#include "externals.hh"
#include "rendertarget.hh"


T_RendertargetSetup::T_RendertargetSetup( )
	: hasAttachments_( false )
{ }

T_RendertargetSetup& T_RendertargetSetup::add(
		__rw__ T_Texture& texture ,
		__rd__ const uint32_t level )
{
	checkAttachment( texture , level );
	colorAttachments_.add( T_Attachment_{ texture , level } );
	return *this;
}


T_RendertargetSetup& T_RendertargetSetup::depth(
		__rw__ T_Texture& texture )
{
	assert( !depthAttachment_.present( ) );
	checkAttachment( texture , 0 );
	depthAttachment_.setNew( texture , 0 );
	return *this;
}


void T_RendertargetSetup::checkAttachment(
		__rw__ T_Texture const& texture ,
		__rd__ const uint32_t level )
{
	const uint32_t tw( texture.width( ) >> level ) ,
			th( texture.height( ) >> level );
	if ( hasAttachments_ ) {
		assert( tw == width_ );
		assert( th == height_ );
	} else {
		width_ = tw;
		height_ = th;
		hasAttachments_ = true;
	}
}


T_Rendertarget T_RendertargetSetup::create( )
{
	const auto nca( colorAttachments_.size( ) );
	assert( hasAttachments_ );
	assert( nca != 0 );

	// Generate / setup the GL framebuffer
	GLuint id( 0 );
	glGenFramebuffers( 1 , &id );
	glBindFramebuffer( GL_FRAMEBUFFER , id );
	for ( auto i = 0u ; i < nca ; i ++ ) {
#ifdef INTRUSIVE_TRACES
		printf( "init %p fb %d att %d tx %p level %d\n" ,
				this , id , i ,
				colorAttachments_[ i ].texture ,
				colorAttachments_[ i ].level );
#endif
		glFramebufferTexture( GL_FRAMEBUFFER ,
				GL_COLOR_ATTACHMENT0 + i ,
				colorAttachments_[ i ].texture->id( ) ,
				colorAttachments_[ i ].level );
	}
	if ( depthAttachment_.present( ) ) {
		T_Attachment_ const& de( depthAttachment_ );
		glFramebufferTexture( GL_FRAMEBUFFER ,
				GL_DEPTH_ATTACHMENT ,
				de.texture->id( ) ,
				de.level );
	}
	assert( glCheckFramebufferStatus( GL_FRAMEBUFFER ) == GL_FRAMEBUFFER_COMPLETE );
	glBindFramebuffer( GL_FRAMEBUFFER , 0 );

	assert( glGetError( ) == GL_NO_ERROR );

	// Reset config
	hasAttachments_ = false;
	colorAttachments_.clear( );
	depthAttachment_.clear( );

	return T_Rendertarget( id , nca , width_ , height_ );
}

/*============================================================================*/

T_Rendertarget::T_Rendertarget(
		__rd__ const uint32_t id ,
		__rd__ const uint32_t nCats ,
		__rd__ const uint32_t width ,
		__rd__ const uint32_t height )
	: id_( id ) , nCats_( nCats ) , width_( width ) , height_( height )
{ }

T_Rendertarget::T_Rendertarget(
		__rw__ T_Rendertarget&& other ) noexcept
	: id_( 0 ) , nCats_( other.nCats_ ) , width_( other.width_ ) ,
		height_( other.height_ )
{
	std::swap( id_ , other.id_ );
}

T_Rendertarget& T_Rendertarget::operator =(
		__rw__ T_Rendertarget&& other ) noexcept
{
	std::swap( id_ , other.id_ );
	std::swap( nCats_ , other.nCats_ );
	std::swap( width_ , other.width_ );
	std::swap( height_ , other.height_ );
	return *this;
}

T_Rendertarget::~T_Rendertarget( )
{
	if ( id_ != 0 ) {
		glDeleteFramebuffers( 1 , &id_ );
	}
}

bool T_Rendertarget::activate( )
{
	if ( id_ != 0 ) {
#ifdef INTRUSIVE_TRACES
		printf( "ACTIVATING FB %d (%dx%d, %d c.a.)\n" ,
				id_ , width_ , height_ , nCats_ );
#endif
		if ( nCats_ != buffers_.size( ) ) {
			buffers_.clear( );
			for ( auto i = 0u ; i < nCats_ ; i ++ ) {
				buffers_.add( GL_COLOR_ATTACHMENT0 + i );
			}
#ifdef INTRUSIVE_TRACES
			printf( "fb %d: created buffers (%d items)\n" , id_ ,
					int( buffers_.size( ) ) );
#endif
		}
		glBindFramebuffer( GL_FRAMEBUFFER , id_ );
		glViewport( 0 , 0 , width_ , height_ );
		glDrawBuffers( nCats_ , &buffers_[ 0 ] );

		assert( glCheckFramebufferStatus( GL_FRAMEBUFFER )
				== GL_FRAMEBUFFER_COMPLETE );
		assert( glGetError( ) == GL_NO_ERROR );
	}
	return id_ != 0;
}

void T_Rendertarget::MainOutput( )
{
	auto const& dspSize( ImGui::GetIO( ).DisplaySize );
	glBindFramebuffer( GL_FRAMEBUFFER , 0 );
	glViewport( 0 , 0 , (int) dspSize.x, (int) dspSize.y );
}