#!/usr/bin/env python3
"""
cuesplit.py — split FLAC files using a .cue sheet, via ffmpeg.
Handles multi-FILE cues, frame-accurate (MM:SS:FF) timestamps, and uses
INDEX 01 (track start, skipping pregap) as the split point.

Usage:
    python3 cuesplit.py "album.cue" [output_dir]

Output dir defaults to "split".
"""
import re
import subprocess
import sys
from pathlib import Path


def parse_cue(cue_path):
    """Returns list of (filename, [(track_num, index01_time_str), ...])"""
    files = []
    current_file = None
    current_tracks = None
    pending_track = None

    with open(cue_path, encoding="utf-8", errors="replace") as f:
        for line in f:
            line = line.strip()

            m = re.match(r'FILE\s+"([^"]+)"', line, re.IGNORECASE)
            if m:
                if current_file is not None:
                    files.append((current_file, current_tracks))
                current_file = m.group(1)
                current_tracks = []
                continue

            m = re.match(r'TRACK\s+(\d+)\s+AUDIO', line, re.IGNORECASE)
            if m:
                pending_track = int(m.group(1))
                continue

            m = re.match(r'INDEX\s+01\s+(\d+:\d+:\d+)', line, re.IGNORECASE)
            if m and pending_track is not None:
                current_tracks.append((pending_track, m.group(1)))
                pending_track = None
                continue

    if current_file is not None:
        files.append((current_file, current_tracks))

    return files


def cue_time_to_seconds(t):
    mm, ss, ff = map(int, t.split(":"))
    return mm * 60 + ss + ff / 75.0


def seconds_to_ffmpeg_ts(total_seconds):
    mm = int(total_seconds // 60)
    ss = total_seconds - mm * 60
    return f"{mm:02d}:{ss:06.3f}"


def main():
    if len(sys.argv) < 2:
        print("Usage: python3 cuesplit.py <cuefile> [output_dir]")
        sys.exit(1)

    cue_path = Path(sys.argv[1])
    out_dir = Path(sys.argv[2]) if len(sys.argv) > 2 else Path("split")
    out_dir.mkdir(parents=True, exist_ok=True)

    if not cue_path.exists():
        print(f"Cue file not found: {cue_path}")
        sys.exit(1)

    files = parse_cue(cue_path)
    if not files:
        print("No FILE/TRACK entries found in cue — check the cue format.")
        sys.exit(1)

    track_counter = 1

    for flac_name, tracks in files:
        flac_path = cue_path.parent / flac_name
        if not flac_path.exists():
            print(f"WARNING: referenced audio file not found: {flac_path}")
            continue

        if not tracks:
            print(f"WARNING: no tracks found for {flac_name}")
            continue

        starts = [cue_time_to_seconds(t) for _, t in tracks]

        for i, start in enumerate(starts):
            out_file = out_dir / f"{track_counter:02d}.flac"
            ss = seconds_to_ffmpeg_ts(start)

            cmd = ["ffmpeg", "-y", "-i", str(flac_path), "-ss", ss]

            if i + 1 < len(starts):
                to = seconds_to_ffmpeg_ts(starts[i + 1])
                cmd += ["-to", to]

            cmd += [str(out_file)]

            print(f"Track {track_counter}: {flac_name} [{ss}"
                  f"{' -> ' + to if i + 1 < len(starts) else ' -> end'}]")

            result = subprocess.run(cmd, capture_output=True, text=True)
            if result.returncode != 0:
                print(f"  FAILED: {result.stderr[-500:]}")
            else:
                print(f"  OK -> {out_file}")

            track_counter += 1

    print(f"\nDone. {track_counter - 1} tracks written to {out_dir}/")


if __name__ == "__main__":
    main()