From abd14e113d67ef35a44d0cf0f8f8bb1e9a24ea2a Mon Sep 17 00:00:00 2001
From: Jeff Kaufman <jeff.t.kaufman@gmail.com>
Date: Sun, 7 Feb 2021 01:13:48 +0000
Subject: [PATCH] Have the server tell the client whether there is a backing
 track, and if so what kind, what's the client can use to decide whether to
 show the backing track volume slider, name it properly, and choose whether
 you can join the first packet. Fixes #169

---
 html/demo.js    | 10 +++++++++-
 html/index.html |  8 +++++---
 server.py       | 16 ++++++++++++----
 3 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/html/demo.js b/html/demo.js
index 4c19847..ed0abfc 100644
--- a/html/demo.js
+++ b/html/demo.js
@@ -1118,7 +1118,7 @@ function update_active_users(
     if (userid == myUserid) {
       for (var j = 0 ; j < N_BUCKETS; j++) {
         window.buckets.children[j].children[0].children[1].disabled =
-          est_bucket === j;
+          (j == 0 && !backingTrackOn && !imLeading) || est_bucket === j;
       }
     }
 
@@ -1638,6 +1638,7 @@ function connect_twilio() {
   });
 }
 
+let backingTrackOn = false;
 async function start_singing() {
   var final_url = server_api_path();
 
@@ -1713,6 +1714,13 @@ async function start_singing() {
     if (metadata["backingVolume"] != null) {
       window.backingVolumeControl.value = metadata["backingVolume"];
     }
+    if (metadata["backing_track_type"] != null) {
+      const backingTrackType = metadata["backing_track_type"];
+      backingTrackOn = !!backingTrackType;
+      window.backingSliderDiv.style.display =
+        backingTrackOn ? "block" : "none";
+      window.backingTrackTypeName.innerText = backingTrackType;
+    }
 
     first_bucket_s = metadata["first_bucket"] || first_bucket_s;
 
diff --git a/html/index.html b/html/index.html
index 335eecf..7edde53 100644
--- a/html/index.html
+++ b/html/index.html
@@ -197,7 +197,9 @@
     width: 12em;
   }
 }
-
+#backingSliderDiv {
+  display: none;
+}
 #remainderWindow {
   flex-grow: 1;
   display: flex;
@@ -1192,8 +1194,8 @@ <h3>Something else weird is going on</h3>
     <div id=spectatorMode>As a spectator, your singing is not included</div>
   </div>
 
-  <div>
-  <label for=backingVolumeSlider>Backing Volume:</label>
+  <div id=backingSliderDiv>
+  <label for=backingVolumeSlider><span id=backingTrackTypeName></span> Volume:</label>
   <input type="range" min="0" max="160" value="100" id="backingVolumeSlider">
   </div>
 
diff --git a/server.py b/server.py
index c380117..7db46f1 100755
--- a/server.py
+++ b/server.py
@@ -104,6 +104,7 @@ def reset(self):
 
         self.backing_track: Any = np.zeros(0)
         self.backing_track_index = 0
+        self.backing_track_type = ""
 
         self.max_position = DELAY_INTERVAL*LAYERING_DEPTH
 
@@ -469,6 +470,7 @@ def run_backing_track() -> None:
                 inf.readframes(-1), np.int16).astype(np.float32) / (2**15)
             state.backing_track *= 0.8 # turn it down a bit
             state.backing_track_index = 0
+            state.backing_track_type = "Backing Track"
 
     # Backing track is used only once.
     state.requested_track = None
@@ -766,6 +768,11 @@ def handle_json_post(in_json_raw, in_data):
         "x-audio-metadata": x_audio_metadata,
     }), out_data
 
+def end_song():
+    state.leader = None
+    state.backing_track_type = ""
+    sendall("backing_track_type", state.backing_track_type)
+
 # Handle special operations that do not require a user (although they may
 #   optionally support one), but can be done server-to-server as well.
 def handle_special(query_params, server_clock, user=None, client_read_clock=None):
@@ -817,8 +824,10 @@ def handle_special(query_params, server_clock, user=None, client_read_clock=None
             state.song_start_clock = server_clock
         state.song_end_clock = 0
 
+        state.backing_track_type = ""
         if state.bpm > 0:
             backfill_metronome()
+            state.backing_track_type = "Metronome"
         elif state.requested_track:
             run_backing_track()
             # These must be separate from song_start/end_clock, because they
@@ -826,7 +835,7 @@ def handle_special(query_params, server_clock, user=None, client_read_clock=None
             #   backing track starts/ends, not merely close.
             #insert_event("backingTrackStart", server_clock)
             #insert_event("backingTrackEnd", server_clock + len(state.backing_track))
-
+        sendall("backing_track_type", state.backing_track_type)
 
     if query_params.get("mark_stop_singing", None):
         # stop the backing track from playing, if it's still going
@@ -842,8 +851,7 @@ def handle_special(query_params, server_clock, user=None, client_read_clock=None
         else:
             state.song_end_clock = server_clock
 
-        state.leader = None
-
+        end_song()
 
     if query_params.get("clear_events", None):
         events.clear()
@@ -977,7 +985,7 @@ def handle_post(in_json, in_data) -> Tuple[Any, str]:
         if state.backing_track_index == len(state.backing_track):
             # the song has ended, mark it so
             state.song_end_clock = clear_index
-            state.leader = None
+            end_song()
 
     if clear_samples > 0:
         if state.bpm > 0: