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

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

// GL includes
#include <learnopengl/shader.h>
#include <learnopengl/camera.h>

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

// Other Libs
#include <SOIL.h>

// Properties
const GLuint SCR_WIDTH = 800, SCR_HEIGHT = 600;

// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void Do_Movement();
GLuint loadTexture(GLchar* path);
void RenderScene(Shader &shader);
void RenderCube();
void RenderQuad();

// Camera
Camera camera(glm::vec3(0.0f, 0.0f, 5.0f));

// Delta
GLfloat deltaTime = 0.0f;
GLfloat lastFrame = 0.0f;

// Options
GLboolean hdr = true; // Change with 'Space'
GLfloat exposure = 1.0f; // Change with Q and E

// Global variables
GLuint woodTexture;

// The MAIN function, from here we start our application and run our Game loop
int main()
{
    // Init GLFW
    glfwInit();
    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);

    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", nullptr, nullptr); // Windowed
    glfwMakeContextCurrent(window);

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

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

    // Initialize GLEW to setup the OpenGL Function pointers
    glewExperimental = GL_TRUE;
    glewInit();

    // Define the viewport dimensions
    glViewport(0, 0, SCR_WIDTH, SCR_HEIGHT);

    // Setup some OpenGL options
    glEnable(GL_DEPTH_TEST);

    // Setup and compile our shaders
    Shader shader("lighting.vs", "lighting.frag");
    Shader hdrShader("hdr.vs", "hdr.frag");

    // Light sources
    // - Positions
    std::vector<glm::vec3> lightPositions;
    lightPositions.push_back(glm::vec3(0.0f, 0.0f, 49.5f)); // back light
    lightPositions.push_back(glm::vec3(-1.4f, -1.9f, 9.0f));
    lightPositions.push_back(glm::vec3(0.0f, -1.8f, 4.0f));
    lightPositions.push_back(glm::vec3(0.8f, -1.7f, 6.0f));
    // - Colors
    std::vector<glm::vec3> lightColors;
    lightColors.push_back(glm::vec3(200.0f, 200.0f, 200.0f));
    lightColors.push_back(glm::vec3(0.1f, 0.0f, 0.0f));
    lightColors.push_back(glm::vec3(0.0f, 0.0f, 0.2f));
    lightColors.push_back(glm::vec3(0.0f, 0.1f, 0.0f));

    // Load textures
    woodTexture = loadTexture("../../../resources/textures/wood.png");

    // Set up floating point framebuffer to render scene to
    GLuint hdrFBO;
    glGenFramebuffers(1, &hdrFBO);
    // - Create floating point color buffer
    GLuint colorBuffer;
    glGenTextures(1, &colorBuffer);
    glBindTexture(GL_TEXTURE_2D, colorBuffer);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, SCR_WIDTH, SCR_HEIGHT, 0, GL_RGBA, GL_FLOAT, NULL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    // - Create depth buffer (renderbuffer)
    GLuint rboDepth;
    glGenRenderbuffers(1, &rboDepth);
    glBindRenderbuffer(GL_RENDERBUFFER, rboDepth);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, SCR_WIDTH, SCR_HEIGHT);
    // - Attach buffers
    glBindFramebuffer(GL_FRAMEBUFFER, hdrFBO);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorBuffer, 0);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rboDepth);
    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        std::cout << "Framebuffer not complete!" << std::endl;
    glBindFramebuffer(GL_FRAMEBUFFER, 0);

    glClearColor(0.1f, 0.1f, 0.1f, 1.0f);

    // Game loop
    while (!glfwWindowShouldClose(window))
    {
        // Set frame time
        GLfloat currentFrame = glfwGetTime();
        deltaTime = currentFrame - lastFrame;
        lastFrame = currentFrame;

        // Check and call events
        glfwPollEvents();
        Do_Movement();

        // 1. Render scene into floating point framebuffer
        glBindFramebuffer(GL_FRAMEBUFFER, hdrFBO);
            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
            glm::mat4 projection = glm::perspective(camera.Zoom, (GLfloat)SCR_WIDTH / (GLfloat)SCR_HEIGHT, 0.1f, 100.0f);
            glm::mat4 view       = camera.GetViewMatrix();
            glm::mat4 model;
            shader.Use();
            glUniformMatrix4fv(glGetUniformLocation(shader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
            glUniformMatrix4fv(glGetUniformLocation(shader.Program, "view"),       1, GL_FALSE, glm::value_ptr(view));
            glActiveTexture(GL_TEXTURE0);
            glBindTexture(GL_TEXTURE_2D, woodTexture);
            // - set lighting uniforms
            for (GLuint i = 0; i < lightPositions.size(); i++)
            {
                glUniform3fv(glGetUniformLocation(shader.Program, ("lights[" + std::to_string(i) + "].Position").c_str()), 1, &lightPositions[i][0]);
                glUniform3fv(glGetUniformLocation(shader.Program, ("lights[" + std::to_string(i) + "].Color").c_str()), 1, &lightColors[i][0]);
            }
            glUniform3fv(glGetUniformLocation(shader.Program, "viewPos"), 1, &camera.Position[0]);
            // - render tunnel
            model = glm::mat4();
            model = glm::translate(model, glm::vec3(0.0f, 0.0f, 25.0));
            model = glm::scale(model, glm::vec3(5.0f, 5.0f, 55.0f));
            glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
            glUniform1i(glGetUniformLocation(shader.Program, "inverse_normals"), GL_TRUE);
            RenderCube();
        glBindFramebuffer(GL_FRAMEBUFFER, 0);      

        // 2. Now render floating point color buffer to 2D quad and tonemap HDR colors to default framebuffer's (clamped) color range
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);        
        hdrShader.Use();
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, colorBuffer);
        glUniform1i(glGetUniformLocation(hdrShader.Program, "hdr"), hdr);
        glUniform1f(glGetUniformLocation(hdrShader.Program, "exposure"), exposure);
        RenderQuad();       

        std::cout << "exposure: " << exposure << std::endl;

        // Swap the buffers
        glfwSwapBuffers(window);
    }

    glfwTerminate();
    return 0;
}


// RenderQuad() Renders a 1x1 quad in NDC, best used for framebuffer color targets
// and post-processing effects.
GLuint quadVAO = 0;
GLuint quadVBO;
void RenderQuad()
{
    if (quadVAO == 0)
    {
        GLfloat quadVertices[] = {
            // Positions        // Texture Coords
            -1.0f, 1.0f, 0.0f, 0.0f, 1.0f,
            -1.0f, -1.0f, 0.0f, 0.0f, 0.0f,
            1.0f, 1.0f, 0.0f, 1.0f, 1.0f,
            1.0f, -1.0f, 0.0f, 1.0f, 0.0f,
        };
        // Setup plane VAO
        glGenVertexArrays(1, &quadVAO);
        glGenBuffers(1, &quadVBO);
        glBindVertexArray(quadVAO);
        glBindBuffer(GL_ARRAY_BUFFER, quadVBO);
        glBufferData(GL_ARRAY_BUFFER, sizeof(quadVertices), &quadVertices, GL_STATIC_DRAW);
        glEnableVertexAttribArray(0);
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)0);
        glEnableVertexAttribArray(1);
        glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
    }
    glBindVertexArray(quadVAO);
    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
    glBindVertexArray(0);
}

// RenderCube() Renders a 1x1 3D cube in NDC.
GLuint cubeVAO = 0;
GLuint cubeVBO = 0;
void RenderCube()
{
    // Initialize (if necessary)
    if (cubeVAO == 0)
    {
        GLfloat vertices[] = {
            // Back face
            -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f, // Bottom-left
            0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f, // top-right
            0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f, // bottom-right         
            0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f,  // top-right
            -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f,  // bottom-left
            -0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f,// top-left
            // Front face
            -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // bottom-left
            0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f,  // bottom-right
            0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f,  // top-right
            0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, // top-right
            -0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f,  // top-left
            -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f,  // bottom-left
            // Left face
            -0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f, // top-right
            -0.5f, 0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top-left
            -0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f,  // bottom-left
            -0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f, // bottom-left
            -0.5f, -0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 0.0f,  // bottom-right
            -0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f, // top-right
            // Right face
            0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, // top-left
            0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f, // bottom-right
            0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top-right         
            0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f,  // bottom-right
            0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f,  // top-left
            0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, // bottom-left     
            // Bottom face
            -0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f, // top-right
            0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 1.0f, // top-left
            0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f,// bottom-left
            0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f, // bottom-left
            -0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 0.0f, // bottom-right
            -0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f, // top-right
            // Top face
            -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f,// top-left
            0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // bottom-right
            0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, // top-right     
            0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // bottom-right
            -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f,// top-left
            -0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f // bottom-left        
        };
        glGenVertexArrays(1, &cubeVAO);
        glGenBuffers(1, &cubeVBO);
        // Fill buffer
        glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
        // Link vertex attributes
        glBindVertexArray(cubeVAO);
        glEnableVertexAttribArray(0);
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0);
        glEnableVertexAttribArray(1);
        glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
        glEnableVertexAttribArray(2);
        glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(6 * sizeof(GLfloat)));
        glBindBuffer(GL_ARRAY_BUFFER, 0);
        glBindVertexArray(0);
    }
    // Render Cube
    glBindVertexArray(cubeVAO);
    glDrawArrays(GL_TRIANGLES, 0, 36);
    glBindVertexArray(0);
}

// This function loads a texture from file. Note: texture loading functions like these are usually 
// managed by a 'Resource Manager' that manages all resources (like textures, models, audio). 
// For learning purposes we'll just define it as a utility function.
GLuint loadTexture(GLchar* path)
{
    // Generate texture ID and load texture data 
    GLuint textureID;
    glGenTextures(1, &textureID);
    int width, height;
    unsigned char* image = SOIL_load_image(path, &width, &height, 0, SOIL_LOAD_RGB);
    // Assign texture to ID
    glBindTexture(GL_TEXTURE_2D, textureID);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_SRGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
    glGenerateMipmap(GL_TEXTURE_2D);

    // Parameters
    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_LINEAR);
    glBindTexture(GL_TEXTURE_2D, 0);
    SOIL_free_image_data(image);
    return textureID;

}

bool keys[1024];
bool keysPressed[1024];
// Moves/alters the camera positions based on user input
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);

    if (keys[GLFW_KEY_SPACE] && !keysPressed[GLFW_KEY_SPACE])
    {
        hdr = !hdr;
        keysPressed[GLFW_KEY_SPACE] = true;
    }

    // Change parallax height scale
    if (keys[GLFW_KEY_Q])
        exposure -= 0.5 * deltaTime;
    else if (keys[GLFW_KEY_E])
        exposure += 0.5 * deltaTime;
}

GLfloat lastX = 400, lastY = 300;
bool firstMouse = true;
// 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;
            keysPressed[key] = false;
        }
    }
}

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;

    lastX = xpos;
    lastY = ypos;

    camera.ProcessMouseMovement(xoffset, yoffset);
}

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