#include "externals.hh"
#include "utilities.hh"
#include "texture.hh"
#include "rendertarget.hh"
#include "programs.hh"
#include "raymarcher.hh"
#include "profiling.hh"

namespace {
	static const std::string Name_( "Raymarcher" );
}

#define PSTART() T_Profiler::Profiler.start( Name_ )
#define PEND() do { glFinish( ); T_Profiler::Profiler.end( Name_ ); } while ( 0 )

T_Raymarcher::T_Raymarcher(
		__rw__ T_FilesWatcher& watcher ,
		__rd__ const uint32_t width ,
		__rd__ const uint32_t height )
	: camera_( ) , program_( GL_FRAGMENT_SHADER , watcher ) ,
		txOutput_( width , height , E_TexType::RGB16F ) ,
		txDepth_( width , height , E_TexType::R16F ) ,
		rtOutput_( T_RendertargetSetup( )
				.add( txOutput_ )
				.add( txDepth_ )
				.create( ) )
{
	glGenProgramPipelines( 1 , &pipeline_ );

	program_.addFile( "raymarch-header.glsl" );
	program_.addFile( "map.glsl" );
	program_.addFile( "raymarcher.glsl" );
	program_.load( );

	auto& fsq( T_ShaderProgram::FullscreenQuad( watcher ) );
	glUseProgramStages( pipeline_ , GL_VERTEX_SHADER_BIT , fsq.id( ) );
	glUseProgramStages( pipeline_ , GL_FRAGMENT_SHADER_BIT , program_.id( ) );
	assert( glGetError( ) == GL_NO_ERROR );
}


void T_Raymarcher::render( )
{
	PSTART( );
	if ( ! rtOutput_.activate( ) ) {
		PEND( );
		return;
	}

	glBindProgramPipeline( pipeline_ );
	glClearColor( 0 , 0 , 0 , 1 );
	glClear( GL_COLOR_BUFFER_BIT );
	enum {
		U_TIME			= 0 ,
		U_RESOLUTION		= 1 ,
		U_CAM_POS		= 2 ,
		U_LOOK_AT		= 3 ,
		U_CAM_UP		= 4 ,
		U_NEAR_PLANE		= 5 ,
		U_LIGHT_DIR		= 6 ,
		U_RAYMARCHER		= 7 ,
	};

	glProgramUniform1f( program_.id( ) , U_TIME , 0 );
	glProgramUniform2f( program_.id( ) , U_RESOLUTION , rtOutput_.width( ) , rtOutput_.height( ) );

	glProgramUniform3fv( program_.id( ) , U_CAM_POS , 1 , &camera_.pos.x );
	glProgramUniform3fv( program_.id( ) , U_LOOK_AT , 1 , &camera_.lookAt.x );
	glProgramUniform3fv( program_.id( ) , U_CAM_UP , 1 , &camera_.up.x );
	glProgramUniform1f( program_.id( ) , U_NEAR_PLANE , camera_.np );

	glProgramUniform3f( program_.id( ) , U_LIGHT_DIR , 0 , 1 , 1 );

	glProgramUniform4f( program_.id( ) , U_RAYMARCHER , rmIterations , rmStep ,
			rmEpsilon , rmMaxDist );

	glDrawArrays( GL_TRIANGLE_STRIP , 0 , 4 );
	glBindProgramPipeline( 0 );

	PEND( );
}

void T_Raymarcher::makeUI( )
{
	camera_.makeUI( );

	if ( !ImGui::CollapsingHeader( "Raymarcher" ) ) {
		return;
	}

	ImGui::DragInt( "Iterations" , &rmIterations , .1 , 1 , 512 );
	ImGui::DragFloat( "Step" , &rmStep , .005 , .1 , 2 );
	ImGui::DragFloat( "Max. dist." , &rmMaxDist , .1f ,
			0.01 , 1000.0 , "%.2f" );
	if ( ImGui::DragFloat( "Epsilon" , &epsLog , .01f ,
			-10 , -0.5 , "10 ^ %.2f" ) ) {
		rmEpsilon = pow( 10 , epsLog );
	}
}