#include <iostream>
#include <cmath>

// GLEW
#define GLEW_STATIC
#include <GL/glew.h>

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

// Other Libs
#include <SOIL.h>
// GLM Mathematics
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

// Other includes
#include <learnopengl/shader.h>
#include <learnopengl/camera.h>
#include <learnopengl/filesystem.h>

// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void do_movement();

// Window dimensions
const GLuint WIDTH = 800, HEIGHT = 600;

// Camera
Camera  camera(glm::vec3(0.0f, 0.0f, 3.0f));
GLfloat lastX  =  WIDTH  / 2.0;
GLfloat lastY  =  HEIGHT / 2.0;
bool    keys[1024];

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

// Deltatime
GLfloat deltaTime = 0.0f;	// Time between current frame and last frame
GLfloat lastFrame = 0.0f;  	// Time of last frame

// The MAIN function, from here we start the application and run the game loop
int main()
{
    // Init GLFW
    glfwInit();
    // Set all the required options for GLFW
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

    // Create a GLFWwindow object that we can use for GLFW's functions
    GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr);
    glfwMakeContextCurrent(window);

    // Set the required callback functions
    glfwSetKeyCallback(window, key_callback);
    glfwSetCursorPosCallback(window, mouse_callback);
    glfwSetScrollCallback(window, scroll_callback);

    // GLFW Options
    glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

    // Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensions
    glewExperimental = GL_TRUE;
    // Initialize GLEW to setup the OpenGL Function pointers
    glewInit();

    // Define the viewport dimensions
    glViewport(0, 0, WIDTH, HEIGHT);

    // OpenGL options
    glEnable(GL_DEPTH_TEST);


    // Build and compile our shader program
    Shader lightingShader("light_casters.vs", "light_casters.frag");
    Shader lampShader("lamp.vs", "lamp.frag");

    // Set up vertex data (and buffer(s)) and attribute pointers
    GLfloat vertices[] = {
        // Positions          // Normals           // Texture Coords
        -0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  0.0f,
         0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  0.0f,
         0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  1.0f,
         0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  1.0f,  1.0f,
        -0.5f,  0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f,  0.0f, -1.0f,  0.0f,  0.0f,

        -0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  0.0f,
         0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  0.0f,
         0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  1.0f,
         0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  1.0f,  1.0f,
        -0.5f,  0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  1.0f,
        -0.5f, -0.5f,  0.5f,  0.0f,  0.0f,  1.0f,  0.0f,  0.0f,

        -0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  0.0f,
        -0.5f,  0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  1.0f,
        -0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  1.0f,
        -0.5f, -0.5f, -0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  1.0f,
        -0.5f, -0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  0.0f,  0.0f,
        -0.5f,  0.5f,  0.5f, -1.0f,  0.0f,  0.0f,  1.0f,  0.0f,

         0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  0.0f,
         0.5f,  0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  1.0f,
         0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  1.0f,
         0.5f, -0.5f, -0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  1.0f,
         0.5f, -0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  0.0f,  0.0f,
         0.5f,  0.5f,  0.5f,  1.0f,  0.0f,  0.0f,  1.0f,  0.0f,

        -0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  1.0f,
         0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  1.0f,
         0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  0.0f,
         0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  1.0f,  0.0f,
        -0.5f, -0.5f,  0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  0.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, -1.0f,  0.0f,  0.0f,  1.0f,

        -0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  1.0f,
         0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  1.0f,
         0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  0.0f,
         0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  1.0f,  0.0f,
        -0.5f,  0.5f,  0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  0.0f,
        -0.5f,  0.5f, -0.5f,  0.0f,  1.0f,  0.0f,  0.0f,  1.0f
    };
    // Positions all containers
    glm::vec3 cubePositions[] = {
        glm::vec3( 0.0f,  0.0f,  0.0f),
        glm::vec3( 2.0f,  5.0f, -15.0f),
        glm::vec3(-1.5f, -2.2f, -2.5f),
        glm::vec3(-3.8f, -2.0f, -12.3f),
        glm::vec3( 2.4f, -0.4f, -3.5f),
        glm::vec3(-1.7f,  3.0f, -7.5f),
        glm::vec3( 1.3f, -2.0f, -2.5f),
        glm::vec3( 1.5f,  2.0f, -2.5f),
        glm::vec3( 1.5f,  0.2f, -1.5f),
        glm::vec3(-1.3f,  1.0f, -1.5f)
    };
    // First, set the container's VAO (and VBO)
    GLuint VBO, containerVAO;
    glGenVertexArrays(1, &containerVAO);
    glGenBuffers(1, &VBO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    glBindVertexArray(containerVAO);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(6 * sizeof(GLfloat)));
    glEnableVertexAttribArray(2);
    glBindVertexArray(0);

    // Then, we set the light's VAO (VBO stays the same. After all, the vertices are the same for the light object (also a 3D cube))
    GLuint lightVAO;
    glGenVertexArrays(1, &lightVAO);
    glBindVertexArray(lightVAO);
    // We only need to bind to the VBO (to link it with glVertexAttribPointer), no need to fill it; the VBO's data already contains all we need.
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    // Set the vertex attributes (only position data for the lamp))
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0); // Note that we skip over the other data in our buffer object (we don't need the normals/textures, only positions).
    glEnableVertexAttribArray(0);
    glBindVertexArray(0);
    

    // Load textures
    GLuint diffuseMap, specularMap, emissionMap;
    glGenTextures(1, &diffuseMap);
    glGenTextures(1, &specularMap);
    glGenTextures(1, &emissionMap);
    int width, height;
    unsigned char* image;
    // Diffuse map
    image = SOIL_load_image(FileSystem::getPath("resources/textures/container2.png").c_str(), &width, &height, 0, SOIL_LOAD_RGB);
    glBindTexture(GL_TEXTURE_2D, diffuseMap);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
    glGenerateMipmap(GL_TEXTURE_2D);
    SOIL_free_image_data(image);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST_MIPMAP_NEAREST);
    // Specular map
    image = SOIL_load_image(FileSystem::getPath("resources/textures/container2_specular.png").c_str(), &width, &height, 0, SOIL_LOAD_RGB);
    glBindTexture(GL_TEXTURE_2D, specularMap);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
    glGenerateMipmap(GL_TEXTURE_2D);
    SOIL_free_image_data(image);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST_MIPMAP_NEAREST);
    glBindTexture(GL_TEXTURE_2D, 0);


    // Set texture units
    lightingShader.Use();
    glUniform1i(glGetUniformLocation(lightingShader.Program, "material.diffuse"),  0);
    glUniform1i(glGetUniformLocation(lightingShader.Program, "material.specular"), 1);


    // Game loop
    while (!glfwWindowShouldClose(window))
    {
        // Calculate deltatime of current frame
        GLfloat currentFrame = glfwGetTime();
        deltaTime = currentFrame - lastFrame;
        lastFrame = currentFrame;

        // Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functions
        glfwPollEvents();
        do_movement();

        // Clear the colorbuffer
        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);


        // Use cooresponding shader when setting uniforms/drawing objects
        lightingShader.Use();
        GLint lightPosLoc             = glGetUniformLocation(lightingShader.Program, "light.position");
        GLint lightSpotdirLoc         = glGetUniformLocation(lightingShader.Program, "light.direction");
        GLint lightSpotCutOffLoc      = glGetUniformLocation(lightingShader.Program, "light.cutOff");        
        GLint lightSpotOuterCutOffLoc = glGetUniformLocation(lightingShader.Program, "light.outerCutOff");
        GLint viewPosLoc              = glGetUniformLocation(lightingShader.Program, "viewPos");
        glUniform3f(lightPosLoc,             camera.Position.x, camera.Position.y, camera.Position.z);
        glUniform3f(lightSpotdirLoc,         camera.Front.x, camera.Front.y, camera.Front.z);
        glUniform1f(lightSpotCutOffLoc,      glm::cos(glm::radians(12.5f)));
        glUniform1f(lightSpotOuterCutOffLoc, glm::cos(glm::radians(17.5f)));
        glUniform3f(viewPosLoc,              camera.Position.x, camera.Position.y, camera.Position.z);
        // Set lights properties
        glUniform3f(glGetUniformLocation(lightingShader.Program, "light.ambient"),   0.1f, 0.1f, 0.1f);
        // We set the diffuse intensity a bit higher; note that the right lighting conditions differ with each lighting method and environment.
        // Each environment and lighting type requires some tweaking of these variables to get the best out of your environment.
        glUniform3f(glGetUniformLocation(lightingShader.Program, "light.diffuse"),   0.8f, 0.8f, 0.8f);
        glUniform3f(glGetUniformLocation(lightingShader.Program, "light.specular"),  1.0f, 1.0f, 1.0f);
        glUniform1f(glGetUniformLocation(lightingShader.Program, "light.constant"),  1.0f);
        glUniform1f(glGetUniformLocation(lightingShader.Program, "light.linear"),    0.09);
        glUniform1f(glGetUniformLocation(lightingShader.Program, "light.quadratic"), 0.032);
        // Set material properties
        glUniform1f(glGetUniformLocation(lightingShader.Program, "material.shininess"), 32.0f);

        // Create camera transformations
        glm::mat4 view;
        view = camera.GetViewMatrix();
        glm::mat4 projection = glm::perspective(camera.Zoom, (GLfloat)WIDTH / (GLfloat)HEIGHT, 0.1f, 100.0f);
        // Get the uniform locations
        GLint modelLoc = glGetUniformLocation(lightingShader.Program, "model");
        GLint viewLoc  = glGetUniformLocation(lightingShader.Program, "view");
        GLint projLoc  = glGetUniformLocation(lightingShader.Program, "projection");
        // Pass the matrices to the shader
        glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
        glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));

        // Bind diffuse map
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, diffuseMap);
        // Bind specular map
        glActiveTexture(GL_TEXTURE1);
        glBindTexture(GL_TEXTURE_2D, specularMap);

        // Draw the container (using container's vertex attributes)
        /*glBindVertexArray(containerVAO);
        glm::mat4 model;
        glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
        glDrawArrays(GL_TRIANGLES, 0, 36);
        glBindVertexArray(0);*/

        // Draw 10 containers with the same VAO and VBO information; only their world space coordinates differ
        glm::mat4 model;
        glBindVertexArray(containerVAO);
        for (GLuint i = 0; i < 10; i++)
        {
            model = glm::mat4();
            model = glm::translate(model, cubePositions[i]);
            GLfloat angle = 20.0f * i;
            model = glm::rotate(model, angle, glm::vec3(1.0f, 0.3f, 0.5f));
            glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));

            glDrawArrays(GL_TRIANGLES, 0, 36);
        }
        glBindVertexArray(0);


        // Again, no need to draw the lamp object
        // Also draw the lamp object, again binding the appropriate shader
        //lampShader.Use();
        //// Get location objects for the matrices on the lamp shader (these could be different on a different shader)
        //modelLoc = glGetUniformLocation(lampShader.Program, "model");
        //viewLoc  = glGetUniformLocation(lampShader.Program, "view");
        //projLoc  = glGetUniformLocation(lampShader.Program, "projection");
        //// Set matrices
        //glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
        //glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));
        //model = glm::mat4();
        //model = glm::translate(model, lightPos);
        //model = glm::scale(model, glm::vec3(0.2f)); // Make it a smaller cube
        //glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
        //// Draw the light object (using light's vertex attributes)
        //glBindVertexArray(lightVAO);
        //glDrawArrays(GL_TRIANGLES, 0, 36);
        //glBindVertexArray(0);


        // Swap the screen buffers
        glfwSwapBuffers(window);
    }

    // Terminate GLFW, clearing any resources allocated by GLFW.
    glfwTerminate();
    return 0;
}

// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(window, GL_TRUE);
    if (key >= 0 && key < 1024)
    {
        if (action == GLFW_PRESS)
            keys[key] = true;
        else if (action == GLFW_RELEASE)
            keys[key] = false;
    }
}

void do_movement()
{
    // Camera controls
    if (keys[GLFW_KEY_W])
        camera.ProcessKeyboard(FORWARD, deltaTime);
    if (keys[GLFW_KEY_S])
        camera.ProcessKeyboard(BACKWARD, deltaTime);
    if (keys[GLFW_KEY_A])
        camera.ProcessKeyboard(LEFT, deltaTime);
    if (keys[GLFW_KEY_D])
        camera.ProcessKeyboard(RIGHT, deltaTime);
}

bool firstMouse = true;
void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{
    if (firstMouse)
    {
        lastX = xpos;
        lastY = ypos;
        firstMouse = false;
    }

    GLfloat xoffset = xpos - lastX;
    GLfloat yoffset = lastY - ypos;  // Reversed since y-coordinates go from bottom to left

    lastX = xpos;
    lastY = ypos;

    camera.ProcessMouseMovement(xoffset, yoffset);
}

void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
    camera.ProcessMouseScroll(yoffset);
}