Add lua functions to get database content

lua/main_menu.lua

@@ -30,9 +30,9 @@ return function()
     legacy_ui.open_now_playing();
   end)
 
-  local indexes = database.get_indexes()
-  for id, name in ipairs(indexes) do
-    local btn = menu.list:add_btn(nil, name)
+  local indexes = database.indexes()
+  for id, idx in ipairs(indexes) do
+    local btn = menu.list:add_btn(nil, tostring(idx))
     btn:onClicked(function()
       legacy_ui.open_browse(id);
     end)

src/database/database.cpp

@@ -857,4 +857,48 @@ auto IndexRecord::Expand(std::size_t page_size) const
   };
 }
 
+Iterator::Iterator(std::weak_ptr<Database> db, const IndexInfo& idx)
+    : db_(db), prev_pos_(), current_pos_() {
+  std::string prefix = EncodeIndexPrefix(
+      IndexKey::Header{.id = idx.id, .depth = 0, .components_hash = 0});
+  current_pos_ = Continuation{.prefix = {prefix.data(), prefix.size()},
+                              .start_key = {prefix.data(), prefix.size()},
+                              .forward = true,
+                              .was_prev_forward = true,
+                              .page_size = 1};
+}
+
+Iterator::Iterator(std::weak_ptr<Database> db, const Continuation& c)
+    : db_(db), prev_pos_(), current_pos_(c) {}
+
+auto Iterator::Prev() -> std::optional<IndexRecord> {
+  if (!prev_pos_) {
+    return {};
+  }
+  auto db = db_.lock();
+  if (!db) {
+    return {};
+  }
+  std::unique_ptr<Result<IndexRecord>> res{
+      db->GetPage<IndexRecord>(&*prev_pos_).get()};
+  prev_pos_ = res->prev_page();
+  current_pos_ = prev_pos_;
+  return *res->values()[0];
+}
+
+auto Iterator::Next() -> std::optional<IndexRecord> {
+  if (!current_pos_) {
+    return {};
+  }
+  auto db = db_.lock();
+  if (!db) {
+    return {};
+  }
+  std::unique_ptr<Result<IndexRecord>> res{
+      db->GetPage<IndexRecord>(&*current_pos_).get()};
+  prev_pos_ = current_pos_;
+  current_pos_ = res->next_page();
+  return *res->values()[0];
+}
+
 }  // namespace database

src/database/include/database.hpp

@@ -183,4 +183,21 @@ auto Database::ParseRecord<std::pmr::string>(const leveldb::Slice& key,
                                              const leveldb::Slice& val)
     -> std::shared_ptr<std::pmr::string>;
 
+/*
+ * Utility for accessing a large set of database records, one record at a time.
+ */
+class Iterator {
+ public:
+  Iterator(std::weak_ptr<Database>, const IndexInfo&);
+  Iterator(std::weak_ptr<Database>, const Continuation&);
+
+  auto Prev() -> std::optional<IndexRecord>;
+  auto Next() -> std::optional<IndexRecord>;
+
+ private:
+  std::weak_ptr<Database> db_;
+  std::optional<Continuation> prev_pos_;
+  std::optional<Continuation> current_pos_;
+};
+
 }  // namespace database

src/lua/CMakeLists.txt

@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: GPL-3.0-only
 
 idf_component_register(
-  SRCS "lua_thread.cpp" "bridge.cpp" "property.cpp"
+  SRCS "lua_thread.cpp" "bridge.cpp" "property.cpp" "lua_database.cpp" "lua_queue.cpp"
   INCLUDE_DIRS "include"
   REQUIRES "drivers" "lvgl" "tinyfsm" "events" "system_fsm" "database" "esp_timer" "battery" "esp-idf-lua" "luavgl")
 target_compile_options(${COMPONENT_LIB} PRIVATE ${EXTRA_WARNINGS})

src/lua/bridge.cpp

@@ -5,13 +5,19 @@
  */
 
 #include "bridge.hpp"
+#include <sys/_stdint.h>
 
 #include <memory>
 #include <string>
 
+#include "database.hpp"
 #include "esp_log.h"
+#include "index.hpp"
 #include "lauxlib.h"
+#include "lua.h"
 #include "lua.hpp"
+#include "lua_database.hpp"
+#include "lua_queue.hpp"
 #include "lvgl.h"
 
 #include "event_queue.hpp"
@@ -22,6 +28,7 @@
 namespace lua {
 
 [[maybe_unused]] static constexpr char kTag[] = "lua_bridge";
+
 static constexpr char kBridgeKey[] = "bridge";
 
 static auto open_settings_fn(lua_State* state) -> int {
@@ -54,32 +61,6 @@ static auto lua_legacy_ui(lua_State* state) -> int {
   return 1;
 }
 
-static auto get_indexes(lua_State* state) -> int {
-  Bridge* instance = Bridge::Get(state);
-
-  lua_newtable(state);
-
-  auto db = instance->services().database().lock();
-  if (!db) {
-    return 1;
-  }
-
-  for (const auto& i : db->GetIndexes()) {
-    lua_pushstring(state, i.name.c_str());
-    lua_rawseti(state, -2, i.id);
-  }
-
-  return 1;
-}
-
-static const struct luaL_Reg kDatabaseFuncs[] = {{"get_indexes", get_indexes},
-                                                 {NULL, NULL}};
-
-static auto lua_database(lua_State* state) -> int {
-  luaL_newlib(state, kDatabaseFuncs);
-  return 1;
-}
-
 auto Bridge::Get(lua_State* state) -> Bridge* {
   lua_pushstring(state, kBridgeKey);
   lua_gettable(state, LUA_REGISTRYINDEX);
@@ -95,8 +76,8 @@ Bridge::Bridge(system_fsm::ServiceLocator& services, lua_State& s)
   luaL_requiref(&s, "legacy_ui", lua_legacy_ui, true);
   lua_pop(&s, 1);
 
-  luaL_requiref(&s, "database", lua_database, true);
-  lua_pop(&s, 1);
+  RegisterDatabaseModule(&s);
+  RegisterQueueModule(&s);
 }
 
 static auto new_property_module(lua_State* state) -> int {

src/lua/include/lua_database.hpp

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2023 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#pragma once
+
+#include "lua.hpp"
+
+namespace lua {
+
+auto RegisterDatabaseModule(lua_State*) -> void;
+
+}  // namespace lua

src/lua/include/lua_queue.hpp

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2023 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#pragma once
+
+#include "lua.hpp"
+
+namespace lua {
+
+auto RegisterQueueModule(lua_State*) -> void;
+
+}  // namespace lua

src/lua/lua_database.cpp

@@ -0,0 +1,199 @@
+/*
+ * Copyright 2023 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#include "lua_database.hpp"
+
+#include <memory>
+#include <string>
+
+#include "lua.hpp"
+
+#include "esp_log.h"
+#include "lauxlib.h"
+#include "lua.h"
+#include "lvgl.h"
+
+#include "database.hpp"
+#include "event_queue.hpp"
+#include "index.hpp"
+#include "property.hpp"
+#include "service_locator.hpp"
+#include "ui_events.hpp"
+
+namespace lua {
+
+[[maybe_unused]] static constexpr char kTag[] = "lua_db";
+
+static constexpr char kDbIndexMetatable[] = "db_index";
+static constexpr char kDbRecordMetatable[] = "db_record";
+static constexpr char kDbIteratorMetatable[] = "db_record";
+
+static auto indexes(lua_State* state) -> int {
+  Bridge* instance = Bridge::Get(state);
+
+  lua_newtable(state);
+
+  auto db = instance->services().database().lock();
+  if (!db) {
+    return 1;
+  }
+
+  for (const auto& i : db->GetIndexes()) {
+    database::IndexInfo** data = reinterpret_cast<database::IndexInfo**>(
+        lua_newuserdata(state, sizeof(uintptr_t)));
+    luaL_setmetatable(state, kDbIndexMetatable);
+    *data = new database::IndexInfo{i};
+    lua_rawseti(state, -2, i.id);
+  }
+
+  return 1;
+}
+
+static const struct luaL_Reg kDatabaseFuncs[] = {{"indexes", indexes},
+                                                 {NULL, NULL}};
+
+static auto db_iterate(lua_State* state) -> int {
+  database::Iterator* it = *reinterpret_cast<database::Iterator**>(
+      lua_touserdata(state, lua_upvalueindex(1)));
+
+  auto res = it->Next();
+  if (res) {
+    database::IndexRecord** record = reinterpret_cast<database::IndexRecord**>(
+        lua_newuserdata(state, sizeof(uintptr_t)));
+    *record = new database::IndexRecord(*res);
+    luaL_setmetatable(state, kDbRecordMetatable);
+    return 1;
+  }
+  return 0;
+}
+
+static auto db_iterator_gc(lua_State* state) -> int {
+  database::Iterator** it = reinterpret_cast<database::Iterator**>(
+      luaL_checkudata(state, 1, kDbIteratorMetatable));
+  if (it != NULL) {
+    delete *it;
+  }
+  return 0;
+}
+
+static auto push_iterator(
+    lua_State* state,
+    std::variant<database::Continuation, database::IndexInfo> val) -> void {
+  Bridge* instance = Bridge::Get(state);
+  database::Iterator** data = reinterpret_cast<database::Iterator**>(
+      lua_newuserdata(state, sizeof(uintptr_t)));
+  std::visit(
+      [&](auto&& arg) {
+        *data = new database::Iterator(instance->services().database(), arg);
+      },
+      val);
+  luaL_setmetatable(state, kDbIteratorMetatable);
+  lua_pushcclosure(state, db_iterate, 1);
+}
+
+static auto record_text(lua_State* state) -> int {
+  database::IndexRecord* data = *reinterpret_cast<database::IndexRecord**>(
+      luaL_checkudata(state, 1, kDbRecordMetatable));
+  lua_pushstring(state,
+                 data->text().value_or("[tell jacqueline u saw this]").c_str());
+  return 1;
+}
+
+static auto record_contents(lua_State* state) -> int {
+  database::IndexRecord* data = *reinterpret_cast<database::IndexRecord**>(
+      luaL_checkudata(state, 1, kDbRecordMetatable));
+
+  if (data->track()) {
+    lua_pushinteger(state, *data->track());
+  } else {
+    push_iterator(state, data->Expand(1).value());
+  }
+
+  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 {
+  database::IndexInfo** data = reinterpret_cast<database::IndexInfo**>(
+      luaL_checkudata(state, 1, kDbIndexMetatable));
+  if (data == NULL) {
+    return 0;
+  }
+  lua_pushstring(state, (*data)->name.c_str());
+  return 1;
+}
+
+static auto index_iter(lua_State* state) -> int {
+  database::IndexInfo** data = reinterpret_cast<database::IndexInfo**>(
+      luaL_checkudata(state, 1, kDbIndexMetatable));
+  if (data == NULL) {
+    return 0;
+  }
+  push_iterator(state, **data);
+  return 1;
+}
+
+static auto index_gc(lua_State* state) -> int {
+  database::IndexInfo** data = reinterpret_cast<database::IndexInfo**>(
+      luaL_checkudata(state, 1, kDbIndexMetatable));
+  if (data != NULL) {
+    delete *data;
+  }
+  return 0;
+}
+
+static const struct luaL_Reg kDbIndexFuncs[] = {{"name", index_name},
+                                                {"iter", index_iter},
+                                                {"__tostring", index_name},
+                                                {"__gc", index_gc},
+                                                {NULL, NULL}};
+
+static auto lua_database(lua_State* state) -> int {
+  // Metatable for indexes
+  luaL_newmetatable(state, kDbIndexMetatable);
+
+  lua_pushliteral(state, "__index");
+  lua_pushvalue(state, -2);
+  lua_settable(state, -3);  // metatable.__index = metatable
+
+  // Add member funcs to the metatable.
+  luaL_setfuncs(state, kDbIndexFuncs, 0);
+
+  luaL_newmetatable(state, kDbIteratorMetatable);
+  lua_pushliteral(state, "__gc");
+  lua_pushcfunction(state, db_iterator_gc);
+  lua_settable(state, -3);
+
+  luaL_newmetatable(state, kDbRecordMetatable);
+  lua_pushliteral(state, "__index");
+  lua_pushvalue(state, -2);
+  lua_settable(state, -3);  // metatable.__index = metatable
+  luaL_setfuncs(state, kDbRecordFuncs, 0);
+
+  luaL_newlib(state, kDatabaseFuncs);
+  return 1;
+}
+
+auto RegisterDatabaseModule(lua_State* s) -> void {
+  luaL_requiref(s, "database", lua_database, true);
+  lua_pop(s, 1);
+}
+
+}  // namespace lua

src/lua/lua_queue.cpp

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2023 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#include "lua_database.hpp"
+
+#include <memory>
+#include <string>
+
+#include "lua.hpp"
+
+#include "esp_log.h"
+#include "lauxlib.h"
+#include "lua.h"
+#include "lvgl.h"
+
+#include "database.hpp"
+#include "event_queue.hpp"
+#include "index.hpp"
+#include "property.hpp"
+#include "service_locator.hpp"
+#include "ui_events.hpp"
+
+namespace lua {
+
+[[maybe_unused]] static constexpr char kTag[] = "lua_queue";
+
+static auto queue_add(lua_State* state) -> int {
+  return 0;
+}
+
+static const struct luaL_Reg kQueueFuncs[] = {{"add", queue_add}, {NULL, NULL}};
+
+static auto lua_queue(lua_State* state) -> int {
+  luaL_newlib(state, kQueueFuncs);
+  return 1;
+}
+
+auto RegisterQueueModule(lua_State* s) -> void {
+  luaL_requiref(s, "queue", lua_queue, true);
+  lua_pop(s, 1);
+}
+
+}  // namespace lua

src/lua/stubs/database.lua

@@ -0,0 +1,59 @@
+--- Module for accessing and updating data about the user's library of tracks.
+-- @module database
+
+local database = {}
+
+--- Returns a list of all indexes in the database.
+-- @treturn Array(Index)
+function database.indexes() end
+
+--- An iterator is a userdata type that behaves like an ordinary Lua iterator.
+-- @type Iterator
+local Iterator = {}
+
+--- A TrackId is a unique identifier, representing a playable track in the
+--- user's library.
+-- @type TrackId
+local TrackId = {}
+
+--- A record is an item within an Index, representing some value at a specific
+--- depth.
+-- @type Record
+local Record = {}
+
+--- Gets the human-readable text representing this record. The `__tostring`
+--- metatable function is an alias of this function.
+-- @treturn string
+function Record:title() end
+
+--- Returns the value that this record represents. This may be either a track
+--- id, for records which uniquely identify a track, or it may be a new
+--- Iterator representing the next level of depth for the current index.
+---
+--- For example, each Record in the "All Albums" index corresponds to an entire
+--- album of tracks; the 'contents' of such a Record is an iterator returning
+--- each track in the album represented by the Record. The contents of each of
+--- the returned 'track' Records would be a full Track, as there is no further
+--- disambiguation needed.
+-- @treturn TrackId|Iterator(Record)
+function Record:contents() end
+
+--- An index is heirarchical, sorted, view of the tracks within the database.
+--- For example, the 'All Albums' index contains, first, a sorted list of every
+--- album name in the library. Then, at the second level of the index, a sorted
+--- list of every track within each album.
+-- @type Index
+local Index = {}
+
+--- Gets the human-readable name of this index. This is typically something
+--- like "All Albums", or "Albums by Artist". The `__tostring` metatable
+--- function is an alias of this function.
+-- @treturn string
+function Index:name() end
+
+--- Returns a new iterator that can be used to access every record within the
+--- first level of this index.
+-- @treturn Iterator(Record)
+function Index:iter() end
+
+return database