#include <iostream>

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

#include <engine/mesh.h>
#include <engine/shader.h>
#include <engine/texture.h>

const int SCREEN_WIDTH = 1920;
const int SCREEN_HEIGHT = 1080;

static bool drawWireframe = false;
static bool wireframeHeld = false;

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

void processInput(GLFWwindow* window)
{
    // Close on Escape
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);

    // Wireframe toggle
    if (glfwGetKey(window, GLFW_KEY_F1) == GLFW_PRESS && !wireframeHeld)
    {
        wireframeHeld = true;
        drawWireframe = !drawWireframe;
        if (drawWireframe)
        {
            glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
        }
        else
        {
            glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
        }
    }
    if (glfwGetKey(window, GLFW_KEY_F1) == GLFW_RELEASE)
        wireframeHeld = false;
}

int main(int argc, char* argv[])
{
    // Initialize GLFW
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    // Create GLFW Window
    GLFWwindow* window = glfwCreateWindow(SCREEN_WIDTH, SCREEN_HEIGHT, "Renderer", NULL, NULL);
    if (window == NULL)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

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

    // Initialize Viewport & setup resize callback
    glViewport(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
    glfwSetFramebufferSizeCallback(window, window_resize_callback);

    // Load Shader
    Shader shaderTest("assets/shaders/basicVertex.vert", "assets/shaders/basicFragment.frag");
    std::vector<Vertex> vertices = {
        {  1,  0.5f, 0.0f,   1.0f, 0.0f, 0.0f,   1.0f, 1.0f },
        {  1, -0.5f, 0.0f,   0.0f, 1.0f, 0.0f,   1.0f, 0.0f },
        {  0, -0.5f, 0.0f,   0.0f, 0.0f, 1.0f,   0.0f, 0.0f },
        {  0,  0.5f, 0.0f,   1.0f, 1.0f, 0.0f,   0.0f, 1.0f }
    };
    std::vector<unsigned int> indices = {
        0, 1, 3,
        1, 2, 3
    };

    Mesh testMesh(vertices, indices);


    std::vector<Vertex> vertices2 = {
        {  0,  0.5f, 0.0f,   1.0f, 0.0f, 0.0f,   0.6f, 1.0f },
        {  0, -0.5f, 0.0f,   0.0f, 1.0f, 0.0f,   1.0f, 0.0f },
        {  -1, -0.5f, 0.0f,   0.0f, 0.0f, 1.0f,   0.0f, 0.0f },
        {  -1,  0.5f, 0.0f,   1.0f, 1.0f, 0.0f,   0.0f, 1.0f }
    };

    Mesh testMesh2(vertices2, indices);

    Texture texture1("assets/wall.jpg");
    Texture texture2("assets/awesomeface.png", true);

    shaderTest.Use(); // don't forget to activate/use the shader before setting uniforms!
    shaderTest.setInt("ourTexture", 0);
    shaderTest.setInt("decal", 1);

    // Render Loop
    while (!glfwWindowShouldClose(window))
    {
        // Input processing
        processInput(window);

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

        shaderTest.Use();

        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, texture1.ID);
        glActiveTexture(GL_TEXTURE1);
        glBindTexture(GL_TEXTURE_2D, texture2.ID);

        testMesh.Draw();
        testMesh2.Draw();

        // Call events & swap buffers
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    // Clean up memory
    glfwTerminate();
    return 0;
}