from __future__ import annotations

import sys
import tempfile
import time
from pathlib import Path
from typing import Optional, List

try:
    from PIL import Image
    HAS_PIL = True
except ImportError:
    HAS_PIL = False

try:
    import requests
    HAS_REQUESTS = True
except ImportError:
    HAS_REQUESTS = False

try:
    import musicbrainzngs as mb
    HAS_MB = True
except ImportError:
    HAS_MB = False

try:
    from mutagen.id3 import ID3, APIC, error as ID3Error
    from mutagen.flac import FLAC, Picture
    from mutagen.mp4 import MP4, MP4Cover
    HAS_MUTAGEN = True
except ImportError:
    HAS_MUTAGEN = False

_MIN_COVER_SIZE = 200   # pixels


def _image_ok(path: Path) -> bool:
    if not HAS_PIL:
        return path.stat().st_size > 5000
    try:
        with Image.open(path) as img:
            w, h = img.size
            return w >= _MIN_COVER_SIZE and h >= _MIN_COVER_SIZE
    except Exception:
        return False


def find_local_cover(image_files: List[Path]) -> Optional[Path]:
    priority = ("folder", "front", "cover", "album")
    # Sort by priority keyword, then size descending
    def key(p: Path):
        name = p.name.lower()
        score = next((i for i, kw in enumerate(priority) if kw in name), len(priority))
        size = p.stat().st_size if p.exists() else 0
        return (score, -size)

    for p in sorted(image_files, key=key):
        if _image_ok(p):
            return p
    return None


def _mb_cover_url(release_mbid: str) -> Optional[str]:
    url = f"https://coverartarchive.org/release/{release_mbid}/front"
    if not HAS_REQUESTS:
        return None
    try:
        r = requests.head(url, timeout=5, allow_redirects=True)
        if r.status_code == 200:
            return url
    except Exception:
        pass
    return None


def download_cover(release_mbid: Optional[str], dest_dir: Path) -> Optional[Path]:
    if not release_mbid or not HAS_REQUESTS:
        return None
    url = _mb_cover_url(release_mbid)
    if not url:
        return None
    dest = dest_dir / "folder.jpg"
    try:
        r = requests.get(url, timeout=15)
        if r.status_code != 200:
            return None
        ct = r.headers.get("content-type", "")
        if "png" in ct and HAS_PIL:
            # PNG → JPEG konvertieren
            import io
            with Image.open(io.BytesIO(r.content)) as img:
                buf = io.BytesIO()
                img.convert("RGB").save(buf, format="JPEG", quality=92)
                dest.write_bytes(buf.getvalue())
        else:
            dest.write_bytes(r.content)
        if _image_ok(dest):
            return dest
        dest.unlink(missing_ok=True)
    except Exception as e:
        print(f"  ⚠️ Cover-Download-Fehler: {e}", file=sys.stderr)
        dest.unlink(missing_ok=True)
    return None


def _load_cover_data(cover_path: Path) -> tuple[bytes, str]:
    """
    Liest Cover-Bilddaten und gibt (bytes, mime_type) zurück.
    WebP wird zu JPEG konvertiert wenn PIL verfügbar (bessere Player-Kompatibilität).
    """
    suffix = cover_path.suffix.lower()
    if suffix in (".jpg", ".jpeg"):
        return cover_path.read_bytes(), "image/jpeg"
    if suffix == ".webp" and HAS_PIL:
        try:
            with Image.open(cover_path) as img:
                img = img.convert("RGB")
                buf = tempfile.SpooledTemporaryFile(max_size=10 * 1024 * 1024)
                img.save(buf, format="JPEG", quality=90)
                buf.seek(0)
                return buf.read(), "image/jpeg"
        except Exception as e:
            print(f"  ⚠️ WebP→JPEG-Konvertierung fehlgeschlagen ({cover_path.name}): {e}",
                  file=sys.stderr)
    if suffix == ".webp":
        return cover_path.read_bytes(), "image/webp"
    if suffix == ".png":
        return cover_path.read_bytes(), "image/png"
    # Fallback: raw bytes, JPEG assumed
    return cover_path.read_bytes(), "image/jpeg"


def embed_cover(audio_path: Path, cover_path: Path) -> bool:
    if not HAS_MUTAGEN:
        return False
    try:
        img_data, mime = _load_cover_data(cover_path)
        ext = audio_path.suffix.lower()

        if ext == ".mp3":
            try:
                tags = ID3(str(audio_path))
            except ID3Error:
                tags = ID3()
            tags.delall("APIC")
            tags.add(APIC(encoding=3, mime=mime, type=3, desc="Cover", data=img_data))
            tags.save(str(audio_path), v2_version=4)
            return True

        elif ext == ".flac":
            audio = FLAC(str(audio_path))
            audio.clear_pictures()
            pic = Picture()
            pic.type = 3
            pic.mime = mime
            pic.desc = "Cover"
            pic.data = img_data
            audio.add_picture(pic)
            audio.save()
            return True

        elif ext == ".m4a":
            audio = MP4(str(audio_path))
            fmt = MP4Cover.FORMAT_JPEG if mime == "image/jpeg" else MP4Cover.FORMAT_PNG
            # WebP wurde bereits zu JPEG konvertiert, mime ist dann "image/jpeg"
            audio.tags["covr"] = [MP4Cover(img_data, imageformat=fmt)]
            audio.save()
            return True

        else:
            # Generic mutagen fallback
            from mutagen import File as MutagenFile
            audio = MutagenFile(str(audio_path), easy=False)
            if audio is not None:
                if audio.tags is None:
                    audio.add_tags()
                if hasattr(audio.tags, "add"):
                    audio.tags.add(
                        APIC(encoding=3, mime=mime, type=3, desc="Cover", data=img_data)
                    )
                    audio.save()
                    return True

    except Exception as e:
        print(f"  ⚠️ Cover-Einbettungsfehler {audio_path.name}: {e}", file=sys.stderr)
    return False


def resolve_cover(
    image_files: List[Path],
    release_mbid: Optional[str],
    album_dir: Path,
) -> tuple[Optional[Path], Optional[str]]:
    """Returns (cover_path, source_label)."""
    local = find_local_cover(image_files)
    if local:
        return local, "local"

    if release_mbid:
        downloaded = download_cover(release_mbid, album_dir)
        if downloaded:
            return downloaded, "musicbrainz"

    return None, None