core: Consolidate top-level system state into a singleton.

src/core/system.h

@@ -4,18 +4,80 @@
 
 #pragma once
 
+#include <string>
+
+#include "core/loader/loader.h"
+
 class EmuWindow;
 
-namespace System {
+namespace Core {
 
-enum class Result {
-    Success,            ///< Everything is fine
-    Error,              ///< Something went wrong (no module specified)
-    ErrorInitCore,      ///< Something went wrong during core init
-    ErrorInitVideoCore, ///< Something went wrong during video core init
+class System {
+public:
+    struct State {
+        std::unique_ptr<Loader::AppLoader> app_loader;
+    };
+
+    /**
+     * Gets the instance of the System singleton class.
+     * @returns Reference to the instance of the System singleton class.
+     */
+    static System& GetInstance() {
+        return s_instance;
+    }
+
+    /// Enumeration representing the return values of the System Initialize and Load process.
+    enum class ResultStatus : u32 {
+        Success, ///< Succeeded
+        ErrorGetLoader, ///< Error finding the correct application loader
+        ErrorSystemMode, ///< Error determining the system mode
+        ErrorLoader, ///< Error loading the specified application
+        ErrorLoader_ErrorEncrypted, ///< Error loading the specified application due to encryption
+        ErrorLoader_ErrorInvalidFormat, ///< Error loading the specified application due to an invalid format
+        ErrorVideoCore, ///< Error in the video core
+    };
+
+    /**
+     * Initialize the emulated system.
+     * @param emu_window Pointer to the host-system window used for video output and keyboard input.
+     * @param system_mode The system mode.
+     * @returns ResultStatus code, indicating if the operation succeeded.
+     */
+    ResultStatus Init(EmuWindow* emu_window, u32 system_mode);
+
+    /// Shutdown the emulated system.
+    void Shutdown();
+
+    /**
+     * Load an executable application.
+     * @param emu_window Pointer to the host-system window used for video output and keyboard input.
+     * @param filepath String path to the executable application to load on the host file system.
+     * @returns ResultStatus code, indicating if the operation succeeded.
+     */
+    ResultStatus Load(EmuWindow* emu_window, const std::string& filepath);
+
+    /**
+     * Indicates if the emulated system is powered on (all subsystems initialized and able to run an
+     * application).
+     * @returns True if the emulated system is powered on, otherwise false.
+     */
+    bool IsPoweredOn() const {
+        return is_powered_on;
+    }
+
+    /**
+     * Gets the internal state of the emulated system.
+     * @returns The internal state of the emulated system
+     */
+    State& GetState() {
+        return state;
+    }
+
+private:
+    bool is_powered_on{};
+    State state;
+
+    static System s_instance;
 };
 
-Result Init(EmuWindow* emu_window, u32 system_mode);
-bool IsPoweredOn();
-void Shutdown();
-}
+} // namespace Core