#ifndef TERMG_PRIVATE_H
#define TERMG_PRIVATE_H

#include "glerminal.h"

#include <stb_image.h>
#include <glad/glad.h>
#include <GLFW/glfw3.h>

#include <fstream>
#include <stdexcept>

namespace glerminal
{
	constexpr unsigned int SCREEN_WIDTH = 1280;
	constexpr unsigned int SCREEN_HEIGHT = 800;
	constexpr unsigned int CELL_SIZE = 8;
	constexpr unsigned int CELL_SCALE = 4;
	constexpr unsigned int LAYER_COUNT = 256;
	constexpr unsigned int GRID_WIDTH = SCREEN_WIDTH / (CELL_SIZE * CELL_SCALE);
	constexpr unsigned int GRID_HEIGHT = SCREEN_HEIGHT / (CELL_SIZE * CELL_SCALE);
	constexpr unsigned int GRID_AREA = GRID_WIDTH * GRID_HEIGHT;

	class glerminal
	{
	public:
		glerminal(glerminal_init_cb init, glerminal_main_cb main);
		~glerminal();

		glerminal(const glerminal&) = delete;
		glerminal(glerminal&&) = delete;

		glerminal& operator=(const glerminal&) = delete;
		glerminal& operator=(glerminal&&) = delete;

		void run();

		void flush();

		void set(unsigned char x, unsigned char y, unsigned char layer, unsigned char sprite);
		unsigned char get(unsigned char x, unsigned char y, unsigned char layer) const;
		void offset(unsigned char x, unsigned char y, unsigned char layer, float x_offset, float y_offset);
		void layer_color(unsigned char layer, unsigned int color);
		void layer_scale(unsigned char layer, float scale);
		void load_atlas(unsigned char w, unsigned char h, const unsigned int* data);

	private:
		// glfw data

		GLFWwindow* m_window;

		// opengl handles

		unsigned int m_vbo;
		unsigned int m_sprites_instance_vbo;
		unsigned int m_offsets_instance_vbo;
		unsigned int m_vao;
		unsigned int m_screen_vao;
		unsigned int m_program;
		unsigned int m_screen_program;
		unsigned int m_sprites_texture;
		unsigned int m_framebuffer;
		unsigned int m_framebuffer_backing_texture;
		unsigned int m_layer_colors_buffer;
		unsigned int m_layer_scales_buffer;
		unsigned int m_screen_size_uniform_location;
		unsigned int m_palette_uniform_location;

		// per-cell data

		unsigned char m_cells[GRID_AREA * LAYER_COUNT];
		float m_offsets[GRID_AREA * LAYER_COUNT * 2];

		// per-layer data

		float m_layer_colors[LAYER_COUNT * 4];
		float m_layer_scales[LAYER_COUNT];

		// library state

		unsigned int m_sprites[CELL_SIZE * CELL_SIZE * (1 << (8 * sizeof(*m_cells)))];
		glerminal_main_cb m_main;

#ifdef _DEBUG
		mutable std::ofstream m_log;
		void log(GLenum type, GLuint id, GLenum severity, const char* message) const;
#endif

		void init_glfw();
		void init_gl();

		void deinit_glfw();
		void deinit_gl();

		void update_sprites();
		void update_layer_colors();
		void update_layer_scales();
	};
}

#endif//TERMG_PRIVATE_H