"""
scanner.py — Scanning af musikbiblioteker i baggrunden.

Kører som en separat subprocess der scanner ét bibliotek ad gangen
og rapporterer fremgang via stdout JSON-linjer.

Kan også importeres direkte og bruges via ScanWorker QThread.
"""
import os
import sys
import json
import sqlite3
import uuid
import logging
from pathlib import Path

logger = logging.getLogger(__name__)

SUPPORTED = {'.mp3', '.flac', '.m4a', '.ogg', '.wav', '.aiff', '.wma'}


def is_supported(path: Path) -> bool:
    return path.suffix.lower() in SUPPORTED


def get_file_mtime(path: Path) -> str:
    try:
        return str(os.path.getmtime(str(path)))
    except Exception:
        return ""


def scan_library(library_id: int, library_path: str, db_path: str,
                 overwrite_bpm: bool = False,
                 progress_callback=None):
    """
    Scan ét bibliotek og upsert sange til SQLite.
    progress_callback(done, total, current_file) kaldes løbende.
    """
    from local.tag_reader import read_tags

    conn = sqlite3.connect(db_path)
    conn.row_factory = sqlite3.Row

    base = Path(library_path)
    if not base.exists():
        conn.close()
        return 0

    # Byg indeks over kendte filer
    known = {}
    for row in conn.execute(
        "SELECT local_path, file_modified_at FROM songs WHERE library_id=?",
        (library_id,)
    ).fetchall():
        known[row["local_path"]] = row["file_modified_at"]

    # Find alle musikfiler
    all_files = []
    for dirpath, _, filenames in os.walk(str(base), followlinks=False):
        for fn in filenames:
            fp = Path(dirpath) / fn
            if is_supported(fp):
                all_files.append(fp)

    total = len(all_files)
    done  = 0

    import time

    for fp in all_files:
        path_str = str(fp)
        mtime    = get_file_mtime(fp)

        if progress_callback:
            progress_callback(done, total, fp.name)

        # Spring over hvis ikke ændret
        if path_str in known and known[path_str] == mtime:
            done += 1
            # Yield hvert 100. fil så andre tråde kan køre
            if done % 100 == 0:
                time.sleep(0.005)
            continue

        try:
            tags = read_tags(fp)
            extra = json.dumps(tags.get("extra_tags", {}), ensure_ascii=False)

            existing = conn.execute(
                "SELECT id, bpm FROM songs WHERE local_path=?", (path_str,)
            ).fetchone()

            if existing:
                bpm = tags.get("bpm", 0)
                if not overwrite_bpm and existing["bpm"] and existing["bpm"] > 0:
                    bpm = existing["bpm"]  # behold eksisterende BPM
                conn.execute("""
                    UPDATE songs SET
                        library_id=?, title=?, artist=?, album=?,
                        bpm=?, duration_sec=?, file_format=?,
                        file_modified_at=?, file_missing=0, extra_tags=?
                    WHERE id=?
                """, (library_id, tags.get("title",""), tags.get("artist",""),
                      tags.get("album",""), bpm, tags.get("duration_sec",0),
                      tags.get("file_format",""), mtime, extra, existing["id"]))
            else:
                song_id = str(uuid.uuid4())
                conn.execute("""
                    INSERT OR IGNORE INTO songs
                        (id, library_id, local_path, title, artist, album,
                         bpm, duration_sec, file_format, file_modified_at, extra_tags)
                    VALUES (?,?,?,?,?,?,?,?,?,?,?)
                """, (song_id, library_id, path_str,
                      tags.get("title",""), tags.get("artist",""),
                      tags.get("album",""), tags.get("bpm",0),
                      tags.get("duration_sec",0), tags.get("file_format",""),
                      mtime, extra))

            conn.commit()
        except Exception as e:
            logger.warning(f"Scan fejl {fp.name}: {e}")

        done += 1
        # Lille pause efter hver scannet fil så GUI ikke hænger
        time.sleep(0.02)

    # Marker manglende filer
    for path_str in known:
        if not Path(path_str).exists():
            conn.execute(
                "UPDATE songs SET file_missing=1 WHERE local_path=?", (path_str,)
            )
    conn.commit()

    conn.execute(
        "UPDATE libraries SET last_full_scan=datetime('now') WHERE id=?",
        (library_id,)
    )
    conn.commit()
    conn.close()
    return done


# ── Subprocess entry point ─────────────────────────────────────────────────────

if __name__ == "__main__":
    """
    Kørsel som subprocess:
    python scanner.py <library_id> <library_path> <db_path>
    Rapporterer JSON-linjer til stdout: {"done":N,"total":M,"file":"..."}
    """
    if len(sys.argv) < 4:
        sys.exit(1)

    lib_id   = int(sys.argv[1])
    lib_path = sys.argv[2]
    db_path  = sys.argv[3]

    # Tilføj app-mappen til path så local.tag_reader kan importeres
    app_dir = str(Path(__file__).parent.parent)
    if app_dir not in sys.path:
        sys.path.insert(0, app_dir)

    def report(done, total, filename):
        print(json.dumps({"done": done, "total": total, "file": filename}),
              flush=True)

    count = scan_library(lib_id, lib_path, db_path,
                         progress_callback=report)
    print(json.dumps({"done": count, "total": count, "finished": True}),
          flush=True)