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

#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>

#include <shader.h>
#include "Canvas/Canvas.h"
#include "point.h"
#include "Canvas/cuda/CalculateCanvasGPU.h"

#include <iostream>
#include <cmath>
#include <vector>

void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow *window);

void loadTexture(std::string path, unsigned int* texture, int* width, int* height);
void generateCanvasTexture(unsigned int *texture, unsigned char color);
void window_size_callback(GLFWwindow* window, int width, int height);

// settings
unsigned int SCR_WIDTH = 768;
unsigned int SCR_HEIGHT = 768;
const std::string PROJECT_PATH = "/home/saintruler/Documents/opengl_gravity/";
unsigned char* canvas = (unsigned char*) malloc(SCR_HEIGHT * SCR_WIDTH * 3);

std::vector<point> points;
const double c = 1e5;
cuda_point* gpuPoints = (cuda_point*) malloc(3 * sizeof(cuda_point));

int main()
{
    // 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);

    // 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);

    // glad: load all OpenGL function pointers
    // ---------------------------------------
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    // build and compile our shader zprogram
    // ------------------------------------
    Shader ourShader((PROJECT_PATH + "4.1.texture.vs").c_str(), (PROJECT_PATH + "4.1.texture.fs").c_str());

    // set up vertex data (and buffer(s)) and configure vertex attributes
    // ------------------------------------------------------------------

    float vertices[] = {
            // positions        // colors           // texture coords
            1.f,  1.f, 0.0f,    1.0f, 0.0f, 0.0f,   1.0f, 1.0f, // top right
            1.f, -1.f, 0.0f,    0.0f, 1.0f, 0.0f,   1.0f, 0.0f, // bottom right
            -1.f, -1.f, 0.0f,   0.0f, 0.0f, 1.0f,   0.0f, 0.0f, // bottom left
            -1.f,  1.f, 0.0f,   1.0f, 1.0f, 0.0f,   0.0f, 1.0f  // top left
    };
    unsigned int indices[] = {
            0, 1, 3, // first triangle
            1, 2, 3  // second triangle
    };
    unsigned int VBO, VAO, EBO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);

    glBindVertexArray(VAO);

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

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    // position attribute
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // color attribute
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);
    // texture coord attribute
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
    glEnableVertexAttribArray(2);


    // load and create a texture
    // -------------------------
    unsigned int texture;
    glGenTextures(1, &texture);
    unsigned char i = 0;

    points.emplace_back(point(100, 100));
    points.emplace_back(point(500, 500));
    points.emplace_back(point(200, 375));

    gpuPoints[0] = cuda_point{.x=100, .y=100};
    gpuPoints[1] = cuda_point{.x=500, .y=500};
    gpuPoints[2] = cuda_point{.x=200, .y=200};


    // render loop
    // -----------
    while (!glfwWindowShouldClose(window))
    {
        // input
        // -----
        processInput(window);

        // render
        // ------
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        generateCanvasTexture(&texture, i++);
        // bind Texture
        glBindTexture(GL_TEXTURE_2D, texture);

        // render container
        ourShader.use();
        glBindVertexArray(VAO);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

        // 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, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteBuffers(1, &EBO);

    // glfw: terminate, clearing all previously allocated GLFW resources.
    // ------------------------------------------------------------------
    glfwTerminate();
    return 0;
}


void loadTexture(std::string path, unsigned int* texture, int* width, int* height)
{
    glGenTextures(1, texture);
    glBindTexture(GL_TEXTURE_2D, *texture); // all upcoming GL_TEXTURE_2D operations now have effect on this texture object
    // set the texture wrapping parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);	// set texture wrapping to GL_REPEAT (default wrapping method)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // set texture filtering parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    // load image, create texture and generate mipmaps
    int nrChannels;
    unsigned char* data = stbi_load(path.c_str(), width, height, &nrChannels, 0);

    if (data)
    {
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, *width, *height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else
    {
        std::cout << "Failed to load texture" << std::endl;
    }
    stbi_image_free(data);
}


void generateCanvasTexture(unsigned int *texture, unsigned char color)
{
    glBindTexture(GL_TEXTURE_2D, *texture); // all upcoming GL_TEXTURE_2D operations now have effect on this texture object
    // set the texture wrapping parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);	// set texture wrapping to GL_REPEAT (default wrapping method)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // set texture filtering parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    // load image, create texture and generate mipmaps


//    for (int x = 0; x < SCR_WIDTH; x++)
//    {
//        for (int y = 0; y < SCR_HEIGHT; y++)
//        {
//
//            point canvas_pt(x, y);
//            double f = 0;
//            for (point pt : points)
//            {
//                point path = pt - canvas_pt;
//
//                f += (c * 20 * 1) / path.length_sqared();
//            }
//
//            int l = (int) f;
//            if (l > 255) l = 255;
//
//
//            canvas[y * SCR_WIDTH * 3 + x * 3 + 0] = l;
//            canvas[y * SCR_WIDTH * 3 + x * 3 + 1] = 0;
//            canvas[y * SCR_WIDTH * 3 + x * 3 + 2] = 0;
//        }
//    }

    generate_canvas(SCR_WIDTH, SCR_HEIGHT, canvas, gpuPoints, 3);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, SCR_WIDTH, SCR_HEIGHT, 0, GL_RGB, GL_UNSIGNED_BYTE, (unsigned char*) canvas);
    glGenerateMipmap(GL_TEXTURE_2D);
}


// 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_LEFT) == GLFW_PRESS)
        points[0].x -= 20;
    if (glfwGetKey(window, GLFW_KEY_RIGHT) == GLFW_PRESS)
        points[0].x += 20;

    if (glfwGetKey(window, GLFW_KEY_DOWN) == GLFW_PRESS)
        points[0].y -= 20;
    if (glfwGetKey(window, GLFW_KEY_UP) == GLFW_PRESS)
        points[0].y += 20;

    double xpos, ypos;
    //getting cursor position
    glfwGetCursorPos(window, &xpos, &ypos);
//    points[0].x = xpos;
//    points[0].y = SCR_HEIGHT - ypos;
    gpuPoints[0].x = xpos;
    gpuPoints[0].y = SCR_HEIGHT - ypos;
}

// 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);
}