Implement small business inventory management system

README.md

@@ -1,3 +1,226 @@
-# FastAPI Application
+# Small Business Inventory Management System
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A FastAPI-based REST API for managing inventory in small businesses. This system helps small businesses track inventory, manage stock levels, categorize products, and generate reports.
+
+## Features
+
+- **User Authentication and Authorization**
+  - JWT-based authentication
+  - Role-based permissions (admin/regular users)
+  - Secure password hashing
+
+- **Inventory Management**
+  - Add, update, and delete inventory items
+  - Track stock levels and set reorder points
+  - Assign items to categories
+  - Track item history with SKU
+
+- **Category Management**
+  - Organize items into categories
+  - Nested categorization support
+  - Category-based reporting
+
+- **Transaction Tracking**
+  - Record purchases, sales, returns, and adjustments
+  - Automatic stock level updates
+  - Transaction history for audit purposes
+
+- **Reporting**
+  - Inventory value reports
+  - Category summary reports
+  - Low stock alerts
+  - Transaction summary reports
+
+- **API Features**
+  - RESTful endpoints following best practices
+  - Comprehensive documentation with Swagger UI
+  - Health check endpoint for monitoring
+
+## Tech Stack
+
+- **FastAPI**: Modern, fast web framework for building APIs
+- **SQLAlchemy**: SQL toolkit and ORM
+- **Alembic**: Database migration tool
+- **SQLite**: Simple, file-based database
+- **Pydantic**: Data validation and settings management
+- **Uvicorn**: ASGI server for FastAPI
+- **Python-Jose**: JWT token handling
+- **Passlib**: Password hashing
+- **Ruff**: Python linter for code quality
+
+## Project Structure
+
+```
+.
+├── app/
+│   ├── api/
+│   │   ├── deps.py                   # Dependency injection
+│   │   └── v1/
+│   │       ├── api.py                # API router
+│   │       └── endpoints/
+│   │           ├── auth.py           # Authentication endpoints
+│   │           ├── categories.py     # Category endpoints
+│   │           ├── health.py         # Health check endpoint
+│   │           ├── items.py          # Inventory item endpoints
+│   │           ├── reports.py        # Reporting endpoints
+│   │           ├── transactions.py   # Transaction endpoints
+│   │           └── users.py          # User endpoints
+│   ├── core/
+│   │   ├── config.py                 # Application configuration
+│   │   └── security.py               # Security utilities
+│   ├── crud/
+│   │   ├── base.py                   # Base CRUD operations
+│   │   ├── category.py               # Category CRUD
+│   │   ├── item.py                   # Item CRUD
+│   │   ├── transaction.py            # Transaction CRUD
+│   │   └── user.py                   # User CRUD
+│   ├── db/
+│   │   ├── init_db.py                # Database initialization
+│   │   ├── session.py                # Database session
+│   │   └── utils.py                  # Database utilities
+│   ├── models/                       # SQLAlchemy models
+│   │   ├── base.py                   # Base model
+│   │   ├── category.py               # Category model
+│   │   ├── item.py                   # Item model
+│   │   ├── transaction.py            # Transaction model
+│   │   └── user.py                   # User model
+│   ├── schemas/                      # Pydantic schemas
+│   │   ├── category.py               # Category schemas
+│   │   ├── item.py                   # Item schemas
+│   │   ├── report.py                 # Report schemas
+│   │   ├── token.py                  # Token schemas
+│   │   ├── transaction.py            # Transaction schemas
+│   │   └── user.py                   # User schemas
+│   └── storage/                      # Storage directory
+│       └── db/                       # Database storage
+├── migrations/                       # Alembic migrations
+│   ├── env.py                        # Alembic environment
+│   ├── script.py.mako               # Migration script template
+│   └── versions/                     # Migration versions
+│       └── initial_migration.py     # Initial database schema
+├── alembic.ini                       # Alembic configuration
+├── main.py                           # Application entry point
+├── pyproject.toml                    # Project configuration
+└── requirements.txt                  # Dependencies
+```
+
+## Getting Started
+
+### Prerequisites
+
+- Python 3.8 or higher
+
+### Installation
+
+1. Clone the repository
+2. Install dependencies:
+
+```bash
+pip install -r requirements.txt
+```
+
+3. Initialize the database:
+
+```bash
+alembic upgrade head
+```
+
+4. (Optional) Create a `.env` file in the root directory to customize environment variables:
+
+```
+PROJECT_NAME="My Inventory System"
+SECRET_KEY="your-secret-key-here"
+ACCESS_TOKEN_EXPIRE_MINUTES=1440  # 24 hours
+```
+
+5. Run the application:
+
+```bash
+uvicorn main:app --reload
+```
+
+6. Open http://localhost:8000/docs to access the Swagger UI documentation
+
+## API Documentation
+
+- **OpenAPI Documentation**: `/docs`
+  - Interactive API documentation with Swagger UI
+  - Test endpoints directly from the browser
+
+- **Alternative Documentation**: `/redoc`
+  - Alternative documentation interface
+
+- **OpenAPI JSON**: `/openapi.json`
+  - Raw OpenAPI specification
+
+## API Endpoints
+
+### Authentication
+
+- `POST /api/v1/auth/login` - Obtain JWT token
+- `POST /api/v1/auth/test-token` - Test 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
+- `GET /api/v1/users/{user_id}` - Get user by ID
+- `PUT /api/v1/users/{user_id}` - Update user (admin only)
+
+### Categories
+
+- `GET /api/v1/categories/` - List categories
+- `POST /api/v1/categories/` - Create category (admin only)
+- `GET /api/v1/categories/{id}` - Get category by ID
+- `PUT /api/v1/categories/{id}` - Update category (admin only)
+- `DELETE /api/v1/categories/{id}` - Delete category (admin only)
+
+### Inventory Items
+
+- `GET /api/v1/items/` - List items (with filtering options)
+- `POST /api/v1/items/` - Create item
+- `GET /api/v1/items/{id}` - Get item by ID
+- `PUT /api/v1/items/{id}` - Update item
+- `DELETE /api/v1/items/{id}` - Delete item
+- `GET /api/v1/items/by-sku/{sku}` - Get item by SKU
+- `GET /api/v1/items/low-stock/` - Get low stock items
+
+### Transactions
+
+- `GET /api/v1/transactions/` - List transactions (with filtering options)
+- `POST /api/v1/transactions/` - Create transaction
+- `GET /api/v1/transactions/{id}` - Get transaction by ID
+
+### Reports
+
+- `GET /api/v1/reports/inventory-value` - Inventory value report
+- `GET /api/v1/reports/category-summary` - Category summary report
+- `GET /api/v1/reports/low-stock` - Low stock report
+- `GET /api/v1/reports/transaction-summary` - Transaction summary report
+
+### Health Check
+
+- `GET /health` - System health check
+- `GET /api/v1/health` - Detailed health check with DB status
+
+## Development
+
+### Linting
+
+The project uses Ruff for linting:
+
+```bash
+ruff check .
+```
+
+### Running Tests
+
+```bash
+pytest
+```
+
+## License
+
+This project is licensed under the MIT License.

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
+
+# 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
+
+# Use absolute path for SQLite URL
+sqlalchemy.url = sqlite:////app/storage/db/db.sqlite

app/api/deps.py

@@ -0,0 +1,82 @@
+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 import verify_password
+from app.db.utils import get_db
+from app.models.user import User
+from app.schemas.token import TokenPayload
+
+# OAuth2 configuration
+oauth2_scheme = OAuth2PasswordBearer(
+    tokenUrl=f"{settings.API_V1_STR}/auth/login"
+)
+
+
+def get_current_user(
+    db: Session = Depends(get_db), token: str = Depends(oauth2_scheme)
+) -> User:
+    """
+    Validate and decode the JWT token to get the current user.
+    """
+    try:
+        payload = jwt.decode(
+            token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM]
+        )
+        token_data = TokenPayload(**payload)
+    except (jwt.JWTError, ValidationError) as e:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="Could not validate credentials",
+        ) from e
+    
+    user = db.query(User).filter(User.id == token_data.sub).first()
+    if not user:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="User not found",
+        )
+    
+    if not user.is_active:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Inactive user",
+        )
+    
+    return user
+
+
+def get_current_active_superuser(
+    current_user: User = Depends(get_current_user),
+) -> User:
+    """
+    Check if the current user is a superuser.
+    """
+    if not current_user.is_superuser:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="The user doesn't have enough privileges",
+        )
+    
+    return current_user
+
+
+def authenticate_user(
+    db: Session, email: str, password: str
+) -> Optional[User]:
+    """
+    Authenticate a user using email and password.
+    """
+    user = db.query(User).filter(User.email == email).first()
+    if not user:
+        return None
+    
+    if not verify_password(password, user.hashed_password):
+        return None
+    
+    return user

app/api/v1/api.py

@@ -0,0 +1,22 @@
+from fastapi import APIRouter
+
+from app.api.v1.endpoints import (
+    auth,
+    categories,
+    health,
+    items,
+    reports,
+    transactions,
+    users,
+)
+
+api_router = APIRouter()
+
+# Include routers for different endpoints
+api_router.include_router(auth.router, prefix="/auth", tags=["authentication"])
+api_router.include_router(users.router, prefix="/users", tags=["users"])
+api_router.include_router(items.router, prefix="/items", tags=["items"])
+api_router.include_router(categories.router, prefix="/categories", tags=["categories"])
+api_router.include_router(transactions.router, prefix="/transactions", tags=["transactions"])
+api_router.include_router(reports.router, prefix="/reports", tags=["reports"])
+api_router.include_router(health.router, prefix="/health", tags=["health"])

app/api/v1/endpoints/__init__.py

@@ -0,0 +1 @@
+# Import endpoints to make them accessible

app/api/v1/endpoints/auth.py

@@ -0,0 +1,52 @@
+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 authenticate_user
+from app.core.config import settings
+from app.core.security import create_access_token
+from app.db.utils import get_db
+from app.schemas.token import Token
+
+router = APIRouter()
+
+
+@router.post("/login", 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.
+    """
+    user = authenticate_user(db, form_data.username, form_data.password)
+    if not user:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect email or password",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    
+    if not user.is_active:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Inactive user",
+        )
+    
+    access_token_expires = timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
+    return {
+        "access_token": create_access_token(
+            user.id, expires_delta=access_token_expires
+        ),
+        "token_type": "bearer",
+    }
+
+
+@router.post("/test-token", response_model=None)
+def test_token() -> Any:
+    """
+    Test access token.
+    """
+    return {"msg": "Token is valid"}

app/api/v1/endpoints/categories.py

@@ -0,0 +1,117 @@
+from typing import Any, List
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_current_active_superuser, get_current_user
+from app.crud import category
+from app.db.utils import get_db
+from app.models.user import User
+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: User = Depends(get_current_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: User = Depends(get_current_active_superuser),
+) -> Any:
+    """
+    Create new category.
+    """
+    db_category = category.get_by_name(db, name=category_in.name)
+    if db_category:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="The category with this name already exists in the system.",
+        )
+    return category.create(db, obj_in=category_in)
+
+
+@router.get("/{id}", response_model=Category)
+def read_category(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Get category by ID.
+    """
+    db_category = category.get(db, id=id)
+    if not db_category:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            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: User = Depends(get_current_active_superuser),
+) -> Any:
+    """
+    Update a category.
+    """
+    db_category = category.get(db, id=id)
+    if not db_category:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Category not found",
+        )
+    
+    # If name is being updated, check that it doesn't conflict with an existing category
+    if category_in.name and category_in.name != db_category.name:
+        existing_category = category.get_by_name(db, name=category_in.name)
+        if existing_category:
+            raise HTTPException(
+                status_code=status.HTTP_400_BAD_REQUEST,
+                detail="The category with this name already exists in the system.",
+            )
+    
+    return category.update(db, db_obj=db_category, obj_in=category_in)
+
+
+@router.delete("/{id}", response_model=Category)
+def delete_category(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: User = Depends(get_current_active_superuser),
+) -> Any:
+    """
+    Delete a category.
+    """
+    db_category = category.get(db, id=id)
+    if not db_category:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Category not found",
+        )
+    
+    # Optional: Check if the category has items and handle accordingly
+    # For now, we'll allow deletion even if items are associated with it
+    
+    return category.remove(db, id=id)

app/api/v1/endpoints/health.py

@@ -0,0 +1,32 @@
+from typing import Any, Dict
+
+from fastapi import APIRouter, Depends
+from sqlalchemy import text
+from sqlalchemy.orm import Session
+
+from app.db.utils import get_db
+
+router = APIRouter()
+
+
+@router.get("/", response_model=Dict[str, Any])
+async def health_check(db: Session = Depends(get_db)) -> Any:
+    """
+    Health check endpoint to verify the API and database are running.
+    """
+    health_status = {
+        "status": "healthy",
+        "api": "ok",
+        "database": "ok",
+    }
+    
+    # Check database connection
+    try:
+        # Execute a simple query to check if the database is responsive
+        db.execute(text("SELECT 1"))
+    except Exception as e:
+        health_status["status"] = "unhealthy"
+        health_status["database"] = "error"
+        health_status["database_error"] = str(e)
+    
+    return health_status

app/api/v1/endpoints/items.py

@@ -0,0 +1,198 @@
+from typing import Any, List, Optional
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_current_user
+from app.crud import category, item
+from app.db.utils import get_db
+from app.models.user import User
+from app.schemas.item import Item, ItemCreate, ItemUpdate
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[Item])
+def read_items(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    category_id: Optional[int] = None,
+    low_stock: Optional[bool] = False,
+    name: Optional[str] = None,
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Retrieve items.
+    
+    - Optional filter by category_id
+    - Optional filter for low stock items
+    - Optional search by name
+    """
+    if low_stock:
+        items = item.get_low_stock_items(db, skip=skip, limit=limit)
+    elif category_id:
+        items = item.get_by_category_id(
+            db, category_id=category_id, skip=skip, limit=limit
+        )
+    elif name:
+        items = item.get_by_name(db, name=name)
+    else:
+        items = item.get_multi(db, skip=skip, limit=limit)
+    
+    return items
+
+
+@router.post("/", response_model=Item)
+def create_item(
+    *,
+    db: Session = Depends(get_db),
+    item_in: ItemCreate,
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Create new item.
+    """
+    # Check if SKU already exists
+    if item.get_by_sku(db, sku=item_in.sku):
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="An item with this SKU already exists.",
+        )
+    
+    # Check if category exists if provided
+    if item_in.category_id is not None:
+        db_category = category.get(db, id=item_in.category_id)
+        if not db_category:
+            raise HTTPException(
+                status_code=status.HTTP_404_NOT_FOUND,
+                detail="Category not found",
+            )
+    
+    # Create item with current user as owner
+    return item.create_with_owner(db, obj_in=item_in, owner_id=current_user.id)
+
+
+@router.get("/{id}", response_model=Item)
+def read_item(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Get item by ID.
+    """
+    db_item = item.get(db, id=id)
+    if not db_item:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Item not found",
+        )
+    return db_item
+
+
+@router.put("/{id}", response_model=Item)
+def update_item(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    item_in: ItemUpdate,
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Update an item.
+    """
+    db_item = item.get(db, id=id)
+    if not db_item:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Item not found",
+        )
+    
+    # Check if SKU is being updated and ensure it doesn't conflict
+    if item_in.sku and item_in.sku != db_item.sku:
+        existing_item = item.get_by_sku(db, sku=item_in.sku)
+        if existing_item:
+            raise HTTPException(
+                status_code=status.HTTP_400_BAD_REQUEST,
+                detail="An item with this SKU already exists.",
+            )
+    
+    # Check if category exists if provided
+    if item_in.category_id is not None:
+        db_category = category.get(db, id=item_in.category_id)
+        if not db_category:
+            raise HTTPException(
+                status_code=status.HTTP_404_NOT_FOUND,
+                detail="Category not found",
+            )
+    
+    # Only superusers or the owner can update items
+    if not current_user.is_superuser and db_item.owner_id != current_user.id:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="Not enough permissions",
+        )
+    
+    return item.update(db, db_obj=db_item, obj_in=item_in)
+
+
+@router.delete("/{id}", response_model=Item)
+def delete_item(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Delete an item.
+    """
+    db_item = item.get(db, id=id)
+    if not db_item:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Item not found",
+        )
+    
+    # Only superusers or the owner can delete items
+    if not current_user.is_superuser and db_item.owner_id != current_user.id:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="Not enough permissions",
+        )
+    
+    return item.remove(db, id=id)
+
+
+@router.get("/by-sku/{sku}", response_model=Item)
+def read_item_by_sku(
+    *,
+    db: Session = Depends(get_db),
+    sku: str,
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Get item by SKU.
+    """
+    db_item = item.get_by_sku(db, sku=sku)
+    if not db_item:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Item not found",
+        )
+    return db_item
+
+
+@router.get("/low-stock/", response_model=List[Item])
+def read_low_stock_items(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Retrieve items with stock below reorder level.
+    """
+    items = item.get_low_stock_items(db, skip=skip, limit=limit)
+    return items

app/api/v1/endpoints/reports.py

@@ -0,0 +1,168 @@
+from datetime import date, datetime
+from typing import Any, Optional
+
+from fastapi import APIRouter, Depends, HTTPException, Query, status
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_current_user
+from app.crud import category, item, transaction
+from app.db.utils import get_db
+from app.models.user import User
+from app.schemas.report import (
+    CategorySummaryItem,
+    CategorySummaryReport,
+    InventoryValueItem,
+    InventoryValueReport,
+    LowStockItem,
+    LowStockReport,
+    TransactionSummaryItem,
+    TransactionSummaryReport,
+)
+
+router = APIRouter()
+
+
+@router.get("/inventory-value", response_model=InventoryValueReport)
+def get_inventory_value(
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Generate inventory value report.
+    """
+    items_db = item.get_multi(db)
+    
+    inventory_items = []
+    total_value = 0.0
+    
+    for item_db in items_db:
+        item_value = item_db.price * item_db.quantity
+        total_value += item_value
+        
+        inventory_items.append(
+            InventoryValueItem(
+                id=item_db.id,
+                name=item_db.name,
+                sku=item_db.sku,
+                quantity=item_db.quantity,
+                price=item_db.price,
+                total_value=item_value
+            )
+        )
+    
+    return InventoryValueReport(
+        total_inventory_value=total_value,
+        items=inventory_items,
+        report_date=datetime.utcnow()
+    )
+
+
+@router.get("/category-summary", response_model=CategorySummaryReport)
+def get_category_summary(
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Generate category summary report.
+    """
+    # Get all categories
+    categories_db = category.get_multi(db)
+    
+    summary_items = []
+    
+    for cat in categories_db:
+        # Get items in this category
+        items_in_category = item.get_by_category_id(db, category_id=cat.id)
+        
+        # Calculate totals
+        item_count = len(items_in_category)
+        total_value = sum(i.price * i.quantity for i in items_in_category)
+        avg_price = sum(i.price for i in items_in_category) / item_count if item_count > 0 else 0
+        
+        summary_items.append(
+            CategorySummaryItem(
+                category_id=cat.id,
+                category_name=cat.name,
+                item_count=item_count,
+                total_value=total_value,
+                average_price=avg_price
+            )
+        )
+    
+    return CategorySummaryReport(
+        categories=summary_items,
+        report_date=datetime.utcnow()
+    )
+
+
+@router.get("/low-stock", response_model=LowStockReport)
+def get_low_stock_report(
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Generate low stock report.
+    """
+    # Get items with stock below reorder level
+    low_stock_items_db = item.get_low_stock_items(db)
+    
+    low_stock_items = []
+    
+    for item_db in low_stock_items_db:
+        low_stock_items.append(
+            LowStockItem(
+                id=item_db.id,
+                name=item_db.name,
+                sku=item_db.sku,
+                quantity=item_db.quantity,
+                reorder_level=item_db.reorder_level,
+                category_name=item_db.category.name if item_db.category else None
+            )
+        )
+    
+    return LowStockReport(
+        low_stock_items=low_stock_items,
+        report_date=datetime.utcnow()
+    )
+
+
+@router.get("/transaction-summary", response_model=TransactionSummaryReport)
+def get_transaction_summary(
+    start_date: date = Query(..., description="Start date for the report period"),
+    end_date: Optional[date] = Query(None, description="End date for the report period"),
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Generate transaction summary report.
+    """
+    if end_date is None:
+        end_date = date.today()
+    
+    if start_date > end_date:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Start date must be before end date",
+        )
+    
+    # Get transaction summary by type
+    summary_data = transaction.get_summary_by_type(
+        db, start_date=start_date, end_date=end_date
+    )
+    
+    summary_items = [
+        TransactionSummaryItem(
+            transaction_type=item["transaction_type"],
+            count=item["count"],
+            total_quantity=item["total_quantity"],
+            total_value=item["total_value"]
+        )
+        for item in summary_data
+    ]
+    
+    return TransactionSummaryReport(
+        start_date=start_date,
+        end_date=end_date,
+        transactions=summary_items,
+        report_date=datetime.utcnow()
+    )

app/api/v1/endpoints/transactions.py

@@ -0,0 +1,105 @@
+from datetime import date
+from typing import Any, List, Optional
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_current_user
+from app.crud import item, transaction
+from app.db.utils import get_db
+from app.models.transaction import TransactionType
+from app.models.user import User
+from app.schemas.transaction import Transaction, TransactionCreate
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[Transaction])
+def read_transactions(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    item_id: Optional[int] = None,
+    start_date: Optional[date] = None,
+    end_date: Optional[date] = None,
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Retrieve transactions.
+    
+    - Optional filter by item_id
+    - Optional filter by date range
+    """
+    if item_id:
+        return transaction.get_by_item_id(db, item_id=item_id, skip=skip, limit=limit)
+    elif start_date:
+        return transaction.get_by_date_range(
+            db, start_date=start_date, end_date=end_date, skip=skip, limit=limit
+        )
+    else:
+        return transaction.get_multi(db, skip=skip, limit=limit)
+
+
+@router.post("/", response_model=Transaction)
+def create_transaction(
+    *,
+    db: Session = Depends(get_db),
+    transaction_in: TransactionCreate,
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Create new transaction and update item quantity.
+    """
+    # Check if item exists
+    db_item = item.get(db, id=transaction_in.item_id)
+    if not db_item:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Item not found",
+        )
+    
+    # Create the transaction
+    db_transaction = transaction.create_with_item_and_user(
+        db, obj_in=transaction_in, recorded_by_id=current_user.id
+    )
+    
+    # Update item quantity based on transaction type
+    if transaction_in.transaction_type == TransactionType.PURCHASE:
+        db_item.quantity += transaction_in.quantity
+    elif transaction_in.transaction_type == TransactionType.SALE:
+        if db_item.quantity < transaction_in.quantity:
+            raise HTTPException(
+                status_code=status.HTTP_400_BAD_REQUEST,
+                detail="Not enough items in stock",
+            )
+        db_item.quantity -= transaction_in.quantity
+    elif transaction_in.transaction_type == TransactionType.ADJUSTMENT:
+        db_item.quantity += transaction_in.quantity  # Can be negative for decrease
+    elif transaction_in.transaction_type == TransactionType.RETURN:
+        db_item.quantity += transaction_in.quantity
+    
+    # Save the updated item
+    db.add(db_item)
+    db.commit()
+    db.refresh(db_item)
+    
+    return db_transaction
+
+
+@router.get("/{id}", response_model=Transaction)
+def read_transaction(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Get transaction by ID.
+    """
+    db_transaction = transaction.get(db, id=id)
+    if not db_transaction:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Transaction not found",
+        )
+    return db_transaction

app/api/v1/endpoints/users.py

@@ -0,0 +1,131 @@
+from typing import Any, List
+
+from fastapi import APIRouter, Body, Depends, HTTPException, status
+from fastapi.encoders import jsonable_encoder
+from pydantic import EmailStr
+from sqlalchemy.orm import Session
+
+from app.api.deps import get_current_active_superuser, get_current_user
+from app.crud import user
+from app.db.utils import get_db
+from app.models.user import User
+from app.schemas.user import User as UserSchema
+from app.schemas.user import UserCreate, UserUpdate
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[UserSchema])
+def read_users(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    current_user: User = Depends(get_current_active_superuser),
+) -> Any:
+    """
+    Retrieve users.
+    """
+    users = user.get_multi(db, skip=skip, limit=limit)
+    return users
+
+
+@router.post("/", response_model=UserSchema)
+def create_user(
+    *,
+    db: Session = Depends(get_db),
+    user_in: UserCreate,
+    current_user: User = Depends(get_current_active_superuser),
+) -> Any:
+    """
+    Create new user.
+    """
+    db_user = user.get_by_email(db, email=user_in.email)
+    if db_user:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="The user with this email already exists in the system.",
+        )
+    new_user = user.create(db, obj_in=user_in)
+    return new_user
+
+
+@router.get("/me", response_model=UserSchema)
+def read_user_me(
+    current_user: User = Depends(get_current_user),
+) -> Any:
+    """
+    Get current user.
+    """
+    return current_user
+
+
+@router.put("/me", response_model=UserSchema)
+def update_user_me(
+    *,
+    db: Session = Depends(get_db),
+    password: str = Body(None),
+    full_name: str = Body(None),
+    email: EmailStr = Body(None),
+    current_user: User = Depends(get_current_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("/{user_id}", response_model=UserSchema)
+def read_user_by_id(
+    user_id: int,
+    current_user: User = Depends(get_current_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=status.HTTP_404_NOT_FOUND,
+            detail="User not found",
+        )
+    
+    # Regular users can only view their own details
+    if not current_user.is_superuser and current_user.id != user_id:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="Not enough permissions",
+        )
+    
+    return db_user
+
+
+@router.put("/{user_id}", response_model=UserSchema)
+def update_user(
+    *,
+    db: Session = Depends(get_db),
+    user_id: int,
+    user_in: UserUpdate,
+    current_user: User = Depends(get_current_active_superuser),
+) -> Any:
+    """
+    Update a user.
+    """
+    db_user = user.get(db, id=user_id)
+    if not db_user:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="User not found",
+        )
+    
+    updated_user = user.update(db, db_obj=db_user, obj_in=user_in)
+    return updated_user

app/core/config.py

@@ -0,0 +1,43 @@
+from pathlib import Path
+from typing import List, Union
+
+from pydantic import AnyHttpUrl, field_validator
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(
+        env_file=".env", 
+        env_file_encoding="utf-8",
+        case_sensitive=True,
+    )
+    
+    # API settings
+    API_V1_STR: str = "/api/v1"
+    PROJECT_NAME: str = "Small Business Inventory Management System"
+    
+    # CORS settings
+    BACKEND_CORS_ORIGINS: List[AnyHttpUrl] = []
+
+    @field_validator("BACKEND_CORS_ORIGINS", mode="before")
+    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)
+    
+    # Database settings
+    DB_DIR: Path = Path("/app") / "storage" / "db"
+    SQLALCHEMY_DATABASE_URL: str = f"sqlite:///{DB_DIR}/db.sqlite"
+    
+    # Security settings
+    SECRET_KEY: str = "secret_key_for_development_only_please_change_in_production"
+    ACCESS_TOKEN_EXPIRE_MINUTES: int = 60 * 24 * 8  # 8 days
+    ALGORITHM: str = "HS256"
+
+
+settings = Settings()
+
+# Create the DB directory if it doesn't exist
+settings.DB_DIR.mkdir(parents=True, exist_ok=True)

app/core/security.py

@@ -0,0 +1,40 @@
+from datetime import datetime, timedelta
+from typing import Any, Union
+
+from jose import jwt
+from passlib.context import CryptContext
+
+from app.core.config import settings
+
+pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+
+
+def create_access_token(
+    subject: Union[str, Any], expires_delta: timedelta = None
+) -> str:
+    """
+    Create a JWT access 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=settings.ALGORITHM)
+    return encoded_jwt
+
+
+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:
+    """
+    Hash a password.
+    """
+    return pwd_context.hash(password)

app/crud/__init__.py

@@ -0,0 +1,5 @@
+# Import CRUD operations to make them accessible
+from app.crud.category import category
+from app.crud.item import item
+from app.crud.transaction import transaction
+from app.crud.user import user

app/crud/base.py

@@ -0,0 +1,83 @@
+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.models.base import Base
+
+ModelType = TypeVar("ModelType", bound=Base)
+CreateSchemaType = TypeVar("CreateSchemaType", bound=BaseModel)
+UpdateSchemaType = TypeVar("UpdateSchemaType", bound=BaseModel)
+
+
+class CRUDBase(Generic[ModelType, CreateSchemaType, UpdateSchemaType]):
+    """
+    Base class for CRUD operations.
+    """
+    def __init__(self, model: Type[ModelType]):
+        """
+        CRUD object with default methods to Create, Read, Update, Delete (CRUD).
+        
+        **Parameters**
+        
+        * `model`: A SQLAlchemy model class
+        """
+        self.model = model
+
+    def get(self, db: Session, id: Any) -> Optional[ModelType]:
+        """
+        Get a single record by ID.
+        """
+        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]:
+        """
+        Get multiple records.
+        """
+        return db.query(self.model).offset(skip).limit(limit).all()
+
+    def create(self, db: Session, *, obj_in: CreateSchemaType) -> ModelType:
+        """
+        Create a new record.
+        """
+        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:
+        """
+        Update a record.
+        """
+        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:
+        """
+        Delete a record.
+        """
+        obj = db.query(self.model).get(id)
+        db.delete(obj)
+        db.commit()
+        return obj

app/crud/category.py

@@ -0,0 +1,35 @@
+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]):
+    """
+    CRUD operations for Category model.
+    """
+    def get_by_name(self, db: Session, *, name: str) -> Optional[Category]:
+        """
+        Get a category by name.
+        """
+        return db.query(Category).filter(Category.name == name).first()
+    
+    def get_multi_with_items(
+        self, db: Session, *, skip: int = 0, limit: int = 100
+    ) -> List[Category]:
+        """
+        Get multiple categories with items.
+        """
+        return (
+            db.query(Category)
+            .offset(skip)
+            .limit(limit)
+            .all()
+        )
+
+
+# Create a singleton instance
+category = CRUDCategory(Category)

app/crud/item.py

@@ -0,0 +1,69 @@
+from typing import List, Optional
+
+from sqlalchemy.orm import Session
+
+from app.crud.base import CRUDBase
+from app.models.item import Item
+from app.schemas.item import ItemCreate, ItemUpdate
+
+
+class CRUDItem(CRUDBase[Item, ItemCreate, ItemUpdate]):
+    """
+    CRUD operations for Item model.
+    """
+    def get_by_sku(self, db: Session, *, sku: str) -> Optional[Item]:
+        """
+        Get an item by SKU.
+        """
+        return db.query(Item).filter(Item.sku == sku).first()
+    
+    def get_by_name(self, db: Session, *, name: str) -> List[Item]:
+        """
+        Get items by name (can return multiple items).
+        """
+        return db.query(Item).filter(Item.name.ilike(f"%{name}%")).all()
+    
+    def get_by_category_id(
+        self, db: Session, *, category_id: int, skip: int = 0, limit: int = 100
+    ) -> List[Item]:
+        """
+        Get items by category ID.
+        """
+        return (
+            db.query(Item)
+            .filter(Item.category_id == category_id)
+            .offset(skip)
+            .limit(limit)
+            .all()
+        )
+    
+    def get_low_stock_items(
+        self, db: Session, *, skip: int = 0, limit: int = 100
+    ) -> List[Item]:
+        """
+        Get items with stock below reorder level.
+        """
+        return (
+            db.query(Item)
+            .filter(Item.quantity <= Item.reorder_level)
+            .offset(skip)
+            .limit(limit)
+            .all()
+        )
+    
+    def create_with_owner(
+        self, db: Session, *, obj_in: ItemCreate, owner_id: int
+    ) -> Item:
+        """
+        Create a new item with owner.
+        """
+        obj_in_data = obj_in.model_dump()
+        db_obj = Item(**obj_in_data, owner_id=owner_id)
+        db.add(db_obj)
+        db.commit()
+        db.refresh(db_obj)
+        return db_obj
+
+
+# Create a singleton instance
+item = CRUDItem(Item)

app/crud/transaction.py

@@ -0,0 +1,111 @@
+from datetime import date, datetime
+from typing import List
+
+from sqlalchemy import func
+from sqlalchemy.orm import Session
+
+from app.crud.base import CRUDBase
+from app.models.transaction import Transaction
+from app.schemas.transaction import TransactionCreate, TransactionUpdate
+
+
+class CRUDTransaction(CRUDBase[Transaction, TransactionCreate, TransactionUpdate]):
+    """
+    CRUD operations for Transaction model.
+    """
+    def create_with_item_and_user(
+        self, db: Session, *, obj_in: TransactionCreate, recorded_by_id: int
+    ) -> Transaction:
+        """
+        Create a new transaction record with item and user.
+        """
+        obj_in_data = obj_in.model_dump()
+        db_obj = Transaction(**obj_in_data, recorded_by_id=recorded_by_id)
+        db.add(db_obj)
+        db.commit()
+        db.refresh(db_obj)
+        return db_obj
+    
+    def get_by_item_id(
+        self, db: Session, *, item_id: int, skip: int = 0, limit: int = 100
+    ) -> List[Transaction]:
+        """
+        Get transactions by item ID.
+        """
+        return (
+            db.query(Transaction)
+            .filter(Transaction.item_id == item_id)
+            .order_by(Transaction.transaction_date.desc())
+            .offset(skip)
+            .limit(limit)
+            .all()
+        )
+    
+    def get_by_date_range(
+        self, 
+        db: Session, 
+        *, 
+        start_date: date, 
+        end_date: date = None,
+        skip: int = 0, 
+        limit: int = 100
+    ) -> List[Transaction]:
+        """
+        Get transactions within a date range.
+        """
+        if end_date is None:
+            end_date = date.today()
+        
+        # Convert dates to datetime for proper comparison
+        start_datetime = datetime.combine(start_date, datetime.min.time())
+        end_datetime = datetime.combine(end_date, datetime.max.time())
+        
+        return (
+            db.query(Transaction)
+            .filter(Transaction.transaction_date >= start_datetime)
+            .filter(Transaction.transaction_date <= end_datetime)
+            .order_by(Transaction.transaction_date.desc())
+            .offset(skip)
+            .limit(limit)
+            .all()
+        )
+    
+    def get_summary_by_type(
+        self, db: Session, *, start_date: date, end_date: date = None
+    ) -> List[dict]:
+        """
+        Get transaction summary aggregated by transaction type.
+        """
+        if end_date is None:
+            end_date = date.today()
+        
+        # Convert dates to datetime for proper comparison
+        start_datetime = datetime.combine(start_date, datetime.min.time())
+        end_datetime = datetime.combine(end_date, datetime.max.time())
+        
+        result = (
+            db.query(
+                Transaction.transaction_type,
+                func.count().label("count"),
+                func.sum(Transaction.quantity).label("total_quantity"),
+                func.sum(Transaction.unit_price * Transaction.quantity).label("total_value")
+            )
+            .filter(Transaction.transaction_date >= start_datetime)
+            .filter(Transaction.transaction_date <= end_datetime)
+            .group_by(Transaction.transaction_type)
+            .all()
+        )
+        
+        return [
+            {
+                "transaction_type": r[0],
+                "count": r[1],
+                "total_quantity": r[2],
+                "total_value": r[3]
+            }
+            for r in result
+        ]
+
+
+# Create a singleton instance
+transaction = CRUDTransaction(Transaction)

app/crud/user.py

@@ -0,0 +1,80 @@
+from typing import Any, Dict, Optional, Union
+
+from sqlalchemy.orm import Session
+
+from app.core.security 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]):
+    """
+    CRUD operations for User model.
+    """
+    def get_by_email(self, db: Session, *, email: str) -> Optional[User]:
+        """
+        Get a user by email.
+        """
+        return db.query(User).filter(User.email == email).first()
+
+    def create(self, db: Session, *, obj_in: UserCreate) -> User:
+        """
+        Create a new user.
+        """
+        db_obj = User(
+            email=obj_in.email,
+            hashed_password=get_password_hash(obj_in.password),
+            full_name=obj_in.full_name,
+            is_superuser=obj_in.is_superuser,
+            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:
+        """
+        Update a 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]:
+        """
+        Authenticate a 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:
+        """
+        Check if a user is active.
+        """
+        return user.is_active
+
+    def is_superuser(self, user: User) -> bool:
+        """
+        Check if a user is a superuser.
+        """
+        return user.is_superuser
+
+
+# Create a singleton instance
+user = CRUDUser(User)

app/db/init_db.py

@@ -0,0 +1,17 @@
+import logging
+
+from app.db.session import Base, engine
+
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)
+
+
+def init_db() -> None:
+    """
+    Initialize the database.
+    Creates all tables defined in the models.
+    """
+    # Create tables
+    logger.info("Creating database tables")
+    Base.metadata.create_all(bind=engine)
+    logger.info("Database tables created")

app/db/session.py

@@ -0,0 +1,17 @@
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+
+from app.core.config import settings
+
+# Create the SQLAlchemy engine
+engine = create_engine(
+    settings.SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False}  # Only needed for SQLite
+)
+
+# Create a SessionLocal class for database sessions
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+# Create a Base class for declarative models
+Base = declarative_base()

app/db/utils.py

@@ -0,0 +1,16 @@
+from typing import Generator
+
+from app.db.session import SessionLocal
+
+
+# Dependency to get DB session
+def get_db() -> Generator:
+    """
+    Dependency for getting a database session.
+    This function yields a SQLAlchemy session and ensures it's closed after use.
+    """
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/models/__init__.py

@@ -0,0 +1,5 @@
+# Import models to ensure they are registered with SQLAlchemy
+from app.models.category import Category
+from app.models.item import Item
+from app.models.transaction import Transaction, TransactionType
+from app.models.user import User

app/models/base.py

@@ -0,0 +1,26 @@
+from datetime import datetime
+from typing import Any
+
+from sqlalchemy import Column, DateTime
+from sqlalchemy.ext.declarative import as_declarative, declared_attr
+
+
+@as_declarative()
+class Base:
+    """
+    Base class for all models.
+    Provides common columns and methods.
+    """
+    id: Any
+    created_at = Column(DateTime, default=datetime.utcnow, nullable=False)
+    updated_at = Column(
+        DateTime, 
+        default=datetime.utcnow,
+        onupdate=datetime.utcnow,
+        nullable=False
+    )
+    
+    # Generate __tablename__ automatically based on class name
+    @declared_attr
+    def __tablename__(cls) -> str:
+        return cls.__name__.lower()

app/models/category.py

@@ -0,0 +1,12 @@
+from sqlalchemy import Column, Integer, String, Text
+
+from app.models.base import Base
+
+
+class Category(Base):
+    """
+    Category model for grouping inventory items.
+    """
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String, unique=True, index=True, nullable=False)
+    description = Column(Text, nullable=True)

app/models/item.py

@@ -0,0 +1,25 @@
+from sqlalchemy import Column, Float, ForeignKey, Integer, String, Text
+from sqlalchemy.orm import relationship
+
+from app.models.base import Base
+
+
+class Item(Base):
+    """
+    Inventory item model.
+    """
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String, index=True, nullable=False)
+    sku = Column(String, index=True, unique=True, nullable=False)
+    description = Column(Text, nullable=True)
+    price = Column(Float, nullable=False)
+    quantity = Column(Integer, default=0, nullable=False)
+    reorder_level = Column(Integer, default=10, nullable=False)
+    
+    # Foreign key to Category
+    category_id = Column(Integer, ForeignKey("category.id"), nullable=True)
+    category = relationship("Category", backref="items")
+    
+    # Foreign key to User (who created the item)
+    owner_id = Column(Integer, ForeignKey("user.id"), nullable=True)
+    owner = relationship("User", backref="items")

app/models/transaction.py

@@ -0,0 +1,38 @@
+from datetime import datetime
+from enum import Enum as PyEnum
+
+from sqlalchemy import Column, DateTime, Enum, Float, ForeignKey, Integer, String
+from sqlalchemy.orm import relationship
+
+from app.models.base import Base
+
+
+class TransactionType(str, PyEnum):
+    """
+    Enum for transaction types.
+    """
+    PURCHASE = "purchase"
+    SALE = "sale"
+    ADJUSTMENT = "adjustment"
+    RETURN = "return"
+
+
+class Transaction(Base):
+    """
+    Transaction model for tracking inventory changes.
+    """
+    id = Column(Integer, primary_key=True, index=True)
+    transaction_type = Column(Enum(TransactionType), nullable=False)
+    quantity = Column(Integer, nullable=False)
+    unit_price = Column(Float, nullable=True)
+    reference_number = Column(String, nullable=True)
+    notes = Column(String, nullable=True)
+    transaction_date = Column(DateTime, default=datetime.utcnow, nullable=False)
+    
+    # Foreign key to Item
+    item_id = Column(Integer, ForeignKey("item.id"), nullable=False)
+    item = relationship("Item", backref="transactions")
+    
+    # Foreign key to User (who recorded the transaction)
+    recorded_by_id = Column(Integer, ForeignKey("user.id"), nullable=True)
+    recorded_by = relationship("User", backref="transactions")

app/models/user.py

@@ -0,0 +1,15 @@
+from sqlalchemy import Boolean, Column, Integer, String
+
+from app.models.base import Base
+
+
+class User(Base):
+    """
+    User model for authentication and authorization.
+    """
+    id = Column(Integer, primary_key=True, index=True)
+    email = Column(String, unique=True, index=True, nullable=False)
+    full_name = Column(String, nullable=True)
+    hashed_password = Column(String, nullable=False)
+    is_active = Column(Boolean, default=True, nullable=False)
+    is_superuser = Column(Boolean, default=False, nullable=False)

app/schemas/__init__.py

@@ -0,0 +1,17 @@
+# Import schemas to make them accessible from app.schemas
+from app.schemas.category import Category, CategoryCreate, CategoryInDB, CategoryUpdate
+from app.schemas.item import Item, ItemCreate, ItemInDB, ItemUpdate
+from app.schemas.report import (
+    CategorySummaryReport,
+    InventoryValueReport,
+    LowStockReport,
+    TransactionSummaryReport,
+)
+from app.schemas.token import Token, TokenPayload
+from app.schemas.transaction import (
+    Transaction,
+    TransactionCreate,
+    TransactionInDB,
+    TransactionUpdate,
+)
+from app.schemas.user import User, UserCreate, UserInDB, UserUpdate

app/schemas/category.py

@@ -0,0 +1,38 @@
+from typing import Optional
+
+from pydantic import BaseModel
+
+
+# Shared properties
+class CategoryBase(BaseModel):
+    name: Optional[str] = None
+    description: Optional[str] = None
+
+
+# Properties to receive on category creation
+class CategoryCreate(CategoryBase):
+    name: str
+
+
+# Properties to receive on category update
+class CategoryUpdate(CategoryBase):
+    pass
+
+
+# Properties shared by models in DB
+class CategoryInDBBase(CategoryBase):
+    id: int
+    name: str
+
+    class Config:
+        from_attributes = True
+
+
+# Properties to return to client
+class Category(CategoryInDBBase):
+    pass
+
+
+# Properties stored in DB
+class CategoryInDB(CategoryInDBBase):
+    pass

app/schemas/item.py

@@ -0,0 +1,48 @@
+from typing import Optional
+
+from pydantic import BaseModel
+
+
+# Shared properties
+class ItemBase(BaseModel):
+    name: Optional[str] = None
+    sku: Optional[str] = None
+    description: Optional[str] = None
+    price: Optional[float] = None
+    quantity: Optional[int] = 0
+    reorder_level: Optional[int] = 10
+    category_id: Optional[int] = None
+
+
+# Properties to receive on item creation
+class ItemCreate(ItemBase):
+    name: str
+    sku: str
+    price: float
+
+
+# Properties to receive on item update
+class ItemUpdate(ItemBase):
+    pass
+
+
+# Properties shared by models in DB
+class ItemInDBBase(ItemBase):
+    id: int
+    name: str
+    sku: str
+    price: float
+    owner_id: Optional[int] = None
+
+    class Config:
+        from_attributes = True
+
+
+# Properties to return to client
+class Item(ItemInDBBase):
+    pass
+
+
+# Properties stored in DB
+class ItemInDB(ItemInDBBase):
+    pass

app/schemas/report.py

@@ -0,0 +1,62 @@
+from datetime import date, datetime
+from typing import List, Optional
+
+from pydantic import BaseModel
+
+from app.models.transaction import TransactionType
+
+
+class InventoryValueItem(BaseModel):
+    id: int
+    name: str
+    sku: str
+    quantity: int
+    price: float
+    total_value: float
+
+
+class InventoryValueReport(BaseModel):
+    total_inventory_value: float
+    items: List[InventoryValueItem]
+    report_date: datetime = datetime.utcnow()
+
+
+class CategorySummaryItem(BaseModel):
+    category_id: int
+    category_name: str
+    item_count: int
+    total_value: float
+    average_price: float
+
+
+class CategorySummaryReport(BaseModel):
+    categories: List[CategorySummaryItem]
+    report_date: datetime = datetime.utcnow()
+
+
+class LowStockItem(BaseModel):
+    id: int
+    name: str
+    sku: str
+    quantity: int
+    reorder_level: int
+    category_name: Optional[str] = None
+
+
+class LowStockReport(BaseModel):
+    low_stock_items: List[LowStockItem]
+    report_date: datetime = datetime.utcnow()
+
+
+class TransactionSummaryItem(BaseModel):
+    transaction_type: TransactionType
+    count: int
+    total_quantity: int
+    total_value: Optional[float] = None
+
+
+class TransactionSummaryReport(BaseModel):
+    start_date: date
+    end_date: date
+    transactions: List[TransactionSummaryItem]
+    report_date: datetime = datetime.utcnow()

app/schemas/token.py

@@ -0,0 +1,13 @@
+from typing import Optional
+
+from pydantic import BaseModel
+
+
+class Token(BaseModel):
+    access_token: str
+    token_type: str
+
+
+class TokenPayload(BaseModel):
+    sub: Optional[int] = None
+    exp: Optional[int] = None

app/schemas/transaction.py

@@ -0,0 +1,53 @@
+from datetime import datetime
+from typing import Optional
+
+from pydantic import BaseModel
+
+from app.models.transaction import TransactionType
+
+
+# Shared properties
+class TransactionBase(BaseModel):
+    transaction_type: Optional[TransactionType] = None
+    quantity: Optional[int] = None
+    unit_price: Optional[float] = None
+    reference_number: Optional[str] = None
+    notes: Optional[str] = None
+    transaction_date: Optional[datetime] = None
+    item_id: Optional[int] = None
+
+
+# Properties to receive on transaction creation
+class TransactionCreate(TransactionBase):
+    transaction_type: TransactionType
+    quantity: int
+    item_id: int
+    transaction_date: Optional[datetime] = datetime.utcnow()
+
+
+# Properties to receive on transaction update
+class TransactionUpdate(TransactionBase):
+    pass
+
+
+# Properties shared by models in DB
+class TransactionInDBBase(TransactionBase):
+    id: int
+    transaction_type: TransactionType
+    quantity: int
+    item_id: int
+    transaction_date: datetime
+    recorded_by_id: Optional[int] = None
+
+    class Config:
+        from_attributes = True
+
+
+# Properties to return to client
+class Transaction(TransactionInDBBase):
+    pass
+
+
+# Properties stored in DB
+class TransactionInDB(TransactionInDBBase):
+    pass

app/schemas/user.py

@@ -0,0 +1,39 @@
+from typing import Optional
+
+from pydantic import BaseModel, EmailStr
+
+
+# Shared properties
+class UserBase(BaseModel):
+    email: Optional[EmailStr] = None
+    is_active: Optional[bool] = True
+    is_superuser: bool = False
+    full_name: Optional[str] = None
+
+
+# Properties to receive via API on creation
+class UserCreate(UserBase):
+    email: EmailStr
+    password: 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 +1,38 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import JSONResponse
+
+from app.api.v1.api import api_router
+from app.core.config import settings
+
+# Create FastAPI app
+app = FastAPI(
+    title=settings.PROJECT_NAME,
+    openapi_url="/openapi.json",
+)
+
+# Configure CORS
+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=["*"],
+    )
+
+# Include API router
+app.include_router(api_router, prefix=settings.API_V1_STR)
+
+# Health check endpoint
+@app.get("/health", response_model=None)
+async def health_check():
+    """
+    Health check endpoint to verify the API is running.
+    """
+    return JSONResponse(content={"status": "healthy"})
+
+
+if __name__ == "__main__":
+    import uvicorn
+    uvicorn.run(app, host="0.0.0.0", port=8000)

migrations/__init__.py

@@ -0,0 +1 @@
+# This file is here to make the migrations directory a Python package.

migrations/env.py

@@ -0,0 +1,86 @@
+import os
+import sys
+from logging.config import fileConfig
+
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+
+# Add the project root directory to the Python path
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+# Import the SQLAlchemy metadata object
+from app.db.session import Base
+from app.models import *  # Import all models for Alembic to detect them
+
+# 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
+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:
+        is_sqlite = connection.dialect.name == "sqlite"
+        context.configure(
+            connection=connection,
+            target_metadata=target_metadata,
+            render_as_batch=is_sqlite,  # Key configuration for SQLite
+            compare_type=True,
+        )
+
+        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/__init__.py

@@ -0,0 +1 @@
+# This file is here to make the versions directory a Python package.

migrations/versions/initial_migration.py

@@ -0,0 +1,114 @@
+"""Initial migration
+
+Revision ID: 001
+Revises: 
+Create Date: 2023-07-20
+
+"""
+import sqlalchemy as sa
+from alembic import op
+
+# 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('email', sa.String(), nullable=False),
+        sa.Column('full_name', sa.String(), nullable=True),
+        sa.Column('hashed_password', sa.String(), nullable=False),
+        sa.Column('is_active', sa.Boolean(), nullable=False, default=True),
+        sa.Column('is_superuser', sa.Boolean(), nullable=False, default=False),
+        sa.Column('created_at', sa.DateTime(), nullable=False),
+        sa.Column('updated_at', sa.DateTime(), nullable=False),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_user_email'), 'user', ['email'], unique=True)
+    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.Column('created_at', sa.DateTime(), nullable=False),
+        sa.Column('updated_at', sa.DateTime(), nullable=False),
+        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=True)
+    
+    # Create item table
+    op.create_table(
+        'item',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('name', sa.String(), nullable=False),
+        sa.Column('sku', sa.String(), nullable=False),
+        sa.Column('description', sa.Text(), nullable=True),
+        sa.Column('price', sa.Float(), nullable=False),
+        sa.Column('quantity', sa.Integer(), nullable=False, default=0),
+        sa.Column('reorder_level', sa.Integer(), nullable=False, default=10),
+        sa.Column('category_id', sa.Integer(), nullable=True),
+        sa.Column('owner_id', sa.Integer(), nullable=True),
+        sa.Column('created_at', sa.DateTime(), nullable=False),
+        sa.Column('updated_at', sa.DateTime(), nullable=False),
+        sa.ForeignKeyConstraint(['category_id'], ['category.id'], ),
+        sa.ForeignKeyConstraint(['owner_id'], ['user.id'], ),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_item_id'), 'item', ['id'], unique=False)
+    op.create_index(op.f('ix_item_name'), 'item', ['name'], unique=False)
+    op.create_index(op.f('ix_item_sku'), 'item', ['sku'], unique=True)
+    
+    # Create transaction table
+    op.create_table(
+        'transaction',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column(
+            'transaction_type', 
+            sa.Enum('purchase', 'sale', 'adjustment', 'return', name='transactiontype'), 
+            nullable=False
+        ),
+        sa.Column('quantity', sa.Integer(), nullable=False),
+        sa.Column('unit_price', sa.Float(), nullable=True),
+        sa.Column('reference_number', sa.String(), nullable=True),
+        sa.Column('notes', sa.String(), nullable=True),
+        sa.Column('transaction_date', sa.DateTime(), nullable=False),
+        sa.Column('item_id', sa.Integer(), nullable=False),
+        sa.Column('recorded_by_id', sa.Integer(), nullable=True),
+        sa.Column('created_at', sa.DateTime(), nullable=False),
+        sa.Column('updated_at', sa.DateTime(), nullable=False),
+        sa.ForeignKeyConstraint(['item_id'], ['item.id'], ),
+        sa.ForeignKeyConstraint(['recorded_by_id'], ['user.id'], ),
+        sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_transaction_id'), 'transaction', ['id'], unique=False)
+
+
+def downgrade():
+    # Drop transaction table
+    op.drop_index(op.f('ix_transaction_id'), table_name='transaction')
+    op.drop_table('transaction')
+    
+    # Drop item table
+    op.drop_index(op.f('ix_item_sku'), table_name='item')
+    op.drop_index(op.f('ix_item_name'), table_name='item')
+    op.drop_index(op.f('ix_item_id'), table_name='item')
+    op.drop_table('item')
+    
+    # Drop category table
+    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')
+    
+    # Drop user table
+    op.drop_index(op.f('ix_user_id'), table_name='user')
+    op.drop_index(op.f('ix_user_email'), table_name='user')
+    op.drop_table('user')

pyproject.toml

@@ -0,0 +1,12 @@
+[tool.ruff]
+line-length = 120
+indent-width = 4
+target-version = "py38"
+
+[tool.ruff.lint]
+select = ["E", "F", "B", "I"]
+ignore = ["B008", "F403", "F401"]  # Allow Depends() calls in function defaults, star imports and unused imports
+
+[tool.ruff.format]
+quote-style = "double"
+indent-style = "space"

requirements.txt

@@ -0,0 +1,12 @@
+fastapi>=0.95.0
+uvicorn>=0.22.0
+sqlalchemy>=2.0.0
+alembic>=1.11.0
+pydantic>=2.0.0
+pydantic-settings>=2.0.0
+python-jose[cryptography]>=3.3.0
+passlib[bcrypt]>=1.7.4
+python-multipart>=0.0.6
+ruff>=0.0.262
+python-dotenv>=1.0.0
+email-validator>=2.0.0