import logging
import os
import time
from typing import Optional
from urllib.parse import unquote
from urllib.parse import urlparse
import yt_dlp
from yt_dlp.networking import Request

logger = logging.getLogger(__name__)

CACHE_TTL = int(os.getenv("CACHE_TTL", 31536000))
SOCKET_TIMEOUT = int(os.getenv("SOCKET_TIMEOUT", 30))

_session_cache = {}
_cache_timestamps = {}

_ydl_instance = None


def _get_ydl():
    """Get or create a singleton yt-dlp instance."""
    global _ydl_instance
    if _ydl_instance is None:
        _ydl_instance = yt_dlp.YoutubeDL({
            "quiet": True,
            "no_warnings": True,
            "socket_timeout": SOCKET_TIMEOUT,
        })
    return _ydl_instance


def _get_cache_key(video_url: str) -> str:
    return video_url


def _is_cache_expired(video_url: str) -> bool:
    key = _get_cache_key(video_url)
    if key not in _cache_timestamps:
        return True
    return time.time() - _cache_timestamps[key] > CACHE_TTL


def _get_cached_info(video_url: str) -> Optional[dict]:
    key = _get_cache_key(video_url)
    if key in _session_cache and not _is_cache_expired(video_url):
        return _session_cache[key]
    return None


def _set_cached_info(video_url: str, info: dict) -> None:
    key = _get_cache_key(video_url)
    _session_cache[key] = info
    _cache_timestamps[key] = time.time()


# store segment mappings per video
_segment_maps = {}


def _get_segment_id(full_url: str) -> str:
    """Build a stable segment id that survives signed query refreshes."""
    import hashlib

    parsed = urlparse(full_url)
    stable_key = parsed.path or full_url.split("?", 1)[0]
    return hashlib.md5(stable_key.encode("utf-8")).hexdigest()


def _refresh_hls_url(video_url: str, attempts: int = 3) -> Optional[str]:
    """Re-extract until yt-dlp returns an HLS URL or we exhaust retries."""
    last_info = None
    for _ in range(attempts):
        _session_cache.pop(video_url, None)
        _cache_timestamps.pop(video_url, None)
        info = _get_video_info(video_url)
        last_info = info
        if info.get("hls_url"):
            return info["hls_url"]
    if last_info and last_info.get("direct_url"):
        logger.info("Extractor returned direct URL but no HLS URL")
    return None


def _get_request_headers(video_url: str) -> dict:
    info = _get_video_info(video_url)
    raw_info = info.get("raw_info") or {}
    return dict(raw_info.get("http_headers") or {})


def _fetch_url(video_url: str, url: str) -> bytes:
    ydl = _get_ydl()
    request = Request(url, headers=_get_request_headers(video_url))
    with ydl.urlopen(request) as response:
        return response.read()


def _populate_nested_maps(video_url: str, content: str, base_url: str, video_id: str, visited: Optional[set[str]] = None, depth: int = 0) -> None:
    """Preload nested playlists so segment ids survive rebuilds after 410s."""
    from urllib.parse import urljoin, urlparse

    if visited is None:
        visited = set()
    if depth >= 3:
        return

    for line in content.splitlines():
        line = line.strip()
        if not line or line.startswith("#"):
            continue

        parsed = urlparse(line)
        full_url = line if parsed.scheme else urljoin(base_url, line)
        if not urlparse(full_url).path.endswith(".m3u8") or full_url in visited:
            continue

        visited.add(full_url)
        try:
            nested_content = _fetch_url(video_url, full_url).decode("utf-8")
            _rewrite_urls(nested_content, video_url, full_url, video_id)
            _populate_nested_maps(video_url, nested_content, full_url, video_id, visited, depth + 1)
        except Exception as e:
            logger.info("Failed to preload nested playlist: %s", e)


def _extract_hls_url(info: dict) -> Optional[str]:
    """Extract HLS URL from yt-dlp info dict."""
    # First check top-level fields (these are set when there's only one format)
    url = info.get("manifest_url") or info.get("url")
    if url and ".m3u8" in url:
        return url
    
    # Check requested_formats (post-processed by yt-dlp)
    if info.get("requested_formats"):
        for f in info["requested_formats"]:
            url = f.get("url") or f.get("manifest_url")
            if url and ".m3u8" in url:
                return url
    
    # Check formats for m3u8_native protocol
    if info.get("formats"):
        for f in reversed(info["formats"]):
            if f.get("protocol") == "m3u8_native":
                url = f.get("manifest_url") or f.get("url")
                if url and ".m3u8" in url:
                    return url
    
    # Try to find any m3u8 URL in formats
    if info.get("formats"):
        for f in info["formats"]:
            url = f.get("url", "")
            if ".m3u8" in url:
                return url
    
    return None


def _extract_direct_url(info: dict) -> Optional[str]:
    """Extract direct video URL when HLS is not available."""
    # Check url field first
    url = info.get("url")
    if url:
        return url
    
    # Check requested_formats
    if info.get("requested_formats"):
        for f in info["requested_formats"]:
            url = f.get("url")
            if url:
                return url
    
    # Check formats for best quality https format
    if info.get("formats"):
        for f in reversed(info["formats"]):
            if f.get("protocol") in ("https", "http"):
                url = f.get("url")
                if url:
                    return url
    
    return None


def _get_video_info(video_url: str) -> dict:
    """Get video info using yt-dlp."""
    cached = _get_cached_info(video_url)
    if cached:
        return cached

    import shutil
    if not shutil.which("node"):
        deno_path = os.path.expanduser("~/.deno/bin/deno")
        if not os.path.exists(deno_path):
            logger.warning("No JavaScript runtime (node/deno) found - YouTube may not work properly")

    ydl = _get_ydl()
    info = ydl.extract_info(video_url, download=False)

    hls_url = _extract_hls_url(info)
    direct_url = _extract_direct_url(info)
    result = {
        "title": info.get("title"),
        "thumbnail": info.get("thumbnail"),
        "hls_url": hls_url,
        "direct_url": direct_url,
        "raw_info": info,
    }
    _set_cached_info(video_url, result)
    return result


def get_stream_info(video_url: str) -> dict:
    """Get video info with all available metadata."""
    info = _get_video_info(video_url)
    
    # Extract useful metadata from raw_info
    raw = info.get("raw_info", {})
    metadata = {
        "title": info["title"],
        "thumbnail": info["thumbnail"],
        "hls_url": info.get("hls_url"),
        "direct_url": info.get("direct_url"),
        # Additional metadata
        "description": raw.get("description"),
        "uploader": raw.get("uploader"),
        "uploader_url": raw.get("uploader_url"),
        "duration": raw.get("duration"),
        "upload_date": raw.get("upload_date"),
        "view_count": raw.get("view_count"),
        "like_count": raw.get("like_count"),
        "dislike_count": raw.get("dislike_count"),
        "comment_count": raw.get("comment_count"),
        "age_limit": raw.get("age_limit"),
        "categories": raw.get("categories"),
        "tags": raw.get("tags"),
        "language": raw.get("language"),
        "license": raw.get("license"),
        "channel": raw.get("channel"),
        "channel_url": raw.get("channel_url"),
        "channel_id": raw.get("channel_id"),
        "extractor": raw.get("extractor"),
        "extractor_key": raw.get("extractor_key"),
        "display_id": raw.get("display_id"),
        "url": raw.get("url"),
        "fulltitle": raw.get("fulltitle"),
        "duration_string": raw.get("duration_string"),
        "resolution": raw.get("resolution"),
        "format": raw.get("format"),
        "format_note": raw.get("format_note"),
        "filesize": raw.get("filesize"),
        "filesize_approx": raw.get("filesize_approx"),
    }
    return metadata


def get_hls_playlist(video_url: str) -> str:
    """Get HLS playlist content with rewritten URLs."""
    info = _get_video_info(video_url)
    hls_url = info.get("hls_url")
    if not hls_url:
        hls_url = _refresh_hls_url(video_url)
        if not hls_url:
            raise ValueError("No HLS stream available for this video")
    
    from utils import get_video_id
    video_id = get_video_id(video_url)

    # Try to get playlist, retry once if URL expired
    for attempt in range(2):
        try:
            playlist_content = _fetch_url(video_url, hls_url).decode("utf-8")
            rewritten = _rewrite_urls(playlist_content, video_url, hls_url, video_id)
            _populate_nested_maps(video_url, playlist_content, hls_url, video_id)
            return rewritten
        except Exception as e:
            if "410" in str(e) and attempt == 0:
                logger.info("HLS URL expired, fetching fresh HLS URL")
                hls_url = _refresh_hls_url(video_url)
                if not hls_url:
                    raise ValueError("No HLS stream available for this video")
                continue
            raise


def get_direct_video_url(video_url: str) -> str:
    """Get direct video URL when HLS is not available."""
    info = _get_video_info(video_url)
    if not info.get("direct_url"):
        raise ValueError("No video URL available for this video")
    return info["direct_url"]


def _rewrite_urls(content: str, video_url: str, base_url: str, video_id: str) -> str:
    """Rewrite relative URLs in HLS playlist to point through proxy."""
    from urllib.parse import urljoin, urlparse

    lines = content.split("\n")
    new_lines = []

    # persist mapping across nested playlists
    if video_url not in _segment_maps:
        _segment_maps[video_url] = {}
    segment_map = _segment_maps[video_url]

    for line in lines:
        if line and not line.startswith("#"):
            parsed = urlparse(line)

            if parsed.scheme:
                full_url = line
            else:
                full_url = urljoin(base_url, line)

            # stable id must ignore expiring signatures in query strings
            seg_id = _get_segment_id(full_url)
            segment_map[seg_id] = full_url

            proxy_url = f"/hls/{video_id}/seg/{seg_id}"
            new_lines.append(proxy_url)
            continue

        new_lines.append(line)

    # mapping already updated in-place

    return "\n".join(new_lines)


def get_hls_segment(video_url: str, segment_url: str) -> bytes:
    """Get HLS segment or sub-playlist content."""
    # Pure mapping-based resolution (no yt-dlp dependency here)
    # New format: segment_url is index
    seg_id = segment_url
    segment_map = _segment_maps.get(video_url)
    if not segment_map:
        # build mapping on-demand to avoid state coupling
        _ = get_hls_playlist(video_url)
        segment_map = _segment_maps.get(video_url)
        if not segment_map:
            raise ValueError("No segment map available")

    if seg_id not in segment_map:
        # try rebuild once to refresh mappings (e.g., after expiry)
        _ = get_hls_playlist(video_url)
        segment_map = _segment_maps.get(video_url) or {}
        if seg_id not in segment_map:
            raise ValueError("Segment not found")

    full_url = segment_map[seg_id]
    
    try:
        data = _fetch_url(video_url, full_url)
    except Exception as e:
        raise ValueError("HLS URL expired (410 Gone)") from e

    # Detect playlist dynamically (covers sub-playlists too)
    try:
        from utils import get_video_id
        video_id = get_video_id(video_url)
        text = data.decode("utf-8", errors="ignore")
        head = text.lstrip()[:200]
        if "#EXTM3U" in head:
            rewritten = _rewrite_urls(text, video_url, full_url, video_id)
            return rewritten.encode("utf-8")
    except Exception:
        pass

    return data


def get_hls_segment_with_retry(video_url: str, segment_url: str) -> bytes:
    """Get HLS segment with one rebuild after signed URL expiry."""
    for attempt in range(2):
        try:
            if video_url not in _segment_maps:
                _ = get_hls_playlist(video_url)
            return get_hls_segment(video_url, segment_url)
        except ValueError as e:
            if "410 Gone" in str(e):
                if attempt == 0:
                    logger.info("Segment 410, retrying")
                    continue

                logger.info("Segment still 410, rebuilding playlist and map")
                _session_cache.pop(video_url, None)
                _cache_timestamps.pop(video_url, None)
                _segment_maps.pop(video_url, None)
                _ = get_hls_playlist(video_url)
                return get_hls_segment(video_url, segment_url)
            raise