std::string readFromFile(const std::string &filename) {
    std::string res;
    std::string line;
    std::ifstream file(filename);
    if (file.is_open()) {
        while (std::getline(file, line)) {
            res += line + "\n";
        }
    }
    else {
        throw std::logic_error("Can't open file: " + filename);
    }
    return res;
}

Shader::Shader(const std::string &vertexPath, const std::string &fragPath) {
    unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
    std::string vShader = readFromFile(vertexPath);
    GLchar const* vSh[] = { vShader.c_str() };
    glShaderSource(vertexShader, 1, vSh, NULL);
    glCompileShader(vertexShader);
    checkShaderCompilation(vertexShader);

    unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    std::string fShader = readFromFile(fragPath);
    GLchar const* fSh[] = { fShader.c_str() };
    glShaderSource(fragmentShader, 1, fSh, NULL);
    glCompileShader(fragmentShader);
    checkShaderCompilation(fragmentShader);

    programID = glCreateProgram();
    glAttachShader(programID, vertexShader);
    glAttachShader(programID, fragmentShader);
    glLinkProgram(programID);
    checkProgramLinking();

    glDeleteShader(fragmentShader);
    glDeleteShader(vertexShader);
}

void Shader::Use() {
    glUseProgram(programID);
}