#!/bin/bash
# Find audio files in the library that have no ALBUM tag, set ALBUM to
# "{TITLE} - Single" — matches Spotify / Apple Music's convention for
# single-track releases. Otherwise these tracks land as [Unknown Album]
# in Navidrome.
#
# Usage:
#   fix-empty-album.sh                # dry run (default)
#   fix-empty-album.sh --apply        # actually rewrite tags
#
# Bandcamp single-track downloads are the most common source of this
# issue (Bandcamp serves single tracks with no ALBUM tag). New downloads
# via sync-bandcamp.py are auto-tagged; this script handles backfill.

set -u
APPLY=0
[[ "${1:-}" == "--apply" ]] && APPLY=1

LOG=${ALEMBIC_CONFIG_DIR:-/config}/logs/fix-empty-album-$(date +%Y%m%d-%H%M%S).log
mkdir -p "$(dirname "$LOG")"

NAVIDROME_ENV="${ALEMBIC_CONFIG_DIR:-/config}/pipeline/navidrome/admin.env"
[ -f "$NAVIDROME_ENV" ] && source "$NAVIDROME_ENV"
ND_BASE="${ND_BASE:-http://navidrome:4533}"
ND_USER="${ND_USER:-}"
ND_PASS="${ND_PASS:-}"
log() { echo "[$(date -Iseconds)] $*" | tee -a "$LOG"; }

if [[ $APPLY -eq 1 ]]; then
  log "=== FIX EMPTY ALBUM (APPLY) ==="
else
  log "=== FIX EMPTY ALBUM (DRY RUN — pass --apply to write) ==="
fi

FIXED=0
SKIPPED=0

while IFS= read -r -d '' f; do
  ext="${f,,}"; ext="${ext##*.}"
  album="" ; title=""
  case "$ext" in
    flac)
      album=$(metaflac --show-tag=ALBUM "$f" 2>/dev/null | sed -n 's/^[^=]*=//p' | head -1)
      title=$(metaflac --show-tag=TITLE "$f" 2>/dev/null | sed -n 's/^[^=]*=//p' | head -1)
      ;;
    mp3)
      album=$(id3v2 -l "$f" 2>/dev/null | sed -n 's/^TALB[^:]*: //p' | head -1)
      title=$(id3v2 -l "$f" 2>/dev/null | sed -n 's/^TIT2[^:]*: //p' | head -1)
      ;;
    *) continue ;;
  esac

  if [[ -n "$album" ]]; then
    continue   # already has an album, leave it alone
  fi
  if [[ -z "$title" ]]; then
    log "[skip-no-title]  $f"
    SKIPPED=$((SKIPPED + 1))
    continue
  fi

  # Some titles have a leading "NN " track-number prefix baked in from a
  # bad filename parse (e.g. title="01 Domestic Violence"). If we use the
  # title as-is, the album becomes "01 Domestic Violence - Single" which
  # is broken. Strip leading 1-3 digits + space, and also fix the title
  # tag in place so it isn't shown with the prefix in clients.
  clean_title=$(echo "$title" | sed -E 's/^[[:space:]]*[0-9]{1,3}[[:space:]]+//')
  if [[ "$clean_title" != "$title" && -n "$clean_title" ]]; then
    log "  trimmed leading track-number from title: \"$title\" -> \"$clean_title\""
    if [[ $APPLY -eq 1 ]]; then
      case "$ext" in
        flac) metaflac --remove-tag=TITLE --set-tag="TITLE=${clean_title}" "$f" 2>>"$LOG" ;;
        mp3)  id3v2 --TIT2 "${clean_title}" "$f" 2>>"$LOG" ;;
      esac
    fi
    title="$clean_title"
  fi

  new_album="${title} - Single"
  log "[$( [[ $APPLY -eq 1 ]] && echo SET || echo WOULD-SET )] album=\"${new_album}\"  -  $f"

  if [[ $APPLY -eq 1 ]]; then
    case "$ext" in
      flac) metaflac --set-tag="ALBUM=${new_album}" "$f" 2>>"$LOG" ;;
      mp3)  id3v2 --TALB "${new_album}" "$f" 2>>"$LOG" ;;
    esac
  fi
  FIXED=$((FIXED + 1))
done < <(find ${MUSIC_DATA_DIR:-/data/music}/Library -type f \( -iname "*.flac" -o -iname "*.mp3" \) -print0 2>/dev/null)

log ""
log "=== Summary: $FIXED fixed, $SKIPPED skipped (no title) ==="

if [[ $APPLY -eq 1 && $FIXED -gt 0 ]]; then
  log "Syncing beets DB from new tags..."
  beet update 2>&1 | tail -3 >> "$LOG"
  log "Moving files to reflect new album in path templates..."
  beet move 2>&1 | tail -3 >> "$LOG"
  log "Triggering Navidrome rescan..."
  curl -s -G "$ND_BASE/rest/startScan.view" \
    --data-urlencode "u=$ND_USER" \
    --data-urlencode "p=$ND_PASS" \
    --data-urlencode 'v=1.16.0' \
    --data-urlencode 'c=fix-empty-album' \
    --data-urlencode 'f=json' \
    --data-urlencode 'fullScan=true' >> "$LOG" 2>&1
fi

log "=== Done. Log: $LOG ==="