#!/bin/bash
# fix-genre.sh — quickly override the GENRE tag for every track by an artist.
#
# Use when spotify-genre.py picks something wrong (e.g. it tagged Yasuha as
# "Asian Music" when "Anime; Soundtrack" is what you actually want), or when
# you want to set a genre on an artist Spotify doesn't have data for.
#
# The new value is written to file tags AND beets's DB. The next nightly
# spotify-genre run will leave these alone (they already match the whitelist
# format), unless you pass --force.
#
# Usage:
#   fix-genre.sh "<artist>" "<Genre1; Genre2; ...>"        # apply
#   fix-genre.sh --dry "<artist>" "<Genre1; ...>"          # preview only
#
# Examples:
#   sudo fix-genre.sh "Yasuha" "Anime; Soundtrack"
#   sudo fix-genre.sh "Aphex Twin" "IDM; Electronic; Ambient"
#   sudo fix-genre.sh --dry "Mac DeMarco" "Indie; Indie Rock"

set -euo pipefail

DRY=0
if [[ "${1:-}" == "--dry" ]]; then
  DRY=1
  shift
fi

ARTIST="${1:?Usage: $0 [--dry] <artist> <Genre1; Genre2; ...>}"
GENRE="${2:?Usage: $0 [--dry] <artist> <Genre1; Genre2; ...>}"

LIBRARY=${MUSIC_DATA_DIR:-/data/music}/Library

# Pull paths via beets (in-process, same container).
mapfile -t paths < <(beet ls -f '$path' "artist:$ARTIST" 2>/dev/null)

if [[ "${#paths[@]}" -eq 0 ]]; then
  echo "[fix-genre] no tracks found in beets for artist:$ARTIST"
  exit 1
fi

echo "[fix-genre] artist=\"$ARTIST\""
echo "[fix-genre] new GENRE=\"$GENRE\""
echo "[fix-genre] ${#paths[@]} track(s) match"
[[ $DRY -eq 1 ]] && echo "[fix-genre] DRY RUN — no tags will be written" && exit 0

ok=0
fail=0
for cp in "${paths[@]}"; do
  hp="${LIBRARY}${cp#/music}"
  if [[ ! -f "$hp" ]]; then
    echo "  MISS  $hp"
    fail=$((fail + 1))
    continue
  fi
  case "${hp,,}" in
    *.flac)
      # remove-tag returns non-zero when the tag isn't present; `|| true` so
      # that expected case doesn't abort under set -e.
      metaflac --remove-tag=GENRE "$hp" 2>/dev/null || true
      metaflac --set-tag="GENRE=$GENRE" "$hp" 2>/dev/null && ok=$((ok + 1)) || fail=$((fail + 1))
      metaflac --remove-tag=GENRE_LOCK "$hp" 2>/dev/null || true
      metaflac --set-tag="GENRE_LOCK=1" "$hp" 2>/dev/null || true
      ;;
    *.mp3)
      # mid3v2 / id3v2 don't have a clean way to set TCON via plain id3v2 here,
      # so use mutagen via a one-liner.
      python3 - "$hp" "$GENRE" <<'PY' && ok=$((ok + 1)) || fail=$((fail + 1))
import sys
from mutagen.id3 import ID3, TCON, TXXX, ID3NoHeaderError
path, g = sys.argv[1], sys.argv[2]
try:
    t = ID3(path)
except ID3NoHeaderError:
    t = ID3()
t.delall("TCON")
t.add(TCON(encoding=3, text=g))
t.delall("TXXX:GENRE_LOCK")
t.add(TXXX(encoding=3, desc="GENRE_LOCK", text="1"))
t.save(path)
PY
      ;;
    *.m4a|*.mp4)
      python3 - "$hp" "$GENRE" <<'PY' && ok=$((ok + 1)) || fail=$((fail + 1))
import sys
from mutagen.mp4 import MP4
path, g = sys.argv[1], sys.argv[2]
m = MP4(path)
m["\xa9gen"] = g
m.save()
PY
      ;;
    *.opus|*.ogg)
      python3 - "$hp" "$GENRE" <<'PY' && ok=$((ok + 1)) || fail=$((fail + 1))
import sys
from mutagen import File as MFile
path, g = sys.argv[1], sys.argv[2]
m = MFile(path)
m.tags["genre"] = [g]
m.save()
PY
      ;;
    *)
      echo "  SKIP  unsupported format: $hp"
      fail=$((fail + 1))
      ;;
  esac
done

echo "[fix-genre] tagged ok=$ok, failed=$fail"

# Sync beets DB so its $genres column matches the file tags.
# `-q` is NOT a flag for `beet update` (only `beet ls`); leaving it off
# lets beets actually apply the diff non-interactively.
echo "[fix-genre] syncing beets DB"
beet update "artist:$ARTIST" 2>&1 | grep -E '^\s+[+-]' || true

# Verify
echo "[fix-genre] new state:"
# `|| true`: head closes the pipe after 5 lines, so beet exits with SIGPIPE for
# any artist with more than 5 tracks; that's expected, not a failure.
beet ls -f '  $title — $genres' "artist:$ARTIST" | head -5 || true
remaining=$(beet ls "artist:$ARTIST" | wc -l)
shown=5
[[ "$remaining" -gt "$shown" ]] && echo "  ...and $((remaining - shown)) more"

echo "[fix-genre] done. Trigger a Navidrome scan to surface the change in the UI."