#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <cmath>
#include <vector>
#include <iostream>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "shader.h"
#include <cstdlib>
#include <imgui.h>
#include <imgui_impl_glfw.h>
#include <imgui_impl_opengl3.h>

const int windowWidth = 1200;
const int windowHeight = 800;

const int ballsAmount = 2;

const float initTimeStep = 0.001f;
const float initCameraScale = 1.0f;

bool shouldUpdate = true;
bool shouldAlwaysUpdate = true;
float t = 0.0f;

float timeStep = initTimeStep;
float cameraScale = initCameraScale;
int currentTrackedBall = -1;

struct Ball {
    glm::vec2 position;
    glm::vec3 color;
    float offset; // Dodajemy przesunięcie
};

GLFWwindow* window;
std::vector<Ball> balls(ballsAmount);
GLuint shaderProgram;
GLuint circleVAO, circleVBO, arcVAO, arcVBO;

void initImGui(){
    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImGuiIO& io = ImGui::GetIO(); (void)io;
    ImGui::StyleColorsDark();
    ImGui_ImplGlfw_InitForOpenGL(window, true);
    ImGui_ImplOpenGL3_Init("#version 330 core");
}

void imGuiTrackBallFrame(){
    ImGui::Begin("Track Ball");

    ImGui::SliderFloat("Camera scale", &cameraScale, 0.1f, 2.0f, "%.3f", 1.0f);


    if(ImGui::Button("Track red ball")){
        currentTrackedBall = 0;
    }

    if(ImGui::Button("Track blue ball")){
        currentTrackedBall = 1;
    }

    if(ImGui::Button("Untrack ball")){
        currentTrackedBall = -1;
    }

    ImGui::End();
}

void imGuiSimulationStateControlsFrame(){
    ImGui::Begin("Simulation State Controls");

    ImGui::Checkbox("Always update", &shouldAlwaysUpdate);

    if(ImGui::Button("Start")){
        shouldUpdate = true;
    }

    if(ImGui::Button("Stop")){
        shouldUpdate = false;
    }

    if(ImGui::Button("Reset")){
        t = 0.0f;
        shouldUpdate = false;
    }

    ImGui::End();
}

void imGuiBallsMetricFrame(){
    ImGui::Begin("Balls Metric");

    float angle1 = abs(atan2(balls[0].position.y, balls[0].position.x) * (180.0 / M_PI));
    float angle2 = abs(atan2(balls[1].position.y, balls[1].position.x) * (180.0 / M_PI));

    if(angle1 > 60.0f){
        angle1 = 60.0f;
    }

    if(angle2 > 150.0f){
        angle2 = 150.0f;
    }

    ImGui::SliderFloat("Time step", &timeStep, 0.001f, 0.1f, "%.3f", 1.0f);

    ImGui::Text("Red ball (60deg): current angle: %.2f", angle1);
    ImGui::Text("Blue ball (150deg): current angle: %.2f", angle2);


    ImGui::End();
}

void renderImGui(){
    ImGui_ImplOpenGL3_NewFrame();
    ImGui_ImplGlfw_NewFrame();
    ImGui::NewFrame();

    imGuiSimulationStateControlsFrame();
    imGuiBallsMetricFrame();
    imGuiTrackBallFrame();

    ImGui::Render();
    ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
}

void cleanUpImGui(){
    ImGui_ImplOpenGL3_Shutdown();
    ImGui_ImplGlfw_Shutdown();
    ImGui::DestroyContext();
}

void initializeBalls() {
    balls[0].position = glm::vec2(1.0f, 0.0f);
    balls[0].color = glm::vec3(1.0f, 0.0f, 0.0f);  // Czerwony
    balls[0].offset = 0.0f; // Przesunięcie dla pierwszego łuku

    balls[1].position = glm::vec2(1.0f, 0.0f);
    balls[1].color = glm::vec3(0.0f, 0.0f, 1.0f);  // Niebieski
    balls[1].offset = 0.0f; // Przesunięcie dla drugiego łuku
}

void compileShaders() {
    Shader shader("circle_vs.glsl", "circle_fs.glsl");
    shaderProgram = shader.programID();
}

glm::vec2 customSlerp(const glm::vec2& start, const glm::vec2& end, float t) {
    float dot = glm::dot(start, end);
    dot = glm::clamp(dot, -1.0f, 1.0f);
    float theta = acos(dot) * t;
    glm::vec2 relativeVec = glm::normalize(end - start * dot);
    return start * cos(theta) + relativeVec * sin(theta);
}

void setupCircleBuffers() {
    const int numSegments = 360;
    std::vector<float> vertices;
    float radius = 1.0f;

    for (int i = 0; i <= numSegments; ++i) {
        float angle = i * 2.0f * M_PI / numSegments;
        vertices.push_back(cos(angle) * radius);
        vertices.push_back(sin(angle) * radius);
    }

    glGenVertexArrays(1, &circleVAO);
    glGenBuffers(1, &circleVBO);

    glBindVertexArray(circleVAO);

    glBindBuffer(GL_ARRAY_BUFFER, circleVBO);
    glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(float), vertices.data(), GL_STATIC_DRAW);
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);

    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);
}



void setupArcBuffers() {
    const int numSegments = 100;
    std::vector<float> arcVertices;

    for (int i = 0; i <= numSegments; ++i) {
        float angle = glm::radians(210.0f) * i / numSegments;
        arcVertices.push_back(cos(angle));
        arcVertices.push_back(sin(angle));
    }

    glGenVertexArrays(1, &arcVAO);
    glGenBuffers(1, &arcVBO);

    glBindVertexArray(arcVAO);

    glBindBuffer(GL_ARRAY_BUFFER, arcVBO);
    glBufferData(GL_ARRAY_BUFFER, arcVertices.size() * sizeof(float), arcVertices.data(), GL_STATIC_DRAW);
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);

    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);
}

void drawCircle() {
    glBindVertexArray(circleVAO);
    glDrawArrays(GL_LINE_LOOP, 0, 361);
    glBindVertexArray(0);
}

void drawSmallCircle() {
    glBindVertexArray(circleVAO);
    glDrawArrays(GL_TRIANGLE_FAN, 0, 361);
    glBindVertexArray(0);
}

void drawArcs() {
    glBindVertexArray(arcVAO);
    // Przesunięcie łuku 60 stopni
    glm::mat4 model = glm::translate(glm::mat4(1.0f), glm::vec3(0.0f, 0.0f, 0.0f));

    model = glm::rotate(model, glm::radians(-60.0f), glm::vec3(0.0f, 0.0f, 1.0f));
    unsigned int modelLoc = glGetUniformLocation(shaderProgram, "model");
    glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
    glDrawArrays(GL_LINE_STRIP, 0, 101);

    // Przesunięcie łuku 150 stopni
//    model = glm::translate(glm::mat4(1.0f), glm::vec3(offset, 0.0f, 0.0f));
    glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
    glDrawArrays(GL_LINE_STRIP, 101, 101);

    glBindVertexArray(0);
}


void display() {
    glClear(GL_COLOR_BUFFER_BIT);
    glUseProgram(shaderProgram);

    glm::mat4 view = glm::mat4(0.5f);
    glm::mat4 projection = glm::ortho(-2.0f, 2.0f, -1.5f, 1.5f);

    if(currentTrackedBall != -1){
        projection = glm::scale(projection, glm::vec3(cameraScale, cameraScale, 1.0f));
        projection = glm::translate(projection, glm::vec3(-balls[currentTrackedBall].position.x, -balls[currentTrackedBall].position.y, 0.0f));
    }

    unsigned int viewLoc = glGetUniformLocation(shaderProgram, "view");
    unsigned int projectionLoc = glGetUniformLocation(shaderProgram, "projection");
    glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
    glUniformMatrix4fv(projectionLoc, 1, GL_FALSE, glm::value_ptr(projection));

    unsigned int modelLoc = glGetUniformLocation(shaderProgram, "model");
    unsigned int colorLoc = glGetUniformLocation(shaderProgram, "color");

    // Rysowanie łuków
    glUniform3f(colorLoc, 1.0f, 1.0f, 1.0f);
    drawArcs();


    // Rysowanie kul
    for (const auto &ball : balls) {
        glm::mat4 model = glm::translate(glm::mat4(1.0f), glm::vec3(ball.position.x + ball.offset, ball.position.y, 0.0f));
        model = glm::scale(model, glm::vec3(0.05f, 0.05f, 1.0f)); // Skala dla małych kul
        glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
        glUniform3f(colorLoc, ball.color.r, ball.color.g, ball.color.b);
        drawSmallCircle(); // Rysujemy małe koło reprezentujące kulę
    }

    renderImGui();
    glfwSwapBuffers(glfwGetCurrentContext());
}



void update() {
    if(!shouldUpdate) {
        balls[0].position = customSlerp(glm::vec2(1.0f, 0.0f), glm::vec2(0.5f, -sqrt(3) / 2.0f), t);  // 60 stopni
        balls[1].position = customSlerp(glm::vec2(1.0f, 0.0f), glm::vec2(-sqrt(3) / 2.0f, 0.5f), t);  // 150 stopni
        return;
    };
    t += timeStep;
    if (t > 1.0f){
        if(shouldAlwaysUpdate){
            t = 0.0f;
        } else {
            shouldUpdate = false;
        }
    };

    balls[0].position = customSlerp(glm::vec2(1.0f, 0.0f), glm::vec2(0.5f, -sqrt(3) / 2.0f), t);  // 60 stopni
    balls[1].position = customSlerp(glm::vec2(1.0f, 0.0f), glm::vec2(-sqrt(3) / 2.0f, 0.5f), t);  // 150 stopni
}

void setupOpenGL() {
    compileShaders();
    setupCircleBuffers();
    setupArcBuffers();
    glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
}

void keyCallback(GLFWwindow* window, int key, int scancode, int action, int mods) {
    if (action == GLFW_PRESS) {
        switch (key) {
            case GLFW_KEY_ESCAPE:
                glfwSetWindowShouldClose(window, GLFW_TRUE);
                break;
        }
    }
}

int main() {
    if (!glfwInit()) {
        std::cerr << "Failed to initialize GLFW" << std::endl;
        return -1;
    }

    glfwWindowHint(GLFW_SAMPLES, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    window = glfwCreateWindow(windowWidth, windowHeight, "Visualizacja 2D - SLERP", nullptr, nullptr);
    if (!window) {
        std::cerr << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }

    glfwMakeContextCurrent(window);
    glfwSetKeyCallback(window, keyCallback);

    glewExperimental = GL_TRUE;
    if (glewInit() != GLEW_OK) {
        std::cerr << "Failed to initialize GLEW" << std::endl;
        return -1;
    }

    initializeBalls();
    setupOpenGL();
    initImGui();

    while (!glfwWindowShouldClose(window)) {
        display();
        update();
        glfwPollEvents();
    }

    glDeleteVertexArrays(1, &circleVAO);
    glDeleteBuffers(1, &circleVBO);
    glDeleteVertexArrays(1, &arcVAO);
    glDeleteBuffers(1, &arcVBO);
    glDeleteProgram(shaderProgram);

    cleanUpImGui();

    glfwDestroyWindow(window);
    glfwTerminate();
    return 0;
}