Implement complete FastAPI inventory management system

- Set up project structure with FastAPI and SQLite
- Created database models for users, categories, suppliers, items, and stock transactions
- Implemented Alembic for database migrations with proper absolute paths
- Built comprehensive CRUD operations for all entities
- Added JWT-based authentication and authorization system
- Created RESTful API endpoints for all inventory operations
- Implemented search, filtering, and low stock alerts
- Added health check endpoint and base URL response
- Configured CORS for all origins
- Set up Ruff for code linting and formatting
- Updated README with comprehensive documentation and usage examples

The system provides complete inventory management functionality for small businesses
including product tracking, supplier management, stock transactions, and reporting.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -1,3 +1,194 @@
-# FastAPI Application
+# Small Business Inventory Management System
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A comprehensive FastAPI-based inventory management system designed for small businesses to track products, manage suppliers, monitor stock levels, and handle inventory transactions.
+
+## Features
+
+- **Product Management**: Add, update, and track inventory items with detailed information
+- **Category Management**: Organize products into categories for better organization
+- **Supplier Management**: Maintain supplier information and relationships
+- **Stock Tracking**: Real-time stock level monitoring with low stock alerts
+- **Transaction History**: Complete audit trail of all stock movements
+- **Authentication**: Secure JWT-based authentication system
+- **Search & Filtering**: Powerful search capabilities across inventory items
+- **RESTful API**: Clean, well-documented API endpoints
+
+## Technology Stack
+
+- **Framework**: FastAPI
+- **Database**: SQLite with SQLAlchemy ORM
+- **Authentication**: JWT tokens with PassLib for password hashing
+- **Migration**: Alembic for database migrations
+- **Validation**: Pydantic for data validation
+- **Documentation**: Auto-generated OpenAPI/Swagger documentation
+
+## Installation
+
+1. Install dependencies:
+```bash
+pip install -r requirements.txt
+```
+
+2. Run database migrations:
+```bash
+alembic upgrade head
+```
+
+3. Start the application:
+```bash
+uvicorn main:app --host 0.0.0.0 --port 8000 --reload
+```
+
+## Environment Variables
+
+The following environment variables can be set to configure the application:
+
+- `SECRET_KEY`: JWT secret key (default: "your-secret-key-change-this-in-production")
+- `FIRST_SUPERUSER_EMAIL`: Admin user email (default: "admin@inventory.com")
+- `FIRST_SUPERUSER_PASSWORD`: Admin user password (default: "admin123")
+
+**Important**: Change the default SECRET_KEY and admin credentials in production!
+
+## API Documentation
+
+Once the application is running, you can access:
+
+- **Interactive API Documentation**: http://localhost:8000/docs
+- **Alternative Documentation**: http://localhost:8000/redoc
+- **OpenAPI Schema**: http://localhost:8000/openapi.json
+
+## API Endpoints
+
+### Authentication
+- `POST /auth/login` - User login
+
+### Categories
+- `GET /categories/` - List all categories
+- `POST /categories/` - Create new category
+- `GET /categories/{id}` - Get category by ID
+- `PUT /categories/{id}` - Update category
+- `DELETE /categories/{id}` - Delete category
+
+### Suppliers
+- `GET /suppliers/` - List all suppliers
+- `POST /suppliers/` - Create new supplier
+- `GET /suppliers/{id}` - Get supplier by ID
+- `PUT /suppliers/{id}` - Update supplier
+- `DELETE /suppliers/{id}` - Delete supplier
+
+### Items
+- `GET /items/` - List all items
+- `POST /items/` - Create new item
+- `GET /items/{id}` - Get item by ID
+- `PUT /items/{id}` - Update item
+- `DELETE /items/{id}` - Delete item
+- `GET /items/search?query={query}` - Search items
+- `GET /items/low-stock` - Get items with low stock
+- `GET /items/active` - Get active items only
+
+### Stock Transactions
+- `GET /stock-transactions/` - List all transactions
+- `POST /stock-transactions/` - Create new transaction (updates stock automatically)
+- `GET /stock-transactions/{id}` - Get transaction by ID
+- `GET /stock-transactions/item/{item_id}` - Get transactions for specific item
+- `GET /stock-transactions/type/{type}` - Get transactions by type (in/out/adjustment)
+
+### System
+- `GET /` - API information and links
+- `GET /health` - Health check endpoint
+
+## Database Schema
+
+The system uses the following main entities:
+
+- **Users**: System users with authentication
+- **Categories**: Product categories for organization
+- **Suppliers**: Supplier information and contacts
+- **Items**: Inventory items with pricing and stock information
+- **StockTransactions**: Record of all stock movements
+
+## Usage Examples
+
+### 1. Login
+```bash
+curl -X POST "http://localhost:8000/auth/login" \
+  -H "Content-Type: application/json" \
+  -d '{"email": "admin@inventory.com", "password": "admin123"}'
+```
+
+### 2. Create a Category
+```bash
+curl -X POST "http://localhost:8000/categories/" \
+  -H "Authorization: Bearer YOUR_TOKEN" \
+  -H "Content-Type: application/json" \
+  -d '{"name": "Electronics", "description": "Electronic devices and components"}'
+```
+
+### 3. Add an Item
+```bash
+curl -X POST "http://localhost:8000/items/" \
+  -H "Authorization: Bearer YOUR_TOKEN" \
+  -H "Content-Type: application/json" \
+  -d '{
+    "name": "Laptop Computer",
+    "description": "High-performance laptop",
+    "sku": "LAP001",
+    "unit_price": 999.99,
+    "cost_price": 750.00,
+    "quantity_in_stock": 10,
+    "minimum_stock_level": 2,
+    "reorder_point": 5,
+    "category_id": 1
+  }'
+```
+
+### 4. Record Stock Transaction
+```bash
+curl -X POST "http://localhost:8000/stock-transactions/" \
+  -H "Authorization: Bearer YOUR_TOKEN" \
+  -H "Content-Type: application/json" \
+  -d '{
+    "item_id": 1,
+    "transaction_type": "out",
+    "quantity": 2,
+    "reference_number": "SALE001",
+    "notes": "Sale to customer"
+  }'
+```
+
+## Development
+
+### Running with Auto-reload
+```bash
+uvicorn main:app --reload
+```
+
+### Code Formatting
+The project uses Ruff for linting and formatting:
+```bash
+ruff check .
+ruff format .
+```
+
+### Database Migrations
+Create a new migration:
+```bash
+alembic revision --autogenerate -m "Description of changes"
+```
+
+Apply migrations:
+```bash
+alembic upgrade head
+```
+
+## Production Deployment
+
+1. Set secure environment variables
+2. Use a production WSGI server like Gunicorn
+3. Configure proper SSL/TLS certificates
+4. Set up database backups
+5. Configure logging and monitoring
+
+## License
+
+This project is open source and available under the MIT License.

alembic.ini

@@ -0,0 +1,41 @@
+[alembic]
+script_location = alembic
+prepend_sys_path = .
+version_path_separator = os
+sqlalchemy.url = sqlite:////app/storage/db/db.sqlite
+
+[post_write_hooks]
+
+[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

alembic/env.py

@@ -0,0 +1,58 @@
+from logging.config import fileConfig
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+from alembic import context
+import os
+import sys
+
+# Add the project root to the Python path
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from app.db.base import Base
+from app.models import User, Category, Supplier, Item, StockTransaction
+
+# 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.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+target_metadata = Base.metadata
+
+
+def run_migrations_offline() -> None:
+    """Run migrations in 'offline' mode."""
+    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() -> None:
+    """Run migrations in 'online' mode."""
+    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()

alembic/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() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

alembic/versions/001_initial_migration.py

@@ -0,0 +1,142 @@
+"""Initial migration
+
+Revision ID: 001
+Revises:
+Create Date: 2024-01-01 12:00:00.000000
+
+"""
+
+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() -> None:
+    # Create users table
+    op.create_table(
+        "users",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column("email", sa.String(), nullable=False),
+        sa.Column("hashed_password", sa.String(), nullable=False),
+        sa.Column("full_name", sa.String(), nullable=True),
+        sa.Column("is_active", sa.Boolean(), nullable=True),
+        sa.Column("is_superuser", sa.Boolean(), nullable=True),
+        sa.Column("created_at", sa.DateTime(), nullable=True),
+        sa.Column("updated_at", sa.DateTime(), nullable=True),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index(op.f("ix_users_email"), "users", ["email"], unique=True)
+    op.create_index(op.f("ix_users_id"), "users", ["id"], unique=False)
+
+    # Create categories table
+    op.create_table(
+        "categories",
+        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=True),
+        sa.Column("updated_at", sa.DateTime(), nullable=True),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index(op.f("ix_categories_id"), "categories", ["id"], unique=False)
+    op.create_index(op.f("ix_categories_name"), "categories", ["name"], unique=True)
+
+    # Create suppliers table
+    op.create_table(
+        "suppliers",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column("name", sa.String(), nullable=False),
+        sa.Column("contact_person", sa.String(), nullable=True),
+        sa.Column("email", sa.String(), nullable=True),
+        sa.Column("phone", sa.String(), nullable=True),
+        sa.Column("address", sa.Text(), nullable=True),
+        sa.Column("created_at", sa.DateTime(), nullable=True),
+        sa.Column("updated_at", sa.DateTime(), nullable=True),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index(op.f("ix_suppliers_id"), "suppliers", ["id"], unique=False)
+    op.create_index(op.f("ix_suppliers_name"), "suppliers", ["name"], unique=True)
+
+    # Create items table
+    op.create_table(
+        "items",
+        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=False),
+        sa.Column("barcode", sa.String(), nullable=True),
+        sa.Column("unit_price", sa.Float(), nullable=False),
+        sa.Column("cost_price", sa.Float(), nullable=True),
+        sa.Column("quantity_in_stock", sa.Integer(), nullable=True),
+        sa.Column("minimum_stock_level", sa.Integer(), nullable=True),
+        sa.Column("maximum_stock_level", sa.Integer(), nullable=True),
+        sa.Column("reorder_point", sa.Integer(), nullable=True),
+        sa.Column("is_active", sa.Boolean(), nullable=True),
+        sa.Column("category_id", sa.Integer(), nullable=True),
+        sa.Column("supplier_id", sa.Integer(), nullable=True),
+        sa.Column("created_at", sa.DateTime(), nullable=True),
+        sa.Column("updated_at", sa.DateTime(), nullable=True),
+        sa.ForeignKeyConstraint(
+            ["category_id"],
+            ["categories.id"],
+        ),
+        sa.ForeignKeyConstraint(
+            ["supplier_id"],
+            ["suppliers.id"],
+        ),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index(op.f("ix_items_barcode"), "items", ["barcode"], unique=True)
+    op.create_index(op.f("ix_items_id"), "items", ["id"], unique=False)
+    op.create_index(op.f("ix_items_name"), "items", ["name"], unique=False)
+    op.create_index(op.f("ix_items_sku"), "items", ["sku"], unique=True)
+
+    # Create stock_transactions table
+    op.create_table(
+        "stock_transactions",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column("item_id", sa.Integer(), nullable=False),
+        sa.Column(
+            "transaction_type",
+            sa.Enum("IN", "OUT", "ADJUSTMENT", name="transactiontype"),
+            nullable=False,
+        ),
+        sa.Column("quantity", sa.Integer(), nullable=False),
+        sa.Column("unit_cost", sa.Float(), nullable=True),
+        sa.Column("reference_number", sa.String(), nullable=True),
+        sa.Column("notes", sa.Text(), nullable=True),
+        sa.Column("created_at", sa.DateTime(), nullable=True),
+        sa.ForeignKeyConstraint(
+            ["item_id"],
+            ["items.id"],
+        ),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index(
+        op.f("ix_stock_transactions_id"), "stock_transactions", ["id"], unique=False
+    )
+
+
+def downgrade() -> None:
+    op.drop_index(op.f("ix_stock_transactions_id"), table_name="stock_transactions")
+    op.drop_table("stock_transactions")
+    op.drop_index(op.f("ix_items_sku"), table_name="items")
+    op.drop_index(op.f("ix_items_name"), table_name="items")
+    op.drop_index(op.f("ix_items_id"), table_name="items")
+    op.drop_index(op.f("ix_items_barcode"), table_name="items")
+    op.drop_table("items")
+    op.drop_index(op.f("ix_suppliers_name"), table_name="suppliers")
+    op.drop_index(op.f("ix_suppliers_id"), table_name="suppliers")
+    op.drop_table("suppliers")
+    op.drop_index(op.f("ix_categories_name"), table_name="categories")
+    op.drop_index(op.f("ix_categories_id"), table_name="categories")
+    op.drop_table("categories")
+    op.drop_index(op.f("ix_users_id"), table_name="users")
+    op.drop_index(op.f("ix_users_email"), table_name="users")
+    op.drop_table("users")

app/api/auth.py

@@ -0,0 +1,36 @@
+from datetime import timedelta
+from typing import Any
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+from app.core import security
+from app.core.config import settings
+from app.crud import user as user_crud
+from app.db.session import get_db
+from app.schemas.user import UserLogin
+
+router = APIRouter()
+
+
+@router.post("/login")
+def login_access_token(
+    db: Session = Depends(get_db), form_data: UserLogin = None
+) -> Any:
+    user = user_crud.authenticate(
+        db, email=form_data.email, password=form_data.password
+    )
+    if not user:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect email or password",
+        )
+    elif not user_crud.is_active(user):
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED, detail="Inactive user"
+        )
+    access_token_expires = timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
+    return {
+        "access_token": security.create_access_token(
+            user.email, expires_delta=access_token_expires
+        ),
+        "token_type": "bearer",
+    }

app/api/categories.py

@@ -0,0 +1,80 @@
+from typing import Any, List
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.orm import Session
+from app.core.auth import get_current_active_user
+from app.crud import category as category_crud
+from app.db.session import get_db
+from app.models 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_active_user),
+) -> Any:
+    categories = category_crud.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_user),
+) -> Any:
+    category = category_crud.get_by_name(db, name=category_in.name)
+    if category:
+        raise HTTPException(
+            status_code=400,
+            detail="Category with this name already exists.",
+        )
+    category = category_crud.create(db, obj_in=category_in)
+    return 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_user),
+) -> Any:
+    category = category_crud.get(db, id=id)
+    if not category:
+        raise HTTPException(status_code=404, detail="Category not found")
+    category = category_crud.update(db, db_obj=category, obj_in=category_in)
+    return category
+
+
+@router.get("/{id}", response_model=Category)
+def read_category(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    category = category_crud.get(db, id=id)
+    if not category:
+        raise HTTPException(status_code=404, detail="Category not found")
+    return category
+
+
+@router.delete("/{id}", response_model=Category)
+def delete_category(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    category = category_crud.get(db, id=id)
+    if not category:
+        raise HTTPException(status_code=404, detail="Category not found")
+    category = category_crud.remove(db, id=id)
+    return category

app/api/items.py

@@ -0,0 +1,121 @@
+from typing import Any, List
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy.orm import Session
+from app.core.auth import get_current_active_user
+from app.crud import item as item_crud
+from app.db.session import get_db
+from app.models import User
+from app.schemas.item import Item, ItemCreate, ItemUpdate, ItemWithLowStock
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[Item])
+def read_items(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    items = item_crud.get_multi(db, skip=skip, limit=limit)
+    return items
+
+
+@router.get("/search", response_model=List[Item])
+def search_items(
+    query: str = Query(..., description="Search query"),
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    items = item_crud.search_items(db, query=query, skip=skip, limit=limit)
+    return items
+
+
+@router.get("/low-stock", response_model=List[ItemWithLowStock])
+def read_low_stock_items(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    items = item_crud.get_low_stock_items(db, skip=skip, limit=limit)
+    return items
+
+
+@router.get("/active", response_model=List[Item])
+def read_active_items(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    items = item_crud.get_active_items(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_active_user),
+) -> Any:
+    item = item_crud.get_by_sku(db, sku=item_in.sku)
+    if item:
+        raise HTTPException(
+            status_code=400,
+            detail="Item with this SKU already exists.",
+        )
+    if item_in.barcode:
+        item = item_crud.get_by_barcode(db, barcode=item_in.barcode)
+        if item:
+            raise HTTPException(
+                status_code=400,
+                detail="Item with this barcode already exists.",
+            )
+    item = item_crud.create(db, obj_in=item_in)
+    return 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_active_user),
+) -> Any:
+    item = item_crud.get(db, id=id)
+    if not item:
+        raise HTTPException(status_code=404, detail="Item not found")
+    item = item_crud.update(db, db_obj=item, obj_in=item_in)
+    return item
+
+
+@router.get("/{id}", response_model=Item)
+def read_item(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    item = item_crud.get(db, id=id)
+    if not item:
+        raise HTTPException(status_code=404, detail="Item not found")
+    return item
+
+
+@router.delete("/{id}", response_model=Item)
+def delete_item(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    item = item_crud.get(db, id=id)
+    if not item:
+        raise HTTPException(status_code=404, detail="Item not found")
+    item = item_crud.remove(db, id=id)
+    return item

app/api/stock_transactions.py

@@ -0,0 +1,78 @@
+from typing import Any, List
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.orm import Session
+from app.core.auth import get_current_active_user
+from app.crud import stock_transaction as stock_transaction_crud
+from app.db.session import get_db
+from app.models import User
+from app.models.stock_transaction import TransactionType
+from app.schemas.stock_transaction import StockTransaction, StockTransactionCreate
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[StockTransaction])
+def read_stock_transactions(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    transactions = stock_transaction_crud.get_multi(db, skip=skip, limit=limit)
+    return transactions
+
+
+@router.get("/item/{item_id}", response_model=List[StockTransaction])
+def read_item_transactions(
+    *,
+    db: Session = Depends(get_db),
+    item_id: int,
+    skip: int = 0,
+    limit: int = 100,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    transactions = stock_transaction_crud.get_by_item(
+        db, item_id=item_id, skip=skip, limit=limit
+    )
+    return transactions
+
+
+@router.get("/type/{transaction_type}", response_model=List[StockTransaction])
+def read_transactions_by_type(
+    *,
+    db: Session = Depends(get_db),
+    transaction_type: TransactionType,
+    skip: int = 0,
+    limit: int = 100,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    transactions = stock_transaction_crud.get_by_type(
+        db, transaction_type=transaction_type, skip=skip, limit=limit
+    )
+    return transactions
+
+
+@router.post("/", response_model=StockTransaction)
+def create_stock_transaction(
+    *,
+    db: Session = Depends(get_db),
+    transaction_in: StockTransactionCreate,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    transaction = stock_transaction_crud.create_with_stock_update(
+        db, obj_in=transaction_in
+    )
+    return transaction
+
+
+@router.get("/{id}", response_model=StockTransaction)
+def read_stock_transaction(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    transaction = stock_transaction_crud.get(db, id=id)
+    if not transaction:
+        raise HTTPException(status_code=404, detail="Stock transaction not found")
+    return transaction

app/api/suppliers.py

@@ -0,0 +1,80 @@
+from typing import Any, List
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.orm import Session
+from app.core.auth import get_current_active_user
+from app.crud import supplier as supplier_crud
+from app.db.session import get_db
+from app.models import User
+from app.schemas.supplier import Supplier, SupplierCreate, SupplierUpdate
+
+router = APIRouter()
+
+
+@router.get("/", response_model=List[Supplier])
+def read_suppliers(
+    db: Session = Depends(get_db),
+    skip: int = 0,
+    limit: int = 100,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    suppliers = supplier_crud.get_multi(db, skip=skip, limit=limit)
+    return suppliers
+
+
+@router.post("/", response_model=Supplier)
+def create_supplier(
+    *,
+    db: Session = Depends(get_db),
+    supplier_in: SupplierCreate,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    supplier = supplier_crud.get_by_name(db, name=supplier_in.name)
+    if supplier:
+        raise HTTPException(
+            status_code=400,
+            detail="Supplier with this name already exists.",
+        )
+    supplier = supplier_crud.create(db, obj_in=supplier_in)
+    return supplier
+
+
+@router.put("/{id}", response_model=Supplier)
+def update_supplier(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    supplier_in: SupplierUpdate,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    supplier = supplier_crud.get(db, id=id)
+    if not supplier:
+        raise HTTPException(status_code=404, detail="Supplier not found")
+    supplier = supplier_crud.update(db, db_obj=supplier, obj_in=supplier_in)
+    return supplier
+
+
+@router.get("/{id}", response_model=Supplier)
+def read_supplier(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    supplier = supplier_crud.get(db, id=id)
+    if not supplier:
+        raise HTTPException(status_code=404, detail="Supplier not found")
+    return supplier
+
+
+@router.delete("/{id}", response_model=Supplier)
+def delete_supplier(
+    *,
+    db: Session = Depends(get_db),
+    id: int,
+    current_user: User = Depends(get_current_active_user),
+) -> Any:
+    supplier = supplier_crud.get(db, id=id)
+    if not supplier:
+        raise HTTPException(status_code=404, detail="Supplier not found")
+    supplier = supplier_crud.remove(db, id=id)
+    return supplier

app/core/auth.py

@@ -0,0 +1,53 @@
+from fastapi import Depends, HTTPException, status
+from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
+from jose import JWTError, jwt
+from sqlalchemy.orm import Session
+from app.core.config import settings
+from app.crud import user as user_crud
+from app.db.session import get_db
+from app.models.user import User
+
+security = HTTPBearer()
+
+
+def get_current_user(
+    db: Session = Depends(get_db),
+    credentials: HTTPAuthorizationCredentials = Depends(security),
+) -> User:
+    credentials_exception = HTTPException(
+        status_code=status.HTTP_401_UNAUTHORIZED,
+        detail="Could not validate credentials",
+        headers={"WWW-Authenticate": "Bearer"},
+    )
+    try:
+        payload = jwt.decode(
+            credentials.credentials,
+            settings.SECRET_KEY,
+            algorithms=[settings.ALGORITHM],
+        )
+        email: str = payload.get("sub")
+        if email is None:
+            raise credentials_exception
+    except JWTError:
+        raise credentials_exception
+
+    user = user_crud.get_by_email(db, email=email)
+    if user is None:
+        raise credentials_exception
+    return user
+
+
+def get_current_active_user(current_user: User = Depends(get_current_user)) -> User:
+    if not user_crud.is_active(current_user):
+        raise HTTPException(status_code=400, detail="Inactive user")
+    return current_user
+
+
+def get_current_active_superuser(
+    current_user: User = Depends(get_current_user),
+) -> User:
+    if not user_crud.is_superuser(current_user):
+        raise HTTPException(
+            status_code=400, detail="The user doesn't have enough privileges"
+        )
+    return current_user

app/core/config.py

@@ -0,0 +1,26 @@
+from decouple import config
+
+
+class Settings:
+    PROJECT_NAME: str = "Small Business Inventory Management System"
+    PROJECT_VERSION: str = "1.0.0"
+
+    SECRET_KEY: str = config(
+        "SECRET_KEY", default="your-secret-key-change-this-in-production"
+    )
+    ALGORITHM: str = "HS256"
+    ACCESS_TOKEN_EXPIRE_MINUTES: int = 30
+
+    # Admin user
+    FIRST_SUPERUSER_EMAIL: str = config(
+        "FIRST_SUPERUSER_EMAIL", default="admin@inventory.com"
+    )
+    FIRST_SUPERUSER_PASSWORD: str = config(
+        "FIRST_SUPERUSER_PASSWORD", default="admin123"
+    )
+
+    # CORS
+    BACKEND_CORS_ORIGINS: list = ["*"]
+
+
+settings = Settings()

app/core/security.py

@@ -0,0 +1,31 @@
+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:
+    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:
+    return pwd_context.verify(plain_password, hashed_password)
+
+
+def get_password_hash(password: str) -> str:
+    return pwd_context.hash(password)

app/crud/__init__.py

@@ -0,0 +1,7 @@
+from .user import user
+from .category import category
+from .supplier import supplier
+from .item import item
+from .stock_transaction import stock_transaction
+
+__all__ = ["user", "category", "supplier", "item", "stock_transaction"]

app/crud/base.py

@@ -0,0 +1,56 @@
+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 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]):
+        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/category.py

@@ -0,0 +1,13 @@
+from typing import 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/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]):
+    def get_by_sku(self, db: Session, *, sku: str) -> Optional[Item]:
+        return db.query(Item).filter(Item.sku == sku).first()
+
+    def get_by_barcode(self, db: Session, *, barcode: str) -> Optional[Item]:
+        return db.query(Item).filter(Item.barcode == barcode).first()
+
+    def get_by_category(
+        self, db: Session, *, category_id: int, skip: int = 0, limit: int = 100
+    ) -> List[Item]:
+        return (
+            db.query(Item)
+            .filter(Item.category_id == category_id)
+            .offset(skip)
+            .limit(limit)
+            .all()
+        )
+
+    def get_by_supplier(
+        self, db: Session, *, supplier_id: int, skip: int = 0, limit: int = 100
+    ) -> List[Item]:
+        return (
+            db.query(Item)
+            .filter(Item.supplier_id == supplier_id)
+            .offset(skip)
+            .limit(limit)
+            .all()
+        )
+
+    def get_low_stock_items(
+        self, db: Session, skip: int = 0, limit: int = 100
+    ) -> List[Item]:
+        return (
+            db.query(Item)
+            .filter(Item.quantity_in_stock <= Item.reorder_point)
+            .offset(skip)
+            .limit(limit)
+            .all()
+        )
+
+    def get_active_items(
+        self, db: Session, skip: int = 0, limit: int = 100
+    ) -> List[Item]:
+        return db.query(Item).filter(Item.is_active).offset(skip).limit(limit).all()
+
+    def search_items(
+        self, db: Session, *, query: str, skip: int = 0, limit: int = 100
+    ) -> List[Item]:
+        return (
+            db.query(Item)
+            .filter(
+                Item.name.contains(query)
+                | Item.description.contains(query)
+                | Item.sku.contains(query)
+            )
+            .offset(skip)
+            .limit(limit)
+            .all()
+        )
+
+
+item = CRUDItem(Item)

app/crud/stock_transaction.py

@@ -0,0 +1,61 @@
+from typing import List
+from sqlalchemy.orm import Session
+from app.crud.base import CRUDBase
+from app.models.stock_transaction import StockTransaction, TransactionType
+from app.schemas.stock_transaction import StockTransactionCreate
+from app.crud.item import item as item_crud
+
+
+class CRUDStockTransaction(CRUDBase[StockTransaction, StockTransactionCreate, None]):
+    def create_with_stock_update(
+        self, db: Session, *, obj_in: StockTransactionCreate
+    ) -> StockTransaction:
+        # Create the transaction
+        transaction = self.create(db, obj_in=obj_in)
+
+        # Update item stock
+        db_item = item_crud.get(db, id=obj_in.item_id)
+        if db_item:
+            if obj_in.transaction_type == TransactionType.IN:
+                db_item.quantity_in_stock += obj_in.quantity
+            elif obj_in.transaction_type == TransactionType.OUT:
+                db_item.quantity_in_stock -= obj_in.quantity
+            elif obj_in.transaction_type == TransactionType.ADJUSTMENT:
+                db_item.quantity_in_stock = obj_in.quantity
+
+            db.add(db_item)
+            db.commit()
+
+        return transaction
+
+    def get_by_item(
+        self, db: Session, *, item_id: int, skip: int = 0, limit: int = 100
+    ) -> List[StockTransaction]:
+        return (
+            db.query(StockTransaction)
+            .filter(StockTransaction.item_id == item_id)
+            .order_by(StockTransaction.created_at.desc())
+            .offset(skip)
+            .limit(limit)
+            .all()
+        )
+
+    def get_by_type(
+        self,
+        db: Session,
+        *,
+        transaction_type: TransactionType,
+        skip: int = 0,
+        limit: int = 100,
+    ) -> List[StockTransaction]:
+        return (
+            db.query(StockTransaction)
+            .filter(StockTransaction.transaction_type == transaction_type)
+            .order_by(StockTransaction.created_at.desc())
+            .offset(skip)
+            .limit(limit)
+            .all()
+        )
+
+
+stock_transaction = CRUDStockTransaction(StockTransaction)

app/crud/supplier.py

@@ -0,0 +1,13 @@
+from typing import Optional
+from sqlalchemy.orm import Session
+from app.crud.base import CRUDBase
+from app.models.supplier import Supplier
+from app.schemas.supplier import SupplierCreate, SupplierUpdate
+
+
+class CRUDSupplier(CRUDBase[Supplier, SupplierCreate, SupplierUpdate]):
+    def get_by_name(self, db: Session, *, name: str) -> Optional[Supplier]:
+        return db.query(Supplier).filter(Supplier.name == name).first()
+
+
+supplier = CRUDSupplier(Supplier)

app/crud/user.py

@@ -0,0 +1,53 @@
+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]):
+    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_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 "password" in update_data:
+            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_superuser(self, user: User) -> bool:
+        return user.is_superuser
+
+
+user = CRUDUser(User)

app/db/base.py

@@ -0,0 +1,3 @@
+from sqlalchemy.ext.declarative import declarative_base
+
+Base = declarative_base()

app/db/session.py

@@ -0,0 +1,22 @@
+from pathlib import Path
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+DB_DIR = Path("/app") / "storage" / "db"
+DB_DIR.mkdir(parents=True, exist_ok=True)
+
+SQLALCHEMY_DATABASE_URL = f"sqlite:///{DB_DIR}/db.sqlite"
+
+engine = create_engine(
+    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/__init__.py

@@ -0,0 +1,14 @@
+from .user import User
+from .category import Category
+from .supplier import Supplier
+from .item import Item
+from .stock_transaction import StockTransaction, TransactionType
+
+__all__ = [
+    "User",
+    "Category",
+    "Supplier",
+    "Item",
+    "StockTransaction",
+    "TransactionType",
+]

app/models/category.py

@@ -0,0 +1,16 @@
+from sqlalchemy import Column, Integer, String, DateTime, Text
+from sqlalchemy.orm import relationship
+from datetime import datetime
+from app.db.base import Base
+
+
+class Category(Base):
+    __tablename__ = "categories"
+
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String, unique=True, index=True, nullable=False)
+    description = Column(Text)
+    created_at = Column(DateTime, default=datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    items = relationship("Item", back_populates="category")

app/models/item.py

@@ -0,0 +1,40 @@
+from sqlalchemy import (
+    Column,
+    Integer,
+    String,
+    DateTime,
+    Text,
+    Float,
+    ForeignKey,
+    Boolean,
+)
+from sqlalchemy.orm import relationship
+from datetime import datetime
+from app.db.base import Base
+
+
+class Item(Base):
+    __tablename__ = "items"
+
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String, index=True, nullable=False)
+    description = Column(Text)
+    sku = Column(String, unique=True, index=True, nullable=False)
+    barcode = Column(String, unique=True, index=True)
+    unit_price = Column(Float, nullable=False)
+    cost_price = Column(Float)
+    quantity_in_stock = Column(Integer, default=0)
+    minimum_stock_level = Column(Integer, default=0)
+    maximum_stock_level = Column(Integer)
+    reorder_point = Column(Integer, default=0)
+    is_active = Column(Boolean, default=True)
+
+    category_id = Column(Integer, ForeignKey("categories.id"))
+    supplier_id = Column(Integer, ForeignKey("suppliers.id"))
+
+    created_at = Column(DateTime, default=datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    category = relationship("Category", back_populates="items")
+    supplier = relationship("Supplier", back_populates="items")
+    transactions = relationship("StockTransaction", back_populates="item")

app/models/stock_transaction.py

@@ -0,0 +1,26 @@
+from sqlalchemy import Column, Integer, String, DateTime, Text, Float, ForeignKey, Enum
+from sqlalchemy.orm import relationship
+from datetime import datetime
+from app.db.base import Base
+import enum
+
+
+class TransactionType(enum.Enum):
+    IN = "in"
+    OUT = "out"
+    ADJUSTMENT = "adjustment"
+
+
+class StockTransaction(Base):
+    __tablename__ = "stock_transactions"
+
+    id = Column(Integer, primary_key=True, index=True)
+    item_id = Column(Integer, ForeignKey("items.id"), nullable=False)
+    transaction_type = Column(Enum(TransactionType), nullable=False)
+    quantity = Column(Integer, nullable=False)
+    unit_cost = Column(Float)
+    reference_number = Column(String)
+    notes = Column(Text)
+    created_at = Column(DateTime, default=datetime.utcnow)
+
+    item = relationship("Item", back_populates="transactions")

app/models/supplier.py

@@ -0,0 +1,19 @@
+from sqlalchemy import Column, Integer, String, DateTime, Text
+from sqlalchemy.orm import relationship
+from datetime import datetime
+from app.db.base import Base
+
+
+class Supplier(Base):
+    __tablename__ = "suppliers"
+
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String, unique=True, index=True, nullable=False)
+    contact_person = Column(String)
+    email = Column(String)
+    phone = Column(String)
+    address = Column(Text)
+    created_at = Column(DateTime, default=datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    items = relationship("Item", back_populates="supplier")

app/models/user.py

@@ -0,0 +1,16 @@
+from sqlalchemy import Column, Integer, String, DateTime, Boolean
+from datetime import datetime
+from app.db.base import Base
+
+
+class User(Base):
+    __tablename__ = "users"
+
+    id = Column(Integer, primary_key=True, index=True)
+    email = Column(String, unique=True, index=True, nullable=False)
+    hashed_password = Column(String, nullable=False)
+    full_name = Column(String)
+    is_active = Column(Boolean, default=True)
+    is_superuser = Column(Boolean, default=False)
+    created_at = Column(DateTime, default=datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)

app/schemas/__init__.py

@@ -0,0 +1,24 @@
+from .user import User, UserCreate, UserUpdate, UserLogin
+from .category import Category, CategoryCreate, CategoryUpdate
+from .supplier import Supplier, SupplierCreate, SupplierUpdate
+from .item import Item, ItemCreate, ItemUpdate, ItemWithLowStock
+from .stock_transaction import StockTransaction, StockTransactionCreate
+
+__all__ = [
+    "User",
+    "UserCreate",
+    "UserUpdate",
+    "UserLogin",
+    "Category",
+    "CategoryCreate",
+    "CategoryUpdate",
+    "Supplier",
+    "SupplierCreate",
+    "SupplierUpdate",
+    "Item",
+    "ItemCreate",
+    "ItemUpdate",
+    "ItemWithLowStock",
+    "StockTransaction",
+    "StockTransactionCreate",
+]

app/schemas/category.py

@@ -0,0 +1,26 @@
+from pydantic import BaseModel
+from datetime import datetime
+from typing import Optional
+
+
+class CategoryBase(BaseModel):
+    name: str
+    description: Optional[str] = None
+
+
+class CategoryCreate(CategoryBase):
+    pass
+
+
+class CategoryUpdate(BaseModel):
+    name: Optional[str] = None
+    description: Optional[str] = None
+
+
+class Category(CategoryBase):
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True

app/schemas/item.py

@@ -0,0 +1,64 @@
+from pydantic import BaseModel
+from datetime import datetime
+from typing import Optional
+from app.schemas.category import Category
+from app.schemas.supplier import Supplier
+
+
+class ItemBase(BaseModel):
+    name: str
+    description: Optional[str] = None
+    sku: str
+    barcode: Optional[str] = None
+    unit_price: float
+    cost_price: Optional[float] = None
+    quantity_in_stock: int = 0
+    minimum_stock_level: int = 0
+    maximum_stock_level: Optional[int] = None
+    reorder_point: int = 0
+    is_active: bool = True
+    category_id: Optional[int] = None
+    supplier_id: Optional[int] = None
+
+
+class ItemCreate(ItemBase):
+    pass
+
+
+class ItemUpdate(BaseModel):
+    name: Optional[str] = None
+    description: Optional[str] = None
+    sku: Optional[str] = None
+    barcode: Optional[str] = None
+    unit_price: Optional[float] = None
+    cost_price: Optional[float] = None
+    quantity_in_stock: Optional[int] = None
+    minimum_stock_level: Optional[int] = None
+    maximum_stock_level: Optional[int] = None
+    reorder_point: Optional[int] = None
+    is_active: Optional[bool] = None
+    category_id: Optional[int] = None
+    supplier_id: Optional[int] = None
+
+
+class Item(ItemBase):
+    id: int
+    created_at: datetime
+    updated_at: datetime
+    category: Optional[Category] = None
+    supplier: Optional[Supplier] = None
+
+    class Config:
+        from_attributes = True
+
+
+class ItemWithLowStock(BaseModel):
+    id: int
+    name: str
+    sku: str
+    quantity_in_stock: int
+    minimum_stock_level: int
+    reorder_point: int
+
+    class Config:
+        from_attributes = True

app/schemas/stock_transaction.py

@@ -0,0 +1,27 @@
+from pydantic import BaseModel
+from datetime import datetime
+from typing import Optional
+from app.models.stock_transaction import TransactionType
+from app.schemas.item import Item
+
+
+class StockTransactionBase(BaseModel):
+    item_id: int
+    transaction_type: TransactionType
+    quantity: int
+    unit_cost: Optional[float] = None
+    reference_number: Optional[str] = None
+    notes: Optional[str] = None
+
+
+class StockTransactionCreate(StockTransactionBase):
+    pass
+
+
+class StockTransaction(StockTransactionBase):
+    id: int
+    created_at: datetime
+    item: Optional[Item] = None
+
+    class Config:
+        from_attributes = True

app/schemas/supplier.py

@@ -0,0 +1,32 @@
+from pydantic import BaseModel, EmailStr
+from datetime import datetime
+from typing import Optional
+
+
+class SupplierBase(BaseModel):
+    name: str
+    contact_person: Optional[str] = None
+    email: Optional[EmailStr] = None
+    phone: Optional[str] = None
+    address: Optional[str] = None
+
+
+class SupplierCreate(SupplierBase):
+    pass
+
+
+class SupplierUpdate(BaseModel):
+    name: Optional[str] = None
+    contact_person: Optional[str] = None
+    email: Optional[EmailStr] = None
+    phone: Optional[str] = None
+    address: Optional[str] = None
+
+
+class Supplier(SupplierBase):
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True

app/schemas/user.py

@@ -0,0 +1,35 @@
+from pydantic import BaseModel, EmailStr
+from datetime import datetime
+from typing import Optional
+
+
+class UserBase(BaseModel):
+    email: EmailStr
+    full_name: Optional[str] = None
+    is_active: bool = True
+
+
+class UserCreate(UserBase):
+    password: str
+
+
+class UserUpdate(BaseModel):
+    email: Optional[EmailStr] = None
+    full_name: Optional[str] = None
+    password: Optional[str] = None
+    is_active: Optional[bool] = None
+
+
+class User(UserBase):
+    id: int
+    is_superuser: bool
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class UserLogin(BaseModel):
+    email: EmailStr
+    password: str

main.py

@@ -0,0 +1,78 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from app.core.config import settings
+from app.db.session import get_db, engine
+from app.db.base import Base
+from app.api import auth, categories, suppliers, items, stock_transactions
+from app.crud import user as user_crud
+from app.schemas.user import UserCreate
+
+# Create database tables
+Base.metadata.create_all(bind=engine)
+
+app = FastAPI(
+    title=settings.PROJECT_NAME,
+    version=settings.PROJECT_VERSION,
+    openapi_url="/openapi.json",
+)
+
+# Set up CORS
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=settings.BACKEND_CORS_ORIGINS,
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Include routers
+app.include_router(auth.router, prefix="/auth", tags=["authentication"])
+app.include_router(categories.router, prefix="/categories", tags=["categories"])
+app.include_router(suppliers.router, prefix="/suppliers", tags=["suppliers"])
+app.include_router(items.router, prefix="/items", tags=["items"])
+app.include_router(
+    stock_transactions.router, prefix="/stock-transactions", tags=["stock-transactions"]
+)
+
+
+@app.get("/")
+async def root():
+    return {
+        "title": settings.PROJECT_NAME,
+        "version": settings.PROJECT_VERSION,
+        "description": "API for managing inventory in small businesses",
+        "documentation": "/docs",
+        "health_check": "/health",
+    }
+
+
+@app.get("/health")
+async def health_check():
+    return {
+        "status": "healthy",
+        "service": settings.PROJECT_NAME,
+        "version": settings.PROJECT_VERSION,
+    }
+
+
+@app.on_event("startup")
+async def startup_event():
+    # Create first superuser if it doesn't exist
+    db = next(get_db())
+    user = user_crud.get_by_email(db, email=settings.FIRST_SUPERUSER_EMAIL)
+    if not user:
+        user_in = UserCreate(
+            email=settings.FIRST_SUPERUSER_EMAIL,
+            password=settings.FIRST_SUPERUSER_PASSWORD,
+            full_name="System Administrator",
+        )
+        user = user_crud.create(db, obj_in=user_in)
+        user.is_superuser = True
+        db.add(user)
+        db.commit()
+
+
+if __name__ == "__main__":
+    import uvicorn
+
+    uvicorn.run(app, host="0.0.0.0", port=8000)

openapi.json

@@ -0,0 +1,41 @@
+{
+  "openapi": "3.0.2",
+  "info": {
+    "title": "Small Business Inventory Management System",
+    "version": "1.0.0"
+  },
+  "paths": {
+    "/": {
+      "get": {
+        "summary": "Root",
+        "operationId": "root__get",
+        "responses": {
+          "200": {
+            "description": "Successful Response",
+            "content": {
+              "application/json": {
+                "schema": {}
+              }
+            }
+          }
+        }
+      }
+    },
+    "/health": {
+      "get": {
+        "summary": "Health Check",
+        "operationId": "health_check_health_get",
+        "responses": {
+          "200": {
+            "description": "Successful Response",
+            "content": {
+              "application/json": {
+                "schema": {}
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}

requirements.txt

@@ -0,0 +1,9 @@
+fastapi==0.104.1
+uvicorn==0.24.0
+sqlalchemy==2.0.23
+alembic==1.13.0
+python-multipart==0.0.6
+python-jose[cryptography]==3.3.0
+passlib[bcrypt]==1.7.4
+python-decouple==3.8
+ruff==0.1.7