//	Voxspatium Engine - Voxel Planets Engine
//	Copyright (C) 2018  Evert "Diamond" Prants <evert@lunasqu.ee>
//
//	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/>.

#include "Application.h"
#include "util/Log.h"
#include "Shader.h"

Application::Application() : m_width(1080), m_height(720)
{

}

Application::~Application()
{

}

void Application::initialize()
{
	if (SDL_Init(SDL_INIT_VIDEO) < 0)
	{
		printf("SDL could not initialize! SDL_Error: %s\n", SDL_GetError());
		return;
	}

	// Create our window centered at 1080x720 resolution
	m_window = SDL_CreateWindow(
		"Voxspatium Engine", 
		SDL_WINDOWPOS_CENTERED,
		SDL_WINDOWPOS_CENTERED,
		m_width,
		m_height,
		SDL_WINDOW_OPENGL
	);

	if (!m_window)
	{
		printf("Window could not be created! SDL_Error: %s\n", SDL_GetError());
		return;
	}

	// Set GL Attributes
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);

	m_glContext = SDL_GL_CreateContext(m_window);

	if(m_glContext == NULL)
	{
		printf("OpenGL context could not be created! SDL Error: %s\n", SDL_GetError());
		return;
	}

	SDL_GL_MakeCurrent(m_window, m_glContext);

	// Initialize GLEW
	glewInit();

	// Create camera
	m_camera = new Camera(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f), 90.0f, 0.0f);

	// Run the engine
	run();
}

void Application::handleEvents()
{
	/* Update the input manager */
	Input::getInstance().flush();

	/* Check for events */
	SDL_Event e;
	while ( SDL_PollEvent(&e) ) 
	{
		switch(e.type)
		{
			case SDL_QUIT:
				exit();
				break;
			case SDL_KEYDOWN:
				Input::getInstance().pressKey(e.key.keysym.sym);
				break;
			case SDL_KEYUP:
				Input::getInstance().releaseKey(e.key.keysym.sym);
				break;
			case SDL_MOUSEMOTION:
				Input::getInstance().setMouseCoords(e.motion.x, e.motion.y);
				break;
			case SDL_MOUSEBUTTONDOWN:
				Input::getInstance().pressKey(e.button.button);
				break;
			case SDL_MOUSEBUTTONUP:
				Input::getInstance().releaseKey(e.button.button);
				break;
			case SDL_MOUSEWHEEL:
				Input::getInstance().setMouseWheel(e.wheel.y, e.wheel.x);
				break;
		}
	}

	glm::vec2 mousepos = Input::getInstance().getMouseCoords();	
	// Force mouse to the center of the screen
	SDL_SetWindowGrab(m_window, SDL_TRUE);
	SDL_WarpMouseInWindow(m_window, m_width/2, m_height/2);

	// Handle Camera Movement
	m_camera->processMouseMovement(-(m_width/2 - mousepos.x), m_height/2 - mousepos.y, GL_TRUE);

	// Handle Camera Movement Keys
	if(Input::getInstance().isKeyDown(SDLK_w))
		m_camera->processKeyboard(Camera_Movement::FORWARD, 0.01f);

	if(Input::getInstance().isKeyDown(SDLK_s))
		m_camera->processKeyboard(Camera_Movement::BACKWARD, 0.01f);

	if(Input::getInstance().isKeyDown(SDLK_d))
		m_camera->processKeyboard(Camera_Movement::RIGHT, 0.01f);

	if(Input::getInstance().isKeyDown(SDLK_a))
		m_camera->processKeyboard(Camera_Movement::LEFT, 0.01f);

	// Handle Camera Zoom
	m_camera->processMouseScroll((float) Input::getInstance().getMouseWheelVertical() / 10.0f);

	// Print mouse position on click
	if(Input::getInstance().isKeyPressed(SDL_BUTTON_LEFT))
		std::cout << "mX: " << mousepos.x << " mY: " << mousepos.y << std::endl;

	// Exit game on Esc
	if(Input::getInstance().isKeyPressed(SDLK_ESCAPE))
		exit();
}


void Application::run()
{
	m_run = true;
	m_now = SDL_GetPerformanceCounter();
	m_last = 0;

	// TEST CODE
	SDL_ShowCursor(SDL_DISABLE);
	Input::getInstance().setMouseCoords(m_width/2, m_height/2);

	static const GLfloat vertices[] = {
		-1.0f,-1.0f,-1.0f,      0.0f, 1.0f, 1.0f, // triangle 1 : begin
		-1.0f,-1.0f, 1.0f,      0.0f, 1.0f, 1.0f,
		-1.0f, 1.0f, 1.0f,      0.0f, 1.0f, 1.0f, // triangle 1 : end
		1.0f, 1.0f,-1.0f,       1.0f, 1.0f, 0.0f, // triangle 2 : begin
		-1.0f,-1.0f,-1.0f,      1.0f, 1.0f, 0.0f,
		-1.0f, 1.0f,-1.0f,      1.0f, 1.0f, 0.0f, // triangle 2 : end
		1.0f,-1.0f, 1.0f,       1.0f, 0.0f, 1.0f,
		-1.0f,-1.0f,-1.0f,      1.0f, 0.0f, 1.0f,
		1.0f,-1.0f,-1.0f,       1.0f, 0.0f, 1.0f,
		1.0f, 1.0f,-1.0f,       1.0f, 1.0f, 0.0f,
		1.0f,-1.0f,-1.0f,       1.0f, 1.0f, 0.0f,
		-1.0f,-1.0f,-1.0f,      1.0f, 1.0f, 0.0f,
		-1.0f,-1.0f,-1.0f,      0.0f, 1.0f, 1.0f,
		-1.0f, 1.0f, 1.0f,      0.0f, 1.0f, 1.0f,
		-1.0f, 1.0f,-1.0f,      0.0f, 1.0f, 1.0f,
		1.0f,-1.0f, 1.0f,       1.0f, 0.0f, 1.0f,
		-1.0f,-1.0f, 1.0f,      1.0f, 0.0f, 1.0f,
		-1.0f,-1.0f,-1.0f,      1.0f, 0.0f, 1.0f,
		-1.0f, 1.0f, 1.0f,      0.0f, 0.0f, 1.0f,
		-1.0f,-1.0f, 1.0f,      0.0f, 0.0f, 1.0f,
		1.0f,-1.0f, 1.0f,       0.0f, 0.0f, 1.0f,
		1.0f, 1.0f, 1.0f,       1.0f, 0.0f, 0.0f,
		1.0f,-1.0f,-1.0f,       1.0f, 0.0f, 0.0f,
		1.0f, 1.0f,-1.0f,       1.0f, 0.0f, 0.0f,
		1.0f,-1.0f,-1.0f,       1.0f, 0.0f, 0.0f,
		1.0f, 1.0f, 1.0f,       1.0f, 0.0f, 0.0f,
		1.0f,-1.0f, 1.0f,       1.0f, 0.0f, 0.0f,
		1.0f, 1.0f, 1.0f,       0.0f, 1.0f, 0.0f,
		1.0f, 1.0f,-1.0f,       0.0f, 1.0f, 0.0f,
		-1.0f, 1.0f,-1.0f,      0.0f, 1.0f, 0.0f,
		1.0f, 1.0f, 1.0f,       0.0f, 1.0f, 0.0f,
		-1.0f, 1.0f,-1.0f,      0.0f, 1.0f, 0.0f,
		-1.0f, 1.0f, 1.0f,      0.0f, 1.0f, 0.0f,
		1.0f, 1.0f, 1.0f,       0.0f, 0.0f, 1.0f,
		-1.0f, 1.0f, 1.0f,      0.0f, 0.0f, 1.0f,
		1.0f,-1.0f, 1.0f,       0.0f, 0.0f, 1.0f
	};

	GLuint vertexArray, vertexBuffer;

	// Create VAO
	glGenVertexArrays(1, &vertexArray);
	glBindVertexArray(vertexArray);

	// Generate 1 buffer, put the resulting identifier in vertexBuffer
	glGenBuffers(1, &vertexBuffer);
	// The following commands will talk about our 'vertexBuffer' buffer
	glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
	// Give our vertices to OpenGL.
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

	// Create the shader and link them together
	Shader& skyboxShader = Shader::createShader("data/shaders/skybox.vert", "data/shaders/skybox.frag");
	skyboxShader.linkShaders();

	// Give the buffers to the shader
	skyboxShader.setBuffers(vertexArray, vertexBuffer, 0);

	// Set attribute arrays
	skyboxShader.setAttribute("position", 3, GL_FALSE, 6, 0, GL_FLOAT);
	skyboxShader.setAttribute("color", 3, GL_FALSE, 6, 3, GL_FLOAT);

	glEnable(GL_DEPTH_TEST);

	// END TEST CODE

	while(m_run)
	{
		m_last = m_now;
		m_now = SDL_GetPerformanceCounter();

		handleEvents();

		// Clear color buffer
		glClearColor(0.39f, 0.58f, 0.93f, 1.f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		deltaTime = ((m_now - m_last) / (double)SDL_GetPerformanceFrequency());

		// TEST CODE

		glm::vec3 cameraPos = m_camera->getPosition();

		glm::mat4 model = glm::scale(glm::translate(glm::mat4(1.0f), cameraPos), glm::vec3(50.0f, 50.0f, 50.0f));
		skyboxShader.use();
		skyboxShader.setUniform("modelMatrix", model);
		m_camera->shaderViewProjection(skyboxShader); // Load view and projection matrices

		glDrawArrays(GL_TRIANGLES, 0, 12*3); // 12*3 indices starting at 0 -> 12 triangles -> 6 squares

		// END TEST CODE

		update(deltaTime);
		render();
		
		// Update window with OpenGL rendering
		SDL_GL_SwapWindow(m_window);
	}

	// After loop exits

	// Destroy window
	SDL_DestroyWindow(m_window);
	m_window = NULL;

	// Destroy context
	SDL_GL_DeleteContext(m_glContext);

	// Quit SDL subsystems
	SDL_Quit();
}

void Application::update(GLfloat dtime)
{

}

void Application::render()
{

}