Give Bluetooth settings a bit of a refresh

It's now a bit more responsive to stuff happening, gives you more information, and remembers your previously paired devices for faster switching between them.

lua/settings.lua

@@ -46,6 +46,7 @@ local BluetoothPairing = SettingsScreen:new {
         for _, dev in pairs(devs) do
           devices:add_btn(nil, dev.name):onClicked(function()
             bluetooth.paired_device:set(dev)
+            backstack.pop()
           end)
         end
       end)
@@ -101,16 +102,15 @@ local BluetoothSettings = SettingsScreen:new {
     theme.set_style(paired_label, "settings_title")
 
     self.bindings = self.bindings + {
-      bluetooth.connected:bind(function(conn)
+      bluetooth.connecting:bind(function(conn)
         if conn then
+          paired_label:set { text = "Connecting to:" }
+        else
+          if bluetooth.connected:get() then
             paired_label:set { text = "Connected to:" }
           else
             paired_label:set { text = "Paired with:" }
           end
-      end),
-      bluetooth.connecting:bind(function(conn)
-        if conn then
-          paired_label:set { text = "Connecting to:" }
         end
       end),
     }
@@ -159,22 +159,42 @@ local BluetoothSettings = SettingsScreen:new {
       h = lvgl.SIZE_CONTENT,
     }
 
+    -- 'Pair new device' button that goes to the discovery screen.
+
+    local button_container = self.content:Object {
+      w = lvgl.PCT(100),
+      h = lvgl.SIZE_CONTENT,
+      flex = {
+        flex_direction = "row",
+        justify_content = "center",
+        align_items = "space-evenly",
+        align_content = "center",
+      },
+      pad_top = 4,
+      pad_column = 4,
+    }
+    button_container:add_style(styles.list_item)
+
+    local pair_new = button_container:Button {}
+    pair_new:Label { text = "Pair new device" }
+    pair_new:onClicked(function()
+      backstack.push(BluetoothPairing:new())
+    end)
+
+
     self.bindings = self.bindings + {
       bluetooth.known_devices:bind(function(devs)
+        local group = lvgl.group.get_default()
+        group.remove_obj(pair_new)
         devices:clean()
         for _, dev in pairs(devs) do
           devices:add_btn(nil, dev.name):onClicked(function()
             bluetooth.paired_device:set(dev)
           end)
         end
+        group:add_obj(pair_new)
       end)
     }
-
-    local pair_new = self.content:Button {}
-    pair_new:Label { text = "Pair new device" }
-    pair_new:onClicked(function()
-      backstack.push(BluetoothPairing:new())
-    end)
   end
 }
 

lua/widgets.lua

@@ -79,11 +79,10 @@ function widgets.Row(parent, left, right)
   }
 end
 
-local bindings_meta = {
-  __add = function(a, b)
-    return table.move(a, 1, #a, #b + 1, b)
-  end
-}
+local bindings_meta = {}
+bindings_meta["__add"] = function(a, b)
+  return setmetatable(table.move(a, 1, #a, #b + 1, b), bindings_meta)
+end
 
 function widgets.StatusBar(parent, opts)
   local root = parent.root:Object {

src/drivers/bluetooth.cpp

@@ -603,16 +603,21 @@ void Disabled::react(const events::Enable&) {
 
 void Idle::entry() {
   ESP_LOGI(kTag, "bt is idle");
+  std::invoke(sEventHandler_, SimpleEvent::kConnectionStateChanged);
 }
 
-void Idle::exit() {}
+void Idle::exit() {
+  std::invoke(sEventHandler_, SimpleEvent::kConnectionStateChanged);
+}
 
 void Idle::react(const events::Disable& ev) {
   transit<Disabled>();
 }
 
 void Idle::react(const events::PairedDeviceChanged& ev) {
+  if (sPairedWith_) {
     connect(*sPairedWith_);
+  }
 }
 
 void Idle::react(events::internal::Gap ev) {
@@ -633,18 +638,10 @@ void Connecting::entry() {
   sTimeoutTimer = xTimerCreate("bt_timeout", pdMS_TO_TICKS(15000), false, NULL,
                                timeoutCallback);
   xTimerStart(sTimeoutTimer, portMAX_DELAY);
-
-  if (sEventHandler_) {
-    std::invoke(sEventHandler_, SimpleEvent::kConnectionStateChanged);
-  }
 }
 
 void Connecting::exit() {
   xTimerDelete(sTimeoutTimer, portMAX_DELAY);
-
-  if (sEventHandler_) {
-    std::invoke(sEventHandler_, SimpleEvent::kConnectionStateChanged);
-  }
 }
 
 void Connecting::react(const events::ConnectTimedOut& ev) {
@@ -751,12 +748,16 @@ void Connected::entry() {
     sStorage_->PreferredBluetoothDevice(sPairedWith_);
   }
 
+  std::invoke(sEventHandler_, SimpleEvent::kConnectionStateChanged);
+
   // TODO: if we already have a source, immediately start playing
 }
 
 void Connected::exit() {
   ESP_LOGI(kTag, "exiting connected state");
   esp_a2d_source_disconnect(connected_to_.data());
+
+  std::invoke(sEventHandler_, SimpleEvent::kConnectionStateChanged);
 }
 
 void Connected::react(const events::Disable& ev) {
@@ -765,6 +766,9 @@ void Connected::react(const events::Disable& ev) {
 
 void Connected::react(const events::PairedDeviceChanged& ev) {
   transit<Idle>();
+  if (sPairedWith_) {
+    connect(*sPairedWith_);
+  }
 }
 
 void Connected::react(const events::SourceChanged& ev) {

src/drivers/include/drivers/nvs.hpp

@@ -34,7 +34,7 @@ class Setting {
       dirty_ = true;
     }
   }
-  auto get() -> std::optional<T>& { return val_; }
+  auto get() -> std::optional<T> { return val_; }
 
   /* Reads the stored value from NVS and parses it into the correct type. */
   auto load(nvs_handle_t) -> std::optional<T>;

src/drivers/nvs.cpp

@@ -391,7 +391,7 @@ auto NvsStorage::BluetoothNames() -> std::vector<bluetooth::MacAndName> {
 auto NvsStorage::BluetoothName(const bluetooth::mac_addr_t& mac,
                                std::optional<std::string> name) -> void {
   std::lock_guard<std::mutex> lock{mutex_};
-  auto& val = bt_names_.get();
+  auto val = bt_names_.get();
   if (!val) {
     val.emplace();
   }

src/tangara/lua/property.cpp

@@ -371,10 +371,10 @@ auto popRichType(lua_State* L) -> LuaValue {
 }
 
 auto Property::popValue(lua_State& s) -> bool {
-  LuaValue new_val;
+  LuaValue new_val{std::monostate{}};
+  if (lua_gettop(&s) >= 2) {
     switch (lua_type(&s, 2)) {
       case LUA_TNIL:
-      new_val = std::monostate{};
         break;
       case LUA_TNUMBER:
         if (lua_isinteger(&s, 2)) {
@@ -399,6 +399,7 @@ auto Property::popValue(lua_State& s) -> bool {
           return false;
         }
     }
+  }
 
   return set(new_val);
 }