# Playback tools and helper
#
# The methods to control the mpv instance are in `src/sh/mpv.sh`. Here,
# a higher-level playback functionality is provided.

# Available playback commands
if [ ! "${PLAYBACK_LOADED:-}" ]; then
  PLAYBACK_CMD_PLAY="play"
  PLAYBACK_CMD_QUEUE="queue"
  PLAYBACK_CMD_QUEUE_NEXT="queue-next"
  PLAYBACK_CMD_TOGGLE_PLAYBACK="toggle"
  PLAYBACK_CMD_PLAY_NEXT="next"
  PLAYBACK_CMD_PLAY_PREV="prev"
  PLAYBACK_CMD_SEEK_FORWARD="seekf"
  PLAYBACK_CMD_SEEK_BACKWARD="seekb"
  export PLAYBACK_CMD_PLAY PLAYBACK_CMD_QUEUE PLAYBACK_CMD_QUEUE_NEXT \
    PLAYBACK_CMD_TOGGLE_PLAYBACK PLAYBACK_CMD_PLAY_NEXT \
    PLAYBACK_CMD_PLAY_PREV PLAYBACK_CMD_SEEK_FORWARD PLAYBACK_CMD_SEEK_BACKWARD

  export PLAYBACK_LOADED=1
fi

# Obtain playback command from key press
# @argument $1: key
__playback_cmd_from_key() {
  key=$1
  case ",$KEYS_PLAY," in *",$key,"*) echo "$PLAYBACK_CMD_PLAY" && return ;; esac
  case ",$KEYS_N_PLAY," in *",$key,"*) echo "$PLAYBACK_CMD_PLAY" && return ;; esac
  case ",$KEYS_QUEUE," in *",$key,"*) echo "$PLAYBACK_CMD_QUEUE" && return ;; esac
  case ",$KEYS_N_QUEUE," in *",$key,"*) echo "$PLAYBACK_CMD_QUEUE" && return ;; esac
  case ",$KEYS_QUEUE_NEXT," in *",$key,"*) echo "$PLAYBACK_CMD_QUEUE_NEXT" && return ;; esac
  case ",$KEYS_N_QUEUE_NEXT," in *",$key,"*) echo "$PLAYBACK_CMD_QUEUE_NEXT" && return ;; esac
  case ",$KEYS_TOGGLE_PLAYBACK," in *",$key,"*) echo "$PLAYBACK_CMD_TOGGLE_PLAYBACK" && return ;; esac
  case ",$KEYS_N_TOGGLE_PLAYBACK," in *",$key,"*) echo "$PLAYBACK_CMD_TOGGLE_PLAYBACK" && return ;; esac
  case ",$KEYS_PLAY_NEXT," in *",$key,"*) echo "$PLAYBACK_CMD_PLAY_NEXT" && return ;; esac
  case ",$KEYS_N_PLAY_NEXT," in *",$key,"*) echo "$PLAYBACK_CMD_PLAY_NEXT" && return ;; esac
  case ",$KEYS_PLAY_PREV," in *",$key,"*) echo "$PLAYBACK_CMD_PLAY_PREV" && return ;; esac
  case ",$KEYS_N_PLAY_PREV," in *",$key,"*) echo "$PLAYBACK_CMD_PLAY_PREV" && return ;; esac
  case ",$KEYS_SEEK_FORWARD," in *",$key,"*) echo "$PLAYBACK_CMD_SEEK_FORWARD" && return ;; esac
  case ",$KEYS_N_SEEK_FORWARD," in *",$key,"*) echo "$PLAYBACK_CMD_SEEK_FORWARD" && return ;; esac
  case ",$KEYS_SEEK_BACKWARD," in *",$key,"*) echo "$PLAYBACK_CMD_SEEK_BACKWARD" && return ;; esac
  case ",$KEYS_N_SEEK_BACKWARD," in *",$key,"*) echo "$PLAYBACK_CMD_SEEK_BACKWARD" && return ;; esac
}

# Generate playlist from MB release ID and path to decoration
# @argument $1: MusicBrainz Release ID
# @argument $2: Path to decoration file
# @argument $3: MusicBrainz Track ID to select (optional)
__generate_playlist() {
  printf "#EXTM3U\n"
  dir="$(dirname "$2")"
  mb_release "$1" |
    $JQ \
      --slurpfile decofile "$2" \
      --arg base "$dir" \
      --arg deco "$2" \
      --arg tid "${3:-}" \
      '$decofile[].tracks as $filenames |
        . |
        .id as $rid |
        .media[] |
        .position as $pos |
        .tracks |
        if ($tid == "") then . else map(select(.id == $tid)) end |
        map({
          t: [
          $rid,
          .id,
          $pos,
          .number,
          .length,
          .title,
          (."artist-credit" | map([.name, .joinphrase] | join("")) | join("")),
          $deco
          ] | join("\t"),
          length: (.length // 0 / 1000 | round | tostring),
          $pos,
          number: .number,
          file: $filenames[.id]
        }) |
        map(if(.number | type == "string" and test("^[0-9]+$")) then .number |= tonumber else . end) |
        sort_by([.pos, .number]) |
        map("#EXTINF:" + .length + "," + .t + "\n" + $base + "/" + .file)[]'
}

# Main playback method
#
# @argument $1: view
# @argument $2: MusicBrainz ID of current object
# @argument $3: MusicBrainz ID of selected object
# @argument $4: Path to decoration file
#
# This option controls the mpv instance via a key pressed in fzf. The key
# pressed is stored in the environment variable FZF_KEY and is resolved to
# the playback command through the method `__playback_cmd_from_key`.
playback() {
  view=${1:-}
  mbid_current="${2:-}"
  mbid="${3:-}"
  path="${4:-}"
  pbcmd=$(__playback_cmd_from_key "$FZF_KEY")
  case "$pbcmd" in
  "$PLAYBACK_CMD_PLAY")
    [ "$path" ] || exit 0
    case "$view" in
    "$VIEW_ARTIST" | "$VIEW_SEARCH_ARTIST" | "$VIEW_SEARCH_ALBUM" | "$VIEW_LIST_ARTISTS" | "$VIEW_LIST_ALBUMS") info "not implemented" ;;
    "$VIEW_RELEASEGROUP") __generate_playlist "$mbid" "$path" | mpv_play_list >/dev/null ;;
    "$VIEW_RELEASE") __generate_playlist "$mbid_current" "$path" "$mbid" | mpv_play_list >/dev/null ;;
    "$VIEW_PLAYLIST") mpv_play_index $((FZF_POS - 1)) >/dev/null ;;
    esac
    ;;
  "$PLAYBACK_CMD_QUEUE")
    [ "$path" ] || exit 0
    case "$view" in
    "$VIEW_ARTIST" | "$VIEW_SEARCH_ARTIST" | "$VIEW_SEARCH_ALBUM" | "$VIEW_LIST_ARTISTS" | "$VIEW_LIST_ALBUMS") info "not implemented" ;;
    "$VIEW_RELEASEGROUP") __generate_playlist "$mbid" "$path" | mpv_queue_list >/dev/null ;;
    "$VIEW_RELEASE") __generate_playlist "$mbid_current" "$path" "$mbid" | mpv_queue_list >/dev/null ;;
    "$VIEW_PLAYLIST") __generate_playlist "$mbid_current" "$path" "$mbid" | mpv_queue_list >/dev/null ;;
    esac
    ;;
  "$PLAYBACK_CMD_QUEUE_NEXT")
    [ "$path" ] || exit 0
    case "$view" in
    "$VIEW_ARTIST" | "$VIEW_SEARCH_ARTIST" | "$VIEW_SEARCH_ALBUM" | "$VIEW_LIST_ARTISTS" | "$VIEW_LIST_ALBUMS") info "not implemented" ;;
    "$VIEW_RELEASEGROUP") __generate_playlist "$mbid" "$path" | mpv_queue_next_list >/dev/null ;;
    "$VIEW_RELEASE") __generate_playlist "$mbid_current" "$path" "$mbid" | mpv_queue_next_list >/dev/null ;;
    "$VIEW_PLAYLIST") __generate_playlist "$mbid_current" "$path" "$mbid" | mpv_queue_next_list >/dev/null ;;
    esac
    ;;
  "$PLAYBACK_CMD_TOGGLE_PLAYBACK") mpv_toggle_pause ;;
  "$PLAYBACK_CMD_PLAY_NEXT") mpv_next ;;
  "$PLAYBACK_CMD_PLAY_PREV") mpv_prev ;;
  "$PLAYBACK_CMD_SEEK_FORWARD") mpv_seek_forward ;;
  "$PLAYBACK_CMD_SEEK_BACKWARD") mpv_seek_backward ;;
  esac
}