fix(mpd): Hide module on empty playlist

Closes #149

include/adapters/mpd.hpp

@@ -139,6 +139,7 @@ namespace mpd {
     bool match_state(mpdstate state) const;
 
     int get_songid() const;
+    int get_queuelen() const;
     unsigned get_total_time() const;
     unsigned get_elapsed_time() const;
     unsigned get_elapsed_percentage();
@@ -157,6 +158,7 @@ namespace mpd {
     bool m_single = false;
 
     int m_songid;
+    int m_queuelen;
 
     unsigned long m_total_time;
     unsigned long m_elapsed_time;

include/modules/mpd.hpp

@@ -25,14 +25,12 @@ namespace modules {
     bool has_event();
     bool update();
     string get_format() const;
+    string get_output();
     bool build(builder* builder, string tag) const;
     bool handle_event(string cmd);
     bool receive_events() const;
 
    private:
-    // static const int PROGRESSBAR_THREAD_SYNC_COUNT = 10;
-    // const chrono::duration<double> PROGRESSBAR_THREAD_INTERVAL = 1s;
-
     static constexpr auto FORMAT_ONLINE = "format-online";
     static constexpr auto TAG_BAR_PROGRESS = "<bar-progress>";
     static constexpr auto TAG_TOGGLE = "<toggle>";

src/adapters/mpd.cpp

@@ -315,6 +315,7 @@ namespace mpd {
     m_status.reset(mpd_run_status(*conn));
     m_updated_at = chrono::system_clock::now();
     m_songid = mpd_status_get_song_id(m_status.get());
+    m_queuelen = mpd_status_get_queue_length(m_status.get());
     m_random = mpd_status_get_random(m_status.get());
     m_repeat = mpd_status_get_repeat(m_status.get());
     m_single = mpd_status_get_single(m_status.get());
@@ -323,7 +324,7 @@ namespace mpd {
   }
 
   void mpdstatus::update(int event, mpdconnection* connection) {
-    if (connection == nullptr || (event & (MPD_IDLE_PLAYER | MPD_IDLE_OPTIONS)) == false)
+    if (connection == nullptr || (event & (MPD_IDLE_PLAYER | MPD_IDLE_OPTIONS | MPD_IDLE_PLAYLIST)) == false)
       return;
 
     fetch_data(connection);
@@ -375,6 +376,10 @@ namespace mpd {
     return m_songid;
   }
 
+  int mpdstatus::get_queuelen() const {
+    return m_queuelen;
+  }
+
   unsigned mpdstatus::get_total_time() const {
     return m_total_time;
   }

src/modules/mpd.cpp

@@ -215,6 +215,15 @@ namespace modules {
     return connected() ? FORMAT_ONLINE : FORMAT_OFFLINE;
   }
 
+  string mpd_module::get_output() {
+    if (m_status && m_status->get_queuelen() == 0) {
+      m_log.info("%s: Hiding module since queue is empty", name());
+      return "";
+    } else {
+      return event_module::get_output();
+    }
+  }
+
   bool mpd_module::build(builder* builder, string tag) const {
     bool is_playing = false;
     bool is_paused = false;