path_exists() {
  [[ -e "$1" || -L "$1" ]]
}

is_recording() {
  case "${1,,}" in
    *.wav | *.flac | *.mp3 | *.ogg | *.opus | *.aac | *.m4a) return 0 ;;
    *) return 1 ;;
  esac
}

move_no_clobber() {
  local source=$1
  local destination=$2

  if path_exists "$destination"; then
    return 1
  fi

  mv -T --no-clobber -- "$source" "$destination"
  ! path_exists "$source" && path_exists "$destination"
}

fail_recording() {
  local source=$1
  local failed_dir=$2
  local message=$3
  local details=${4:-}
  local base target error_tmp suffix=0

  base=$(basename "$source")
  target="$failed_dir/$base"
  rm -f -- "${source}.transcribe-state"

  while path_exists "$target" || path_exists "${target}.error.txt"; do
    ((suffix += 1))
    target="$failed_dir/$base.failed-$suffix"
  done

  if ! move_no_clobber "$source" "$target"; then
    printf 'Could not quarantine %s: destination collision or move failure\n' "$source" >&2
    return 1
  fi

  error_tmp=$(mktemp "$failed_dir/.transcription-error.XXXXXX")
  {
    printf '%s\n' "$message"
    if [[ -n "$details" && -s "$details" ]]; then
      printf '\n'
      cat -- "$details"
    fi
  } >"$error_tmp"

  if ! ln -- "$error_tmp" "${target}.error.txt"; then
    printf 'Could not publish error sidecar for %s\n' "$target" >&2
    rm -f -- "$error_tmp"
    return 1
  fi
  rm -f -- "$error_tmp"
  printf 'Moved failed recording to %s\n' "$target" >&2
}

recover_completed_recording() {
  local source=$1
  local transcript=$2
  local archive=$3
  local state_file="${source}.transcribe-state"

  if [[ ! -f "$state_file" ]]; then
    return 1
  fi

  if ! path_exists "$transcript"; then
    rm -f -- "$state_file"
    return 1
  fi

  if ! move_no_clobber "$source" "$archive"; then
    return 2
  fi

  rm -f -- "$state_file"
  printf 'Recovered completed transcription and archived %s\n' "$archive"
  return 0
}

process_recording() (
  set -o errexit

  local source=$1
  local inbox_dir=$2
  local transcript_dir=$3
  local archive_dir=$4
  local failed_dir=$5
  local base stem transcript archive original_path recorded_at transcribed_at duration
  local work_dir log_file raw_output rendered_output draft state_file recovery_status
  local diarization_succeeded=false

  base=$(basename "$source")
  stem=${base%.*}
  transcript="$transcript_dir/$stem.md"
  archive="$archive_dir/$base"
  original_path="$inbox_dir/$base"
  state_file="${source}.transcribe-state"

  if recover_completed_recording "$source" "$transcript" "$archive"; then
    return 0
  else
    recovery_status=$?
  fi
  if [[ $recovery_status -eq 2 ]]; then
    fail_recording "$source" "$failed_dir" "Archive collision after transcription: $archive"
    return 1
  fi

  if path_exists "$transcript"; then
    fail_recording "$source" "$failed_dir" "Transcript already exists: $transcript"
    return 1
  fi
  if path_exists "$archive"; then
    fail_recording "$source" "$failed_dir" "Archived recording already exists: $archive"
    return 1
  fi

  recorded_at=$(date --date="@$(stat -c %Y -- "$source")" --iso-8601=seconds)
  transcribed_at=$(date --utc --iso-8601=seconds)
  work_dir=$(mktemp -d "$runtime_dir/work.XXXXXX")
  trap 'rm -r -- "$work_dir"' EXIT
  log_file="$work_dir/transcription.log"
  raw_output="$work_dir/transcript"
  rendered_output="$work_dir/transcript.md"

  if ! duration=$(ffprobe \
    -v error \
    -show_entries format=duration \
    -of default=noprint_wrappers=1:nokey=1 \
    "$source" 2>"$log_file"); then
    fail_recording "$source" "$failed_dir" "Media validation failed" "$log_file"
    return 1
  fi
  if [[ ! $duration =~ ^[0-9]+([.][0-9]+)?$ || -z ${duration//[.0]/} ]]; then
    printf 'Invalid media duration: %s\n' "$duration" >"$log_file"
    fail_recording "$source" "$failed_dir" "Media validation failed" "$log_file"
    return 1
  fi

  if ! ffmpeg \
    -nostdin \
    -hide_banner \
    -loglevel error \
    -i "$source" \
    -vn \
    -ac 1 \
    -ar 16000 \
    -c:a pcm_s16le \
    "$work_dir/audio.wav" >"$log_file" 2>&1; then
    fail_recording "$source" "$failed_dir" "FFmpeg conversion failed" "$log_file"
    return 1
  fi

  if ! whisper-cli \
    --model "$TRANSCRIBE_MODEL" \
    --file "$work_dir/audio.wav" \
    --language auto \
    --output-json-full \
    --output-txt \
    --output-file "$raw_output" >>"$log_file" 2>&1 \
    || [[ ! -s "${raw_output}.json" || ! -s "${raw_output}.txt" ]]; then
    fail_recording "$source" "$failed_dir" "Whisper transcription failed" "$log_file"
    return 1
  fi

  if [[ -f "$TRANSCRIBE_DIARIZATION_MODEL/.complete" && -f "$TRANSCRIBE_DIARIZATION_MODEL/config.yaml" ]] \
    && diarize-transcript \
      --audio "$work_dir/audio.wav" \
      --model "$TRANSCRIBE_DIARIZATION_MODEL" \
      --transcript "${raw_output}.json" \
      --output "$rendered_output" >>"$log_file" 2>&1 \
    && [[ -s "$rendered_output" ]]; then
    diarization_succeeded=true
  else
    printf 'Speaker diarization unavailable; publishing unlabeled transcript\n' >&2
    cp -- "${raw_output}.txt" "$rendered_output"
  fi

  draft=$(mktemp "$transcript_dir/.transcript.XXXXXX")
  {
    printf '# %s\n\n' "$stem"
    printf -- '- Original recording: %s\n' "$original_path"
    printf -- '- Recording timestamp: %s\n' "$recorded_at"
    printf -- '- Transcription timestamp: %s\n' "$transcribed_at"
    printf -- '- Duration: %s seconds\n' "$duration"
    printf -- '- Engine: whisper.cpp %s (%s)\n' "$TRANSCRIBE_ENGINE_VERSION" "$TRANSCRIBE_ENGINE_ACCELERATION"
    printf -- '- Model: %s\n' "$TRANSCRIBE_MODEL_NAME"
    printf -- '- Model SHA-256: %s\n' "$TRANSCRIBE_MODEL_SHA256"
    if [[ $diarization_succeeded == true ]]; then
      printf -- '- Diarization engine: pyannote.audio %s (CPU)\n' "$TRANSCRIBE_DIARIZATION_ENGINE_VERSION"
      printf -- '- Diarization model: %s\n' "$TRANSCRIBE_DIARIZATION_MODEL_NAME"
      printf -- '- Diarization model revision: %s\n\n' "$TRANSCRIBE_DIARIZATION_MODEL_REVISION"
    else
      printf -- '- Diarization: unavailable; unlabeled fallback published\n\n'
    fi
    cat -- "$rendered_output"
  } >"$draft"
  chmod 0644 "$draft"

  touch -- "$state_file"

  if ! ln -- "$draft" "$transcript"; then
    rm -f -- "$draft" "$state_file"
    fail_recording "$source" "$failed_dir" "Transcript appeared while transcription was running: $transcript" "$log_file"
    return 1
  fi
  rm -f -- "$draft"

  if ! move_no_clobber "$source" "$archive"; then
    printf 'Could not archive %s; leaving recoverable state in processing\n' "$source" >&2
    return 1
  fi

  rm -f -- "$state_file"
  printf 'Transcribed %s to %s\n' "$archive" "$transcript"
)

process_scope() {
  local recordings_dir=$1
  local transcript_dir=$2
  local inbox_dir="$recordings_dir/inbox"
  local processing_dir="$recordings_dir/processing"
  local archive_dir="$recordings_dir/archive"
  local failed_dir="$recordings_dir/failed"
  local source processing_target recording_status signature index scope_status=0
  local -a sources signatures

  mkdir -p "$inbox_dir" "$processing_dir" "$archive_dir" "$failed_dir" "$transcript_dir" || return 1

  while IFS= read -r -d '' source; do
    if is_recording "$source"; then
      process_recording "$source" "$inbox_dir" "$transcript_dir" "$archive_dir" "$failed_dir"
      recording_status=$?
      if [[ $recording_status -ne 0 ]]; then
        scope_status=1
      fi
    fi
  done < <(find "$processing_dir" -maxdepth 1 -type f -print0 | sort -z)

  while true; do
    sources=()
    signatures=()

    while IFS= read -r -d '' source; do
      if is_recording "$source" && signature=$(stat -c '%s:%y:%i' -- "$source"); then
        sources+=("$source")
        signatures+=("$signature")
      fi
    done < <(find "$inbox_dir" -maxdepth 1 -type f -print0 | sort -z)

    if [[ ${#sources[@]} -eq 0 ]]; then
      break
    fi

    sleep "${TRANSCRIBE_SETTLE_SECONDS:-300}"

    for index in "${!sources[@]}"; do
      source=${sources[$index]}
      if [[ ! -f "$source" ]] || [[ $(stat -c '%s:%y:%i' -- "$source") != "${signatures[$index]}" ]]; then
        continue
      fi

      processing_target="$processing_dir/$(basename "$source")"
      if ! move_no_clobber "$source" "$processing_target"; then
        fail_recording "$source" "$failed_dir" "Processing filename already exists: $processing_target"
        scope_status=1
        continue
      fi
      process_recording "$processing_target" "$inbox_dir" "$transcript_dir" "$archive_dir" "$failed_dir"
      recording_status=$?
      if [[ $recording_status -ne 0 ]]; then
        scope_status=1
      fi
    done
  done

  return "$scope_status"
}

runtime_dir="${XDG_RUNTIME_DIR:?}/transcribe-recordings"
mkdir -p "$runtime_dir"

set +o errexit
process_scope "$TRANSCRIBE_SYNC_ROOT/recordings" "$TRANSCRIBE_SYNC_ROOT/notes/transcripts"