from __future__ import annotations

import json
import re
from datetime import datetime, timezone
from pathlib import Path
from urllib.parse import urljoin

import httpx
from bs4 import BeautifulSoup

from .config import settings
from .models import MenuItem, MenuSnapshot


SHOP_PAYLOAD_MARKERS = (
    "MsJsShop.init(",
    "MsJsPublishedManager.addJsData(",
)
SIZE_PATTERN = re.compile(
    r"(\d+\s*(?:см|г|мл)(?:\s*/\s*\d+\s*(?:см|г|мл))*)",
    re.IGNORECASE,
)


def normalize_spaces(value: str) -> str:
    return " ".join(value.replace("\xa0", " ").split())


def compact_text(value: str) -> str:
    return re.sub(r"\s+", "", value.replace("\xa0", " ")).lower()


def parse_price(price_label: str) -> int | None:
    cleaned = normalize_spaces(price_label).lower()
    if "бесплатно" in cleaned:
        return None

    digits = re.sub(r"[^\d]", "", cleaned)
    return int(digits) if digits else None


def parse_ingredients(description: str) -> list[str]:
    cleaned = normalize_spaces(description)
    if not cleaned:
        return []

    lower_cleaned = cleaned.lower()
    if lower_cleaned.startswith("состав:"):
        cleaned = cleaned.split(":", 1)[1].strip()

    return [part.strip() for part in cleaned.split(",") if part.strip()]


def extract_size(*values: str) -> str | None:
    for value in values:
        match = SIZE_PATTERN.search(value)
        if match:
            return match.group(1).replace(" ", "")
    return None


def is_size_only_line(value: str) -> bool:
    size = extract_size(value)
    return size is not None and compact_text(value) == compact_text(size)


def extract_first_json_object(html: str, marker: str) -> dict[str, object]:
    marker_index = html.find(marker)
    if marker_index == -1:
        raise ValueError(f"{marker} payload not found in page")

    object_start = html.find("{", marker_index)
    if object_start == -1:
        raise ValueError("Shop payload start not found")

    depth = 0
    in_string = False
    escaped = False
    object_end = None

    for index in range(object_start, len(html)):
        char = html[index]

        if in_string:
            if escaped:
                escaped = False
            elif char == "\\":
                escaped = True
            elif char == '"':
                in_string = False
            continue

        if char == '"':
            in_string = True
        elif char == "{":
            depth += 1
        elif char == "}":
            depth -= 1
            if depth == 0:
                object_end = index + 1
                break

    if object_end is None:
        raise ValueError("Shop payload end not found")

    return json.loads(html[object_start:object_end])


def find_shop_container(payload: object) -> dict[str, object] | None:
    if isinstance(payload, dict):
        shop = payload.get("shop")
        if isinstance(shop, dict) and isinstance(shop.get("products"), list):
            return payload

        ds_shop = payload.get("dsShop")
        if isinstance(ds_shop, dict) and isinstance(ds_shop.get("data"), list):
            return {
                "shop": {
                    "products": ds_shop.get("data", []),
                    "settings": ds_shop.get("settings", {}),
                }
            }

        for value in payload.values():
            found = find_shop_container(value)
            if found:
                return found

    if isinstance(payload, list):
        for value in payload:
            found = find_shop_container(value)
            if found:
                return found

    return None


def extract_shop_payload(html: str) -> dict[str, object]:
    errors: list[str] = []
    for marker in SHOP_PAYLOAD_MARKERS:
        try:
            payload = extract_first_json_object(html, marker)
        except ValueError as exc:
            errors.append(str(exc))
            continue

        shop_container = find_shop_container(payload)
        if shop_container is not None:
            return shop_container

        errors.append(f"{marker} found, but shop container is missing")

    raise ValueError("; ".join(errors) or "Shop payload not found in page")


def html_fragment_to_lines(fragment: str) -> list[str]:
    if not fragment:
        return []

    soup = BeautifulSoup(fragment, "html.parser")
    return [
        normalize_spaces(line)
        for line in soup.get_text("\n", strip=True).splitlines()
        if normalize_spaces(line)
    ]


class GorichMenuScraper:
    def __init__(self) -> None:
        self.site_url = settings.site_url
        self.output_path = Path(settings.output_path)
        self.timeout = settings.request_timeout

    async def fetch_html(self) -> str:
        async with self._build_client() as client:
            response = await client.get(self.site_url)
            response.raise_for_status()
            return response.text

    def _build_client(self) -> httpx.AsyncClient:
        return httpx.AsyncClient(
            headers={"User-Agent": "Mozilla/5.0"},
            follow_redirects=True,
            timeout=self.timeout,
        )

    def parse_menu(self, html: str) -> MenuSnapshot:
        payload = extract_shop_payload(html)
        shop = payload.get("shop") or {}
        if not isinstance(shop, dict):
            raise ValueError("Shop payload has unexpected format")

        shop_settings = shop.get("settings") or {}
        categories = shop_settings.get("categories") or []
        products = shop.get("products") or []
        if not isinstance(categories, list) or not isinstance(products, list):
            raise ValueError("Shop categories or products have unexpected format")

        category_by_id: dict[int, dict[str, object]] = {}
        for category in categories:
            if not isinstance(category, dict):
                continue
            category_id = category.get("id")
            if isinstance(category_id, int):
                category_by_id[category_id] = category

        scraped_at = datetime.now(timezone.utc)
        items: list[MenuItem] = []

        for product in products:
            if not isinstance(product, dict):
                continue
            if not product.get("is_visible", True):
                continue

            product_id = product.get("id")
            name = normalize_spaces(str(product.get("name", "")))
            if not product_id or not name:
                continue

            raw_description = str(product.get("short_description", "") or "")
            description_lines = html_fragment_to_lines(raw_description)
            size = extract_size(name, *description_lines)
            description_parts = [line for line in description_lines if not is_size_only_line(line)]
            description = " ".join(description_parts).strip()
            if not description and description_lines:
                description = " ".join(description_lines).strip()

            raw_category_ids = [
                category_id
                for category_id in product.get("category_list", [])
                if isinstance(category_id, int)
            ]
            sorted_category_ids = sorted(
                raw_category_ids,
                key=lambda category_id: int(category_by_id.get(category_id, {}).get("pos", 10_000)),
            )
            category_name = "прочее"
            primary_category_id: int | None = None
            if sorted_category_ids:
                primary_category_id = sorted_category_ids[0]
                category_name = normalize_spaces(
                    str(category_by_id.get(primary_category_id, {}).get("name", "прочее"))
                ).lower()

            image_url = ""
            image_list = product.get("image_list", [])
            if isinstance(image_list, list):
                for image in image_list:
                    if not isinstance(image, dict):
                        continue
                    raw_url = str(image.get("url", "") or "")
                    if raw_url:
                        image_url = urljoin(self.site_url, raw_url)
                        break

            price = product.get("price")
            numeric_price = int(price) if isinstance(price, int) else None
            currency = normalize_spaces(str(product.get("currency", "руб.") or "руб."))
            price_label = (
                f"{numeric_price} {currency}" if numeric_price is not None else "Цена не указана"
            )

            description_url = str(product.get("description_url", "") or "")
            source_url = urljoin(self.site_url, description_url) if description_url else self.site_url

            items.append(
                MenuItem(
                    item_id=str(product_id),
                    name=name,
                    category=category_name,
                    description=description,
                    ingredients=parse_ingredients(description),
                    price=parse_price(price_label),
                    price_label=price_label,
                    size=size,
                    photo_url=image_url,
                    source_url=source_url,
                    scraped_at=scraped_at,
                    metadata={
                        "category_id": primary_category_id,
                        "category_ids": sorted_category_ids,
                        "raw_short_description": raw_description,
                        "amount": product.get("amount"),
                        "sku": product.get("sku"),
                    },
                )
            )

        return MenuSnapshot(
            source_url=self.site_url,
            scraped_at=scraped_at,
            total_items=len(items),
            items=items,
        )

    def save_snapshot(self, snapshot: MenuSnapshot) -> None:
        self.output_path.parent.mkdir(parents=True, exist_ok=True)
        self.output_path.write_text(
            json.dumps(snapshot.model_dump(mode="json"), ensure_ascii=False, indent=2),
            encoding="utf-8",
        )

    async def scrape_and_save(self) -> MenuSnapshot:
        html = await self.fetch_html()
        snapshot = self.parse_menu(html)
        self.save_snapshot(snapshot)
        return snapshot