#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 <learnopengl/shader_m.h>
#include <learnopengl/camera.h>

#include <iostream>

void framebuffer_size_callback(GLFWwindow* window, int width, int height);
// void mouse_callback(GLFWwindow* window, double xpos, double ypos);
// void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void processInput(GLFWwindow *window);

// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;

// camera
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
float lastX = SCR_WIDTH / 2.0f;
float lastY = SCR_HEIGHT / 2.0f;
bool firstMouse = true;

// // timing
// float deltaTime = 0.0f;	
// float lastFrame = 0.0f;

// lighting
glm::vec3 lightPos(1.2f, 1.0f, 2.0f);

struct Vertex {
    // position
    float Position[3];
    // normal
    float Normal[3];
    // texCoords
    float TexCoords[2];
};

struct BlobHeader {
    uint32_t numVertices;
    uint32_t numIndices;
};


int main()
{
    // glfw: initialize and configure
    // ------------------------------
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

#ifdef __APPLE__
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif

    // glfw window creation
    // --------------------
    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "See through walls", NULL, NULL);
    if (window == NULL)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
    // glfwSetCursorPosCallback(window, mouse_callback);
    // glfwSetScrollCallback(window, scroll_callback);

    // tell GLFW to capture our mouse
    //glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

    // glad: load all OpenGL function pointers
    // ---------------------------------------
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    // configure global opengl state
    // -----------------------------
    glEnable(GL_DEPTH_TEST);

    // build and compile our shader zprogram
    // ------------------------------------
    Shader lightingShader("basic_lighting.vs", "basic_lighting.fs");
    // Shader lightCubeShader("2.1.light_cube.vs", "2.1.light_cube.fs");

    // set up vertex data (and buffer(s)) and configure vertex attributes
    // ------------------------------------------------------------------

    std::vector<Vertex> vertices;
    std::vector<unsigned int> indices;
    BlobHeader hdr;
    {
        FILE* fp = fopen("data.bin", "rb");
        if (!fp) {
            std::cerr << "Failed to open data.bin" << std::endl;
            return -1;
        }

        if (fread(&hdr, sizeof(BlobHeader), 1, fp) != 1) {
            std::cerr << "Failed to read data.bin" << std::endl;
            return -1;
        }

        vertices.resize(hdr.numVertices);
        indices.resize(hdr.numIndices);

        if (fread(const_cast<Vertex*>(vertices.data()), sizeof(Vertex), hdr.numVertices, fp) != hdr.numVertices) {
            std::cerr << "Failed to read data.bin" << std::endl;
            return -1;
        }

        if (fread(const_cast<unsigned int*>(indices.data()), sizeof(unsigned int), hdr.numIndices, fp) != hdr.numIndices) {
            std::cerr << "Failed to read data.bin" << std::endl;
            return -1;
        }

        //printf("Vertices: %zd, Indices: %zd\n", vertices.size(), indices.size());

    }

    // first, configure the cube's VAO (and VBO)
    unsigned int VBO, cubeVAO;
    glGenVertexArrays(1, &cubeVAO);
    glGenBuffers(1, &VBO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * vertices.size(), vertices.data(), GL_STATIC_DRAW);

    glBindVertexArray(cubeVAO);

    // position attribute
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // normal attribute
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);


    // // second, configure the light's VAO (VBO stays the same; the vertices are the same for the light object which is also a 3D cube)
    // unsigned int lightCubeVAO;
    // glGenVertexArrays(1, &lightCubeVAO);
    // glBindVertexArray(lightCubeVAO);

    // glBindBuffer(GL_ARRAY_BUFFER, VBO);
    // // note that we update the lamp's position attribute's stride to reflect the updated buffer data
    // glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
    // glEnableVertexAttribArray(0);


    // render loop
    // -----------
    while (!glfwWindowShouldClose(window))
    {
        // per-frame time logic
        // --------------------
        // float currentFrame = glfwGetTime();
        // deltaTime = currentFrame - lastFrame;
        // lastFrame = currentFrame;

        // input
        // -----
        processInput(window);

        // render
        // ------
        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        // be sure to activate shader when setting uniforms/drawing objects
        lightingShader.use();
        lightingShader.setVec3("objectColor", 1.0f, 0.5f, 0.31f);
        lightingShader.setVec3("lightColor", 1.0f, 1.0f, 1.0f);
        lightingShader.setVec3("lightPos", lightPos);

        // view/projection transformations
        glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
        glm::mat4 view = camera.GetViewMatrix();
        lightingShader.setMat4("projection", projection);
        lightingShader.setMat4("view", view);

        // world transformation
        glm::mat4 model = glm::mat4(1.0f);
        lightingShader.setMat4("model", model);

        // render the cube
        glBindVertexArray(cubeVAO);
        glDrawElements(GL_TRIANGLES, indices.size(), GL_UNSIGNED_INT, indices.data());
        //glDrawArrays(GL_TRIANGLES, 0, 36);


        //// also draw the lamp object
        //lightCubeShader.use();
        //lightCubeShader.setMat4("projection", projection);
        //lightCubeShader.setMat4("view", view);
        //model = glm::mat4(1.0f);
        //model = glm::translate(model, lightPos);
        //model = glm::scale(model, glm::vec3(0.2f)); // a smaller cube
        //lightCubeShader.setMat4("model", model);

        //glBindVertexArray(lightCubeVAO);
        //glDrawElements(GL_TRIANGLES, vertices.size(), GL_UNSIGNED_INT, indices.data());
        //glDrawArrays(GL_TRIANGLES, 0, 36);


        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
        // -------------------------------------------------------------------------------
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    // optional: de-allocate all resources once they've outlived their purpose:
    // ------------------------------------------------------------------------
    glDeleteVertexArrays(1, &cubeVAO);
    // glDeleteVertexArrays(1, &lightCubeVAO);
    glDeleteBuffers(1, &VBO);

    // glfw: terminate, clearing all previously allocated GLFW resources.
    // ------------------------------------------------------------------
    glfwTerminate();
    return 0;
}

// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);

    // if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
    //     camera.ProcessKeyboard(FORWARD, deltaTime);
    // if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
    //     camera.ProcessKeyboard(BACKWARD, deltaTime);
    // if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
    //     camera.ProcessKeyboard(LEFT, deltaTime);
    // if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
    //     camera.ProcessKeyboard(RIGHT, deltaTime);
}

// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
    // make sure the viewport matches the new window dimensions; note that width and 
    // height will be significantly larger than specified on retina displays.
    glViewport(0, 0, width, height);
}


// // glfw: whenever the mouse moves, this callback is called
// // -------------------------------------------------------
// void mouse_callback(GLFWwindow* window, double xpos, double ypos)
// {
//     if (firstMouse)
//     {
//         lastX = xpos;
//         lastY = ypos;
//         firstMouse = false;
//     }

//     float xoffset = xpos - lastX;
//     float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top

//     lastX = xpos;
//     lastY = ypos;

//     camera.ProcessMouseMovement(xoffset, yoffset);
// }

// // glfw: whenever the mouse scroll wheel scrolls, this callback is called
// // ----------------------------------------------------------------------
// void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
// {
//     camera.ProcessMouseScroll(yoffset);
// }