from __future__ import annotations

import csv
import re
import shutil
import subprocess
import sys
from pathlib import Path
from typing import Optional, List, Dict, Any

from models import AlbumProposal, TrackProposal

try:
    from mutagen import File as MutagenFile
    from mutagen.easyid3 import EasyID3
    from mutagen.flac import FLAC
    from mutagen.mp4 import MP4, MP4Tags
    HAS_MUTAGEN = True
except ImportError:
    HAS_MUTAGEN = False

from cover_handler import embed_cover

_SAFE_RE = re.compile(r'[<>:"/\\|?*\x00-\x1f]')
_CLASSICAL_GENRES = re.compile(
    r"(?i)class|baroque|romantic|renaissance|opera|symphony|chamber|concerto|sonata|oratorio"
)
REPORT_FIELDS = [
    "status", "album_dir", "track_path",
    "old_title", "new_title",
    "old_artist", "new_artist",
    "album", "albumartist", "date", "genre", "label",
    "track_number", "disc_number",
    "cover_embedded", "renamed_to",
    "confidence", "sources",
]


def _safe_name(s: str) -> str:
    """Filesystem-safe name: illegal chars → '_', spaces → '_'."""
    s = _SAFE_RE.sub("_", s)
    return re.sub(r"\s+", "_", s).strip("._-")


def _is_classical(albumartist: str, track_artist: str, genre: str) -> bool:
    """
    Classical schema applies when performer (albumartist) ≠ composer (track_artist),
    which covers both 'real' classical music and jazz-on-classical-themes albums.
    Genre keyword matching is used as additional signal but not required.
    """
    aa = (albumartist or "").casefold().strip()
    ta = (track_artist or "").casefold().strip()
    if not aa or aa in ("various artists", "unknown artist", "unknown"):
        return False
    if aa == ta:
        return False
    return True  # performer ≠ composer → classical naming


def _proposed_filename(
    proposal: TrackProposal,
    ext: str,
    albumartist: str = "",
    genre: str = "",
) -> str:
    """
    Pop/Default:  TT_-_Artist_-_Titel.ext
    Klassik:      TT_-_Performer_-_Komponist_-_Titel[-_Orchester_Dirigent].ext

    Separator zwischen Teilen: _-_
    Leerzeichen innerhalb von Namen: _
    Fehlende Teile werden weggelassen.
    """
    tn = f"{proposal.track_number:02d}" if proposal.track_number else "00"
    # disc_prefix nur bei echtem Multi-CD (disc > 1). disc=1 oder None → Einzel-CD → kein Präfix.
    disc_prefix = f"{proposal.disc_number}-" if (proposal.disc_number and proposal.disc_number > 1) else ""
    prefix = f"{disc_prefix}{tn}"

    track_artist = _safe_name(proposal.artist or "Unknown")
    aa = _safe_name(albumartist)
    title = _safe_name(proposal.title or "Unknown")

    if _is_classical(aa, track_artist, genre):
        # Klassik-Schema: Performer _-_ Komponist _-_ Werk [_-_ Orchester,Dirigent]
        parts = [prefix, aa, track_artist, title]
        # Orchester und Dirigent anhängen wenn vorhanden
        extra = "_".join(filter(None, [
            _safe_name(proposal.orchestra or ""),
            _safe_name(proposal.conductor or ""),
        ]))
        if extra:
            parts.append(extra)
        return "_-_".join(parts) + ext
    else:
        # Pop/Default-Schema: Tracknummer _-_ Artist _-_ Titel
        return f"{prefix}_-_{track_artist}_-_{title}{ext}"


def backup_file(path: Path, backup_dir: Path) -> bool:
    try:
        backup_dir.mkdir(parents=True, exist_ok=True)
        rel = path.parent.name + "__" + path.name
        dest = backup_dir / rel
        if not dest.exists():
            shutil.copy2(path, dest)
        return True
    except Exception as e:
        print(f"  ⚠️ Backup-Fehler {path.name}: {e}", file=sys.stderr)
        return False


def write_tags(path: Path, proposal: TrackProposal, album_proposal: AlbumProposal) -> bool:
    if not HAS_MUTAGEN:
        return False
    ext = path.suffix.lower()
    tags_to_write = {
        "title": proposal.title or "",
        "artist": proposal.artist or "",
        "album": album_proposal.album or "",
        "albumartist": album_proposal.albumartist or "",
    }
    if proposal.track_number:
        total = len(album_proposal.tracks)
        tags_to_write["tracknumber"] = f"{proposal.track_number}/{total}"
    if proposal.disc_number and proposal.disc_number > 1:
        tags_to_write["discnumber"] = str(proposal.disc_number)
    if album_proposal.date:
        # Strip everything except valid ID3 timestamp characters to prevent ID3TimeStamp errors
        date_clean = re.sub(r"[^\d\-T:+Z]", "", str(album_proposal.date)).strip()
        if date_clean:
            tags_to_write["date"] = date_clean
    if album_proposal.genre:
        tags_to_write["genre"] = album_proposal.genre
    if album_proposal.label:
        tags_to_write["organization"] = album_proposal.label

    try:
        if ext == ".mp3":
            try:
                audio = EasyID3(str(path))
            except Exception:
                # File has no ID3 header — add one without wiping audio data
                from mutagen.id3 import ID3NoHeaderError
                try:
                    from mutagen.mp3 import MP3
                    full = MP3(str(path))
                    full.tags = None
                    full.add_tags()
                    full.save(str(path), v2_version=4)
                except Exception:
                    pass
                audio = EasyID3(str(path))
            for k, v in tags_to_write.items():
                try:
                    audio[k] = [v]
                except Exception as tag_err:
                    print(f"  ⚠️ Tag-Feld '{k}' übersprungen ({path.name}): {tag_err}", file=sys.stderr)
            audio.save(v2_version=4)
            return True

        elif ext == ".flac":
            audio = FLAC(str(path))
            for k, v in tags_to_write.items():
                audio[k] = [v]
            audio.save()
            return True

        elif ext == ".m4a":
            audio = MP4(str(path))
            mapping = {
                "title": "\xa9nam", "artist": "\xa9ART",
                "album": "\xa9alb", "albumartist": "aART",
                "tracknumber": "trkn", "date": "\xa9day",
                "genre": "\xa9gen",
            }
            for k, v in tags_to_write.items():
                tag_key = mapping.get(k)
                if tag_key:
                    if tag_key == "trkn":
                        try:
                            num, total = v.split("/") if "/" in v else (v, "0")
                            audio[tag_key] = [(int(num), int(total))]
                        except Exception:
                            pass
                    else:
                        audio[tag_key] = [v]
            audio.save()
            return True

        else:
            audio = MutagenFile(str(path), easy=True)
            if audio is not None:
                if audio.tags is None:
                    audio.add_tags()
                for k, v in tags_to_write.items():
                    try:
                        audio[k] = [v]
                    except Exception:
                        pass
                audio.save()
                return True

    except Exception as e:
        print(f"  ⚠️ Tag-Schreibfehler {path.name}: {e}", file=sys.stderr)
    return False


def _update_m3u(m3u_path: Path, tracks: List[tuple]) -> bool:
    """
    Schreibt M3U neu mit den umbenannten Dateien in Track-Reihenfolge.
    tracks: [(TrackProposal, actual_path_after_rename), ...]
    """
    try:
        lines = ["#EXTM3U"]
        for tp, track_path in tracks:
            duration = -1
            if HAS_MUTAGEN:
                try:
                    audio = MutagenFile(str(track_path))
                    if audio and hasattr(audio, "info") and audio.info:
                        duration = int(audio.info.length)
                except Exception:
                    pass
            label = f"{tp.artist} - {tp.title}" if tp.artist else (tp.title or track_path.stem)
            lines.append(f"#EXTINF:{duration},{label}")
            lines.append(track_path.name)
        m3u_path.write_text("\n".join(lines) + "\n", encoding="utf-8")
        print(f"  📋 Playlist aktualisiert: {m3u_path.name}")
        return True
    except Exception as e:
        print(f"  ⚠️ M3U-Fehler {m3u_path.name}: {e}", file=sys.stderr)
        return False


def execute_album(
    proposal: AlbumProposal,
    backup_dir: Optional[Path],
    do_rename: bool,
    embed_cover_art: bool,
    dry_run: bool,
    report_data: List[Dict[str, Any]],
) -> Dict[str, int]:
    stats = {"tags_written": 0, "covers_embedded": 0, "files_renamed": 0, "errors": 0}
    final_tracks: List[tuple] = []  # (TrackProposal, final_path) für M3U

    for tp in proposal.tracks:
        old_title = tp.path.stem
        old_artist = ""
        if HAS_MUTAGEN:
            try:
                audio = MutagenFile(str(tp.path), easy=True)
                if audio and audio.tags:
                    old_artist = str(audio.tags.get("artist", [""])[0])
                    old_title = str(audio.tags.get("title", [tp.path.stem])[0])
            except Exception:
                pass

        new_path = tp.path
        renamed_to = ""
        cover_embedded = False

        if not dry_run:
            if backup_dir:
                backup_file(tp.path, backup_dir)

            if write_tags(tp.path, tp, proposal):
                stats["tags_written"] += 1
            else:
                stats["errors"] += 1

            if embed_cover_art and proposal.cover_path:
                if embed_cover(tp.path, proposal.cover_path):
                    stats["covers_embedded"] += 1
                    cover_embedded = True

            if do_rename:
                new_name = _proposed_filename(
                    tp, tp.path.suffix,
                    albumartist=proposal.albumartist or "",
                    genre=proposal.genre or "",
                )
                candidate = tp.path.parent / new_name
                if candidate != tp.path:
                    try:
                        tp.path.rename(candidate)
                        new_path = candidate
                        renamed_to = new_name
                        stats["files_renamed"] += 1
                    except Exception as e:
                        print(f"  ⚠️ Umbenennungsfehler {tp.path.name}: {e}", file=sys.stderr)
                        stats["errors"] += 1

        if not dry_run:
            final_tracks.append((tp, new_path))

        report_data.append({
            "status": "dry-run" if dry_run else "ok",
            "album_dir": str(proposal.album_dir.name),
            "track_path": str(new_path),
            "old_title": old_title,
            "new_title": tp.title,
            "old_artist": old_artist,
            "new_artist": tp.artist,
            "album": proposal.album,
            "albumartist": proposal.albumartist,
            "date": proposal.date or "",
            "genre": proposal.genre or "",
            "label": proposal.label or "",
            "track_number": tp.track_number or "",
            "disc_number": tp.disc_number or "",
            "cover_embedded": cover_embedded,
            "renamed_to": renamed_to,
            "confidence": f"{proposal.confidence:.2f}",
            "sources": ", ".join(proposal.sources),
        })

    # M3U-Playlist aktualisieren wenn Dateien umbenannt wurden
    if do_rename and not dry_run and stats["files_renamed"] > 0 and final_tracks:
        m3u_files = (
            list(proposal.album_dir.glob("*.m3u")) +
            list(proposal.album_dir.glob("*.m3u8"))
        )
        if m3u_files:
            _update_m3u(m3u_files[0], final_tracks)

    # Nach allen Umbenennungen: Verzeichnis Linux-kompatibel bereinigen
    if do_rename and not dry_run:
        sanitize_dir_names(proposal.album_dir)

    return stats


def sanitize_dir_names(directory: Path) -> None:
    """
    Macht alle Dateinamen im Verzeichnis Linux-kompatibel.
    Bevorzugt 'NameToUnix <dir>', fällt auf 'detox <file>' zurück.
    """
    name_to_unix = shutil.which("NameToUnix")
    if name_to_unix:
        try:
            subprocess.run([name_to_unix, str(directory)], check=True, capture_output=True)
            return
        except subprocess.CalledProcessError as e:
            print(f"  ⚠️ NameToUnix-Fehler: {e.stderr.decode(errors='replace').strip()}", file=sys.stderr)

    detox = shutil.which("detox")
    if detox:
        for f in sorted(directory.rglob("*")):
            if f.is_file():
                try:
                    subprocess.run([detox, str(f)], check=True, capture_output=True)
                except subprocess.CalledProcessError as e:
                    print(f"  ⚠️ detox-Fehler {f.name}: {e.stderr.decode(errors='replace').strip()}", file=sys.stderr)
    else:
        print("  ℹ️  Weder NameToUnix noch detox gefunden — Dateinamen nicht nachbereinigt.", file=sys.stderr)


def write_report(report_data: List[Dict[str, Any]], report_path: Path) -> None:
    try:
        report_path.parent.mkdir(parents=True, exist_ok=True)
        with report_path.open("w", encoding="utf-8", newline="") as f:
            w = csv.DictWriter(f, fieldnames=REPORT_FIELDS)
            w.writeheader()
            w.writerows(report_data)
        print(f"📊 Report gespeichert: {report_path}")
    except Exception as e:
        print(f"⚠️ Report-Fehler: {e}", file=sys.stderr)