# Shopping List API

A simple internal API to track shopping list items using SQLite and FastAPI.

## Setup

```bash
# Install dependencies
pip install -r requirements.txt

# Run the server
uvicorn main:app --reload
```

The API will be available at http://localhost:8000.

## Database

SQLite database file: `shopping.db` (created automatically on first startup).

Schema:

- `products` (id, name, sku?, created_at)
- `lists` (id, name, created_at)
- `list_items` (id, list_id, product_id, quantity, added_at; foreign keys with cascade)

## API Reference

### Root

**GET /**  
Returns a welcome message.

Response:
```json
{ "message": "Shopping List API" }
```

### Products

**POST /products**  
Create a product.

Body:
```json
{ "name": "string", "sku": "optional string" }
```

**GET /products**  
List all products.

**GET /products/{id}**  
Get a product by ID.

**DELETE /products/{id}**  
Delete a product.

### Lists

**POST /lists**  
Create a shopping list.

Body:
```json
{ "name": "string" }
```

**GET /lists**  
List all lists.

**GET /lists/{id}**  
Get a list with its items (includes product details in items).

**DELETE /lists/{id}**  
Delete a list (cascades to items).

### List Items

**POST /lists/{list_id}/items**  
Add a product to a list.

Body:
```json
{ "product_id": 1, "quantity": 2 }
```

**PATCH /lists/{list_id}/items/{item_id}**  
Update the quantity of an item in a list.

Body:
```json
{ "quantity": 5 }
```

**DELETE /lists/{list_id}/items/{item_id}**  
Remove an item from a list.

**GET /lists/{list_id}/items**  
List items in a list (includes product name and sku).

## Manual Testing

You can use curl or any HTTP client.

Example flow:

```bash
# Create products
curl -X POST http://localhost:8000/products -H "Content-Type: application/json" -d '{"name":"Paper Plates","sku":"PP-001"}'
curl -X POST http://localhost:8000/products -H "Content-Type: application/json" -d '{"name":"Bread"}'

# Create a list
curl -X POST http://localhost:8000/lists -H "Content-Type: application/json" -d '{"name":"Picnic List"}'

# Add items to the list (use IDs from previous responses)
curl -X POST http://localhost:8000/lists/1/items -H "Content-Type: application/json" -d '{"product_id":1,"quantity":2}'
curl -X POST http://localhost:8000/lists/1/items -H "Content-Type: application/json" -d '{"product_id":2,"quantity":1}'

# Get list with items
curl http://localhost:8000/lists/1

# Update quantity
curl -X PATCH http://localhost:8000/lists/1/items/1 -H "Content-Type: application/json" -d '{"quantity":5}'

# List items in list
curl http://localhost:8000/lists/1/items

# Delete item
curl -X DELETE http://localhost:8000/lists/1/items/2

# Delete list (cascades)
curl -X DELETE http://localhost:8000/lists/1
```

## Running Tests

```bash
pytest test_main.py
```

Tests cover:
- Root endpoint
- Product CRUD
- List CRUD
- List items management (add, update, delete, cascade)

## Notes

- This is an internal API; security/auth not implemented.
- For production use, add proper error handling, validation, and possibly a connection pool.