import subprocess
import os
 
def transcode_file(transcoding_tasks, socketio, file_path, codec, resolution, crf, preset, cpu_used):
    width = resolution
    output_file = file_path.replace('.mkv', '_transcoded.mkv')
 
    if os.path.exists(output_file):  # Проверяем существование файла
        os.remove(output_file)  # Удаляем файл
        print(f"File already exists. {output_file} was deleted.")
 
    command = [
        "ffmpeg", "-i", file_path,
        "-map", "0",
        "-c:v", codec,
        "-vf", f"scale={width}:-1",
        "-c:a", "copy",
        "-crf", crf
    ]
 
    if codec == "libaom-av1":
        command.append("-cpu-used")
        command.append(cpu_used)
    elif codec == "libvpx-vp9":
        command.append("-cpu-used")
        command.append(cpu_used)
    else:
        command.append("-preset")
        command.append(preset)    
 
    command.append(output_file);
 
    print(" ".join(command))
 
    process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, text=True)
    task = {
        "id": "id_" + str(len(transcoding_tasks) + 1),
        "file": file_path,
        "output": output_file,
        "command": command,
        "process": process 
    }
 
    transcoding_tasks[task["id"]] = task;
 
    for line in process.stdout:
        # Parse progress from ffmpeg output and send via WebSocket
        if "frame=" in line:
            socketio.emit('progress', {
                "task": {
                    "id": task["id"],
                    "file": task["file"],
                    "command": task["command"]
                },
                "message": line.strip()
            })
    process.wait()
 
    # Step 3: Replace the original file with the transcoded file
    if process.returncode == 0:
        os.replace(output_file, file_path)
        socketio.emit('completed', {
            "task": {
                "id": task["id"],
                "file": task["file"],
                "command": task["command"]
            },
            "message": f"File {file_path} transcoded successfully"
        })
 
        os.rename(output_file, file_path)
        del transcoding_tasks[task["id"]]
    else:
        if(task["id"] in transcoding_tasks):
            socketio.emit('error', {
                "task": {
                    "id": task["id"],
                    "file": task["file"],
                    "command": task["command"]
                },
                "message": f"Transcoding failed for {file_path}"
            })
            del transcoding_tasks[task["id"]]
        else:
            # canceled
            socketio.emit('canceled', {
                "task": {
                    "id": task["id"],
                    "file": task["file"],
                    "command": task["command"]
                },
                "message": f"Transcoding canceled for {file_path}"
            })
 
        if os.path.exists(output_file):
            os.remove(output_file)