// Std. Includes
#include <string>

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

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

// GL includes
#include "Shader.h"
#include "Camera.h"
#include "Model.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();

// 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 the 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
    glEnable(GL_DEPTH_TEST);

    // Setup and compile our shaders
    Shader shader("../../../Path/To/Shaders/model_loading.vs", "../../../Path/To/Shaders/model_loading.frag");
    Shader lampShader("../../../Path/To/Shaders/lamp.vs", "../../../Path/To/Shaders/lamp.frag");

    // Load models
    Model ourModel("../../../Path/To/Nanosuit/nanosuit.obj");
    // Used a lamp object here. Find one yourself on the internet, or create your own one ;) (or be oldschool and set the VBO and VAO yourselves)
    Model lightBulb("../../../Path/To/Lamps/Bulb.obj"); 
    
    // Draw in wireframe
    //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

    // Point light positions
    glm::vec3 pointLightPositions[] = {
        glm::vec3(2.3f, -1.6f, -3.0f),
        glm::vec3(-1.7f, 0.9f, 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();

        // Clear the colorbuffer
        glClearColor(0.05f, 0.05f, 0.05f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        shader.Use();   // <-- Don't forget this one!
        // Transformation matrices
        glm::mat4 projection = glm::perspective(camera.Zoom, (float)screenWidth/(float)screenHeight, 0.1f, 100.0f);
        glm::mat4 view = camera.GetViewMatrix();
        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));

        // Set the lighting uniforms
        glUniform3f(glGetUniformLocation(shader.Program, "viewPos"), camera.Position.x, camera.Position.y, camera.Position.z);
        // Point light 1
        glUniform3f(glGetUniformLocation(shader.Program, "pointLights[0].position"), pointLightPositions[0].x, pointLightPositions[0].y, pointLightPositions[0].z);		
        glUniform3f(glGetUniformLocation(shader.Program, "pointLights[0].ambient"), 0.05f, 0.05f, 0.05f);		
        glUniform3f(glGetUniformLocation(shader.Program, "pointLights[0].diffuse"), 1.0f, 1.0f, 1.0f); 
        glUniform3f(glGetUniformLocation(shader.Program, "pointLights[0].specular"), 1.0f, 1.0f, 1.0f);
        glUniform1f(glGetUniformLocation(shader.Program, "pointLights[0].constant"), 1.0f);
        glUniform1f(glGetUniformLocation(shader.Program, "pointLights[0].linear"), 0.009);
        glUniform1f(glGetUniformLocation(shader.Program, "pointLights[0].quadratic"), 0.0032);		
        // Point light 2
        glUniform3f(glGetUniformLocation(shader.Program, "pointLights[1].position"), pointLightPositions[1].x, pointLightPositions[1].y, pointLightPositions[1].z);		
        glUniform3f(glGetUniformLocation(shader.Program, "pointLights[1].ambient"), 0.05f, 0.05f, 0.05f);		
        glUniform3f(glGetUniformLocation(shader.Program, "pointLights[1].diffuse"), 1.0f, 1.0f, 1.0f); 
        glUniform3f(glGetUniformLocation(shader.Program, "pointLights[1].specular"), 1.0f, 1.0f, 1.0f);
        glUniform1f(glGetUniformLocation(shader.Program, "pointLights[1].constant"), 1.0f);
        glUniform1f(glGetUniformLocation(shader.Program, "pointLights[1].linear"), 0.009);
        glUniform1f(glGetUniformLocation(shader.Program, "pointLights[1].quadratic"), 0.0032);		

        // Draw the loaded model
        glm::mat4 model;
        model = glm::translate(model, glm::vec3(0.0f, -1.75f, 0.0f)); // Translate it down a bit so it's at the center of the scene
        model = glm::scale(model, glm::vec3(0.2f, 0.2f, 0.2f));	// It's a bit too big for our scene, so scale it down
        glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
        ourModel.Draw(shader);

        // Draw the lamps
        lampShader.Use();
        glUniformMatrix4fv(glGetUniformLocation(lampShader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
        glUniformMatrix4fv(glGetUniformLocation(lampShader.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));
        for(GLuint i = 0; i < 2; i++)
        {
            model = glm::mat4();
            model = glm::translate(model, pointLightPositions[i]);
            model = glm::scale(model, glm::vec3(0.3f, 0.3f, 0.3f)); // Downscale lamp object (a bit too large)
            glUniformMatrix4fv(glGetUniformLocation(lampShader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
            lightBulb.Draw(lampShader);
        }

        // Swap the buffers
        glfwSwapBuffers(window);
    }

    glfwTerminate();
    return 0;
}

#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