#include "client/engine/shader/SSAOBlurShader.h"
#include "client/engine/Wrapper.h"

SSAOBlurShader::SSAOBlurShader()
{
}

SSAOBlurShader::~SSAOBlurShader()
{
    glDeleteFramebuffers(1, &framebuffer);
    glDeleteTextures(1, &texture);
}

bool SSAOBlurShader::init()
{
    program.compile("resources/shader/ssaoBlurVertex.vs", "resources/shader/ssaoBlurFragment.fs");
    if(!program.isValid())
    {
        return false;
    }
    
    // generate framebuffer
    glGenFramebuffers(1, &framebuffer);
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
    
    // color texture
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, Engine::getWidth(), Engine::getHeight(), 0, GL_RGB, GL_FLOAT, NULL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    // attache color texture to framebuffer
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);  
    
    // check if framebuffer is okay
    if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
    {
	cout << "ssao blur frame buffer is not complete!" << endl;
        return false;
    }
    // unbind framebuffer
    glBindFramebuffer(GL_FRAMEBUFFER, 0);

    return true;
}

void SSAOBlurShader::resize()
{
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, Engine::getWidth(), Engine::getHeight(), 0, GL_RGB, GL_FLOAT, NULL);
}

void SSAOBlurShader::preRender()
{
    // bind ssao blur shader program
    glUseProgram(program.getProgram());
    
    // bind ssao blur framebuffer
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
    //glBindFramebuffer(GL_FRAMEBUFFER, 0);
    
    // clear color buffer
    glClear(GL_COLOR_BUFFER_BIT);
    
    // depth testing is not needed
    glDisable(GL_DEPTH_TEST);
}

void SSAOBlurShader::bindTexture(unsigned int textureUnit)
{
    glActiveTexture(GL_TEXTURE0 + textureUnit);
    glBindTexture(GL_TEXTURE_2D, texture);
}