Shader::Shader(std::string VShader, std::string FShader)
{
    std::string vsh_src((std::istreambuf_iterator<char>(std::fstream(VShader))),
        std::istreambuf_iterator<char>());

    std::string fsh_src((std::istreambuf_iterator<char>(std::fstream(FShader))),
        std::istreambuf_iterator<char>());

    VertexShader = vsh_src;
    FragmentShader = fsh_src;

    Compile();
}

void Shader::AddShader(GLuint ShaderProgram, const std::string& pShaderText, GLenum ShaderType)
{
    GLuint ShaderObj = glCreateShader(ShaderType);

    const GLchar* p[1];
    p[0] = pShaderText.data();
    GLint Lengths[1];
    Lengths[0] = pShaderText.length();
    glShaderSource(ShaderObj, 1, p, Lengths);

    glCompileShader(ShaderObj);

    GLint success;
    glGetShaderiv(ShaderObj, GL_COMPILE_STATUS, &success);

    if (!success) {
        GLchar InfoLog[1024];
        glGetShaderInfoLog(ShaderObj, 1024, NULL, InfoLog);
        printf("Error compiling shader type %d: '%s'\n", ShaderType, InfoLog);
    }

    glAttachShader(ShaderProgram, ShaderObj);
}

void Shader::Compile()
{
    ShaderProgram = glCreateProgram();

    AddShader(ShaderProgram, VertexShader, GL_VERTEX_SHADER);
    AddShader(ShaderProgram, FragmentShader, GL_FRAGMENT_SHADER);

    glLinkProgram(ShaderProgram);

    GLint Success = 0;
    GLchar ErrorLog[1024] = { 0 };
    glGetProgramiv(ShaderProgram, GL_LINK_STATUS, &Success);
    if (Success == 0) {
        glGetProgramInfoLog(ShaderProgram, sizeof(ErrorLog), NULL, ErrorLog);
        printf("Error linking shader program: '%s'\n", ErrorLog);
    }
    glValidateProgram(ShaderProgram);
    glGetProgramiv(ShaderProgram, GL_VALIDATE_STATUS, &Success);
    if (Success == 0) {
        glGetProgramInfoLog(ShaderProgram, sizeof(ErrorLog), NULL, ErrorLog);
        printf("Invalid shader program: '%s'\n", ErrorLog);
    }
    glUseProgram(ShaderProgram);
}