#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <stb_image.h>
#define STB_IMAGE_IMPLEMENTATION // dodane do pliku z kursu 
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

#include <learnopengl/filesystem.h>
#include <learnopengl/shader_m.h>
#include <learnopengl/camera.h>
#include <learnopengl/model.h>

#include <iostream>

void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void processInput(GLFWwindow *window);
unsigned int loadTexture(const char *path);
unsigned int loadCubemap(vector<std::string> faces);

// settings
const unsigned int SCR_WIDTH = 800 * 2;
const unsigned int SCR_HEIGHT = 600 * 2;

// camera
Camera camera(glm::vec3(-1.75f, 4.0f, 2.25f), glm::vec3(0.0f, 1.0f, 0.0f), 295.0f, -14.3f);
float lastX = (float)SCR_WIDTH / 2.0;
float lastY = (float)SCR_HEIGHT / 2.0;
bool firstMouse = true;

glm::vec3 spaceshipTranslate(0.0f, 3.5f, -40.0f);

// timing
float deltaTime = 0.0f;
float lastFrame = 0.0f;

glm::vec3 lightPos(-2.0f, 4.0f, -1.0f);

// positions of the point lights
glm::vec3 pointLightPositions[] = {
        glm::vec3(-18.0f, 3.0f, 99999.0f),
        glm::vec3( 0.8f, -16.6f, -0.6f),
        glm::vec3( 6.8f, -7.4f, -7.2f),
        glm::vec3( 0.0f,  0.0f,  0.0f),
        glm::vec3(-14.0f, 3.0f, 2.0f),
};
size_t pointLightPositionsNum = sizeof(pointLightPositions) / sizeof(pointLightPositions[0]);


int main(int argc, char** argv)
{
    // glfw: initialize and configure
    // ------------------------------
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

#ifdef __APPLE__
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif

    // glfw window creation
    // --------------------
    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
    if (window == NULL)
    {
        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);

    // 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 shaders
    // -------------------------
    Shader cubeShader("6.2.cubemaps.vert", "6.2.cubemaps.frag");
    Shader skyboxShader("6.2.skybox.vert", "6.2.skybox.frag");
    Shader lightingShader("6.multiple_lights.vert", "6.multiple_lights.frag");

    // build and compile models
    // ------------------------
    Model kniedeModel("../resources/objects/kniede/kniede.obj");
    Model spaceshipModel("../resources/objects/spaceship/Intergalactic_Spaceship.obj");
    Model barrelModel("../resources/objects/barrel/barrel.obj");

    Model cabinetModel("../resources/objects/cabinet/cabinet.obj");
    Model chairModel("../resources/objects/chair/chair.obj");
    Model commodeModel("../resources/objects/commode/commode.obj");

    stbi_set_flip_vertically_on_load(true);
    Model backpackModel("../resources/objects/backpack/backpack.obj");
    stbi_set_flip_vertically_on_load(false);

    // set up vertex data (and buffer(s)) and configure vertex attributes
    // ------------------------------------------------------------------
    float cubeVertices[] = {
        // positions          // normals
        -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
    };
    float skyboxVertices[] = {
        // positions          
        -1.0f,  1.0f, -1.0f,
        -1.0f, -1.0f, -1.0f,
         1.0f, -1.0f, -1.0f,
         1.0f, -1.0f, -1.0f,
         1.0f,  1.0f, -1.0f,
        -1.0f,  1.0f, -1.0f,

        -1.0f, -1.0f,  1.0f,
        -1.0f, -1.0f, -1.0f,
        -1.0f,  1.0f, -1.0f,
        -1.0f,  1.0f, -1.0f,
        -1.0f,  1.0f,  1.0f,
        -1.0f, -1.0f,  1.0f,

         1.0f, -1.0f, -1.0f,
         1.0f, -1.0f,  1.0f,
         1.0f,  1.0f,  1.0f,
         1.0f,  1.0f,  1.0f,
         1.0f,  1.0f, -1.0f,
         1.0f, -1.0f, -1.0f,

        -1.0f, -1.0f,  1.0f,
        -1.0f,  1.0f,  1.0f,
         1.0f,  1.0f,  1.0f,
         1.0f,  1.0f,  1.0f,
         1.0f, -1.0f,  1.0f,
        -1.0f, -1.0f,  1.0f,

        -1.0f,  1.0f, -1.0f,
         1.0f,  1.0f, -1.0f,
         1.0f,  1.0f,  1.0f,
         1.0f,  1.0f,  1.0f,
        -1.0f,  1.0f,  1.0f,
        -1.0f,  1.0f, -1.0f,

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

    // cube VAO
    unsigned int 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, 6 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));

    // skybox VAO
    unsigned int skyboxVAO, skyboxVBO;
    glGenVertexArrays(1, &skyboxVAO);
    glGenBuffers(1, &skyboxVBO);
    glBindVertexArray(skyboxVAO);
    glBindBuffer(GL_ARRAY_BUFFER, skyboxVBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(skyboxVertices), &skyboxVertices, GL_STATIC_DRAW);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

    // load textures
    // -------------
    string dir = "../resources/textures/skybox/park-skyboxes/Park/";

    vector<std::string> faces
    {
          dir + "posx.jpg",
          dir + "negx.jpg",
          dir + "posy.jpg",
          dir + "negy.jpg",
          dir + "posz.jpg",
          dir + "negz.jpg"
    };

    unsigned int cubemapTexture = loadCubemap(faces);

    // shader configuration
    // --------------------
    cubeShader.use();
    cubeShader.setInt("skybox", 0);
    skyboxShader.use();
    skyboxShader.setInt("skybox", 0);
    lightingShader.use();
    lightingShader.setInt("material.diffuse", 0);
    lightingShader.setInt("material.specular", 1);

    // render loop
    // -----------
    float angle = 0;
    while (!glfwWindowShouldClose(window))
    {
        // per-frame time logic
        // --------------------
        float currentFrame = glfwGetTime();
        deltaTime = currentFrame - lastFrame;
        lastFrame = currentFrame;
        angle += deltaTime;

        // input
        // -----
        processInput(window);

        // 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("viewPos", camera.Position);
        lightingShader.setFloat("material.shininess", 12.0f);

        // directional light
        lightingShader.setVec3("dirLight.direction", -0.2f, -1.0f, -0.3f);
        lightingShader.setVec3("dirLight.ambient", 0.05f, 0.05f, 0.05f);
        lightingShader.setVec3("dirLight.diffuse", 0.4f, 0.4f, 0.4f);
        lightingShader.setVec3("dirLight.specular", 0.5f, 0.5f, 0.5f);
        // point light 1
        lightingShader.setVec3("pointLights[0].position", pointLightPositions[0]);
        lightingShader.setVec3("pointLights[0].ambient", 8.0f, 8.0f, 5.0f);
        lightingShader.setVec3("pointLights[0].diffuse", 0.8f, 0.8f, 0.8f);
        lightingShader.setVec3("pointLights[0].specular", 1.0f, 1.0f, 1.0f);
        lightingShader.setFloat("pointLights[0].constant", 1.0f);
        lightingShader.setFloat("pointLights[0].linear", 0.09);
        lightingShader.setFloat("pointLights[0].quadratic", 0.032);
        // point light 2
        lightingShader.setVec3("pointLights[1].position", pointLightPositions[1]);
        lightingShader.setVec3("pointLights[1].ambient", 0.1f, 0.3f, 0.0f);
        lightingShader.setVec3("pointLights[1].diffuse", 0.5f, 5.0f, 0.5f);
        lightingShader.setVec3("pointLights[1].specular", 0.6f, 0.6f, 0.6f);
        lightingShader.setFloat("pointLights[1].constant", 0.1f);
        lightingShader.setFloat("pointLights[1].linear", 0.19);
        lightingShader.setFloat("pointLights[1].quadratic", 0.032);
        // point light 3
        lightingShader.setVec3("pointLights[2].position", pointLightPositions[2]);
        lightingShader.setVec3("pointLights[2].ambient", 0.4f, 0.1f, 0.0f);
        lightingShader.setVec3("pointLights[2].diffuse", 0.5f, 0.5f, 0.0f);
        lightingShader.setVec3("pointLights[2].specular", 0.2f, 0.2f, 0.0f);
        lightingShader.setFloat("pointLights[2].constant", 1.0f);
        lightingShader.setFloat("pointLights[2].linear", 0.19);
        lightingShader.setFloat("pointLights[2].quadratic", 0.012);
        // point light 4
//        pointLightPositions[3].z =  14.0f + (glm::cos(glfwGetTime() * 3) * 2);
        lightingShader.setVec3("pointLights[3].position", pointLightPositions[3]);
        lightingShader.setVec3("pointLights[3].ambient", 1.0f, (pointLightPositions[3].z - 12) / 10, 0.0f);
        lightingShader.setVec3("pointLights[3].diffuse", 1.0f, 1.0f, 0.0f);
        lightingShader.setVec3("pointLights[3].specular", 0.5f, 0.5f, 0.0f);
        lightingShader.setFloat("pointLights[3].constant", 0.3f);
        lightingShader.setFloat("pointLights[3].linear", 0.09);
        lightingShader.setFloat("pointLights[3].quadratic", 0.033);
        // spotLight
        lightingShader.setVec3("spotLight.position", pointLightPositions[4]);
        lightingShader.setVec3("spotLight.direction", glm::vec3(0.82f, -0.24f, -0.5f));
        lightingShader.setVec3("spotLight.ambient", 0.0f, 0.0f, 0.0f);
        lightingShader.setVec3("spotLight.diffuse", 30.0f, 30.0f, 30.0f);
        lightingShader.setVec3("spotLight.specular", 1.0f, 1.0f, 1.0f);
        lightingShader.setFloat("spotLight.constant", 0.5f);
        lightingShader.setFloat("spotLight.linear", 0.09);
        lightingShader.setFloat("spotLight.quadratic", 0.032);
        lightingShader.setFloat("spotLight.cutOff", glm::cos(glm::radians(10.0f)));
        lightingShader.setFloat("spotLight.outerCutOff", glm::cos(glm::radians(20.0f + glm::sin(glfwGetTime()) * 8)));

        // DEFAULTS
        glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
        glm::mat4 view = camera.GetViewMatrix();
        glm::mat4 model = glm::mat4(1.0f);

        // ---------------------------------------------------------------------------------------------------
        // --------------------------------------------------------------- R Y S O W A N I E   M O D E L I ---
        // ---------------------------------------------------------------------------------------------------

        // wspólne dla modeli oteksturowanych
        lightingShader.setMat4("projection", projection);
        lightingShader.setMat4("view", view);

        // plecak
        model = glm::translate(glm::mat4(1.0f), glm::vec3(4, 0.5, -4));
        model = glm::rotate(model, glm::radians(-90.0f), glm::vec3(0.0f, 1.0f, 0.0f));
        model = glm::scale(model, glm::vec3(0.2f));
        lightingShader.setMat4("model", model);
        backpackModel.Draw(lightingShader);

        // pomnik
        pointLightPositions[4] = glm::vec3(-12, 10, -15);
        model = glm::translate(glm::mat4(1.0f), glm::vec3(3, -10, -20));
        model = glm::rotate(model, glm::radians(-90.0f), glm::vec3(1.0f, 0.0f, 0.0f));
        model = glm::rotate(model, glm::radians((float)glfwGetTime() * 10), glm::vec3(0.0f, 0.0f, 1.0f));
        lightingShader.setMat4("model", model);
        kniedeModel.Draw(lightingShader);

        // beczka
        model = glm::translate(glm::mat4(1.0f), glm::vec3(0, 0, -5));
        model = glm::rotate(model, glm::radians(-90.0f), glm::vec3(1.0f, 0.0f, 0.0f));
        lightingShader.setMat4("model", model);
        barrelModel.Draw(lightingShader);

        // światła nad meblami
        pointLightPositions[1] = glm::vec3(5 + (glm::cos((float)glfwGetTime() * 2)) * 8, 1, +5);
        pointLightPositions[2] = glm::vec3(1 + (glm::sin((float)glfwGetTime() * 2)) * 4, 5, -5);

        // krzesło
        model = glm::translate(glm::mat4(1.0f), glm::vec3(1, 0, -5));
        lightingShader.setMat4("model", model);
        chairModel.Draw(lightingShader);

        // komoda
        model = glm::translate(glm::mat4(1.0f), glm::vec3(2, 0, -5));
        lightingShader.setMat4("model", model);
        commodeModel.Draw(lightingShader);

        // szafa
        model = glm::translate(glm::mat4(1.0f), glm::vec3(3.5, 0, -5));
        lightingShader.setMat4("model", model);
        cabinetModel.Draw(lightingShader);

        // statek kosmiczny
        pointLightPositions[3] = spaceshipTranslate + glm::vec3(3.5f, 0.0f, -7.0f);
        model = glm::translate(model, spaceshipTranslate);
        model = glm::scale(model, glm::vec3(0.4f));
        lightingShader.setMat4("model", model);
        spaceshipModel.Draw(lightingShader);

        // kostka z odbiciem
        model = glm::rotate(glm::mat4(1.0f), angle, glm::vec3(0, 1, 0));
        model = glm::translate(model, glm::vec3(5, 0, 0));
        model = glm::rotate(model, -angle, glm::vec3(0, 1, 0));
        model = glm::translate(model, glm::vec3(0, -5, 0));
        model = glm::translate(model, lightPos);
        cubeShader.use();
        cubeShader.setMat4("projection", projection);
        cubeShader.setMat4("view", view);
        cubeShader.setMat4("model", model);
        glBindVertexArray(cubeVAO);
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_CUBE_MAP, cubemapTexture);
        glDrawArrays(GL_TRIANGLES, 0, 36);

        // światła (kostki)
        for (unsigned int i = 0; i < pointLightPositionsNum; i++)
        {
            model = glm::translate(glm::mat4(1.0f), pointLightPositions[i]);
            model = glm::scale(model, glm::vec3(0.2f));
            cubeShader.setMat4("model", model);
            glDrawArrays(GL_TRIANGLES, 0, 36);
        }

        // skybox
        view = glm::mat4(glm::mat3(camera.GetViewMatrix()));
        skyboxShader.use();
        skyboxShader.setMat4("view", view);
        skyboxShader.setMat4("projection", projection);
        glBindVertexArray(skyboxVAO);
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_CUBE_MAP, cubemapTexture);
        glDepthFunc(GL_LEQUAL);
        glDrawArrays(GL_TRIANGLES, 0, 36);
        glDepthFunc(GL_LESS);

        // 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, &skyboxVAO);
    glDeleteBuffers(1, &cubeVBO);
    glDeleteBuffers(1, &skyboxVAO);

    glfwTerminate();
    return 0;
}

// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{
    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);

    if (glfwGetKey(window, GLFW_KEY_LEFT) == GLFW_PRESS)
        spaceshipTranslate.x += 0.1f;
    if (glfwGetKey(window, GLFW_KEY_RIGHT) == GLFW_PRESS)
        spaceshipTranslate.x -= 0.1f;
    if (glfwGetKey(window, GLFW_KEY_DOWN) == GLFW_PRESS)
        spaceshipTranslate.y -= 0.1f;
    if (glfwGetKey(window, GLFW_KEY_UP) == GLFW_PRESS)
        spaceshipTranslate.y += 0.1f;
    if (glfwGetKey(window, GLFW_KEY_X) == GLFW_PRESS)
        spaceshipTranslate.z += 0.1f;
    if (glfwGetKey(window, GLFW_KEY_Z) == GLFW_PRESS)
        spaceshipTranslate.z -= 0.1f;

    if (glfwGetKey(window, GLFW_KEY_P) == GLFW_PRESS)
        std::cout
            << camera.Position.x << ", "
            << camera.Position.y << ", "
            << camera.Position.z << " - "
        << camera.Yaw << ", "
        << camera.Pitch << std::endl;
    if (glfwGetKey(window, GLFW_KEY_R) == GLFW_PRESS)
        spaceshipTranslate = glm::vec3(1.0f);
}

// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
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);
}

// glfw: whenever the mouse moves, this callback is called
// -------------------------------------------------------
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);
}

// glfw: whenever the mouse scroll wheel scrolls, this callback is called
// ----------------------------------------------------------------------
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
    camera.ProcessMouseScroll(yoffset);
}

// utility function for loading a 2D texture from file
// ---------------------------------------------------
unsigned int loadTexture(char const * path)
{
    unsigned int textureID;
    glGenTextures(1, &textureID);

    int width, height, nrComponents;
    unsigned char *data = stbi_load(path, &width, &height, &nrComponents, 0);
    if (data)
    {
        GLenum format;
        if (nrComponents == 1)
            format = GL_RED;
        else if (nrComponents == 3)
            format = GL_RGB;
        else if (nrComponents == 4)
            format = GL_RGBA;

        glBindTexture(GL_TEXTURE_2D, textureID);
        glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);

        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);

        stbi_image_free(data);
    }
    else
    {
        std::cout << "Texture failed to load at path: " << path << std::endl;
        stbi_image_free(data);
    }

    return textureID;
}

// loads a cubemap texture from 6 individual texture faces
// order:
// +X (right)
// -X (left)
// +Y (top)
// -Y (bottom)
// +Z (front) 
// -Z (back)
// -------------------------------------------------------
unsigned int loadCubemap(vector<std::string> faces)
{
    unsigned int textureID;
    glGenTextures(1, &textureID);
    glBindTexture(GL_TEXTURE_CUBE_MAP, textureID);

    int width, height, nrComponents;
    for (unsigned int i = 0; i < faces.size(); i++)
    {
        unsigned char *data = stbi_load(faces[i].c_str(), &width, &height, &nrComponents, 0);
        if (data)
        {
            glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
            stbi_image_free(data);
        }
        else
        {
            std::cout << "Cubemap texture failed to load at path: " << faces[i] << std::endl;
            stbi_image_free(data);
        }
    }
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);

    return textureID;
}