mpd: Add a format option for artist + title, or filename

include/modules/mpd/mpd.hpp

@@ -41,6 +41,7 @@ class MPD : public ALabel {
 
  private:
   std::string getTag(mpd_tag_type type, unsigned idx = 0) const;
+  Glib::ustring getArtistTitleOrFilename() const;
   std::string getFilename() const;
   void setLabel();
   std::string getStateIcon() const;

src/modules/mpd/mpd.cpp

@@ -77,6 +77,49 @@ std::string waybar::modules::MPD::getTag(mpd_tag_type type, unsigned idx) const
   return result;
 }
 
+Glib::ustring waybar::modules::MPD::getArtistTitleOrFilename() const {
+  const char* artist = mpd_song_get_tag(this->song_.get(), MPD_TAG_ARTIST, 0);
+  const char* title = mpd_song_get_tag(this->song_.get(), MPD_TAG_TITLE, 0);
+  // https://mpd.readthedocs.io/en/latest/protocol.html#tags
+  const char* name = mpd_song_get_tag(this->song_.get(), MPD_TAG_NAME, 0);
+  // it is important to use Glib::ustring here, as filenames may be utf8 encoded
+  // DECO＊27 x ピノキオピー - デビルじゃないもん feat. 初音ミク-lMEt3RdqB9Y.m4a
+  Glib::ustring result;
+
+  auto starts_with = [&](const Glib::ustring& str, const char* other) {
+    size_t other_len = strlen(other);
+    if (str.size() < other_len) {
+      return false;
+    }
+
+    for (size_t i = 0; i < other_len; i++) {
+      if (str[i] != other[i]) {
+        return false;
+      }
+    }
+    return true;
+  };
+
+  if (title || name) {
+    result = title ? title : name;
+    bool prepend_artist = artist != nullptr && !starts_with(result, artist);
+
+    if (config_["title-len"].isInt()) {
+      result = result.substr(0, config_["title-len"].asInt());
+    }
+    if (prepend_artist) {
+      result = std::string(artist) + " - " + std::move(result);
+    }
+    return result;
+  }
+
+  result = this->getFilename();
+  if (config_["title-len"].isInt()) {
+    result = result.substr(0, config_["title-len"].asInt());
+  }
+  return result;
+}
+
 std::string waybar::modules::MPD::getFilename() const {
   std::string path = mpd_song_get_uri(song_.get());
   size_t position = path.find_last_of("/");
@@ -117,7 +160,7 @@ void waybar::modules::MPD::setLabel() {
   label_.get_style_context()->remove_class("disconnected");
 
   auto format = format_;
-  Glib::ustring artist, album_artist, album, title;
+  Glib::ustring artist, album_artist, album, title, artist_title_or_filename;
   std::string date, filename;
   int song_pos = 0, queue_length = 0, volume = 0;
   std::chrono::seconds elapsedTime, totalTime;
@@ -151,6 +194,7 @@ void waybar::modules::MPD::setLabel() {
     title = sanitize_string(getTag(MPD_TAG_TITLE));
     date = sanitize_string(getTag(MPD_TAG_DATE));
     filename = sanitize_string(getFilename());
+    artist_title_or_filename = sanitize_string(this->getArtistTitleOrFilename());
     song_pos = mpd_status_get_song_pos(status_.get()) + 1;
     volume = mpd_status_get_volume(status_.get());
     if (volume < 0) {
@@ -179,7 +223,8 @@ void waybar::modules::MPD::setLabel() {
     auto text = fmt::format(
         fmt::runtime(format), fmt::arg("artist", artist.raw()),
         fmt::arg("albumArtist", album_artist.raw()), fmt::arg("album", album.raw()),
-        fmt::arg("title", title.raw()), fmt::arg("date", date), fmt::arg("volume", volume),
+        fmt::arg("title", title.raw()), fmt::arg("artistTitleOrFilename", artist_title_or_filename.raw()),
+        fmt::arg("date", date), fmt::arg("volume", volume),
         fmt::arg("elapsedTime", elapsedTime), fmt::arg("totalTime", totalTime),
         fmt::arg("songPosition", song_pos), fmt::arg("queueLength", queue_length),
         fmt::arg("stateIcon", stateIcon), fmt::arg("consumeIcon", consumeIcon),