#!/usr/bin/env bash
# reorganize-music.sh
#
# Reads metadata tags from audio files and reorganises them into the
# NovaSonic folder/filename convention:
#
#   <dest>/<AlbumArtist>/<Album>/<NN - Artist - Title.ext>
#
# The sanitize(), folder and filename rules exactly mirror
# backend/lib/ytdlp.js and backend/lib/metadata.js.
#
# Usage:
#   ./reorganize-music.sh <source_dir> <dest_dir> [--copy] [--move] [--clean]
#
#   <source_dir>   Root of the old genre-folder tree (searched recursively)
#   <dest_dir>     Music root to write into  (can be the same as source)
#   --copy         Copy files to new location (originals kept — safe default)
#   --move         Move files to new location (originals removed)
#   --clean        After moving, remove empty directories under <source_dir>
#
# Requires: ffprobe (part of ffmpeg)

set -uo pipefail

# ── Args ──────────────────────────────────────────────────────────────────────
if [[ $# -lt 2 ]]; then
  echo "Usage: $0 <source_dir> <dest_dir> [--move] [--clean]"
  exit 1
fi

SOURCE="$(realpath "$1")"
DEST="$(realpath "$2")"
DO_COPY=false
DO_MOVE=false
DO_CLEAN=false
for arg in "${@:3}"; do
  [[ "$arg" == "--copy"  ]] && DO_COPY=true
  [[ "$arg" == "--move"  ]] && DO_MOVE=true
  [[ "$arg" == "--clean" ]] && DO_CLEAN=true
done

MOVED=0; SKIPPED=0; ERRORS=0

# ── sanitize(s): mirrors backend/lib/metadata.js sanitize() ──────────────────
# Replace filesystem-illegal chars with _, trim whitespace, cap at 100 chars.
sanitize() {
  local s="${1:-Unknown}"
  s="$(printf '%s' "$s" | sed 's/[\\/:*?"<>|]/_/g' | sed 's/^[[:space:]]*//;s/[[:space:]]*$//')"
  printf '%s' "${s:0:100}"
}

# ── Read a single ffprobe tag (returns empty string if absent) ────────────────
get_tag() {
  ffprobe -v quiet \
    -show_entries "format_tags=$2" \
    -of "default=noprint_wrappers=1:nokey=1" \
    "$1" 2>/dev/null | head -1
}

# ── First segment before any artist separator (, ; &) ────────────────────────
# Used for the artist *folder* name (album artist, first name only).
first_artist() {
  printf '%s' "$1" | sed 's/[,;&].*//' | sed 's/^[[:space:]]*//;s/[[:space:]]*$//'
}

# ── Normalise all artists for the filename (; → ,) ───────────────────────────
# Mirrors: artistRomaji.replace(/;/g, ',')
artists_for_file() {
  printf '%s' "$1" | sed 's/;[[:space:]]*/\, /g' | sed 's/^[[:space:]]*//;s/[[:space:]]*$//'
}

# ── Print header ──────────────────────────────────────────────────────────────
echo "NovaSonic Music Reorganiser"
echo "Source : $SOURCE"
echo "Dest   : $DEST"
if $DO_MOVE; then
  echo "Mode   : MOVE  (files will be moved, originals removed)"
elif $DO_COPY; then
  echo "Mode   : COPY  (files will be copied, originals kept)"
else
  echo "Mode   : DRY-RUN  (nothing will change — add --copy or --move to execute)"
fi
echo "──────────────────────────────────────────────────────────────────────"

# ── Main loop: every audio file under SOURCE ──────────────────────────────────
while IFS= read -r -d '' file; do
  # ── Extension (lowercase) ───────────────────────────────────────────────
  filename_base="$(basename "$file")"
  ext_lower="$(printf '%s' "${filename_base##*.}" | tr '[:upper:]' '[:lower:]')"

  # ── Read tags via ffprobe ────────────────────────────────────────────────
  raw_title=$(get_tag "$file" "title")
  raw_artist=$(get_tag "$file" "artist")
  raw_album_artist=$(get_tag "$file" "album_artist")
  raw_album=$(get_tag "$file" "album")
  raw_track=$(get_tag "$file" "track")

  # ── Fallbacks when tags are missing ─────────────────────────────────────
  # Title: use filename stem (strip extension + leading "NN - " prefix)
  if [[ -z "$raw_title" ]]; then
    raw_title="$(printf '%s' "${filename_base%.*}" | sed 's/^[0-9][0-9][[:space:]]*-[[:space:]]*//')"
    raw_title="$(printf '%s' "$raw_title" | sed 's/[[:space:]]*-[[:space:]]*.*//')"  # strip "Artist - " prefix if present
    [[ -z "$raw_title" ]] && raw_title="Unknown Title"
  fi

  artist="${raw_artist:-Unknown Artist}"
  # Album artist preferred for folder; fall back to track artist
  main_artist="${raw_album_artist:-$artist}"
  album="${raw_album:-Singles}"

  # ── Track number: "5/12" or "05" → zero-padded "05 - " ──────────────────
  track_num="$(printf '%s' "$raw_track" | cut -d'/' -f1 | tr -dc '0-9')"
  if [[ -n "$track_num" && "$track_num" -gt 0 ]] 2>/dev/null; then
    track_prefix="$(printf '%02d - ' "$track_num")"
  else
    track_prefix=""
  fi

  # ── Build folder path ────────────────────────────────────────────────────
  # Convention: {dest}/{first_albumArtist}/{album}/
  dir_artist="$(first_artist "$main_artist")"
  safe_artist_dir="$(sanitize "$dir_artist")"
  safe_album_dir="$(sanitize "$album")"
  target_dir="$DEST/$safe_artist_dir/$safe_album_dir"

  # ── Build filename ───────────────────────────────────────────────────────
  # Convention: {NN - }Artist1, Artist2 - Title.ext
  file_artists="$(artists_for_file "$artist")"
  safe_artist_file="$(sanitize "$file_artists")"
  safe_title="$(sanitize "$raw_title")"
  new_filename="${track_prefix}${safe_artist_file} - ${safe_title}.${ext_lower}"

  target="$target_dir/$new_filename"

  # ── Already in the right place? ──────────────────────────────────────────
  if [[ "$file" == "$target" ]]; then
    printf '  ✓ already correct  %s\n' "$safe_artist_dir/$safe_album_dir/$new_filename"
    SKIPPED=$((SKIPPED + 1))
    continue
  fi

  # ── Conflict: target already exists (don't overwrite) ────────────────────
  if [[ -e "$target" ]]; then
    printf '  ⚠ SKIP (exists)    %s\n' "$target"
    SKIPPED=$((SKIPPED + 1))
    continue
  fi

  # ── Report what we will / would do ───────────────────────────────────────
  printf '  →  %s/%s/%s\n' "$safe_artist_dir" "$safe_album_dir" "$new_filename"

  if $DO_MOVE; then
    if mkdir -p "$target_dir" && mv -- "$file" "$target"; then
      MOVED=$((MOVED + 1))
    else
      printf '     ERROR moving: %s\n' "$file" >&2
      ERRORS=$((ERRORS + 1))
    fi
  elif $DO_COPY; then
    if mkdir -p "$target_dir" && cp -- "$file" "$target"; then
      MOVED=$((MOVED + 1))
    else
      printf '     ERROR copying: %s\n' "$file" >&2
      ERRORS=$((ERRORS + 1))
    fi
  else
    MOVED=$((MOVED + 1))
  fi

done < <(find "$SOURCE" -type f \( \
  -iname "*.mp3" -o -iname "*.flac" -o \
  -iname "*.m4a" -o -iname "*.opus" -o \
  -iname "*.ogg" -o -iname "*.wav"  \
\) -print0 | sort -z)

# ── Remove empty source dirs (optional) ──────────────────────────────────────
if $DO_MOVE && $DO_CLEAN; then  # --clean only applies to --move (copy keeps originals)
  echo ""
  echo "Cleaning empty directories under $SOURCE …"
  find "$SOURCE" -mindepth 1 -type d -empty -delete 2>/dev/null && \
    echo "  Done." || echo "  (nothing to clean or permission denied)"
fi

# ── Summary ──────────────────────────────────────────────────────────────────
echo "──────────────────────────────────────────────────────────────────────"
if $DO_MOVE; then
  echo "Done: $MOVED moved, $SKIPPED skipped, $ERRORS errors"
elif $DO_COPY; then
  echo "Done: $MOVED copied, $SKIPPED skipped, $ERRORS errors"
else
  echo "Dry-run: $MOVED would be processed, $SKIPPED already correct or conflicting"
  echo ""
  echo "Re-run with --copy to copy (safe) or --move to move.  Add --clean to remove empty source dirs after --move."
fi