    if not db_user:
+        raise HTTPException(status_code=404, detail="User not found")
+    return db_user
+
+
+def get_current_active_user(
+    current_user: User = Depends(get_current_user),
+) -> User:
+    """
+    Get current active user
+    """
+    if not current_user.is_active:
+        raise HTTPException(status_code=400, detail="Inactive user")
+    return current_user
+
+
+def get_current_admin_user(
+    current_user: User = Depends(get_current_user),
+) -> User:
+    """
+    Get current admin user
+    """
+    if not current_user.is_admin:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN, 
+            detail="The user doesn't have enough privileges"
+        )
+    return current_user

app/core/security/jwt.py

@@ -0,0 +1,46 @@
+from datetime import datetime, timedelta
+from typing import Any, Optional, Union
+
+from jose import jwt
+from pydantic import ValidationError
+
+from app.core.config import settings
+from app.schemas.token import TokenPayload
+
+
+ALGORITHM = "HS256"
+
+
+def create_access_token(
+    subject: Union[str, Any], expires_delta: Optional[timedelta] = None
+) -> str:
+    """
+    Create a new JWT token
+    """
+    if expires_delta:
+        expire = datetime.utcnow() + expires_delta
+    else:
+        expire = datetime.utcnow() + timedelta(
+            minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES
+        )
+    to_encode = {"exp": expire, "sub": str(subject)}
+    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=ALGORITHM)
+    return encoded_jwt
+
+
+def decode_token(token: str) -> Optional[TokenPayload]:
+    """
+    Decode and validate a JWT token
+    """
+    try:
+        payload = jwt.decode(
+            token, settings.SECRET_KEY, algorithms=[ALGORITHM]
+        )
+        token_data = TokenPayload(**payload)
+        
+        if datetime.fromtimestamp(token_data.exp) < datetime.utcnow():
+            return None
+            
+        return token_data
+    except (jwt.JWTError, ValidationError):
+        return None

app/core/security/password.py

@@ -0,0 +1,18 @@
+from passlib.context import CryptContext
+
+# Password hashing context
+pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+
+
+def verify_password(plain_password: str, hashed_password: str) -> bool:
+    """
+    Verify a password against a hash
+    """
+    return pwd_context.verify(plain_password, hashed_password)
+
+
+def get_password_hash(password: str) -> str:
+    """
+    Generate password hash from plain text password
+    """
+    return pwd_context.hash(password)

app/crud/base.py

@@ -0,0 +1,66 @@
+from typing import Any, Dict, Generic, List, Optional, Type, TypeVar, Union
+
+from fastapi.encoders import jsonable_encoder
+from pydantic import BaseModel
+from sqlalchemy.orm import Session
+
+from app.db.base_class import Base
+
+ModelType = TypeVar("ModelType", bound=Base)
+CreateSchemaType = TypeVar("CreateSchemaType", bound=BaseModel)
+UpdateSchemaType = TypeVar("UpdateSchemaType", bound=BaseModel)
+
+
+class CRUDBase(Generic[ModelType, CreateSchemaType, UpdateSchemaType]):
+    def __init__(self, model: Type[ModelType]):
+        """
+        CRUD object with default methods to Create, Read, Update, Delete (CRUD).
+
+        **Parameters**
+
+        * `model`: A SQLAlchemy model class
+        * `schema`: A Pydantic model (schema) class
+        """
+        self.model = model
+
+    def get(self, db: Session, id: Any) -> Optional[ModelType]:
+        return db.query(self.model).filter(self.model.id == id).first()
+
+    def get_multi(
+        self, db: Session, *, skip: int = 0, limit: int = 100
+    ) -> List[ModelType]:
+        return db.query(self.model).offset(skip).limit(limit).all()
+
+    def create(self, db: Session, *, obj_in: CreateSchemaType) -> ModelType:
+        obj_in_data = jsonable_encoder(obj_in)
+        db_obj = self.model(**obj_in_data)
+        db.add(db_obj)
+        db.commit()
+        db.refresh(db_obj)
+        return db_obj
+
+    def update(
+        self,
+        db: Session,
+        *,
+        db_obj: ModelType,
+        obj_in: Union[UpdateSchemaType, Dict[str, Any]]
+    ) -> ModelType:
+        obj_data = jsonable_encoder(db_obj)
+        if isinstance(obj_in, dict):
+            update_data = obj_in
+        else:
+            update_data = obj_in.model_dump(exclude_unset=True)
+        for field in obj_data:
+            if field in update_data:
+                setattr(db_obj, field, update_data[field])
+        db.add(db_obj)
+        db.commit()
+        db.refresh(db_obj)
+        return db_obj
+
+    def remove(self, db: Session, *, id: int) -> ModelType:
+        obj = db.query(self.model).get(id)
+        db.delete(obj)
+        db.commit()
+        return obj

app/crud/crud_category.py

@@ -0,0 +1,15 @@
+from typing import List, Optional
+
+from sqlalchemy.orm import Session
+
+from app.crud.base import CRUDBase
+from app.models.category import Category
+from app.schemas.category import CategoryCreate, CategoryUpdate
+
+
+class CRUDCategory(CRUDBase[Category, CategoryCreate, CategoryUpdate]):
+    def get_by_name(self, db: Session, *, name: str) -> Optional[Category]:
+        return db.query(Category).filter(Category.name == name).first()
+
+
+category = CRUDCategory(Category)

app/crud/crud_inventory.py

@@ -0,0 +1,84 @@
+from typing import List, Optional, Dict, Any
+from sqlalchemy import func
+from sqlalchemy.orm import Session
+
+from app.crud.base import CRUDBase
+from app.models.inventory import Inventory, InventoryTransaction
+from app.models.product import Product
+from app.schemas.inventory import InventoryCreate, InventoryUpdate, InventoryAdjustment
+
+
+class CRUDInventory(CRUDBase[Inventory, InventoryCreate, InventoryUpdate]):
+    def get_by_product_and_location(
+        self, db: Session, *, product_id: int, location: Optional[str] = None
+    ) -> Optional[Inventory]:
+        """Get inventory by product and location"""
+        query = db.query(Inventory).filter(Inventory.product_id == product_id)
+        if location:
+            query = query.filter(Inventory.location == location)
+        return query.first()
+    
+    def get_product_inventory(
+        self, db: Session, *, product_id: int
+    ) -> List[Inventory]:
+        """Get all inventory records for a product"""
+        return db.query(Inventory).filter(Inventory.product_id == product_id).all()
+    
+    def get_total_product_quantity(
+        self, db: Session, *, product_id: int
+    ) -> int:
+        """Get total inventory quantity for a product across all locations"""
+        result = db.query(
+            func.sum(Inventory.quantity).label("total")
+        ).filter(
+            Inventory.product_id == product_id
+        ).scalar()
+        return result or 0
+    
+    def adjust_inventory(
+        self, db: Session, *, adjustment: InventoryAdjustment
+    ) -> Dict[str, Any]:
+        """Adjust inventory quantity and record the transaction"""
+        # Find or create inventory record
+        inventory = self.get_by_product_and_location(
+            db, product_id=adjustment.product_id, location=adjustment.location
+        )
+        
+        if not inventory:
+            # Create new inventory record if it doesn't exist
+            inventory = Inventory(
+                product_id=adjustment.product_id,
+                quantity=0,  # Start with 0, will add adjustment below
+                location=adjustment.location
+            )
+            db.add(inventory)
+            db.flush()
+        
+        # Update quantity
+        inventory.quantity += adjustment.quantity
+        
+        # Ensure quantity is never negative
+        if inventory.quantity < 0:
+            inventory.quantity = 0
+        
+        # Record transaction
+        transaction = InventoryTransaction(
+            product_id=adjustment.product_id,
+            quantity=adjustment.quantity,
+            transaction_type="adjustment",
+            reason=adjustment.reason,
+            location=adjustment.location
+        )
+        db.add(transaction)
+        
+        db.commit()
+        db.refresh(inventory)
+        db.refresh(transaction)
+        
+        return {
+            "inventory": inventory,
+            "transaction": transaction
+        }
+
+
+inventory = CRUDInventory(Inventory)

app/crud/crud_product.py

@@ -0,0 +1,69 @@
+from typing import List, Optional, Dict, Any
+from sqlalchemy import func
+from sqlalchemy.orm import Session, joinedload
+
+from app.crud.base import CRUDBase
+from app.models.product import Product
+from app.models.inventory import Inventory
+from app.schemas.product import ProductCreate, ProductUpdate
+
+
+class CRUDProduct(CRUDBase[Product, ProductCreate, ProductUpdate]):
+    def get_with_inventory(self, db: Session, id: int) -> Optional[Dict[str, Any]]:
+        """Get product with inventory quantities"""
+        product = db.query(Product).filter(Product.id == id).first()
+        
+        if not product:
+            return None
+            
+        # Get total inventory for this product
+        inventory = db.query(
+            func.sum(Inventory.quantity).label("total_quantity")
+        ).filter(
+            Inventory.product_id == id
+        ).scalar() or 0
+        
+        result = {
+            **product.__dict__,
+            "total_quantity": inventory,
+            "available_quantity": inventory  # For now they're the same since we don't track reserved items
+        }
+        
+        return result
+    
+    def get_multi_with_inventory(
+        self, db: Session, *, skip: int = 0, limit: int = 100
+    ) -> List[Dict[str, Any]]:
+        """Get multiple products with their inventory quantities"""
+        products = db.query(Product).offset(skip).limit(limit).all()
+        
+        # Get inventory counts for all products in one query
+        inventory_counts = dict(
+            db.query(
+                Inventory.product_id,
+                func.sum(Inventory.quantity).label("total")
+            ).group_by(
+                Inventory.product_id
+            ).all()
+        )
+        
+        result = []
+        for product in products:
+            total_quantity = inventory_counts.get(product.id, 0)
+            
+            result.append({
+                **product.__dict__,
+                "total_quantity": total_quantity,
+                "available_quantity": total_quantity  # For now they're the same
+            })
+            
+        return result
+    
+    def get_by_sku(self, db: Session, *, sku: str) -> Optional[Product]:
+        return db.query(Product).filter(Product.sku == sku).first()
+    
+    def get_by_barcode(self, db: Session, *, barcode: str) -> Optional[Product]:
+        return db.query(Product).filter(Product.barcode == barcode).first()
+
+
+product = CRUDProduct(Product)

app/crud/crud_purchase_order.py

@@ -0,0 +1,129 @@
+from typing import List, Optional, Dict, Any
+from sqlalchemy import func
+from sqlalchemy.orm import Session, joinedload
+from decimal import Decimal
+
+from app.crud.base import CRUDBase
+from app.models.purchase_order import PurchaseOrder, PurchaseOrderItem
+from app.models.inventory import Inventory, InventoryTransaction
+from app.schemas.purchase_order import PurchaseOrderCreate, PurchaseOrderUpdate
+
+
+class CRUDPurchaseOrder(CRUDBase[PurchaseOrder, PurchaseOrderCreate, PurchaseOrderUpdate]):
+    def create_with_items(
+        self, db: Session, *, obj_in: PurchaseOrderCreate, user_id: int
+    ) -> PurchaseOrder:
+        """Create purchase order with items"""
+        # Create purchase order
+        db_obj = PurchaseOrder(
+            supplier_name=obj_in.supplier_name,
+            notes=obj_in.notes,
+            status=obj_in.status,
+            created_by=user_id
+        )
+        db.add(db_obj)
+        db.flush()
+        
+        # Create items
+        for item in obj_in.items:
+            db_item = PurchaseOrderItem(
+                purchase_order_id=db_obj.id,
+                product_id=item.product_id,
+                quantity=item.quantity,
+                unit_price=item.unit_price
+            )
+            db.add(db_item)
+        
+        db.commit()
+        db.refresh(db_obj)
+        return db_obj
+    
+    def get_with_items(self, db: Session, id: int) -> Optional[PurchaseOrder]:
+        """Get purchase order with its items"""
+        return db.query(PurchaseOrder).options(
+            joinedload(PurchaseOrder.items).joinedload(PurchaseOrderItem.product)
+        ).filter(PurchaseOrder.id == id).first()
+    
+    def get_multi_with_items(
+        self, db: Session, *, skip: int = 0, limit: int = 100
+    ) -> List[PurchaseOrder]:
+        """Get multiple purchase orders with their items"""
+        return db.query(PurchaseOrder).options(
+            joinedload(PurchaseOrder.items).joinedload(PurchaseOrderItem.product)
+        ).offset(skip).limit(limit).all()
+    
+    def receive_order(self, db: Session, *, id: int) -> Optional[PurchaseOrder]:
+        """Mark a purchase order as received and update inventory"""
+        purchase_order = self.get_with_items(db, id)
+        
+        if not purchase_order:
+            return None
+            
+        if purchase_order.status != "pending":
+            return purchase_order  # Already processed or cancelled
+        
+        # Update purchase order status
+        purchase_order.status = "received"
+        
+        # Update inventory for each item
+        for item in purchase_order.items:
+            # Find or create inventory
+            inventory = db.query(Inventory).filter(
+                Inventory.product_id == item.product_id,
+                Inventory.location == None  # Default location
+            ).first()
+            
+            if not inventory:
+                inventory = Inventory(
+                    product_id=item.product_id,
+                    quantity=0,
+                    location=None  # Default location
+                )
+                db.add(inventory)
+                db.flush()
+            
+            # Update quantity
+            inventory.quantity += item.quantity
+            
+            # Record transaction
+            transaction = InventoryTransaction(
+                product_id=item.product_id,
+                quantity=item.quantity,
+                transaction_type="purchase",
+                reference_id=purchase_order.id,
+                reason=f"Received from {purchase_order.supplier_name}"
+            )
+            db.add(transaction)
+        
+        db.commit()
+        db.refresh(purchase_order)
+        return purchase_order
+    
+    def cancel_order(self, db: Session, *, id: int) -> Optional[PurchaseOrder]:
+        """Cancel a purchase order"""
+        purchase_order = db.query(PurchaseOrder).filter(PurchaseOrder.id == id).first()
+        
+        if not purchase_order:
+            return None
+            
+        if purchase_order.status != "pending":
+            return purchase_order  # Already processed or cancelled
+            
+        purchase_order.status = "cancelled"
+        
+        db.commit()
+        db.refresh(purchase_order)
+        return purchase_order
+    
+    def get_total_amount(self, db: Session, *, id: int) -> Decimal:
+        """Calculate total amount for a purchase order"""
+        result = db.query(
+            func.sum(PurchaseOrderItem.quantity * PurchaseOrderItem.unit_price).label("total")
+        ).filter(
+            PurchaseOrderItem.purchase_order_id == id
+        ).scalar()
+        
+        return result or Decimal("0.00")
+
+
+purchase_order = CRUDPurchaseOrder(PurchaseOrder)

app/crud/crud_sale.py

@@ -0,0 +1,177 @@
+from typing import List, Optional, Dict, Any
+from sqlalchemy import func
+from sqlalchemy.orm import Session, joinedload
+from decimal import Decimal
+
+from app.crud.base import CRUDBase
+from app.models.sale import Sale, SaleItem
+from app.models.inventory import Inventory, InventoryTransaction
+from app.schemas.sale import SaleCreate, SaleUpdate
+
+
+class CRUDSale(CRUDBase[Sale, SaleCreate, SaleUpdate]):
+    def create_with_items(
+        self, db: Session, *, obj_in: SaleCreate, user_id: int
+    ) -> Optional[Sale]:
+        """Create sale with items and update inventory"""
+        # First check if we have enough inventory
+        for item in obj_in.items:
+            inventory_qty = db.query(func.sum(Inventory.quantity)).filter(
+                Inventory.product_id == item.product_id
+            ).scalar() or 0
+            
+            if inventory_qty < item.quantity:
+                # Not enough inventory
+                return None
+        
+        # Create sale
+        db_obj = Sale(
+            customer_name=obj_in.customer_name,
+            notes=obj_in.notes,
+            status=obj_in.status,
+            created_by=user_id
+        )
+        db.add(db_obj)
+        db.flush()
+        
+        # Create items and update inventory
+        for item in obj_in.items:
+            db_item = SaleItem(
+                sale_id=db_obj.id,
+                product_id=item.product_id,
+                quantity=item.quantity,
+                unit_price=item.unit_price
+            )
+            db.add(db_item)
+            
+            # Update inventory - reduce quantities
+            self._reduce_inventory(
+                db, 
+                product_id=item.product_id, 
+                quantity=item.quantity,
+                sale_id=db_obj.id
+            )
+        
+        db.commit()
+        db.refresh(db_obj)
+        return db_obj
+    
+    def _reduce_inventory(
+        self, db: Session, *, product_id: int, quantity: int, sale_id: int
+    ) -> None:
+        """Reduce inventory for a product, starting with oldest inventory first"""
+        remaining = quantity
+        
+        # Get all inventory for this product, ordered by id (assuming oldest first)
+        inventories = db.query(Inventory).filter(
+            Inventory.product_id == product_id,
+            Inventory.quantity > 0
+        ).order_by(Inventory.id).all()
+        
+        for inv in inventories:
+            if remaining <= 0:
+                break
+                
+            if inv.quantity >= remaining:
+                # This inventory is enough to cover remaining quantity
+                inv.quantity -= remaining
+                
+                # Record transaction
+                transaction = InventoryTransaction(
+                    product_id=product_id,
+                    quantity=-remaining,  # Negative for reduction
+                    transaction_type="sale",
+                    reference_id=sale_id,
+                    location=inv.location
+                )
+                db.add(transaction)
+                
+                remaining = 0
+            else:
+                # Use all of this inventory and continue to next
+                remaining -= inv.quantity
+                
+                # Record transaction
+                transaction = InventoryTransaction(
+                    product_id=product_id,
+                    quantity=-inv.quantity,  # Negative for reduction
+                    transaction_type="sale",
+                    reference_id=sale_id,
+                    location=inv.location
+                )
+                db.add(transaction)
+                
+                inv.quantity = 0
+    
+    def get_with_items(self, db: Session, id: int) -> Optional[Sale]:
+        """Get sale with its items"""
+        return db.query(Sale).options(
+            joinedload(Sale.items).joinedload(SaleItem.product)
+        ).filter(Sale.id == id).first()
+    
+    def get_multi_with_items(
+        self, db: Session, *, skip: int = 0, limit: int = 100
+    ) -> List[Sale]:
+        """Get multiple sales with their items"""
+        return db.query(Sale).options(
+            joinedload(Sale.items).joinedload(SaleItem.product)
+        ).offset(skip).limit(limit).all()
+    
+    def cancel_sale(self, db: Session, *, id: int) -> Optional[Sale]:
+        """Cancel a sale and return items to inventory"""
+        sale = self.get_with_items(db, id)
+        
+        if not sale:
+            return None
+            
+        if sale.status != "completed":
+            return sale  # Already cancelled or returned
+            
+        sale.status = "cancelled"
+        
+        # Return items to inventory
+        for item in sale.items:
+            # Find or create inventory at default location
+            inventory = db.query(Inventory).filter(
+                Inventory.product_id == item.product_id,
+                Inventory.location == None  # Default location
+            ).first()
+            
+            if not inventory:
+                inventory = Inventory(
+                    product_id=item.product_id,
+                    quantity=0,
+                    location=None
+                )
+                db.add(inventory)
+                db.flush()
+            
+            # Update quantity
+            inventory.quantity += item.quantity
+            
+            # Record transaction
+            transaction = InventoryTransaction(
+                product_id=item.product_id,
+                quantity=item.quantity,
+                transaction_type="return",
+                reference_id=sale.id,
+                reason="Sale cancelled"
+            )
+            db.add(transaction)
+        
+        db.commit()
+        db.refresh(sale)
+        return sale
+    
+    def get_total_amount(self, db: Session, *, id: int) -> Decimal:
+        """Calculate total amount for a sale"""
+        result = db.query(
+            func.sum(SaleItem.quantity * SaleItem.unit_price).label("total")
+        ).filter(
+            SaleItem.sale_id == id
+        ).scalar()
+        
+        return result or Decimal("0.00")
+
+
+sale = CRUDSale(Sale)

app/crud/crud_user.py

@@ -0,0 +1,56 @@
+from typing import Any, Dict, Optional, Union
+
+from sqlalchemy.orm import Session
+
+from app.core.security.password import get_password_hash, verify_password
+from app.crud.base import CRUDBase
+from app.models.user import User
+from app.schemas.user import UserCreate, UserUpdate
+
+
+class CRUDUser(CRUDBase[User, UserCreate, UserUpdate]):
+    def get_by_email(self, db: Session, *, email: str) -> Optional[User]:
+        return db.query(User).filter(User.email == email).first()
+
+    def create(self, db: Session, *, obj_in: UserCreate) -> User:
+        db_obj = User(
+            email=obj_in.email,
+            hashed_password=get_password_hash(obj_in.password),
+            full_name=obj_in.full_name,
+            is_admin=obj_in.is_admin,
+            is_active=obj_in.is_active
+        )
+        db.add(db_obj)
+        db.commit()
+        db.refresh(db_obj)
+        return db_obj
+
+    def update(
+        self, db: Session, *, db_obj: User, obj_in: Union[UserUpdate, Dict[str, Any]]
+    ) -> User:
+        if isinstance(obj_in, dict):
+            update_data = obj_in
+        else:
+            update_data = obj_in.model_dump(exclude_unset=True)
+        if update_data.get("password"):
+            hashed_password = get_password_hash(update_data["password"])
+            del update_data["password"]
+            update_data["hashed_password"] = hashed_password
+        return super().update(db, db_obj=db_obj, obj_in=update_data)
+
+    def authenticate(self, db: Session, *, email: str, password: str) -> Optional[User]:
+        user = self.get_by_email(db, email=email)
+        if not user:
+            return None
+        if not verify_password(password, user.hashed_password):
+            return None
+        return user
+
+    def is_active(self, user: User) -> bool:
+        return user.is_active
+
+    def is_admin(self, user: User) -> bool:
+        return user.is_admin
+
+
+user = CRUDUser(User)

app/db/base.py

@@ -0,0 +1,9 @@
+# Import all the models, so that Base has them before being
+# imported by Alembic
+from app.db.base_class import Base  # noqa
+from app.models.user import User  # noqa
+from app.models.product import Product  # noqa
+from app.models.category import Category  # noqa
+from app.models.inventory import Inventory  # noqa
+from app.models.purchase_order import PurchaseOrder, PurchaseOrderItem  # noqa
+from app.models.sale import Sale, SaleItem  # noqa

app/db/base_class.py

@@ -0,0 +1,13 @@
+from typing import Any
+from sqlalchemy.ext.declarative import as_declarative, declared_attr
+
+
+@as_declarative()
+class Base:
+    id: Any
+    __name__: str
+    
+    # Generate __tablename__ automatically based on class name
+    @declared_attr
+    def __tablename__(cls) -> str:
+        return cls.__name__.lower()

app/db/session.py

@@ -0,0 +1,18 @@
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+from app.core.config import settings
+
+engine = create_engine(
+    settings.SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False}
+)
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/models/category.py

@@ -0,0 +1,13 @@
+from sqlalchemy import Column, Integer, String, Text
+from sqlalchemy.orm import relationship
+
+from app.db.base_class import Base
+
+
+class Category(Base):
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String, index=True, nullable=False)
+    description = Column(Text, nullable=True)
+    
+    # Relationships
+    products = relationship("Product", back_populates="category")

app/models/inventory.py

@@ -0,0 +1,29 @@
+from sqlalchemy import Column, Integer, String, ForeignKey, DateTime
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+
+from app.db.base_class import Base
+
+
+class Inventory(Base):
+    id = Column(Integer, primary_key=True, index=True)
+    product_id = Column(Integer, ForeignKey("product.id"), nullable=False)
+    quantity = Column(Integer, nullable=False, default=0)
+    location = Column(String, nullable=True)
+    
+    # Relationships
+    product = relationship("Product", back_populates="inventory_items")
+
+
+class InventoryTransaction(Base):
+    id = Column(Integer, primary_key=True, index=True)
+    product_id = Column(Integer, ForeignKey("product.id"), nullable=False)
+    quantity = Column(Integer, nullable=False)  # Can be positive or negative
+    transaction_type = Column(String, nullable=False)  # purchase, sale, adjustment
+    reference_id = Column(Integer, nullable=True)  # ID of related transaction
+    reason = Column(String, nullable=True)
+    timestamp = Column(DateTime(timezone=True), server_default=func.now(), nullable=False)
+    location = Column(String, nullable=True)
+    
+    # Relationships
+    product = relationship("Product")

app/models/product.py

@@ -0,0 +1,21 @@
+from sqlalchemy import Column, Integer, String, Text, Numeric, ForeignKey
+from sqlalchemy.orm import relationship
+
+from app.db.base_class import Base
+
+
+class Product(Base):
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String, index=True, nullable=False)
+    description = Column(Text, nullable=True)
+    sku = Column(String, index=True, nullable=True, unique=True)
+    barcode = Column(String, index=True, nullable=True, unique=True)
+    unit_price = Column(Numeric(precision=10, scale=2), nullable=False)
+    cost_price = Column(Numeric(precision=10, scale=2), nullable=False)
+    category_id = Column(Integer, ForeignKey("category.id"), nullable=True)
+    
+    # Relationships
+    category = relationship("Category", back_populates="products")
+    inventory_items = relationship("Inventory", back_populates="product", cascade="all, delete-orphan")
+    purchase_order_items = relationship("PurchaseOrderItem", back_populates="product")
+    sale_items = relationship("SaleItem", back_populates="product")

app/models/purchase_order.py

@@ -0,0 +1,31 @@
+from sqlalchemy import Column, Integer, String, Text, Numeric, ForeignKey, DateTime
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+
+from app.db.base_class import Base
+
+
+class PurchaseOrder(Base):
+    id = Column(Integer, primary_key=True, index=True)
+    supplier_name = Column(String, nullable=False)
+    notes = Column(Text, nullable=True)
+    status = Column(String, nullable=False, default="pending")  # pending, received, cancelled
+    created_at = Column(DateTime(timezone=True), server_default=func.now(), nullable=False)
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now(), nullable=True)
+    created_by = Column(Integer, ForeignKey("user.id"), nullable=False)
+    
+    # Relationships
+    items = relationship("PurchaseOrderItem", back_populates="purchase_order", cascade="all, delete-orphan")
+    created_by_user = relationship("User", back_populates="purchase_orders")
+
+
+class PurchaseOrderItem(Base):
+    id = Column(Integer, primary_key=True, index=True)
+    purchase_order_id = Column(Integer, ForeignKey("purchaseorder.id"), nullable=False)
+    product_id = Column(Integer, ForeignKey("product.id"), nullable=False)
+    quantity = Column(Integer, nullable=False)
+    unit_price = Column(Numeric(precision=10, scale=2), nullable=False)
+    
+    # Relationships
+    purchase_order = relationship("PurchaseOrder", back_populates="items")
+    product = relationship("Product", back_populates="purchase_order_items")

app/models/sale.py

@@ -0,0 +1,31 @@
+from sqlalchemy import Column, Integer, String, Text, Numeric, ForeignKey, DateTime
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+
+from app.db.base_class import Base
+
+
+class Sale(Base):
+    id = Column(Integer, primary_key=True, index=True)
+    customer_name = Column(String, nullable=True)
+    notes = Column(Text, nullable=True)
+    status = Column(String, nullable=False, default="completed")  # completed, cancelled, returned
+    created_at = Column(DateTime(timezone=True), server_default=func.now(), nullable=False)
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now(), nullable=True)
+    created_by = Column(Integer, ForeignKey("user.id"), nullable=False)
+    
+    # Relationships
+    items = relationship("SaleItem", back_populates="sale", cascade="all, delete-orphan")
+    created_by_user = relationship("User", back_populates="sales")
+
+
+class SaleItem(Base):
+    id = Column(Integer, primary_key=True, index=True)
+    sale_id = Column(Integer, ForeignKey("sale.id"), nullable=False)
+    product_id = Column(Integer, ForeignKey("product.id"), nullable=False)
+    quantity = Column(Integer, nullable=False)
+    unit_price = Column(Numeric(precision=10, scale=2), nullable=False)
+    
+    # Relationships
+    sale = relationship("Sale", back_populates="items")
+    product = relationship("Product", back_populates="sale_items")

app/models/user.py

@@ -0,0 +1,17 @@
+from sqlalchemy import Boolean, Column, Integer, String
+from sqlalchemy.orm import relationship
+
+from app.db.base_class import Base
+
+
+class User(Base):
+    id = Column(Integer, primary_key=True, index=True)
+    full_name = Column(String, index=True)
+    email = Column(String, unique=True, index=True, nullable=False)
+    hashed_password = Column(String, nullable=False)
+    is_active = Column(Boolean(), default=True)
+    is_admin = Column(Boolean(), default=False)
+    
+    # Relationships
+    purchase_orders = relationship("PurchaseOrder", back_populates="created_by_user")
+    sales = relationship("Sale", back_populates="created_by_user")

app/schemas/category.py

@@ -0,0 +1,31 @@
+from typing import Optional
+from pydantic import BaseModel, Field
+
+
+# Shared properties
+class CategoryBase(BaseModel):
+    name: str
+    description: Optional[str] = None
+
+
+# Properties to receive on category creation
+class CategoryCreate(CategoryBase):
+    pass
+
+
+# Properties to receive on category update
+class CategoryUpdate(CategoryBase):
+    name: Optional[str] = None
+
+
+# Properties shared by models returned from API
+class CategoryInDBBase(CategoryBase):
+    id: int
+
+    class Config:
+        from_attributes = True
+
+
+# Properties to return via API
+class Category(CategoryInDBBase):
+    pass

app/schemas/inventory.py

@@ -0,0 +1,41 @@
+from typing import Optional, List
+from pydantic import BaseModel, Field
+
+
+# Shared properties
+class InventoryBase(BaseModel):
+    product_id: int
+    quantity: int = Field(..., gt=0)
+    location: Optional[str] = None
+
+
+# Properties to receive on inventory creation
+class InventoryCreate(InventoryBase):
+    pass
+
+
+# Properties to receive on inventory update
+class InventoryUpdate(InventoryBase):
+    product_id: Optional[int] = None
+    quantity: Optional[int] = None
+
+
+# Properties shared by models in DB
+class InventoryInDBBase(InventoryBase):
+    id: int
+
+    class Config:
+        from_attributes = True
+
+
+# Properties to return via API
+class Inventory(InventoryInDBBase):
+    pass
+
+
+# Properties for inventory adjustment
+class InventoryAdjustment(BaseModel):
+    product_id: int
+    quantity: int  # Can be positive (add) or negative (remove)
+    reason: str
+    location: Optional[str] = None

app/schemas/product.py

@@ -0,0 +1,45 @@
+from typing import Optional, List
+from decimal import Decimal
+from pydantic import BaseModel, Field, condecimal
+
+
+# Shared properties
+class ProductBase(BaseModel):
+    name: str
+    description: Optional[str] = None
+    sku: Optional[str] = None
+    barcode: Optional[str] = None
+    unit_price: condecimal(decimal_places=2, ge=0) = Field(..., description="Selling price per unit")
+    cost_price: condecimal(decimal_places=2, ge=0) = Field(..., description="Cost price per unit")
+    category_id: Optional[int] = None
+
+
+# Properties to receive on product creation
+class ProductCreate(ProductBase):
+    pass
+
+
+# Properties to receive on product update
+class ProductUpdate(ProductBase):
+    name: Optional[str] = None
+    unit_price: Optional[condecimal(decimal_places=2, ge=0)] = None
+    cost_price: Optional[condecimal(decimal_places=2, ge=0)] = None
+
+
+# Properties shared by models in DB
+class ProductInDBBase(ProductBase):
+    id: int
+
+    class Config:
+        from_attributes = True
+
+
+# Properties to return via API
+class Product(ProductInDBBase):
+    pass
+
+
+# Properties for product with detailed inventory information
+class ProductWithInventory(Product):
+    total_quantity: int
+    available_quantity: int

app/schemas/purchase_order.py

@@ -0,0 +1,66 @@
+from typing import Optional, List
+from datetime import datetime
+from decimal import Decimal
+from pydantic import BaseModel, Field, condecimal
+
+
+# Shared properties for purchase order item
+class PurchaseOrderItemBase(BaseModel):
+    product_id: int
+    quantity: int = Field(..., gt=0)
+    unit_price: condecimal(decimal_places=2, ge=0)
+
+
+# Properties for purchase order item creation
+class PurchaseOrderItemCreate(PurchaseOrderItemBase):
+    pass
+
+
+# Properties for purchase order item in DB
+class PurchaseOrderItemInDBBase(PurchaseOrderItemBase):
+    id: int
+    purchase_order_id: int
+    
+    class Config:
+        from_attributes = True
+
+
+# Properties to return via API
+class PurchaseOrderItem(PurchaseOrderItemInDBBase):
+    pass
+
+
+# Shared properties for purchase order
+class PurchaseOrderBase(BaseModel):
+    supplier_name: str
+    notes: Optional[str] = None
+    status: str = "pending"  # pending, received, cancelled
+
+
+# Properties for purchase order creation
+class PurchaseOrderCreate(PurchaseOrderBase):
+    items: List[PurchaseOrderItemCreate]
+
+
+# Properties for purchase order update
+class PurchaseOrderUpdate(BaseModel):
+    supplier_name: Optional[str] = None
+    notes: Optional[str] = None
+    status: Optional[str] = None
+
+
+# Properties for purchase order in DB
+class PurchaseOrderInDBBase(PurchaseOrderBase):
+    id: int
+    created_at: datetime
+    updated_at: Optional[datetime] = None
+    created_by: int
+    
+    class Config:
+        from_attributes = True
+
+
+# Properties to return via API
+class PurchaseOrder(PurchaseOrderInDBBase):
+    items: List[PurchaseOrderItem]
+    total_amount: condecimal(decimal_places=2)

app/schemas/sale.py

@@ -0,0 +1,66 @@
+from typing import Optional, List
+from datetime import datetime
+from decimal import Decimal
+from pydantic import BaseModel, Field, condecimal
+
+
+# Shared properties for sale item
+class SaleItemBase(BaseModel):
+    product_id: int
+    quantity: int = Field(..., gt=0)
+    unit_price: condecimal(decimal_places=2, ge=0)
+
+
+# Properties for sale item creation
+class SaleItemCreate(SaleItemBase):
+    pass
+
+
+# Properties for sale item in DB
+class SaleItemInDBBase(SaleItemBase):
+    id: int
+    sale_id: int
+    
+    class Config:
+        from_attributes = True
+
+
+# Properties to return via API
+class SaleItem(SaleItemInDBBase):
+    pass
+
+
+# Shared properties for sale
+class SaleBase(BaseModel):
+    customer_name: Optional[str] = None
+    notes: Optional[str] = None
+    status: str = "completed"  # completed, cancelled, returned
+
+
+# Properties for sale creation
+class SaleCreate(SaleBase):
+    items: List[SaleItemCreate]
+
+
+# Properties for sale update
+class SaleUpdate(BaseModel):
+    customer_name: Optional[str] = None
+    notes: Optional[str] = None
+    status: Optional[str] = None
+
+
+# Properties for sale in DB
+class SaleInDBBase(SaleBase):
+    id: int
+    created_at: datetime
+    updated_at: Optional[datetime] = None
+    created_by: int
+    
+    class Config:
+        from_attributes = True
+
+
+# Properties to return via API
+class Sale(SaleInDBBase):
+    items: List[SaleItem]
+    total_amount: condecimal(decimal_places=2)

app/schemas/token.py

@@ -0,0 +1,12 @@
+from typing import Optional
+from pydantic import BaseModel
+
+
+class Token(BaseModel):
+    access_token: str
+    token_type: str
+
+
+class TokenPayload(BaseModel):
+    sub: Optional[str] = None
+    exp: int

app/schemas/user.py

@@ -0,0 +1,39 @@
+from typing import Optional
+from pydantic import BaseModel, EmailStr, Field
+
+
+# Shared properties
+class UserBase(BaseModel):
+    email: Optional[EmailStr] = None
+    full_name: Optional[str] = None
+    is_active: Optional[bool] = True
+    is_admin: bool = False
+
+
+# Properties to receive via API on creation
+class UserCreate(UserBase):
+    email: EmailStr
+    password: str
+    full_name: str
+    
+    
+# Properties to receive via API on update
+class UserUpdate(UserBase):
+    password: Optional[str] = None
+
+
+class UserInDBBase(UserBase):
+    id: Optional[int] = None
+
+    class Config:
+        from_attributes = True
+
+
+# Additional properties to return via API
+class User(UserInDBBase):
+    pass
+
+
+# Additional properties stored in DB
+class UserInDB(UserInDBBase):
+    hashed_password: str

main.py

@@ -0,0 +1,34 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.core.config import settings
+from app.api.api_v1.api import api_router
+from app.core.health import health_router
+
+app = FastAPI(
+    title=settings.PROJECT_NAME,
+    openapi_url=f"{settings.API_V1_STR}/openapi.json",
+    description="Small Business Inventory Management System API",
+    version="0.1.0",
+)
+
+# Set all CORS enabled origins
+if settings.BACKEND_CORS_ORIGINS:
+    app.add_middleware(
+        CORSMiddleware,
+        allow_origins=[str(origin) for origin in settings.BACKEND_CORS_ORIGINS],
+        allow_credentials=True,
+        allow_methods=["*"],
+        allow_headers=["*"],
+    )
+
+app.include_router(api_router, prefix=settings.API_V1_STR)
+app.include_router(health_router)
+
+@app.get("/")
+async def root():
+    return {"message": "Welcome to the Small Business Inventory Management System"}
+
+if __name__ == "__main__":
+    import uvicorn
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

migrations/env.py

@@ -0,0 +1,79 @@
+import os
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+from app.db.base import Base  # noqa
+target_metadata = Base.metadata
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+
+def run_migrations_offline():
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online():
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection, target_metadata=target_metadata
+        )
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

migrations/script.py.mako

@@ -0,0 +1,24 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = ${repr(branch_labels)}
+depends_on = ${repr(depends_on)}
+
+
+def upgrade():
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade():
+    ${downgrades if downgrades else "pass"}

migrations/versions/001_initial_migration.py

@@ -0,0 +1,168 @@
+"""Initial migration
+
+Revision ID: 001
+Revises: 
+Create Date: 2023-08-12 00:00:00.000000
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '001'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # Create user table
+    op.create_table('user',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('full_name', sa.String(), nullable=True),
+        sa.Column('email', sa.String(), nullable=False),
+        sa.Column('hashed_password', sa.String(), nullable=False),
+        sa.Column('is_active', sa.Boolean(), nullable=True),
+        sa.Column('is_admin', sa.Boolean(), nullable=True),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_user_email'), 'user', ['email'], unique=True)
+    op.create_index(op.f('ix_user_full_name'), 'user', ['full_name'], unique=False)
+    op.create_index(op.f('ix_user_id'), 'user', ['id'], unique=False)
+    
+    # Create category table
+    op.create_table('category',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('name', sa.String(), nullable=False),
+        sa.Column('description', sa.Text(), nullable=True),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_category_id'), 'category', ['id'], unique=False)
+    op.create_index(op.f('ix_category_name'), 'category', ['name'], unique=False)
+    
+    # Create product table
+    op.create_table('product',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('name', sa.String(), nullable=False),
+        sa.Column('description', sa.Text(), nullable=True),
+        sa.Column('sku', sa.String(), nullable=True),
+        sa.Column('barcode', sa.String(), nullable=True),
+        sa.Column('unit_price', sa.Numeric(precision=10, scale=2), nullable=False),
+        sa.Column('cost_price', sa.Numeric(precision=10, scale=2), nullable=False),
+        sa.Column('category_id', sa.Integer(), nullable=True),
+        sa.ForeignKeyConstraint(['category_id'], ['category.id'], ),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_product_barcode'), 'product', ['barcode'], unique=True)
+    op.create_index(op.f('ix_product_id'), 'product', ['id'], unique=False)
+    op.create_index(op.f('ix_product_name'), 'product', ['name'], unique=False)
+    op.create_index(op.f('ix_product_sku'), 'product', ['sku'], unique=True)
+    
+    # Create inventory table
+    op.create_table('inventory',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('product_id', sa.Integer(), nullable=False),
+        sa.Column('quantity', sa.Integer(), nullable=False),
+        sa.Column('location', sa.String(), nullable=True),
+        sa.ForeignKeyConstraint(['product_id'], ['product.id'], ),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_inventory_id'), 'inventory', ['id'], unique=False)
+    
+    # Create inventory transaction table
+    op.create_table('inventorytransaction',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('product_id', sa.Integer(), nullable=False),
+        sa.Column('quantity', sa.Integer(), nullable=False),
+        sa.Column('transaction_type', sa.String(), nullable=False),
+        sa.Column('reference_id', sa.Integer(), nullable=True),
+        sa.Column('reason', sa.String(), nullable=True),
+        sa.Column('timestamp', sa.DateTime(timezone=True), nullable=False, server_default=sa.text('CURRENT_TIMESTAMP')),
+        sa.Column('location', sa.String(), nullable=True),
+        sa.ForeignKeyConstraint(['product_id'], ['product.id'], ),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_inventorytransaction_id'), 'inventorytransaction', ['id'], unique=False)
+    
+    # Create purchase order table
+    op.create_table('purchaseorder',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('supplier_name', sa.String(), nullable=False),
+        sa.Column('notes', sa.Text(), nullable=True),
+        sa.Column('status', sa.String(), nullable=False),
+        sa.Column('created_at', sa.DateTime(timezone=True), nullable=False, server_default=sa.text('CURRENT_TIMESTAMP')),
+        sa.Column('updated_at', sa.DateTime(timezone=True), nullable=True),
+        sa.Column('created_by', sa.Integer(), nullable=False),
+        sa.ForeignKeyConstraint(['created_by'], ['user.id'], ),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_purchaseorder_id'), 'purchaseorder', ['id'], unique=False)
+    
+    # Create purchase order item table
+    op.create_table('purchaseorderitem',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('purchase_order_id', sa.Integer(), nullable=False),
+        sa.Column('product_id', sa.Integer(), nullable=False),
+        sa.Column('quantity', sa.Integer(), nullable=False),
+        sa.Column('unit_price', sa.Numeric(precision=10, scale=2), nullable=False),
+        sa.ForeignKeyConstraint(['product_id'], ['product.id'], ),
+        sa.ForeignKeyConstraint(['purchase_order_id'], ['purchaseorder.id'], ),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_purchaseorderitem_id'), 'purchaseorderitem', ['id'], unique=False)
+    
+    # Create sale table
+    op.create_table('sale',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('customer_name', sa.String(), nullable=True),
+        sa.Column('notes', sa.Text(), nullable=True),
+        sa.Column('status', sa.String(), nullable=False),
+        sa.Column('created_at', sa.DateTime(timezone=True), nullable=False, server_default=sa.text('CURRENT_TIMESTAMP')),
+        sa.Column('updated_at', sa.DateTime(timezone=True), nullable=True),
+        sa.Column('created_by', sa.Integer(), nullable=False),
+        sa.ForeignKeyConstraint(['created_by'], ['user.id'], ),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_sale_id'), 'sale', ['id'], unique=False)
+    
+    # Create sale item table
+    op.create_table('saleitem',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('sale_id', sa.Integer(), nullable=False),
+        sa.Column('product_id', sa.Integer(), nullable=False),
+        sa.Column('quantity', sa.Integer(), nullable=False),
+        sa.Column('unit_price', sa.Numeric(precision=10, scale=2), nullable=False),
+        sa.ForeignKeyConstraint(['product_id'], ['product.id'], ),
+        sa.ForeignKeyConstraint(['sale_id'], ['sale.id'], ),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_saleitem_id'), 'saleitem', ['id'], unique=False)
+
+
+def downgrade():
+    # Drop tables in reverse order of creation
+    op.drop_index(op.f('ix_saleitem_id'), table_name='saleitem')
+    op.drop_table('saleitem')
+    op.drop_index(op.f('ix_sale_id'), table_name='sale')
+    op.drop_table('sale')
+    op.drop_index(op.f('ix_purchaseorderitem_id'), table_name='purchaseorderitem')
+    op.drop_table('purchaseorderitem')
+    op.drop_index(op.f('ix_purchaseorder_id'), table_name='purchaseorder')
+    op.drop_table('purchaseorder')
+    op.drop_index(op.f('ix_inventorytransaction_id'), table_name='inventorytransaction')
+    op.drop_table('inventorytransaction')
+    op.drop_index(op.f('ix_inventory_id'), table_name='inventory')
+    op.drop_table('inventory')
+    op.drop_index(op.f('ix_product_sku'), table_name='product')
+    op.drop_index(op.f('ix_product_name'), table_name='product')
+    op.drop_index(op.f('ix_product_id'), table_name='product')
+    op.drop_index(op.f('ix_product_barcode'), table_name='product')
+    op.drop_table('product')
+    op.drop_index(op.f('ix_category_name'), table_name='category')
+    op.drop_index(op.f('ix_category_id'), table_name='category')
+    op.drop_table('category')
+    op.drop_index(op.f('ix_user_id'), table_name='user')
+    op.drop_index(op.f('ix_user_full_name'), table_name='user')
+    op.drop_index(op.f('ix_user_email'), table_name='user')
+    op.drop_table('user')

migrations/versions/002_add_admin_user.py

@@ -0,0 +1,51 @@
+"""Add admin user
+
+Revision ID: 002
+Revises: 001
+Create Date: 2023-08-12 00:01:00.000000
+
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.sql import table, column
+import datetime
+from passlib.context import CryptContext
+
+# revision identifiers, used by Alembic.
+revision = '002'
+down_revision = '001'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # Create a pwd_context object for password hashing
+    pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+    
+    # Define the user table for inserting data
+    user_table = table('user',
+        column('id', sa.Integer),
+        column('full_name', sa.String),
+        column('email', sa.String),
+        column('hashed_password', sa.String),
+        column('is_active', sa.Boolean),
+        column('is_admin', sa.Boolean)
+    )
+    
+    # Insert admin user with hashed password
+    op.bulk_insert(user_table,
+        [
+            {
+                'full_name': 'Admin User',
+                'email': 'admin@example.com',
+                'hashed_password': pwd_context.hash('admin123'),  # Default password, should be changed
+                'is_active': True,
+                'is_admin': True
+            }
+        ]
+    )
+
+
+def downgrade():
+    # Remove the admin user - find by email
+    op.execute("DELETE FROM user WHERE email = 'admin@example.com'")

migrations/versions/003_add_sample_data.py

@@ -0,0 +1,166 @@
+"""Add sample data
+
+Revision ID: 003
+Revises: 002
+Create Date: 2023-08-12 00:02:00.000000
+
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.sql import table, column
+import datetime
+from decimal import Decimal
+
+# revision identifiers, used by Alembic.
+revision = '003'
+down_revision = '002'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # Define tables for inserting data
+    category_table = table('category',
+        column('id', sa.Integer),
+        column('name', sa.String),
+        column('description', sa.Text)
+    )
+    
+    product_table = table('product',
+        column('id', sa.Integer),
+        column('name', sa.String),
+        column('description', sa.Text),
+        column('sku', sa.String),
+        column('barcode', sa.String),
+        column('unit_price', sa.Numeric),
+        column('cost_price', sa.Numeric),
+        column('category_id', sa.Integer)
+    )
+    
+    # Insert sample categories
+    op.bulk_insert(category_table,
+        [
+            {
+                'id': 1,
+                'name': 'Electronics',
+                'description': 'Electronic devices and accessories'
+            },
+            {
+                'id': 2,
+                'name': 'Office Supplies',
+                'description': 'Stationery and office equipment'
+            },
+            {
+                'id': 3,
+                'name': 'Furniture',
+                'description': 'Home and office furniture'
+            }
+        ]
+    )
+    
+    # Insert sample products
+    op.bulk_insert(product_table,
+        [
+            {
+                'id': 1,
+                'name': 'Laptop',
+                'description': 'High-performance laptop for work and gaming',
+                'sku': 'EL-LAP-001',
+                'barcode': '1234567890123',
+                'unit_price': 1299.99,
+                'cost_price': 899.99,
+                'category_id': 1
+            },
+            {
+                'id': 2,
+                'name': 'Wireless Mouse',
+                'description': 'Ergonomic wireless mouse',
+                'sku': 'EL-MOU-001',
+                'barcode': '1234567890124',
+                'unit_price': 29.99,
+                'cost_price': 12.50,
+                'category_id': 1
+            },
+            {
+                'id': 3,
+                'name': 'Notebook',
+                'description': 'Premium quality hardcover notebook',
+                'sku': 'OS-NOT-001',
+                'barcode': '2234567890123',
+                'unit_price': 12.99,
+                'cost_price': 4.75,
+                'category_id': 2
+            },
+            {
+                'id': 4,
+                'name': 'Desk Chair',
+                'description': 'Comfortable office chair with lumbar support',
+                'sku': 'FN-CHR-001',
+                'barcode': '3234567890123',
+                'unit_price': 199.99,
+                'cost_price': 89.50,
+                'category_id': 3
+            },
+            {
+                'id': 5,
+                'name': 'Standing Desk',
+                'description': 'Adjustable height standing desk',
+                'sku': 'FN-DSK-001',
+                'barcode': '3234567890124',
+                'unit_price': 349.99,
+                'cost_price': 175.00,
+                'category_id': 3
+            }
+        ]
+    )
+    
+    # Define inventory table
+    inventory_table = table('inventory',
+        column('id', sa.Integer),
+        column('product_id', sa.Integer),
+        column('quantity', sa.Integer),
+        column('location', sa.String)
+    )
+    
+    # Insert sample inventory
+    op.bulk_insert(inventory_table,
+        [
+            {
+                'id': 1,
+                'product_id': 1,
+                'quantity': 10,
+                'location': 'Warehouse A'
+            },
+            {
+                'id': 2,
+                'product_id': 2,
+                'quantity': 50,
+                'location': 'Warehouse A'
+            },
+            {
+                'id': 3,
+                'product_id': 3,
+                'quantity': 100,
+                'location': 'Warehouse B'
+            },
+            {
+                'id': 4,
+                'product_id': 4,
+                'quantity': 20,
+                'location': 'Warehouse C'
+            },
+            {
+                'id': 5,
+                'product_id': 5,
+                'quantity': 15,
+                'location': 'Warehouse C'
+            }
+        ]
+    )
+
+
+def downgrade():
+    # Delete sample data in reverse order
+    op.execute("DELETE FROM inventory WHERE id IN (1, 2, 3, 4, 5)")
+    op.execute("DELETE FROM product WHERE id IN (1, 2, 3, 4, 5)")
+    op.execute("DELETE FROM category WHERE id IN (1, 2, 3)")

pyproject.toml

@@ -0,0 +1,14 @@
+[tool.ruff]
+line-length = 100
+target-version = "py39"
+select = [
+    "E",   # pycodestyle errors
+    "F",   # pyflakes
+    "I",   # isort
+]
+ignore = [
+    "E501",  # line too long (handled by formatter)
+]
+
+[tool.ruff.isort]
+known-third-party = ["fastapi", "pydantic", "sqlalchemy", "alembic", "jose", "passlib"]

requirements.txt

@@ -0,0 +1,10 @@
+fastapi>=0.95.0
+uvicorn>=0.21.1
+sqlalchemy>=2.0.7
+alembic>=1.10.2
+pydantic>=2.0.0
+python-jose[cryptography]>=3.3.0
+passlib[bcrypt]>=1.7.4
+python-multipart>=0.0.6
+ruff>=0.0.257
+python-dotenv>=1.0.0

run.py

@@ -0,0 +1,10 @@
+import os
+import uvicorn
+from pathlib import Path
+
+# Make sure storage directory exists
+storage_dir = Path("/app/storage/db")
+storage_dir.mkdir(parents=True, exist_ok=True)
+
+if __name__ == "__main__":
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)