platform.h

// =====================================================================================================================
//  fennec, a free and open source game engine
//  Copyright © 2025  Medusa Slockbower
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
// =====================================================================================================================
 
#ifndef FENNEC_PLATFORM_INTERFACE_PLATFORM_H
#define FENNEC_PLATFORM_INTERFACE_PLATFORM_H
 
#include <fennec/string/cstring.h>
 
#include <fennec/platform/window_manager.h>
 
#include <fennec/rtti/enable.h>
#include <fennec/rtti/singleton.h>
#include <fennec/rtti/detail/_this_t.h>
 
/*
 * This class should resemble the target platform as a whole. By itself, it will represent the OS, i.e. Linux, Windows,
 * etc.
 *
 * We want everything to be type agnostic from the top level down
 *
 * The general structure is:
 * Platform -> Display Protocol -> GFX Context    -> GFX API
 *                              -> Window         -> GFX Surface
 *                              -> Input Protocol
 *
 * For example, let's say we are on Linux, using Wayland and OpenGL with EGL
 * EGL will know that we are using OpenGL, but won't know we are using Wayland
 * OpenGL won't know or care that Linux, EGL, or Wayland is being used
 * Wayland won't know or care that OpenGL or EGL is being used
 * Linux won't know or care that OpenGL, Wayland, or EGL are in use
 *
 * Why do we want everything to be type agnostic?
 * Let's say someone wants to add a DirectX extension for Windows. They shouldn't have to touch the
 * Windows platform class or Win32 display manager class at all to write the implementation. This
 * allows the extension to remain entirely independent of the engine which allows you to just drop
 * it into your project, and it will work as expected. This should also keep version compatibility
 * issues to the absolute minimum.
 *
 * We can allow this by notifying the platform of all available drivers at startup and give them priorities.
 * Then, the platform will load the highest priority first, only falling back when a driver fails to load or is
 * deemed incompatible for whatever reason.
 *
 *
 */
 
namespace fennec
{
 
class platform : public singleton<platform*> {
public:
    using shared_object = struct shared_object;
    using symbol        = void*;
 
    platform();
    virtual ~platform() = default;
    platform(const platform&) = delete;
 
    // Dynamically linked objects
    virtual shared_object* load_object(const cstring& file)  = 0;
    virtual void           unload_object(shared_object* obj) = 0;
    virtual symbol         find_symbol(shared_object* obj, const cstring& name) = 0;
 
    virtual void initialize(); // Initialize Drivers and Contexts
    virtual void shutdown();   // Close Drivers and Contexts
 
protected:
    unique_ptr<window_manager> wmanager;
 
    FENNEC_RTTI_CLASS_ENABLE() {
    }
};
 
}
 
#endif // FENNEC_PLATFORM_INTERFACE_PLATFORM_H