from __future__ import annotations

import csv
from dataclasses import dataclass
import hashlib
import html as html_lib
import io
import json
from urllib.parse import urljoin, urlparse
import re

import requests


REQUEST_TIMEOUT_SECONDS = 30
L4D2CENTER_CSV_URL = "https://l4d2center.com/maps/servers/index.csv"
CEDAPUG_CUSTOM_URL = "https://cedapug.com/custom"


@dataclass(frozen=True, slots=True)
class GlobalMapManifestItem:
    item_key: str
    display_name: str
    download_url: str
    expected_vpk_name: str = ""
    expected_size: int | None = None
    expected_md5: str = ""


def fetch_l4d2center_manifest() -> tuple[str, list[GlobalMapManifestItem]]:
    response = requests.get(L4D2CENTER_CSV_URL, timeout=REQUEST_TIMEOUT_SECONDS)
    response.raise_for_status()
    text = response.text
    return _sha256(text), parse_l4d2center_csv(text)


def fetch_cedapug_manifest() -> tuple[str, list[GlobalMapManifestItem]]:
    response = requests.get(CEDAPUG_CUSTOM_URL, timeout=REQUEST_TIMEOUT_SECONDS)
    response.raise_for_status()
    text = response.text
    return _sha256(text), parse_cedapug_custom_html(text)


def parse_l4d2center_csv(raw: str) -> list[GlobalMapManifestItem]:
    reader = csv.DictReader(io.StringIO(raw), delimiter=";")
    expected = ["Name", "Size", "md5", "Download link"]
    if reader.fieldnames != expected:
        raise ValueError("expected L4D2Center CSV header: Name;Size;md5;Download link")
    items: list[GlobalMapManifestItem] = []
    for row in reader:
        name = (row.get("Name") or "").strip()
        size_raw = (row.get("Size") or "").strip()
        md5 = (row.get("md5") or "").strip().lower()
        url = (row.get("Download link") or "").strip()
        if not name or not url:
            continue
        items.append(
            GlobalMapManifestItem(
                item_key=name,
                display_name=name,
                download_url=url,
                expected_vpk_name=name,
                expected_size=int(size_raw) if size_raw else None,
                expected_md5=md5,
            )
        )
    return items


def parse_cedapug_custom_html(raw: str) -> list[GlobalMapManifestItem]:
    match = re.search(r"renderCustomMapDownloads\((\[.*?\])\)</script>", raw, re.DOTALL)
    if match is None:
        raise ValueError("CEDAPUG page did not contain renderCustomMapDownloads data")
    rows = json.loads(match.group(1))
    items: list[GlobalMapManifestItem] = []
    for row in rows:
        if len(row) < 3:
            continue
        label = str(row[1])
        link = str(row[2])
        if link.startswith("http"):
            continue
        if not link:
            continue
        url = urljoin(CEDAPUG_CUSTOM_URL, link)
        parsed = urlparse(url)
        basename = parsed.path.rsplit("/", 1)[-1]
        items.append(
            GlobalMapManifestItem(
                item_key=basename,
                display_name=_strip_html(label),
                download_url=url,
            )
        )
    return items


def _strip_html(raw: str) -> str:
    no_tags = re.sub(r"<[^>]+>", "", raw)
    return html_lib.unescape(no_tags).strip()


def _sha256(raw: str) -> str:
    return hashlib.sha256(raw.encode("utf-8")).hexdigest()