#!/bin/bash
# Convert m4a files in-place: AAC -> MP3 (V0 VBR), ALAC -> FLAC (lossless).
# Preserves metadata + embedded cover art. Deletes original on success.
set -u

LOG=${ALEMBIC_CONFIG_DIR:-/config}/logs/convert-m4a-$(date +%Y%m%d-%H%M%S).log
mkdir -p "$(dirname "$LOG")"

log() { echo "[$(date -Iseconds)] $*" | tee -a "$LOG"; }

OK_AAC=0
OK_ALAC=0
FAIL=0

while IFS= read -r -d '' f; do
  codec=$(ffprobe -v error -select_streams a:0 -show_entries stream=codec_name -of csv=p=0 "$f" 2>/dev/null | tr -d ',')
  base="${f%.m4a}"
  case "$codec" in
    aac)
      out="${base}.mp3"
      if [[ -e "$out" ]]; then log "SKIP-EXISTS: $out"; FAIL=$((FAIL+1)); continue; fi
      if ffmpeg -nostdin -hide_banner -loglevel error -i "$f" \
           -map 0 -c:v copy -c:a libmp3lame -q:a 0 -id3v2_version 3 \
           "$out" 2>>"$LOG"; then
        rm -f "$f"
        log "AAC→MP3:    $out"
        OK_AAC=$((OK_AAC+1))
      else
        log "FAIL-AAC:   $f"
        rm -f "$out" 2>/dev/null
        FAIL=$((FAIL+1))
      fi
      ;;
    alac)
      out="${base}.flac"
      if [[ -e "$out" ]]; then log "SKIP-EXISTS: $out"; FAIL=$((FAIL+1)); continue; fi
      if ffmpeg -nostdin -hide_banner -loglevel error -i "$f" \
           -map 0 -c:v copy -c:a flac -compression_level 8 \
           "$out" 2>>"$LOG"; then
        rm -f "$f"
        log "ALAC→FLAC:  $out"
        OK_ALAC=$((OK_ALAC+1))
      else
        log "FAIL-ALAC:  $f"
        rm -f "$out" 2>/dev/null
        FAIL=$((FAIL+1))
      fi
      ;;
    *)
      log "SKIP-OTHER ($codec): $f"
      ;;
  esac
done < <(find ${MUSIC_DATA_DIR:-/data/music}/Library -type f -iname "*.m4a" -print0 2>/dev/null)

log ""
log "=== AAC→MP3:  $OK_AAC | ALAC→FLAC: $OK_ALAC | Failed: $FAIL ==="
log "Log: $LOG"