from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy.orm import Session
from typing import List
import uuid

from app.db.session import get_db
from app.models.cart import Cart, CartItem
from app.schemas import (
    CartCreate,
    CartResponse,
    CartItemCreate,
    CartItemResponse,
    CheckoutRequest,
    CheckoutResponse,
)

router = APIRouter()


@router.post("/carts/", response_model=CartResponse)
def create_cart(cart: CartCreate, db: Session = Depends(get_db)):
    db_cart = Cart(user_id=cart.user_id)
    db.add(db_cart)
    db.commit()
    db.refresh(db_cart)

    # Calculate total
    total = sum(item.price * item.quantity for item in db_cart.items)

    response = CartResponse.model_validate(db_cart)
    response.total = total
    return response


@router.get("/carts/{cart_id}", response_model=CartResponse)
def get_cart(cart_id: int, db: Session = Depends(get_db)):
    cart = db.query(Cart).filter(Cart.id == cart_id).first()
    if cart is None:
        raise HTTPException(status_code=404, detail="Cart not found")

    # Calculate total
    total = sum(item.price * item.quantity for item in cart.items)

    response = CartResponse.model_validate(cart)
    response.total = total
    return response


@router.get("/carts/user/{user_id}", response_model=List[CartResponse])
def get_user_carts(user_id: str, db: Session = Depends(get_db)):
    carts = db.query(Cart).filter(Cart.user_id == user_id).all()

    response_carts = []
    for cart in carts:
        total = sum(item.price * item.quantity for item in cart.items)
        cart_response = CartResponse.model_validate(cart)
        cart_response.total = total
        response_carts.append(cart_response)

    return response_carts


@router.post("/carts/{cart_id}/items/", response_model=CartItemResponse)
def add_item_to_cart(cart_id: int, item: CartItemCreate, db: Session = Depends(get_db)):
    cart = db.query(Cart).filter(Cart.id == cart_id).first()
    if cart is None:
        raise HTTPException(status_code=404, detail="Cart not found")

    if cart.status != "active":
        raise HTTPException(status_code=400, detail="Cannot add items to inactive cart")

    # Check if item already exists in cart
    existing_item = (
        db.query(CartItem)
        .filter(CartItem.cart_id == cart_id, CartItem.product_id == item.product_id)
        .first()
    )

    if existing_item:
        # Update quantity if item exists
        existing_item.quantity += item.quantity
        db.commit()
        db.refresh(existing_item)
        return CartItemResponse.model_validate(existing_item)
    else:
        # Create new item if it doesn't exist
        db_item = CartItem(
            cart_id=cart_id,
            product_id=item.product_id,
            product_name=item.product_name,
            price=item.price,
            quantity=item.quantity,
        )
        db.add(db_item)
        db.commit()
        db.refresh(db_item)
        return CartItemResponse.model_validate(db_item)


@router.put("/carts/{cart_id}/items/{item_id}", response_model=CartItemResponse)
def update_cart_item(
    cart_id: int, item_id: int, quantity: int, db: Session = Depends(get_db)
):
    cart = db.query(Cart).filter(Cart.id == cart_id).first()
    if cart is None:
        raise HTTPException(status_code=404, detail="Cart not found")

    if cart.status != "active":
        raise HTTPException(
            status_code=400, detail="Cannot modify items in inactive cart"
        )

    item = (
        db.query(CartItem)
        .filter(CartItem.id == item_id, CartItem.cart_id == cart_id)
        .first()
    )

    if item is None:
        raise HTTPException(status_code=404, detail="Cart item not found")

    if quantity <= 0:
        db.delete(item)
        db.commit()
        return {"message": "Item removed from cart"}
    else:
        item.quantity = quantity
        db.commit()
        db.refresh(item)
        return CartItemResponse.model_validate(item)


@router.delete("/carts/{cart_id}/items/{item_id}")
def remove_item_from_cart(cart_id: int, item_id: int, db: Session = Depends(get_db)):
    cart = db.query(Cart).filter(Cart.id == cart_id).first()
    if cart is None:
        raise HTTPException(status_code=404, detail="Cart not found")

    if cart.status != "active":
        raise HTTPException(
            status_code=400, detail="Cannot remove items from inactive cart"
        )

    item = (
        db.query(CartItem)
        .filter(CartItem.id == item_id, CartItem.cart_id == cart_id)
        .first()
    )

    if item is None:
        raise HTTPException(status_code=404, detail="Cart item not found")

    db.delete(item)
    db.commit()
    return {"message": "Item removed from cart"}


@router.delete("/carts/{cart_id}")
def clear_cart(cart_id: int, db: Session = Depends(get_db)):
    cart = db.query(Cart).filter(Cart.id == cart_id).first()
    if cart is None:
        raise HTTPException(status_code=404, detail="Cart not found")

    if cart.status != "active":
        raise HTTPException(status_code=400, detail="Cannot clear inactive cart")

    # Delete all items in the cart
    db.query(CartItem).filter(CartItem.cart_id == cart_id).delete()
    db.commit()
    return {"message": "Cart cleared successfully"}


@router.post("/checkout/", response_model=CheckoutResponse)
def checkout(checkout_request: CheckoutRequest, db: Session = Depends(get_db)):
    cart = db.query(Cart).filter(Cart.id == checkout_request.cart_id).first()
    if cart is None:
        raise HTTPException(status_code=404, detail="Cart not found")

    if cart.status != "active":
        raise HTTPException(status_code=400, detail="Cart is not active")

    if not cart.items:
        raise HTTPException(status_code=400, detail="Cart is empty")

    # Calculate total
    total_amount = sum(item.price * item.quantity for item in cart.items)

    # In a real system, you would process payment here
    # For now, we'll simulate a successful payment

    # Generate order ID
    order_id = str(uuid.uuid4())

    # Update cart status to checked_out
    cart.status = "checked_out"
    db.commit()

    return CheckoutResponse(
        success=True,
        order_id=order_id,
        total_amount=total_amount,
        message="Checkout completed successfully",
    )