// Copyright (c) 2022 Dominic Masters
// 
// This software is released under the MIT License.
// https://opensource.org/licenses/MIT

#pragma once
#include "RenderTarget.hpp"
#include "display/shader/Shader.hpp"
#include "display/shader/UIShader.hpp"
#include "util/flag.hpp"

#define RENDER_MANAGER_RENDER_FLAG_DEPTH_TEST FLAG_DEFINE(0)
#define RENDER_MANAGER_RENDER_FLAG_BLEND FLAG_DEFINE(1)

typedef flag_t renderflag_t;

namespace Dawn {
  class DawnGame;
  class RenderPipeline;

  class IRenderManager {
    protected:
      renderflag_t renderFlags = 0;

    public:
      DawnGame *game;
      RenderPipeline *renderPipeline;

      /**
       * Default constructor for a render manager instance.
       * 
       * @param game Game that this render manager belongs to.
       */
      IRenderManager(DawnGame *game) {
        assertNotNull(game);
        this->game = game;
      }

      /**
       * Returns the primary render target (the backbuffer) that draws directly
       * to the screen.
       * 
       * @return Shared pointer to the backbuffer render target.
       */
      virtual RenderTarget * getBackBuffer() = 0;

      /**
       * Returns the current render pipeline intended to be used for rendering
       * the currently active scene on the game instance.
       * 
       * @return Reference to the currently active main scene render pipeline.
       */
      virtual RenderPipeline * getRenderPipeline() = 0;

      /**
       * Returns the default shader, the default shader will be applied to the
       * materials first.
       * 
       * @return Reference to the default shader.
       */
      virtual Shader * getDefaultShader() = 0;

      /**
       * Returns the UI Shader used by the game's UI engine.
       * 
       * @return Pointer to the UI Shader.
       */
      virtual UIShader * getUIShader() = 0;
      
      /**
       * Sets the render flags for the render manager to use.
       * 
       * @param renderFlags Render flags to use.
       */
      virtual void setRenderFlags(renderflag_t renderFlags) = 0;

      /**
       * Initialize / Start the Render Manager.
       * 
       * @param game Game instance this render manager belongs to.
       */
      virtual void init() = 0;

      /**
       * Perform a synchronous frame update on the render manager.
       */
      virtual void update() = 0;
  };
}