Add basic lua browser screen

4 files changed, 72 insertions, 33 deletions

diff --git a/src/database/database.cpp b/src/database/database.cpp
index 88ae7bbe..dad983d0 100644
--- a/src/database/database.cpp
+++ b/src/database/database.cpp
@@ -846,8 +846,7 @@ auto IndexRecord::Expand(std::size_t page_size) const
   if (track_) {
     return {};
   }
-  IndexKey::Header new_header = ExpandHeader(key_.header, key_.item);
-  std::string new_prefix = EncodeIndexPrefix(new_header);
+  std::string new_prefix = EncodeIndexPrefix(ExpandHeader());
   return Continuation{
       .prefix = {new_prefix.data(), new_prefix.size()},
       .start_key = {new_prefix.data(), new_prefix.size()},
@@ -857,6 +856,10 @@ auto IndexRecord::Expand(std::size_t page_size) const
   };
 }
 
+auto IndexRecord::ExpandHeader() const -> IndexKey::Header {
+  return ::database::ExpandHeader(key_.header, key_.item);
+}
+
 Iterator::Iterator(std::weak_ptr<Database> db, const IndexInfo& idx)
     : db_(db), pos_mutex_(), current_pos_(), prev_pos_() {
   std::string prefix = EncodeIndexPrefix(
@@ -887,6 +890,11 @@ auto Iterator::Next(Callback cb) -> void {
         db->dbGetPage<IndexRecord>(*current_pos_)};
     prev_pos_ = current_pos_;
     current_pos_ = res->next_page();
+    if (!res || res->values().empty() || !res->values()[0]) {
+      ESP_LOGI(kTag, "dropping empty result");
+      InvokeNull(cb);
+      return;
+    }
     std::invoke(cb, *res->values()[0]);
   });
 }
diff --git a/src/database/include/database.hpp b/src/database/include/database.hpp
index 63014bed..e18701eb 100644
--- a/src/database/include/database.hpp
+++ b/src/database/include/database.hpp
@@ -80,6 +80,7 @@ class IndexRecord {
   auto track() const -> std::optional<TrackId>;
 
   auto Expand(std::size_t) const -> std::optional<Continuation>;
+  auto ExpandHeader() const -> IndexKey::Header;
 
  private:
   IndexKey key_;
diff --git a/src/lua/lua_database.cpp b/src/lua/lua_database.cpp
index d8ae86f6..79916115 100644
--- a/src/lua/lua_database.cpp
+++ b/src/lua/lua_database.cpp
@@ -20,7 +20,9 @@
 #include "event_queue.hpp"
 #include "index.hpp"
 #include "property.hpp"
+#include "records.hpp"
 #include "service_locator.hpp"
+#include "track.hpp"
 #include "ui_events.hpp"
 
 namespace lua {
@@ -55,6 +57,42 @@ static auto indexes(lua_State* state) -> int {
 static const struct luaL_Reg kDatabaseFuncs[] = {{"indexes", indexes},
                                                  {NULL, NULL}};
 
+/*
+ * Struct to be used as userdata for the Lua representation of database records.
+ * In order to push these large values into PSRAM as much as possible, memory
+ * for these is allocated and managed by Lua. This struct must therefore be
+ * trivially copyable.
+ */
+struct LuaRecord {
+  database::TrackId id_or_zero;
+  database::IndexKey::Header header_at_next_depth;
+  size_t text_size;
+  char text[];
+};
+
+static_assert(std::is_trivially_copyable_v<LuaRecord> == true);
+
+static auto push_lua_record(lua_State* L, const database::IndexRecord& r)
+    -> void {
+  // Bake out the text into something concrete.
+  auto text = r.text().value_or("");
+
+  // Create and init the userdata.
+  LuaRecord* record = reinterpret_cast<LuaRecord*>(
+      lua_newuserdata(L, sizeof(LuaRecord) + text.size()));
+  luaL_setmetatable(L, kDbRecordMetatable);
+
+  // Init all the fields
+  *record = {
+      .id_or_zero = r.track().value_or(0),
+      .header_at_next_depth = r.ExpandHeader(),
+      .text_size = text.size(),
+  };
+
+  // Copy the string data across.
+  std::memcpy(record->text, text.data(), text.size());
+}
+
 static auto db_iterate(lua_State* state) -> int {
   luaL_checktype(state, 1, LUA_TFUNCTION);
   int callback_ref = luaL_ref(state, LUA_REGISTRYINDEX);
@@ -66,11 +104,7 @@ static auto db_iterate(lua_State* state) -> int {
     events::Ui().RunOnTask([=]() {
       lua_rawgeti(state, LUA_REGISTRYINDEX, callback_ref);
       if (res) {
-        database::IndexRecord** record =
-            reinterpret_cast<database::IndexRecord**>(
-                lua_newuserdata(state, sizeof(uintptr_t)));
-        *record = new database::IndexRecord(*res);
-        luaL_setmetatable(state, kDbRecordMetatable);
+        push_lua_record(state, *res);
       } else {
         lua_pushnil(state);
       }
@@ -105,40 +139,37 @@ static auto push_iterator(
   lua_pushcclosure(state, db_iterate, 1);
 }
 
+
 static auto record_text(lua_State* state) -> int {
-  database::IndexRecord* data = *reinterpret_cast<database::IndexRecord**>(
+  LuaRecord* data = reinterpret_cast<LuaRecord*>(
       luaL_checkudata(state, 1, kDbRecordMetatable));
-  lua_pushstring(state,
-                 data->text().value_or("[tell jacqueline u saw this]").c_str());
+  lua_pushlstring(state, data->text, data->text_size);
   return 1;
 }
 
 static auto record_contents(lua_State* state) -> int {
-  database::IndexRecord* data = *reinterpret_cast<database::IndexRecord**>(
+  LuaRecord* data = reinterpret_cast<LuaRecord*>(
       luaL_checkudata(state, 1, kDbRecordMetatable));
 
-  if (data->track()) {
-    lua_pushinteger(state, *data->track());
+  if (data->id_or_zero) {
+    lua_pushinteger(state, data->id_or_zero);
   } else {
-    push_iterator(state, data->Expand(1).value());
+    std::string p = database::EncodeIndexPrefix(data->header_at_next_depth);
+    push_iterator(state, database::Continuation{
+                             .prefix = {p.data(), p.size()},
+                             .start_key = {p.data(), p.size()},
+                             .forward = true,
+                             .was_prev_forward = true,
+                             .page_size = 1,
+                         });
   }
 
   return 1;
 }
 
-static auto record_gc(lua_State* state) -> int {
-  database::IndexRecord** data = reinterpret_cast<database::IndexRecord**>(
-      luaL_checkudata(state, 1, kDbRecordMetatable));
-  if (data != NULL) {
-    delete *data;
-  }
-  return 0;
-}
-
 static const struct luaL_Reg kDbRecordFuncs[] = {{"title", record_text},
                                                  {"contents", record_contents},
                                                  {"__tostring", record_text},
-                                                 {"__gc", record_gc},
                                                  {NULL, NULL}};
 
 static auto index_name(lua_State* state) -> int {
@@ -207,4 +238,4 @@ auto RegisterDatabaseModule(lua_State* s) -> void {
   lua_pop(s, 1);
 }
 
-}  // namespace lua
\ No newline at end of file
+}  // namespace lua
diff --git a/src/ui/ui_fsm.cpp b/src/ui/ui_fsm.cpp
index d5de53f0..ed0624df 100644
--- a/src/ui/ui_fsm.cpp
+++ b/src/ui/ui_fsm.cpp
@@ -219,6 +219,7 @@ void Lua::entry() {
             {"pop", [&](lua_State* s) { return PopLuaScreen(s); }},
         });
 
+    sCurrentScreen.reset();
     sLua->RunScript("/lua/main.lua");
   }
 }
@@ -243,12 +244,6 @@ auto Lua::PushLuaScreen(lua_State* s) -> int {
   // Store the reference for the table the constructor returned.
   new_screen->SetObjRef(s);
 
-  // Ensure that we don't pollute the new screen's group. We leave the luavgl
-  // root alone.
-  // FIXME: maybe we should set the luavgl root to some catch-all that throws
-  // when anything is added to it? this may help catch bugs!
-  lv_group_set_default(NULL);
-
   // Finally, push the now-initialised screen as if it were a regular C++
   // screen.
   PushScreen(new_screen);
@@ -256,12 +251,16 @@ auto Lua::PushLuaScreen(lua_State* s) -> int {
   return 0;
 }
 
-auto Lua::PopLuaScreen(lua_State*) -> int {
+auto Lua::PopLuaScreen(lua_State* s) -> int {
   PopScreen();
+  luavgl_set_root(s, sCurrentScreen->root());
+  lv_group_set_default(sCurrentScreen->group());
   return 0;
 }
 
-void Lua::exit() {}
+void Lua::exit() {
+  lv_group_set_default(NULL);
+}
 
 void Lua::react(const internal::IndexSelected& ev) {
   auto db = sServices->database().lock();