#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <fstream>
#include <iostream>
#include <sstream>
#include <string>
#include <signal.h>

#define ASSERT(x) if (!(x)) raise(SIGTRAP)
#define GL_CALL(x) GLClearError();\
    x;\
    ASSERT(GLLogCall(#x, __FILE__, __LINE__))

static void GLClearError() {
    while(glGetError() != GL_NO_ERROR);
}

static bool GLLogCall(const char *function_name, const char *file, int line) {
    while(GLenum error = glGetError()) {
        std::cout << "Open GL error lel: (0x" << std::hex << error << "): " << file << ": " << function_name << ":" << std::dec << line << std::endl;
        return false;
    }

    return true;
}

struct ShaderProgramSource {
    std::string vertexSource;
    std::string fragmentSource;
};

static ShaderProgramSource ParseShader(const std::string& path) {
    std::fstream stream(path);
    std::string line;
    std::stringstream ss[2];

    enum {
        VERTEX = 0,
        FRAGMENT = 1,
        NONE = -1
    } mode = NONE;

    while (getline(stream, line)) {
        if(line.find("#shader") != std::string::npos) {
            if(line.find("vertex") != std::string::npos) {
                mode = VERTEX;
            } else if(line.find("fragment") != std::string::npos) {
                mode = FRAGMENT;
            }
        } else {
            ss[(int)mode] << line << "\n";
        }
    }

    return ShaderProgramSource { ss[0].str(), ss[1].str() };
}

static GLuint CompileShader(unsigned int type, std::string &source) {
    GLuint id = glCreateShader(type);
    const char *src = source.c_str();
    glShaderSource(id, 1, &src, nullptr);
    glCompileShader(id);

    int result;
    glGetShaderiv(id, GL_COMPILE_STATUS, &result);

    if(result == GL_FALSE) {
        int len;

        glGetShaderiv(id, GL_INFO_LOG_LENGTH, &len);

        char *val = new char[len];

        glGetShaderInfoLog(id, len, &len, val);

        std::cout << "You dumb fuck " << val;

        glDeleteShader(id);

        return 0;
    }

    return id;
}

static GLuint CreateShader(std::string &vertexShader, std::string &fragmentShader) {
    GLuint program = glCreateProgram();
    GLuint vs = CompileShader(GL_VERTEX_SHADER, vertexShader);
    GLuint fs = CompileShader(GL_FRAGMENT_SHADER, fragmentShader);

    glAttachShader(program, vs);
    glAttachShader(program, fs);

    glLinkProgram(program);
    glValidateProgram(program);

    glDeleteShader(vs);
    glDeleteShader(fs);

    return program;
}

int main(void)
{
    GLFWwindow* window;

    /* Initialize the library */
    if (!glfwInit())
        return -1;

    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    /* Create a windowed mode window and its OpenGL context */
    window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
    if (!window)
    {
        glfwTerminate();
        return -1;
    }

    /* Make the window's context current */
    glfwMakeContextCurrent(window);

    if (glewInit() != GLEW_OK) {
        std::cout << "Ure fucked\n";
    }

    std::cout << glGetString(GL_VERSION) << std::endl;

    float positions[] = {
        -0.5f, -0.5f,
         0.5f, -0.5f,
         0.5f,  0.5f,
        -0.5F,  0.5f
    };

    unsigned int indicies[] = {
        0, 1, 2,
        2, 3, 0
    };

    GLuint vao;
    GL_CALL(glGenVertexArrays(1, &vao));
    GL_CALL(glBindVertexArray(vao));

    GLuint buffer;
    glGenBuffers(1, &buffer);
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, 4 * 2 * sizeof(float), positions, GL_STATIC_DRAW);

    GL_CALL(glEnableVertexAttribArray(0));
    GL_CALL(glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0));

    GLuint index_buffer_object;

    glGenBuffers(1, &index_buffer_object);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer_object);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, 6 * sizeof(unsigned int), indicies, GL_STATIC_DRAW);

    glBindBuffer(GL_ARRAY_BUFFER, 0);

    ShaderProgramSource source = ParseShader("../res/shaders/Basic.shader");

    GLuint shader = CreateShader(source.vertexSource, source.fragmentSource);
    glUseProgram(shader);

    GLuint location = glGetUniformLocation(shader, "u_Color");
    ASSERT(location != -1);

    glUniform4f(location, 0.2f, 0.3f, 1.0f, 1.0f);

    /* Loop until the user closes the window */
    while (!glfwWindowShouldClose(window))
    {
        /* Render here */

        /* Swap front and back buffers */
        glfwSwapBuffers(window);

        //glDrawArrays(GL_TRIANGLES, 0, 3);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr);

        /* Poll for and process events */
        glfwPollEvents();
    }

    glDeleteProgram(shader);

    glfwTerminate();
    return 0;
}