app.py

"""YT Proxy — lightweight YouTube downloader for Mazinger Dubber."""

import os
import tempfile

import gradio as gr
import yt_dlp


def download_video(url: str) -> str:
    """Download a YouTube video and return the local file path."""
    if not url or not url.strip():
        raise gr.Error("Please provide a YouTube URL.")

    tmp_dir = tempfile.mkdtemp(prefix="yt_proxy_")
    output_template = os.path.join(tmp_dir, "%(title).50s.%(ext)s")

    ydl_opts = {
        "format": "bestvideo[height<=720][ext=mp4]+bestaudio[ext=m4a]/best[height<=720][ext=mp4]/best",
        "outtmpl": output_template,
        "merge_output_format": "mp4",
        "quiet": True,
        "no_warnings": True,
    }

    try:
        with yt_dlp.YoutubeDL(ydl_opts) as ydl:
            info = ydl.extract_info(url, download=True)
            filename = ydl.prepare_filename(info)
            # yt-dlp may change extension after merge
            if not os.path.exists(filename):
                for f in os.listdir(tmp_dir):
                    filename = os.path.join(tmp_dir, f)
                    break
            return filename
    except Exception as e:
        raise gr.Error(f"Download failed: {e}")


def download_audio(url: str) -> str:
    """Download audio only from a YouTube video."""
    if not url or not url.strip():
        raise gr.Error("Please provide a YouTube URL.")

    tmp_dir = tempfile.mkdtemp(prefix="yt_proxy_")
    output_template = os.path.join(tmp_dir, "%(title).50s.%(ext)s")

    ydl_opts = {
        "format": "bestaudio/best",
        "outtmpl": output_template,
        "postprocessors": [{
            "key": "FFmpegExtractAudio",
            "preferredcodec": "mp3",
            "preferredquality": "192",
        }],
        "quiet": True,
        "no_warnings": True,
    }

    try:
        with yt_dlp.YoutubeDL(ydl_opts) as ydl:
            info = ydl.extract_info(url, download=True)
            # Find the output file (may have .mp3 extension after postprocessing)
            for f in os.listdir(tmp_dir):
                return os.path.join(tmp_dir, f)
            raise gr.Error("No output file found.")
    except gr.Error:
        raise
    except Exception as e:
        raise gr.Error(f"Download failed: {e}")


with gr.Blocks(title="YT Proxy") as demo:
    gr.Markdown("## YT Proxy\nDownload YouTube videos/audio. Used by Mazinger Dubber.")

    url_input = gr.Textbox(label="YouTube URL", placeholder="https://youtube.com/watch?v=...")

    with gr.Row():
        video_btn = gr.Button("Download Video (MP4)")
        audio_btn = gr.Button("Download Audio (MP3)")

    output_file = gr.File(label="Downloaded file")

    video_btn.click(fn=download_video, inputs=url_input, outputs=output_file, api_name="download_video")
    audio_btn.click(fn=download_audio, inputs=url_input, outputs=output_file, api_name="download_audio")

demo.queue().launch()