from typing import Optional

from fastapi import APIRouter, Depends, HTTPException, Query
from fastapi.responses import StreamingResponse
from sqlalchemy.orm import Session
from app.core.database import get_db
from app.api.deps import get_current_user
from models.api_models import (ProductListResponse, ProductResponse, ProductCreate, ProductDetailResponse,
                               StockLocationResponse, StockSummaryResponse, ProductUpdate)
from models.database_models import User, Product, Stock
from datetime import datetime
import logging

from utils.data_processing import GTINProcessor, PriceProcessor

router = APIRouter()
logger = logging.getLogger(__name__)

# Initialize processors
gtin_processor = GTINProcessor()
price_processor = PriceProcessor()


# Enhanced Product Routes with Marketplace Support
@router.get("/products", response_model=ProductListResponse)
def get_products(
        skip: int = Query(0, ge=0),
        limit: int = Query(100, ge=1, le=1000),
        brand: Optional[str] = Query(None),
        category: Optional[str] = Query(None),
        availability: Optional[str] = Query(None),
        marketplace: Optional[str] = Query(None, description="Filter by marketplace"),
        shop_name: Optional[str] = Query(None, description="Filter by shop name"),
        search: Optional[str] = Query(None),
        db: Session = Depends(get_db),
        current_user: User = Depends(get_current_user)
):
    """Get products with advanced filtering including marketplace and shop (Protected)"""

    query = db.query(Product)

    # Apply filters
    if brand:
        query = query.filter(Product.brand.ilike(f"%{brand}%"))
    if category:
        query = query.filter(Product.google_product_category.ilike(f"%{category}%"))
    if availability:
        query = query.filter(Product.availability == availability)
    if marketplace:
        query = query.filter(Product.marketplace.ilike(f"%{marketplace}%"))
    if shop_name:
        query = query.filter(Product.shop_name.ilike(f"%{shop_name}%"))
    if search:
        # Search in title, description, and marketplace
        search_term = f"%{search}%"
        query = query.filter(
            (Product.title.ilike(search_term)) |
            (Product.description.ilike(search_term)) |
            (Product.marketplace.ilike(search_term)) |
            (Product.shop_name.ilike(search_term))
        )

    # Get total count for pagination
    total = query.count()

    # Apply pagination
    products = query.offset(skip).limit(limit).all()

    return ProductListResponse(
        products=products,
        total=total,
        skip=skip,
        limit=limit
    )


@router.post("/products", response_model=ProductResponse)
def create_product(
        product: ProductCreate,
        db: Session = Depends(get_db),
        current_user: User = Depends(get_current_user)
):
    """Create a new product with validation and marketplace support (Protected)"""

    # Check if product_id already exists
    existing = db.query(Product).filter(Product.product_id == product.product_id).first()
    if existing:
        raise HTTPException(status_code=400, detail="Product with this ID already exists")

    # Process and validate GTIN if provided
    if product.gtin:
        normalized_gtin = gtin_processor.normalize(product.gtin)
        if not normalized_gtin:
            raise HTTPException(status_code=400, detail="Invalid GTIN format")
        product.gtin = normalized_gtin

    # Process price if provided
    if product.price:
        parsed_price, currency = price_processor.parse_price_currency(product.price)
        if parsed_price:
            product.price = parsed_price
            product.currency = currency

    # Set default marketplace if not provided
    if not product.marketplace:
        product.marketplace = "Letzshop"

    db_product = Product(**product.dict())
    db.add(db_product)
    db.commit()
    db.refresh(db_product)

    logger.info(
        f"Created product {db_product.product_id} for marketplace {db_product.marketplace}, "
        f"shop {db_product.shop_name}")
    return db_product


@router.get("/products/{product_id}", response_model=ProductDetailResponse)
def get_product(product_id: str, db: Session = Depends(get_db), current_user: User = Depends(get_current_user)):
    """Get product with stock information (Protected)"""

    product = db.query(Product).filter(Product.product_id == product_id).first()
    if not product:
        raise HTTPException(status_code=404, detail="Product not found")

    # Get stock information if GTIN exists
    stock_info = None
    if product.gtin:
        stock_entries = db.query(Stock).filter(Stock.gtin == product.gtin).all()
        if stock_entries:
            total_quantity = sum(entry.quantity for entry in stock_entries)
            locations = [
                StockLocationResponse(location=entry.location, quantity=entry.quantity)
                for entry in stock_entries
            ]
            stock_info = StockSummaryResponse(
                gtin=product.gtin,
                total_quantity=total_quantity,
                locations=locations
            )

    return ProductDetailResponse(
        product=product,
        stock_info=stock_info
    )


@router.put("/products/{product_id}", response_model=ProductResponse)
def update_product(
        product_id: str,
        product_update: ProductUpdate,
        db: Session = Depends(get_db),
        current_user: User = Depends(get_current_user)
):
    """Update product with validation and marketplace support (Protected)"""

    product = db.query(Product).filter(Product.product_id == product_id).first()
    if not product:
        raise HTTPException(status_code=404, detail="Product not found")

    # Update fields
    update_data = product_update.dict(exclude_unset=True)

    # Validate GTIN if being updated
    if "gtin" in update_data and update_data["gtin"]:
        normalized_gtin = gtin_processor.normalize(update_data["gtin"])
        if not normalized_gtin:
            raise HTTPException(status_code=400, detail="Invalid GTIN format")
        update_data["gtin"] = normalized_gtin

    # Process price if being updated
    if "price" in update_data and update_data["price"]:
        parsed_price, currency = price_processor.parse_price_currency(update_data["price"])
        if parsed_price:
            update_data["price"] = parsed_price
            update_data["currency"] = currency

    for key, value in update_data.items():
        setattr(product, key, value)

    product.updated_at = datetime.utcnow()
    db.commit()
    db.refresh(product)

    return product


@router.delete("/products/{product_id}")
def delete_product(
        product_id: str,
        db: Session = Depends(get_db),
        current_user: User = Depends(get_current_user)
):
    """Delete product and associated stock (Protected)"""

    product = db.query(Product).filter(Product.product_id == product_id).first()
    if not product:
        raise HTTPException(status_code=404, detail="Product not found")

    # Delete associated stock entries if GTIN exists
    if product.gtin:
        db.query(Stock).filter(Stock.gtin == product.gtin).delete()

    db.delete(product)
    db.commit()

    return {"message": "Product and associated stock deleted successfully"}

# Export with streaming for large datasets (Protected)
@router.get("/export-csv")
async def export_csv(
        marketplace: Optional[str] = Query(None, description="Filter by marketplace"),
        shop_name: Optional[str] = Query(None, description="Filter by shop name"),
        db: Session = Depends(get_db),
        current_user: User = Depends(get_current_user)
):
    """Export products as CSV with streaming and marketplace filtering (Protected)"""

    def generate_csv():
        # Stream CSV generation for memory efficiency
        yield "product_id,title,description,link,image_link,availability,price,currency,brand,gtin,marketplace,shop_name\n"

        batch_size = 1000
        offset = 0

        while True:
            query = db.query(Product)

            # Apply marketplace filters
            if marketplace:
                query = query.filter(Product.marketplace.ilike(f"%{marketplace}%"))
            if shop_name:
                query = query.filter(Product.shop_name.ilike(f"%{shop_name}%"))

            products = query.offset(offset).limit(batch_size).all()
            if not products:
                break

            for product in products:
                # Create CSV row with marketplace fields
                row = (f'"{product.product_id}","{product.title or ""}","{product.description or ""}",'
                       f'"{product.link or ""}","{product.image_link or ""}","{product.availability or ""}",'
                       f'"{product.price or ""}","{product.currency or ""}","{product.brand or ""}",'
                       f'"{product.gtin or ""}","{product.marketplace or ""}","{product.shop_name or ""}"\n')
                yield row

            offset += batch_size

    filename = "products_export"
    if marketplace:
        filename += f"_{marketplace}"
    if shop_name:
        filename += f"_{shop_name}"
    filename += ".csv"

    return StreamingResponse(
        generate_csv(),
        media_type="text/csv",
        headers={"Content-Disposition": f"attachment; filename={filename}"}
    )