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

#include "input.h"

#include <iostream>

const char *vertexShaderSource = R"(
#version 330 core
layout (location = 0) in vec3 aPos;

void main()
{
    gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);
}
)";
const char *fragmentShaderSource = R"(
#version 330 core
out vec4 FragColor;

void main()
{
    FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);
} 
)";

float vertices[] = {
     0.5f,  0.5f, 0.0f,  // top right
     0.5f, -0.5f, 0.0f,  // bottom right
    -0.5f, -0.5f, 0.0f,  // bottom left
    -0.5f,  0.5f, 0.0f   // top left 
};
unsigned int indices[] = {  // note that we start from 0!
    0, 1, 3,   // first triangle
    1, 2, 3    // second triangle
};  

void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
	glViewport(0, 0, width, height);
}

int main() {
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); // 4.6 is highest
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

	GLFWwindow* window = glfwCreateWindow(800, 600, "Ogle", NULL, NULL);
	if (window == NULL)
	{
		std::cout << "Failed to create GLFW window" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);

	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{
		std::cout << "Failed to init GLAD" << std::endl;
		return -1;
	}

	glViewport(0, 0, 800, 600);

	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

	unsigned int vertexShader;
	vertexShader = glCreateShader(GL_VERTEX_SHADER); // create a blank shader
	glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
	glCompileShader(vertexShader);
	{ // check if shader compiled successfully
		int success;
		char infoLog[512];
		glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
		if(!success)
		{
			glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
			std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
		}
	}

	unsigned int fragmentShader;
	fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
	glCompileShader(fragmentShader);
	{ // check if shader compiled successfully
		int success;
		char infoLog[512];
		glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
		if(!success)
		{
			glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
			std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
		}
	}

	unsigned int shaderProgram;
	shaderProgram = glCreateProgram();
	glAttachShader(shaderProgram, vertexShader);
	glAttachShader(shaderProgram, fragmentShader);
	glLinkProgram(shaderProgram);
	{ // check if shader compiled successfully
		int success;
		char infoLog[512];
		glGetShaderiv(shaderProgram, GL_LINK_STATUS, &success);
		if(!success)
		{
			glGetShaderInfoLog(shaderProgram, 512, NULL, infoLog);
			std::cout << "ERROR::SHADER::PROGRAM::COMPILATION_FAILED\n" << infoLog << std::endl;
		}
	}

	glDeleteShader(vertexShader); // we dont need these anymore once they are linked in the shader program
	glDeleteShader(fragmentShader);

	unsigned int VBO, VAO, EBO;
	glGenBuffers(1, &VBO); // generate the buffer
	glGenBuffers(1, &EBO);

	glGenVertexArrays(1, &VAO); // generate array
	glBindVertexArray(VAO); // bind array to apply "settings" to it
							
	glBindBuffer(GL_ARRAY_BUFFER, VBO); // bind(activate) the buffer to the ARRAY_BUFFER
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); // upload the data
																			   //
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0); // configure how the vertex array looks
	glEnableVertexAttribArray(0);

	glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

	// game loop
	while(!glfwWindowShouldClose(window))
	{
		processInput(window);

		glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT);


		glUseProgram(shaderProgram); // this will activate the shader and use them for all subsequent shader and render calls
		glBindVertexArray(VAO); // activate the preconfigured settings
		glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0); // :)
		glBindVertexArray(0);

		glfwSwapBuffers(window);
		glfwPollEvents();
	}

	glfwTerminate();
	return 0;
}