from pydub import AudioSegment, silence
import os

def process_mp3(filepath):
    audio = AudioSegment.from_mp3(filepath)
    
    # 無音区間を検出して削除
    non_silent_audio = silence.detect_nonsilent(audio, min_silence_len=500, silence_thresh=-50)[0]
    trimmed_audio = audio[non_silent_audio[0]:]
    
    # 1秒の無音を作成
    silence_segment = AudioSegment.silent(duration=1000)
    
    # 無音を冒頭に追加
    audio_with_silence = silence_segment + trimmed_audio
    
    # トリミング
    final_trimmed_audio = audio_with_silence[:15000]
    
    # フェードアウト
    faded_audio = final_trimmed_audio.fade_out(1000)
    
    processed_filepath = filepath.replace('.mp3', '_intro.mp3')
    faded_audio.export(processed_filepath, format='mp3')
    
    return processed_filepath