from fastapi import FastAPI, HTTPException
from pydantic import BaseModel
import sqlite3
from datetime import datetime

app = FastAPI()

DB_PATH = "shopping.db"

def init_db():
    conn = sqlite3.connect(DB_PATH)
    c = conn.cursor()
    c.execute("""
        CREATE TABLE IF NOT EXISTS products (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            name TEXT NOT NULL UNIQUE,
            sku TEXT,
            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
        )
    """)
    c.execute("""
        CREATE TABLE IF NOT EXISTS lists (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            name TEXT NOT NULL,
            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
        )
    """)
    c.execute("""
        CREATE TABLE IF NOT EXISTS list_items (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            list_id INTEGER NOT NULL,
            product_id INTEGER NOT NULL,
            quantity INTEGER NOT NULL DEFAULT 1,
            added_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
            FOREIGN KEY (list_id) REFERENCES lists(id) ON DELETE CASCADE,
            FOREIGN KEY (product_id) REFERENCES products(id)
        )
    """)
    conn.commit()
    conn.close()

@app.on_event("startup")
def startup():
    init_db()

class Product(BaseModel):
    name: str
    sku: str | None = None

class List(BaseModel):
    name: str

class ListItem(BaseModel):
    product_id: int
    quantity: int = 1

@app.get("/")
def read_root():
    return {"message": "Shopping List API"}