import subprocess, os, asyncio

from yt_dlp import YoutubeDL
from yt_dlp.utils import DownloadError
#
#  The download folder. 
#  It goes:
#  FOLDER/<user_id>/<filename>
#
DOWNLOAD_FOLDER = os.environ.get("DOWNLOAD_FOLDER","/tmp/downloads")  # Where the converted files will be saved
if not os.path.exists(DOWNLOAD_FOLDER):
    os.makedirs(DOWNLOAD_FOLDER)
    
# Throw error if the env is incorrect
try:
    AUTODELETE_DELAY_SECS = int(os.environ.get("FILE_AUTODELETE_DELAY_SECS", 0))
except ValueError:
    raise EnvironmentError("You must set AUTODELETE_DELAY_SECS to a valid number (int) of seconds! To disable auto delete (not recommended), set it to 0")
    
#
# Asyncioway of scheduling a file delete with asyncio.sleep() and os.unlink()
#
async def delay_delete_file(file:str):
    if (AUTODELETE_DELAY_SECS > 0):
        await asyncio.sleep(AUTODELETE_DELAY_SECS)
        if os.path.exists(file): os.unlink(file)


#
# Downloads the video and extracts the audio
#
def download_audio(video_url: str, output_folder: str, kbps:int) -> str:
    ydl_opts = {
        'format': 'bestaudio/best',
        'outtmpl': os.path.join(output_folder, '%(title)s.%(ext)s'),
        'postprocessors': [{
            'key': 'FFmpegExtractAudio',
            'preferredcodec': 'mp3',
            'preferredquality': str(kbps),
        }, {
            'key': 'FFmpegMetadata',
            'add_metadata': True,
        }],
        'quiet': True,
        'noplaylist': True
    }

    with YoutubeDL(ydl_opts) as ydl:
        info = ydl.extract_info(video_url, download=True)
        filename = ydl.prepare_filename(info)
        return os.path.splitext(filename)[0] + ".mp3"  # path to final MP3

#
# Uses FFmpeg to edit the artist and album if specified
#
def set_metadata_and_rename(mp3_file: str, name: str, artist: str = None, album: str = None) -> str:
    new_file = os.path.abspath(os.path.join(os.path.dirname(mp3_file), f"{name}.mp3"))
    
    cmd = ["ffmpeg", "-y", "-i", mp3_file]
    
    # Only add metadata if provided
    cmd += ["-metadata", f"title={name}"]
    if artist:
        cmd += ["-metadata", f"artist={artist}"]
    if album:
        cmd += ["-metadata", f"album={album}"]
    
    cmd += [new_file]
    
    subprocess.run(cmd, check=True)
    os.remove(mp3_file)  # clean original
    return new_file