# Votify Download System

## Overview

Votify is the primary Spotify download backend. It invokes the `votify` CLI tool (a third-party Python package) as a subprocess, streams its output to the job log, and post-processes the resulting files.

Upstream is the official [glomatico/votify](https://github.com/glomatico/votify) project, installed from git in the Dockerfile. It previously used the `GladistonXD/votify-fix` fork; the fork's CLI flag names differ from upstream's, so `run_download()` was remapped when the swap was made (see [CLI flag mapping](#cli-flag-mapping)).

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## How It Works

1. User submits Spotify URLs and options via `POST /api/download`.
2. A job is created and a background thread runs `run_download()`.
3. `run_download()` builds a `votify` CLI command and launches it via `subprocess.Popen`.
4. stdout is streamed line-by-line into the job's output log.
5. On completion, post-processing runs:
   - Flatten nested directories
   - Rename files from embedded metadata
   - Wrap single-track downloads in a folder
   - Convert to MP3 if requested

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## Authentication

Votify authenticates with Spotify using a `cookies.txt` file in Netscape format. This file must be uploaded by an admin via the Settings page before any downloads will succeed.

Upstream supports three session types (`--session-type`: `librespot`, `desktop`, `web`), defaulting to `librespot`. The app does not pass the flag, so the default applies — which is why the Dockerfile installs the `[librespot]` extra. Installing plain `votify` without the extra will fail at runtime under the default session type.

Path: `/config/cookies.txt` (configurable via `COOKIES_PATH` env var)

A Widevine device certificate (`device.wvd`) may also be required depending on the content. It is uploaded separately via Settings.

Path: `/config/device.wvd` (configurable via `WVD_PATH` env var)

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## Download Options

| Option | Values | Description |
|--------|--------|-------------|
| `audio_quality` | `aac-medium`, `aac-high`, `vorbis-low`, `vorbis-medium`, `vorbis-high` | Audio quality |
| `output_format` | `original`, `mp3` | Keep original format or convert to MP3 |
| `download_mode` | `ytdlp`, `aria2c` | Download backend |
| `save_cover` | bool | Save cover art as a separate image file |
| `save_playlist` | bool | Save playlist metadata file |
| `overwrite` | bool | Re-download if file already exists |
| `download_music_videos` | bool | Prefer video streams where available |
| `no_lrc` | bool | Skip LRC (lyrics) file generation |
| `save_lrc` | bool | Download *only* the synced-lyrics file |
| `video_format` | `mp4`, `webm` | Format for music videos |
| `cover_size` | `small`, `medium`, `large`, `extra-large` | Cover art resolution |
| `truncate` | int (optional) | Max file/folder **name length** (not a track-count limit) |

These are the app-level option names sent to `POST /api/download`; they are stable and unchanged by the upstream swap. The CLI flags they translate into are not — see below.

Upstream also accepts `curl` for `--audio-download-mode` and the FLAC qualities `flac-flac`, `flac-mp4`, `flac-flac-24`, `flac-mp4-24` (premium accounts only). Neither is exposed in the UI; the values above are what the frontend offers.

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## CLI Flag Mapping

`run_download()` builds the argv. Most flags were renamed between the old fork and upstream:

| App option | Old (`votify-fix`) flag | Current (official) flag |
|------------|------------------------|-------------------------|
| output dir | `--output-path` | `--output` |
| temp dir | `--temp-path` | `--temp` |
| `download_mode` | `--download-mode` | `--audio-download-mode` |
| `save_cover` | `--save-cover` | `--save-cover-file` |
| `save_playlist` | `--save-playlist` | `--save-playlist-file` |
| `download_music_videos` | `--download-music-videos` | `--prefer-video` |
| `save_lrc` | `--lrc-only` | `--synced-lyrics-only` |
| `no_lrc` | `--no-lrc` | `--no-synced-lyrics-file` |
| folder flattening | `--template-folder-{album,compilation,episode,music-video}` | `--album-folder-template`, `--compilation-folder-template`, `--podcast-folder-template`, `--no-album-folder-template` |

Unchanged: `--cookies-path`, `--wvd-path`, `--audio-quality`, `--video-format`, `--cover-size`, `--overwrite`, `--truncate`.

All four folder templates are set to `.` so downloads land flat in the job's output directory; `post_process_votify_files()` then imposes the final layout. Upstream has no music-video folder template — `--no-album-folder-template` (used for albumless tracks) took that slot.

`--no-config-file` is always passed so a stray `~/.votify/config.ini` cannot silently override these flags.

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## MP3 Conversion

If `output_format` is set to `mp3`, files are converted after download using `ffmpeg` at 320 kbps. The conversion preserves embedded metadata. Original files are deleted after successful conversion.

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## Cancellation

The Popen process handle is stored on the job dict. `POST /api/jobs/<id>/cancel` calls `process.terminate()`, which sends SIGTERM to the votify subprocess.

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## Post-Processing Detail

After the subprocess exits, `post_process_votify_files()` runs:

1. **Snapshot before** — records which audio files existed before the download started (to identify new files).
2. **Flatten** — collapses single-subdirectory chains into the parent folder.
3. **Rename** — calls `rename_from_metadata()` to produce `Title - Artist.ext` filenames.
4. **Wrap singles** — if exactly one file downloaded with no enclosing folder, wraps it in a folder named after the file.
5. **Cleanup** — removes leftover empty directories.

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## External Dependencies

| Dependency | Purpose |
|------------|---------|
| `votify` (GitHub: glomatico/votify, `[librespot]` extra) | Spotify download CLI |
| `ffmpeg` | MP3 conversion |
| `aria2c` | Optional download manager |
| `yt-dlp` | Default download manager |
| `mp4decrypt` (Bento4) | MP4 DRM decryption |

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## Limitations

- Requires valid Spotify cookies (must be refreshed periodically when they expire).
- DRM-protected content requires a Widevine device certificate.
- Quality options are limited to what Votify and the Spotify API expose.
- Upstream warns that some users have had their Spotify accounts suspended for using it.
- **Interactive prompts can break jobs.** Upstream uses `inquirerpy` and will prompt on stdin for artist URLs (unless `--auto-media-option` is passed) and for `--video-format ask`. The subprocess has no usable stdin under Gunicorn, so such a job fails rather than completing. The UI only offers `mp4`/`webm`, so in practice this is reachable only via artist URLs or direct API calls.

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## Key Files

| File | Relevance |
|------|-----------|
| [app.py](../app.py) | `run_download()`, `post_process_votify_files()`, route `/api/download` |
| [utils.py](../utils.py) | `rename_from_metadata()`, `cleanup_empty_dirs()` |
| [Dockerfile](../Dockerfile) | Installation of votify, ffmpeg, aria2, Bento4 |