from io import BytesIO
from typing import List, Dict, Optional

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload, joinedload
from weasyprint import HTML, CSS

from constants import DEAL_STATUS_STR, ENV, APP_PATH
from generators.deal_pdf_generator.deal_data import DealTechSpecProductData, DealTechSpecData
from models import Deal, DealProduct, DealService as DealServiceModel, Product, DealGroup
from utils.images_fetcher import fetch_images


# Генерация ключа для группировки deal_product по артикулу и услугам
def _gen_key_for_product(deal_product: DealProduct) -> str:
    return f"{deal_product.product.article} - " + ",".join(
        str(service.service_id) for service in deal_product.services
    )


# Генерация ключа для группировки deal_product из группы сделок по артикулу, сервисам, а также товарам
def _regen_key_for_product(product_data: DealTechSpecProductData) -> str:
    if len(product_data['deal_products']) == 0:
        return ""

    article = product_data['deal_products'][0].product.article
    services_ids = ",".join(str(service.service_id) for service in product_data['deal_products'][0].services)

    if len(product_data['deal_products']) == 1:
        products = product_data['deal_products'][0].product_id
    else:
        products = ",".join(
            f"{deal_product.product_id}-{deal_product.quantity}" for deal_product in product_data['deal_products']
        )

    return f"{article}+{services_ids}+{products}"


class DealTechSpecPdfGenerator:
    def __init__(self, session: AsyncSession):
        self._session = session
        self.deal_doc: DealTechSpecData = {
            "deals": [],
            "products": {},
            "product_images": (),
            "deal_ids_header": "",
            "deal_status_str": DEAL_STATUS_STR,
        }
        self.deal: Deal

    @staticmethod
    async def _group_deal_products_by_products(deal_products: List[DealProduct]) -> Dict[str, DealTechSpecProductData]:
        products: Dict[str, DealTechSpecProductData] = {}
        additional_info: Optional[str]

        for deal_product in deal_products:
            # Для группировки по артикулу и услугам
            key = _gen_key_for_product(deal_product)

            if key not in products:
                products[key] = {
                    "deal": deal_product.deal,
                    "deal_products": [deal_product],
                    "quantity": deal_product.quantity,
                    "additional_info": deal_product.product.additional_info,
                    "warehouses_and_quantities": [],
                }
            else:
                products[key]["deal_products"].append(deal_product)
                products[key]["quantity"] += deal_product.quantity
                if not products[key]["additional_info"]:
                    products[key]["additional_info"] = deal_product.product.additional_info

        return products

    async def _get_deal_by_id(self, deal_id: int) -> Optional[Deal]:
        deal: Deal | None = await self._session.scalar(
            select(Deal)
            .where(Deal.id == deal_id)
            .options(
                selectinload(Deal.products).selectinload(DealProduct.services),
                selectinload(Deal.products).selectinload(DealProduct.product).selectinload(Product.barcodes),
                selectinload(Deal.services).selectinload(DealServiceModel.service),
                selectinload(Deal.status_history),
                selectinload(Deal.group).selectinload(DealGroup.deals),
                joinedload(Deal.client),
                joinedload(Deal.shipping_warehouse),
            )
        )
        return deal

    async def _get_deals_by_group_id(self, group_id: int) -> List[Deal]:
        group: DealGroup | None = await self._session.scalar(
            select(DealGroup)
            .where(DealGroup.id == group_id)
            .options(
                selectinload(DealGroup.deals).selectinload(Deal.products).selectinload(DealProduct.services),
                selectinload(DealGroup.deals).selectinload(Deal.products)
                .selectinload(DealProduct.product).selectinload(Product.barcodes),
                selectinload(DealGroup.deals).selectinload(Deal.services).selectinload(DealServiceModel.service),
                selectinload(DealGroup.deals).selectinload(Deal.status_history),
                selectinload(DealGroup.deals).selectinload(Deal.group).selectinload(DealGroup.deals),
                selectinload(DealGroup.deals).joinedload(Deal.client),
                selectinload(DealGroup.deals).joinedload(Deal.shipping_warehouse),
            )
        )
        return group.deals if group else []

    def _set_deals_ids_header(self):
        self.deal_doc["deal_ids_header"] = f"ID: {self.deal.id}"
        if self.deal.group:
            self.deal_doc["deal_ids_header"] = "ID: " + ", ".join(str(d.id) for d in self.deal.group.deals)

    async def _create_deal_tech_spec_document_html(self, deal_id: int):
        deal = await self._get_deal_by_id(deal_id)
        if not deal:
            return ""
        self.deal = deal

        self._set_deals_ids_header()

        if deal.group:
            deals = await self._get_deals_by_group_id(deal.group.id)
            for d in deals:
                self.deal_doc["deals"].append(d)
                grouped_products = await self._group_deal_products_by_products(d.products)
                for product in grouped_products.values():
                    key = _regen_key_for_product(product)
                    if key not in self.deal_doc["products"]:
                        self.deal_doc["products"][key] = product
                    else:
                        self.deal_doc["products"][key]["quantity"] += product["quantity"]
                    self.deal_doc["products"][key]["warehouses_and_quantities"].append((
                        product["deal"].shipping_warehouse.name, product["quantity"],
                    ))
        else:
            self.deal_doc["deals"] = [deal]
            self.deal_doc["products"] = await self._group_deal_products_by_products(deal.products)

        product_urls: List[Optional[str]] = []
        for product in self.deal_doc["products"].values():
            if len(product["deal_products"][0].product.images) > 0:
                product_urls.append(product["deal_products"][0].product.images[0].image_url)
            else:
                product_urls.append(None)
        self.deal_doc["product_images"] = await fetch_images(product_urls)

        template = ENV.get_template("deal/deal-tech-spec.html")

        result = template.render({"data": self.deal_doc, "sign_place_text": "_" * 22})
        return result

    async def create_deal_tech_spec_pdf(self, deal_id) -> BytesIO:
        doc = await self._create_deal_tech_spec_document_html(deal_id)
        pdf_file = BytesIO()
        HTML(string=doc).write_pdf(pdf_file, stylesheets=[CSS(APP_PATH + '/static/css/deal-tech-spec.css')])
        return pdf_file