#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <string>
#include <fstream>

using namespace std;

void printShaderLog(GLuint shader) {
    int len = 0;
    int chWrittn = 0;
    char *log;
    glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &len);
    if (len > 0) {
        log = (char *) malloc(len);
        glGetShaderInfoLog(shader, len, &chWrittn, log);
        cout << "Shader Info Log: " << log << endl;
        free(log);
    }
}

void printProgramLog(int prog) {
    int len = 0;
    int chWrittn = 0;
    char *log;
    glGetProgramiv(prog, GL_INFO_LOG_LENGTH, &len);
    if (len > 0) {
        log = (char *) malloc(len);
        glGetProgramInfoLog(prog, len, &chWrittn, log);
        cout << "Program Info Log: " << log << endl;
        free(log);
    }
}

bool checkOpenGLError() {
    bool foundError = false;
    int glErr = glGetError();
    while (glErr != GL_NO_ERROR) {
        cout << "glError : " << glErr << endl;
        foundError = true;
        glErr = glGetError();
    }
    return foundError;
}

string readShaderSource(const char *filePath) {
    string content;
    ifstream fileStream(filePath, ios::in);
    string line = "";
    while (!fileStream.eof()) {
        getline(fileStream, line);
        content.append(line + "\n");
    }
    fileStream.close();
    return content;
}

using namespace std;

#define numVAOs 1

GLuint renderingProgram;
GLuint vao[numVAOs];
float x = 0.0f;
float inc = 0.01f;

GLuint createShaderProgram() {

    const char *vshaderSource = readShaderSource("../tri.vert").c_str();
//    const char *vshaderSource = "#version 430 \n"
//                                "\n"
//                                "void main(void)\n"
//                                "{\n"
//                                " if (gl_VertexID == 0) gl_Position = vec4( 0.25, -0.25, 0.0, 1.0);\n"
//                                "else if (gl_VertexID == 1) gl_Position = vec4(-0.25, -0.25, 0.0, 1.0);\n"
//                                " else gl_Position = vec4( 0.25, 0.25, 0.0, 1.0);}";
//    cout<<vshaderSource;
    const char *fshaderSource = readShaderSource("../firstvert.vert").c_str();
//    cout<<fshaderSource;
    GLuint vShader = glCreateShader(GL_VERTEX_SHADER);
    GLuint fShader = glCreateShader(GL_FRAGMENT_SHADER);

    glShaderSource(vShader, 1, &vshaderSource, NULL);
    glShaderSource(fShader, 1, &fshaderSource, NULL);

    printShaderLog(vShader);
    printShaderLog(fShader);

    glCompileShader(fShader);
    glCompileShader(vShader);

    cout<<"on vShader";
    printShaderLog(vShader);
    cout<<"on fShader";
    printShaderLog(fShader);

    GLuint vfProgram = glCreateProgram();
    glAttachShader(vfProgram, vShader);
    glAttachShader(vfProgram, fShader);
    glLinkProgram(vfProgram);
    return vfProgram;
}


void init(GLFWwindow *window) {
    renderingProgram = createShaderProgram();
    glGenVertexArrays(numVAOs, vao);
    glBindVertexArray(vao[0]);
}

void display(GLFWwindow *window, double currentTime) {

    glClear(GL_DEPTH_BUFFER_BIT);
    glClearColor(0, 0, 0, 1);
    glClear(GL_COLOR_BUFFER_BIT);
    glUseProgram(renderingProgram);

//    printProgramLog(renderingProgram);
    //     glPointSize(3);
//    x += inc;
//    if (x > 1.0f) inc = -0.01f;
//    if (x < -1.0f) inc = 0.01f;
//    cout << x << endl;;
//    GLuint offsetLoc = glGetUniformLocation(renderingProgram, "offset");
//    glProgramUniform1f(renderingProgram, offsetLoc, x);
    glDrawArrays(GL_TRIANGLES, 0, 3);

}

int main(void) {
    if (!glfwInit()) { exit(EXIT_FAILURE); }
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    GLFWwindow *window = glfwCreateWindow(600, 600, "GLAPP0", NULL, NULL);
    glfwMakeContextCurrent(window);
    if (glewInit() != GLEW_OK) {
        exit(EXIT_FAILURE);
    }
    glfwSwapInterval(1);
    init(window);

    checkOpenGLError();
    while (!glfwWindowShouldClose(window)) {
        display(window, glfwGetTime());
        glfwSwapBuffers(window);
        glfwPollEvents();
    }


    glfwDestroyWindow(window);
    glfwTerminate();
    exit(EXIT_SUCCESS);
}