GBuffer::GBuffer()  {

}

GBuffer::~GBuffer() {
    glDeleteTextures(2, &mTextures[0]);
    glDeleteTextures(1, &mDepthBuffer);
    glDeleteFramebuffers(1, &mFrameBuffer);
}

bool GBuffer::create(std::uint32_t width, std::uint32_t height) {
    mWidth = width;
    mHeight = height;

    mRenderState = RenderState(mWidth, mHeight);

    return initialize();
}

void GBuffer::readBind() {
    glBindFramebuffer(GL_FRAMEBUFFER, 0);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, mTextures[TEX_DIFFUSE]);

    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, mTextures[TEX_NORMALS]);
}

void GBuffer::readUnbind() {
    //glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
}

void GBuffer::writeBind(RenderContext *context) {
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, mFrameBuffer);
    context->push(&mRenderState);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}

void GBuffer::writeUnbind(RenderContext *context) {
    context->pop();
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
}

RenderState* GBuffer::state() {
    return &mRenderState;
}

bool GBuffer::initialize() {
    // Create textures
    glGenTextures(2, &mTextures[0]);
    glGenTextures(1, &mDepthBuffer);

    // Setup diffuse and normal maps
    for(int i = 0; i < 2; i++)  {
        glBindTexture(GL_TEXTURE_2D, mTextures[0]);

        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, mWidth, mHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, 0);
    }

    // Setup depth buffer
    glBindTexture(GL_TEXTURE_2D, mDepthBuffer);

    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameterf(GL_TEXTURE_2D, GL_DEPTH_TEXTURE_MODE, GL_INTENSITY);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE,
        GL_COMPARE_R_TO_TEXTURE);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FUNC, GL_LEQUAL);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, mWidth, mHeight, 0,
        GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, 0);

    glBindTexture(GL_TEXTURE_2D, 0);

    // Create the framebuffer
    glGenFramebuffers(1, &mFrameBuffer);
    glBindFramebuffer(GL_FRAMEBUFFER, mFrameBuffer);

    glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, mTextures[0],0);
    glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, mTextures[1],0);
    glFramebufferTexture(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, mDepthBuffer, 0);

    GLenum attachments[] = {GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1};
    glDrawBuffers(2, &attachments[0]);

    GLenum err = glCheckFramebufferStatus(GL_FRAMEBUFFER);
    if(err != GL_FRAMEBUFFER_COMPLETE) {
        LOG_ERROR(mLog, "Failed to create GBuffer: " + StringParser::intToString(err));
        return false;
    }

    glBindFramebuffer(GL_FRAMEBUFFER, 0);

    return true;
}