// Std. Includes
#include <string>
#include <algorithm>
using namespace std;

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

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

// GL includes
#include "Shader.h"
#include "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
GLuint screenWidth = 800, screenHeight = 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, GLboolean alpha = false);
GLuint generateAttachmentTexture(GLboolean depth, GLboolean stencil);

// Camera
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
bool keys[1024];
GLfloat lastX = 400, lastY = 300;
bool firstMouse = true;

GLfloat deltaTime = 0.0f;
GLfloat lastFrame = 0.0f;

// 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(screenWidth, screenHeight, "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, screenWidth, screenHeight);

    // Setup some OpenGL options
    glDepthFunc(GL_LESS);
    
    // Setup and compile our shaders
    Shader shader("../../../Path/To/Shaders/advanced.vs", "../../../Path/To/Shaders/advanced.frag");
    Shader screenShader("../../../Path/To/Shaders/screen.vs", "../../../Path/To/Shaders/screen.frag");

    #pragma region "object_initialization"
    // Set the object data (buffers, vertex attributes)
    GLfloat cubeVertices[] = {
        // Positions          // Texture Coords
        -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,
         0.5f, -0.5f, -0.5f,  1.0f, 0.0f,
         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,

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

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

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

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

        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
        -0.5f,  0.5f,  0.5f,  0.0f, 0.0f,
        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f
    };
    GLfloat floorVertices[] = {
        // Positions          // Texture Coords (note we set these higher than 1 that together with GL_REPEAT as texture wrapping mode will cause the floor texture to repeat)
        5.0f,  -0.5f,  5.0f,  2.0f, 0.0f,
        -5.0f, -0.5f,  5.0f,  0.0f, 0.0f,
        -5.0f, -0.5f, -5.0f,  0.0f, 2.0f,

        5.0f,  -0.5f,  5.0f,  2.0f, 0.0f,
        -5.0f, -0.5f, -5.0f,  0.0f, 2.0f,
        5.0f,  -0.5f, -5.0f,  2.0f, 2.0f								
    };
    GLfloat quadVertices[] = {   // Vertex attributes for a quad that fills the entire screen in Normalized Device Coordinates.
        // Positions   // TexCoords
        -1.0f,  1.0f,  0.0f, 1.0f,
        -1.0f, -1.0f,  0.0f, 0.0f,
         1.0f, -1.0f,  1.0f, 0.0f,

        -1.0f,  1.0f,  0.0f, 1.0f,
         1.0f, -1.0f,  1.0f, 0.0f,
         1.0f,  1.0f,  1.0f, 1.0f
    };	

    // Setup cube VAO
    GLuint cubeVAO, cubeVBO;
    glGenVertexArrays(1, &cubeVAO);
    glGenBuffers(1, &cubeVBO);
    glBindVertexArray(cubeVAO);
    glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(cubeVertices), &cubeVertices, 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(0);
    // Setup plane VAO
    GLuint floorVAO, floorVBO;
    glGenVertexArrays(1, &floorVAO);
    glGenBuffers(1, &floorVBO);
    glBindVertexArray(floorVAO);
    glBindBuffer(GL_ARRAY_BUFFER, floorVBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(floorVertices), &floorVertices, 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(0);
    // Setup screen VAO
    GLuint quadVAO, quadVBO;
    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, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (GLvoid*)0);
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (GLvoid*)(2 * sizeof(GLfloat)));
    glBindVertexArray(0);

    // Load textures
    GLuint cubeTexture = loadTexture("../../../Path/To/Textures/container.jpg");
    GLuint floorTexture = loadTexture("../../../Path/To/Textures/metal.png");
    #pragma endregion

    // Framebuffers
    GLuint framebuffer;
    glGenFramebuffers(1, &framebuffer);
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);  
    // Create a color attachment texture
    GLuint textureColorbuffer = generateAttachmentTexture(false, false);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textureColorbuffer, 0);
    // Create a renderbuffer object for depth and stencil attachment (we won't be sampling these)
    GLuint rbo;
    glGenRenderbuffers(1, &rbo);
    glBindRenderbuffer(GL_RENDERBUFFER, rbo); 
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, screenWidth, screenHeight); // Use a single renderbuffer object for both a depth AND stencil buffer.
    glBindRenderbuffer(GL_RENDERBUFFER, 0);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, rbo); // Now actually attach it
    // Now that we actually created the framebuffer and added all attachments we want to check if it is actually complete now
    if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        cout << "ERROR::FRAMEBUFFER:: Framebuffer is not complete!" << endl;
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    

    // Draw as wireframe
    //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

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

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

        
        /////////////////////////////////////////////////////
        // Bind to framebuffer and draw to color texture 
        // as we normally would.
        // //////////////////////////////////////////////////
        glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
        // Clear all attached buffers        
        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // We're not using stencil buffer so why bother with clearing?

        glEnable(GL_DEPTH_TEST);
        // Set uniforms
        shader.Use();
        glm::mat4 model;
        glm::mat4 view = camera.GetViewMatrix();
        glm::mat4 projection = glm::perspective(camera.Zoom, (float)screenWidth/(float)screenHeight, 0.1f, 100.0f);
        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));
        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));

        // Floor
        glBindVertexArray(floorVAO);
        glBindTexture(GL_TEXTURE_2D, floorTexture);
        model = glm::mat4();
        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
        glDrawArrays(GL_TRIANGLES, 0, 6);		
        glBindVertexArray(0);	
        // Cubes
        glBindVertexArray(cubeVAO);
        glBindTexture(GL_TEXTURE_2D, cubeTexture);  
        model = glm::translate(model, glm::vec3(-1.0f, 0.0f, -1.0f));
        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
        glDrawArrays(GL_TRIANGLES, 0, 36);
        model = glm::mat4();
        model = glm::translate(model, glm::vec3(2.0f, 0.0f, 0.0f));
        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
        glDrawArrays(GL_TRIANGLES, 0, 36);
        glBindVertexArray(0);			

        /////////////////////////////////////////////////////
        // Bind to default framebuffer again and draw the 
        // quad plane with attched screen texture.
        // //////////////////////////////////////////////////
        glBindFramebuffer(GL_FRAMEBUFFER, 0);
        // Clear all relevant buffers
        glClearColor(1.0f, 1.0f, 1.0f, 1.0f); // Set clear color to white (not really necessery actually, since we won't be able to see behind the quad anyways)
        glClear(GL_COLOR_BUFFER_BIT);
        glDisable(GL_DEPTH_TEST); // We don't care about depth information when rendering a single quad

        // Draw Screen
        screenShader.Use();
        glBindVertexArray(quadVAO);
        glBindTexture(GL_TEXTURE_2D, textureColorbuffer);	// Use the color attachment texture as the texture of the quad plane
        glDrawArrays(GL_TRIANGLES, 0, 6);
        glBindVertexArray(0);


        // Swap the buffers
        glfwSwapBuffers(window);
    }

    // Clean up
    glDeleteFramebuffers(1, &framebuffer);

    glfwTerminate();
    return 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, GLboolean alpha)
{
    //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, alpha ? SOIL_LOAD_RGBA : SOIL_LOAD_RGB);
    // Assign texture to ID
    glBindTexture(GL_TEXTURE_2D, textureID);
    glTexImage2D(GL_TEXTURE_2D, 0, alpha ? GL_RGBA : GL_RGB, width, height, 0, alpha ? GL_RGBA : GL_RGB, GL_UNSIGNED_BYTE, image);
    glGenerateMipmap(GL_TEXTURE_2D);	

    // Parameters
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, alpha ? GL_CLAMP_TO_EDGE : GL_REPEAT );	// Use GL_MIRRORED_REPEAT to prevent white borders. Due to interpolation it takes value from next repeat 
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, alpha ? GL_CLAMP_TO_EDGE : 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;
}

// Generates a texture that is suited for attachments to a framebuffer
GLuint generateAttachmentTexture(GLboolean depth, GLboolean stencil)
{
    // What enum to use?
    GLenum attachment_type;
    if(!depth && !stencil)
        attachment_type = GL_RGB;
    else if(depth && !stencil)
        attachment_type = GL_DEPTH_COMPONENT;
    else if(!depth && stencil)
        attachment_type = GL_STENCIL_INDEX;

    //Generate texture ID and load texture data 
    GLuint textureID;
    glGenTextures(1, &textureID);
    glBindTexture(GL_TEXTURE_2D, textureID);
    if(!depth && !stencil)
        glTexImage2D(GL_TEXTURE_2D, 0, attachment_type, screenWidth, screenHeight, 0, attachment_type, GL_UNSIGNED_BYTE, NULL);
    else // Using both a stencil and depth test, needs special format arguments
        glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH24_STENCIL8, screenWidth, screenHeight, 0, GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8, NULL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glBindTexture(GL_TEXTURE_2D, 0);

    return textureID;
}

#pragma region "User input"

// 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);
}

// 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(action == GLFW_PRESS)
        keys[key] = true;
    else if(action == GLFW_RELEASE)
        keys[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);
}

#pragma endregion
HI