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

WorldShader::WorldShader()
{
}

WorldShader::~WorldShader()
{
    glDeleteFramebuffers(1, &framebuffer);
    glDeleteTextures(1, &positionTexture);
    glDeleteTextures(1, &normalTexture);
    glDeleteTextures(1, &colorTexture);
    glDeleteTextures(1, &depthTexture);
}

bool WorldShader::init()
{
    program.compile("resources/shader/worldVertex.vs", "resources/shader/worldFragment.fs");
    if(!program.isValid())
    {
        return false;
    }
    
    // generate framebuffer
    glGenFramebuffers(1, &framebuffer);
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
    
    // position texture
    glGenTextures(1, &positionTexture);
    glBindTexture(GL_TEXTURE_2D, positionTexture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, 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);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    // attache position texture to framebuffer
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, positionTexture, 0);   
    
    // normal texture
    glGenTextures(1, &normalTexture);
    glBindTexture(GL_TEXTURE_2D, normalTexture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, 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 normal texture to framebuffer
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, normalTexture, 0);   
    
    // color texture
    glGenTextures(1, &colorTexture);
    glBindTexture(GL_TEXTURE_2D, colorTexture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, Engine::getWidth(), Engine::getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, 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_ATTACHMENT2, GL_TEXTURE_2D, colorTexture, 0);  
    
    // depth texture
    glGenTextures(1, &depthTexture);
    glBindTexture(GL_TEXTURE_2D, depthTexture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH24_STENCIL8, Engine::getWidth(), Engine::getHeight(), 0, GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8, NULL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    // attache depth texture to framebuffer
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_TEXTURE_2D, depthTexture, 0); 
    
    // set color attachements for the framebuffer
    GLuint attachments[3] = 
    {
        GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2 
    };
    glDrawBuffers(3, attachments);   
    
    // check if framebuffer is okay
    if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
    {
	cout << "world frame buffer is not complete!" << endl;
        return false;
    }
    // unbind framebuffer
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    
    // get uniform locations
    unifProjMatrix = glGetUniformLocation(program.getProgram(), "projMatrix");
    unifViewMatrix = glGetUniformLocation(program.getProgram(), "viewMatrix");
    unifModelMatrix = glGetUniformLocation(program.getProgram(), "modelMatrix");
    
    return true;
}

void WorldShader::resize()
{
    glBindTexture(GL_TEXTURE_2D, positionTexture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, Engine::getWidth(), Engine::getHeight(), 0, GL_RGB, GL_FLOAT, NULL);
   
    glBindTexture(GL_TEXTURE_2D, normalTexture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, Engine::getWidth(), Engine::getHeight(), 0, GL_RGB, GL_FLOAT, NULL);
 
    glBindTexture(GL_TEXTURE_2D, colorTexture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, Engine::getWidth(), Engine::getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
 
    glBindTexture(GL_TEXTURE_2D, depthTexture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH24_STENCIL8, Engine::getWidth(), Engine::getHeight(), 0, GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8, NULL);
}

void WorldShader::preRender(const float* projMatrix)
{
    // bind world shader program
    glUseProgram(program.getProgram());
    
    // set projection matrix uniform
    glUniformMatrix4fv(unifProjMatrix, 1, 0, projMatrix);

    // all textures bind to texture unit 0
    glActiveTexture(GL_TEXTURE0);
    
    // bind world framebuffer
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
    
    // clear color, depth and stencil buffer
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
    
    // depth testing is needed
    glEnable(GL_DEPTH_TEST);
}

void WorldShader::bindPositionTexture(unsigned int textureUnit)
{
    glActiveTexture(GL_TEXTURE0 + textureUnit);
    glBindTexture(GL_TEXTURE_2D, positionTexture);
}

void WorldShader::bindNormalTexture(unsigned int textureUnit)
{
    glActiveTexture(GL_TEXTURE0 + textureUnit);
    glBindTexture(GL_TEXTURE_2D, normalTexture);
}

void WorldShader::bindColorTexture(unsigned int textureUnit)
{
    glActiveTexture(GL_TEXTURE0 + textureUnit);
    glBindTexture(GL_TEXTURE_2D, colorTexture);
}

void WorldShader::bindDepthTexture(unsigned int textureUnit)
{
    glActiveTexture(GL_TEXTURE0 + textureUnit);
    glBindTexture(GL_TEXTURE_2D, depthTexture);
}

void WorldShader::setViewMatrix(const float* data)
{
    glUniformMatrix4fv(unifViewMatrix, 1, 0, data);
}

void WorldShader::setModelMatrix(const float* data)
{
    glUniformMatrix4fv(unifModelMatrix, 1, 0, data);
}