use prototype inheritance for lua screens, rather than functions

this gives us a way to give each screen nice little hooks, like
'onShown' and 'onHidden'. later we can use these hooks to disable
bindings for screens that aren't in-use.

4 files changed, 79 insertions, 21 deletions

diff --git a/src/ui/include/screen.hpp b/src/ui/include/screen.hpp
index 60939660..4241c712 100644
--- a/src/ui/include/screen.hpp
+++ b/src/ui/include/screen.hpp
@@ -27,6 +27,9 @@ class Screen {
   Screen();
   virtual ~Screen();
 
+  virtual auto onShown() -> void {}
+  virtual auto onHidden() -> void {}
+
   auto root() -> lv_obj_t* { return root_; }
   auto content() -> lv_obj_t* { return content_; }
   auto alert() -> lv_obj_t* { return alert_; }
diff --git a/src/ui/include/screen_lua.hpp b/src/ui/include/screen_lua.hpp
index ee9f6813..0ed3a508 100644
--- a/src/ui/include/screen_lua.hpp
+++ b/src/ui/include/screen_lua.hpp
@@ -18,6 +18,9 @@ class Lua : public Screen {
   Lua();
   ~Lua();
 
+  auto onShown() -> void override;
+  auto onHidden() -> void override;
+
   auto SetObjRef(lua_State*) -> void;
 
  private:
diff --git a/src/ui/screen_lua.cpp b/src/ui/screen_lua.cpp
index 5130b4f7..d6c7a26f 100644
--- a/src/ui/screen_lua.cpp
+++ b/src/ui/screen_lua.cpp
@@ -7,8 +7,10 @@
 #include "screen_lua.hpp"
 
 #include "core/lv_obj_tree.h"
+#include "lua.h"
 #include "lua.hpp"
 
+#include "lua_thread.hpp"
 #include "luavgl.h"
 
 namespace ui {
@@ -22,6 +24,40 @@ Lua::~Lua() {
   }
 }
 
+auto Lua::onShown() -> void {
+  if (!s_ || !obj_ref_) {
+    return;
+  }
+  lua_rawgeti(s_, LUA_REGISTRYINDEX, *obj_ref_);
+  lua_pushliteral(s_, "onShown");
+
+  if (lua_gettable(s_, -2) == LUA_TFUNCTION) {
+    lua_pushvalue(s_, -2);
+    lua::CallProtected(s_, 1, 0);
+  } else {
+    lua_pop(s_, 1);
+  }
+
+  lua_pop(s_, 1);
+}
+
+auto Lua::onHidden() -> void {
+  if (!s_ || !obj_ref_) {
+    return;
+  }
+  lua_rawgeti(s_, LUA_REGISTRYINDEX, *obj_ref_);
+  lua_pushliteral(s_, "onHidden");
+
+  if (lua_gettable(s_, -2) == LUA_TFUNCTION) {
+    lua_pushvalue(s_, -2);
+    lua::CallProtected(s_, 1, 0);
+  } else {
+    lua_pop(s_, 1);
+  }
+
+  lua_pop(s_, 1);
+}
+
 auto Lua::SetObjRef(lua_State* s) -> void {
   assert(s_ == nullptr);
   s_ = s;
diff --git a/src/ui/ui_fsm.cpp b/src/ui/ui_fsm.cpp
index d98e435d..5c22e90e 100644
--- a/src/ui/ui_fsm.cpp
+++ b/src/ui/ui_fsm.cpp
@@ -125,21 +125,24 @@ lua::Property UiState::sPlaybackPlaying{
     }};
 
 lua::Property UiState::sPlaybackTrack{};
-lua::Property UiState::sPlaybackPosition{0, [](const lua::LuaValue& val) {
-    int current_val = std::get<int>(sPlaybackPosition.Get());
-    if (!std::holds_alternative<int>(val)) {
-      return false;
-    }
-    int new_val = std::get<int>(val);
-    if (current_val != new_val) {
-      auto track = sPlaybackTrack.Get();
-      if (!std::holds_alternative<audio::Track>(track)) {
+lua::Property UiState::sPlaybackPosition{
+    0, [](const lua::LuaValue& val) {
+      int current_val = std::get<int>(sPlaybackPosition.Get());
+      if (!std::holds_alternative<int>(val)) {
         return false;
       }
-      events::Audio().Dispatch(audio::SeekFile{.offset = (uint32_t)new_val, .filename = std::get<audio::Track>(track).filepath});
-    }
-    return true;
-}};
+      int new_val = std::get<int>(val);
+      if (current_val != new_val) {
+        auto track = sPlaybackTrack.Get();
+        if (!std::holds_alternative<audio::Track>(track)) {
+          return false;
+        }
+        events::Audio().Dispatch(audio::SeekFile{
+            .offset = (uint32_t)new_val,
+            .filename = std::get<audio::Track>(track).filepath});
+      }
+      return true;
+    }};
 
 lua::Property UiState::sQueuePosition{0};
 lua::Property UiState::sQueueSize{0};
@@ -294,21 +297,29 @@ auto UiState::InitBootSplash(drivers::IGpios& gpios) -> bool {
 }
 
 void UiState::PushScreen(std::shared_ptr<Screen> screen) {
+  lv_obj_set_parent(sAlertContainer, screen->alert());
+
   if (sCurrentScreen) {
+    sCurrentScreen->onHidden();
     sScreens.push(sCurrentScreen);
   }
   sCurrentScreen = screen;
-  lv_obj_set_parent(sAlertContainer, sCurrentScreen->alert());
+  sCurrentScreen->onShown();
 }
 
 int UiState::PopScreen() {
   if (sScreens.empty()) {
     return 0;
   }
-  sCurrentScreen = sScreens.top();
-  lv_obj_set_parent(sAlertContainer, sCurrentScreen->alert());
+  lv_obj_set_parent(sAlertContainer, sScreens.top()->alert());
+
+  sCurrentScreen->onHidden();
 
+  sCurrentScreen = sScreens.top();
   sScreens.pop();
+
+  sCurrentScreen->onShown();
+
   return sScreens.size();
 }
 
@@ -539,7 +550,7 @@ void Lua::entry() {
 
 auto Lua::PushLuaScreen(lua_State* s) -> int {
   // Ensure the arg looks right before continuing.
-  luaL_checktype(s, 1, LUA_TFUNCTION);
+  luaL_checktype(s, 1, LUA_TTABLE);
 
   // First, create a new plain old Screen object. We will use its root and
   // group for the Lua screen. Allocate it in external ram so that arbitrarily
@@ -554,10 +565,15 @@ auto Lua::PushLuaScreen(lua_State* s) -> int {
   lv_group_set_default(new_screen->group());
 
   // Call the constructor for this screen.
-  lua_settop(s, 1);  // Make sure the function is actually at top of stack
-  lua::CallProtected(s, 0, 1);
+  // lua_settop(s, 1);  // Make sure the screen is actually at top of stack
+  lua_pushliteral(s, "createUi");
+  if (lua_gettable(s, 1) == LUA_TFUNCTION) {
+    lua_pushvalue(s, 1);
+    lua::CallProtected(s, 1, 0);
+  }
 
-  // Store the reference for the table the constructor returned.
+  // Store the reference for this screen's table.
+  lua_settop(s, 1);
   new_screen->SetObjRef(s);
 
   // Finally, push the now-initialised screen as if it were a regular C++
@@ -585,7 +601,7 @@ auto Lua::PopLuaScreen(lua_State* s) -> int {
 }
 
 auto Lua::Ticks(lua_State* s) -> int {
-  lua_pushinteger(s, esp_timer_get_time()/1000);
+  lua_pushinteger(s, esp_timer_get_time() / 1000);
   return 1;
 }