feat(item): add item manager with JSON asset loading

Implement ItemManager to load and query item definitions from assets/item JSON files. Add ItemData struct, item asset metadata, CMake source registration, and initialize the manager during app startup. Also add AGENTS.md repository guidelines.

src/gameplay/item_manager.cpp

@@ -0,0 +1,106 @@
+#include "Cubed/gameplay/item_manager.hpp"
+
+#include "Cubed/tools/cubed_assert.hpp"
+#include "Cubed/tools/log.hpp"
+
+#include <filesystem>
+#include <fstream>
+#include <rapidjson/document.h>
+#include <rapidjson/istreamwrapper.h>
+namespace fs = std::filesystem;
+using namespace rapidjson;
+namespace Cubed {
+ItemManager::ItemManager() {}
+
+ItemManager& ItemManager::instance() {
+    static ItemManager inst;
+    return inst;
+}
+
+void ItemManager::init() {
+    m_id_map.clear();
+    m_map.clear();
+
+    fs::path dir = ASSETS_PATH "item";
+    if (!fs::is_directory(dir)) {
+        throw std::runtime_error("Item path not exist!");
+    }
+    for (const auto& entry : fs::recursive_directory_iterator(
+             dir, fs::directory_options::skip_permission_denied)) {
+        if (fs::is_regular_file(entry)) {
+            if (entry.path().extension().string() == ".json") {
+                add(entry.path());
+            }
+        }
+    }
+}
+
+void ItemManager::add(const std::filesystem::path& path) {
+
+    std::ifstream s(path);
+    if (!s.is_open()) {
+        return;
+    }
+    IStreamWrapper isw(s);
+
+    Document doc;
+    doc.ParseStream(isw);
+    if (doc.HasParseError()) {
+        Logger::error("Can't Parse File {}, error code {}", path.string(),
+                      static_cast<int>(doc.GetParseError()));
+        return;
+    }
+    ItemData data;
+    if (doc.HasMember("id")) {
+        data.id = static_cast<ItemID>(doc["id"].GetInt());
+    }
+    if (doc.HasMember("name")) {
+        data.name = doc["name"].GetString();
+    }
+    if (doc.HasMember("description")) {
+        data.description = doc["description"].GetString();
+    }
+    if (doc.HasMember("texture")) {
+        data.path = doc["texture"].GetString();
+    }
+    acc a;
+    if (m_map.emplace(a, data.id, std::move(data))) {
+        if (!m_id_map.emplace(a->second.name, a->first)) {
+            Logger::error("ItemManager: Can't Insterd {} {} to id map",
+                          a->second.name, a->first);
+        }
+    } else {
+        Logger::error("ItemManager: Can't Insterd {} to map", path.string());
+    }
+}
+
+const ItemData& ItemManager::get_item_data(std::string_view key) const {
+    IDMap::const_accessor cacc;
+    ItemID id = 0;
+    if (m_id_map.find(cacc, key)) {
+        id = cacc->second;
+    } else {
+        Logger::error("Can't Find key {} in id map", key);
+        ASSERT(false);
+        return EMPTY;
+    }
+    return get_item_data(id);
+}
+const ItemData& ItemManager::get_item_data(ItemID id) const {
+    cacc c;
+    if (!m_map.find(c, id)) {
+        Logger::error("Can't find item {} in map", id);
+        ASSERT(false);
+        return EMPTY;
+    }
+    return c->second;
+}
+
+const ItemData& ItemManager::get(std::string_view key) {
+    return instance().get_item_data(key);
+}
+const ItemData& ItemManager::get(ItemID id) {
+    return instance().get_item_data(id);
+}
+
+} // namespace Cubed