import subprocess
import shutil
from pathlib import Path

def shift_mka(file: Path, offset: float) -> None:
    """
    Hard-edits an MKA file by shifting audio data.
    Positive offset: Adds silence at start (Delay).
    Negative offset: Trims the beginning (Advance).
    """
    if not file.is_file():
        print(f"File not found: {file}")
        return

    # Create a normal file path right next to the original file
    # If the file is "/folder/audio.mka", this becomes "/folder/shifted_audio.mka"
    new_file = file.parent / f"shifted_{file.name}"
    
    # 1. Determine the filter
    if offset > 0:
        # Delay all channels by X milliseconds
        ms = int(offset * 1000)
        audio_filter = f"adelay={ms}:all=1"
    elif offset < 0:
        # Trim the start and reset timestamps to 0
        audio_filter = f"atrim=start={abs(offset)},asetpts=PTS-STARTPTS"
    else:
        print("Offset is 0, no shift needed.")
        return

    # 2. Execute FFmpeg
    cmd = [
        "ffmpeg", "-y",
        "-i", str(file),
        "-af", audio_filter,
        "-c:a", "libopus", 
        str(new_file)
    ]

    print(f"Processing shift: {offset}s...")
    
    result = subprocess.run(cmd, capture_output=True, text=True)

    if result.returncode == 0:
        # Move the new file over the original file (overwriting it)
        shutil.move(str(new_file), str(file))
        print(f"Successfully updated: {file.name}")
    else:
        print(f"FFmpeg Error:\n{result.stderr}")
        # Clean up the leftover file if the process failed
        if new_file.exists():
            new_file.unlink()

shift_mka(Path("/home/honney/mount/Media/tmp/serien/ready/Classroom of the Elite/Season 01/E01_german_audio.mka"), 0.9592916666666667)