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

#include "stb_image.h"
#include "shader.h"
#include "Camera.h"

#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

#include <iostream>

void framebuffer_size_callback(GLFWwindow* window, int width, int height);
static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);


// 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(0.5f, 0.5f, 2.0f);

int main() {
    // glfw: initialize and configure
    // ------------------------------
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    
#ifdef __APPLE__
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // uncomment this statement to fix compilation on OS X
#endif
    
    // glfw window creation
    // --------------------
    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", nullptr, nullptr);
    if (window == nullptr) {
        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);
    glfwSetKeyCallback(window, key_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("4.0.shader.vs", "4.0.shader.fs");
    Shader lampShader("4.0.lamp.vs", "4.0.lamp.fs");
    
    // set up vertex data (and buffer(s)) and configure vertex attributes
    // ------------------------------------------------------------------
    float vertices[] = {
        -0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
        0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
        0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
        0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
        -0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,
        
        -0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,
        0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,
        0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,
        0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,
        -0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,
        -0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,
        
        -0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,
        -0.5f,  0.5f, -0.5f, -1.0f,  0.0f,  0.0f,
        -0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,
        -0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,
        -0.5f, -0.5f,  0.5f, -1.0f,  0.0f,  0.0f,
        -0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,
        
        0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,
        0.5f,  0.5f, -0.5f,  1.0f,  0.0f,  0.0f,
        0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,
        0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,
        0.5f, -0.5f,  0.5f,  1.0f,  0.0f,  0.0f,
        0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,
        
        -0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,
        0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,
        0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,
        0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,
        -0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,
        
        -0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,
        0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,
        0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,
        0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,
        -0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,
        -0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f
    };
    
    // 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(vertices), vertices, GL_STATIC_DRAW);
    
    glBindVertexArray(cubeVAO);
    
    // position attribute
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // normal attribute
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * 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 lightVAO;
    glGenVertexArrays(1, &lightVAO);
    glBindVertexArray(lightVAO);
    
    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)) {

        float currentFrame = glfwGetTime();
        deltaTime = currentFrame - lastFrame;
        lastFrame = currentFrame;
        
        // 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("light.position", lightPos);
        lightingShader.setVec3("viewPos", camera.Position);
        
        // light properties
        glm::vec3 lightColor;
        lightColor.x = sin(glfwGetTime() * 2.0f);
        lightColor.y = sin(glfwGetTime() * 0.7f);
        lightColor.z = sin(glfwGetTime() * 1.3f);
        glm::vec3 diffuseColor = lightColor   * glm::vec3(0.5f); // decrease the influence
        glm::vec3 ambientColor = diffuseColor * glm::vec3(0.2f); // low influence
        lightingShader.setVec3("light.ambient", ambientColor);
        lightingShader.setVec3("light.diffuse", diffuseColor);
        lightingShader.setVec3("light.specular", 1.0f, 1.0f, 1.0f);
        
        ///////////////////////////////////////

        // material properties
        // bronze
        lightingShader.setVec3("material.ambient", 0.2125f, 0.1275f, 0.054f);
        lightingShader.setVec3("material.diffuse", 0.714f,    0.4284f,    0.18144f);
        lightingShader.setVec3("material.specular", 0.393548f,    0.271906f,    0.166721f); // specular lighting doesn't have full effect on this object's material
        lightingShader.setFloat("material.shininess", 64.0f);
        
        // (smaragd)emerald
        // lightingShader.setVec3("material.ambient", 0.0215f,    0.1745f,    0.0215f);
        // lightingShader.setVec3("material.diffuse", 0.07568f,    0.61424f,    0.07568f);
        // lightingShader.setVec3("material.specular", 0.633f,    0.727811f,    0.633f); // specular lighting doesn't have full effect on this object's material
        // lightingShader.setFloat("material.shininess", 192);
        
        //green rubber
        // lightingShader.setVec3("material.ambient", 0.0f,    0.05f,    0.0f);
        // lightingShader.setVec3("material.diffuse", 0.4f,    0.5f,    0.4f);
        // lightingShader.setVec3("material.specular", 0.04f,    0.7f,    0.04f); // specular lighting doesn't have full effect on this object's material
        // lightingShader.setFloat("material.shininess", 8);
        
        ///////////////////////////////////////
        
        // 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);
        glDrawArrays(GL_TRIANGLES, 0, 36);
        
        // also draw the lamp object
        lampShader.use();
        lampShader.setMat4("projection", projection);
        lampShader.setMat4("view", view);
        model = glm::mat4(1.0f);
        model = glm::translate(model, lightPos);
        model = glm::scale(model, glm::vec3(0.2f)); // a smaller cube
        lampShader.setMat4("model", model);
        
        glBindVertexArray(lightVAO);
        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, &lightVAO);
    glDeleteBuffers(1, &VBO);
    
    // glfw: terminate, clearing all previously allocated GLFW resources.
    // ------------------------------------------------------------------
    glfwTerminate();
    return 0;
}


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);
}

static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) {
    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);
}

// FPS like kamera mozgas
// 1) Calculate the mouse's offset since the last frame.
// 2) Add the offset values to the camera's yaw and pitch values.
// 3) Add some constraints to the maximum/minimum pitch values
// 4) Calculate the direction vector

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);
}

// zooming
// amikor a fov kisebb lesz akkor a projektalt space is kisebb lesz ami olyan hatast kelt mintha zoom olnank
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset) {
    camera.ProcessMouseScroll(yoffset);
}