#include "externals.hh"
#include "programs.hh"


/*= T_ShaderCode =============================================================*/

T_ShaderCode::T_ShaderCode(
		__rd__	const int nparts )
	: code( nparts , nullptr )
{ }

T_ShaderCode::~T_ShaderCode( )
{
	for ( char* str : code ) {
		delete[] str;
	}
}

/*----------------------------------------------------------------------------*/

void T_ShaderCode::setPart(
			__rd__	const int index ,
			__rd__	char const* const string )
{
	assert( code[ index ] == nullptr );

	const int len( strlen( string ) + 1 );
	char buffer[ 32 ];
	const int extraLen( index == 0 ? 0
			: snprintf( buffer , sizeof( buffer ) ,
				"\n#line 0 %d\n" , index ) );

	char* const output( new char[ extraLen + len ] );
	if ( index != 0 ) {
		memcpy( output , buffer , extraLen );
	}
	strcpy( output + extraLen , string );
	code[ index ] = output;
}

void T_ShaderCode::setPart(
		__rd__	const int index ,
		__rd__	void const* const data ,
		__rd__	const int size )
{
	assert( code[ index ] == nullptr );

	char buffer[ 32 ];
	const int extraLen( index == 0 ? 0
			: snprintf( buffer , sizeof( buffer ) ,
				"\n#line 0 %d\n" , index ) );

	char* const output( new char[ extraLen + size + 1 ] );
	if ( index != 0 ) {
		memcpy( output , buffer , extraLen );
	}
	memcpy( output + extraLen , data , size );
	output[ extraLen + size ] = 0;
	code[ index ] = output;
}

bool T_ShaderCode::loadPart(
		__rd__	const int index ,
		__rd__	std::string const& source ,
		__rw__	std::vector< std::string >& errors )
{
	assert( code[ index ] == nullptr );

	const std::string sPath( "shaders/" + source );
	FILE * f = fopen( sPath.c_str( ) , "r" );
	if ( !f ) {
		errors.push_back( std::string( "File not found: " + sPath ) );
		return false;
	}

	char buffer[ 32 ];
	const int extraLen( index == 0 ? 0
			: snprintf( buffer , sizeof( buffer ) ,
				"\n#line 0 %d\n" , index ) );

	fseek( f , 0 , SEEK_END );
	const size_t size( ftell( f ) );
	fseek( f , 0 , SEEK_SET );

	char* const output( new char[ extraLen + size + 1 ] );
	if ( index != 0 ) {
		memcpy( output , buffer , extraLen );
	}
	if ( fread( output + extraLen , 1 , size , f ) != size ) {
		fclose( f );
		delete[] output;
		std::string error( "Could not read file: " );
		error += source;
		errors.push_back( error );
		return false;
	}
	output[ extraLen + size ] = 0;
	fclose( f );
	code[ index ] = output;
	return true;
}

/*----------------------------------------------------------------------------*/

GLuint T_ShaderCode::createProgram(
		__rd__	GLenum type ,
		__rw__	std::vector< std::string >& errors ) const
{
	GLenum sid = glCreateShaderProgramv( type , code.size( ) , &code[ 0 ] );
	if ( sid == 0 ) {
		errors.push_back( "Failed to create GL program" );
		return sid;
	}

	int infoLogLength;
	glGetProgramiv( sid , GL_INFO_LOG_LENGTH , &infoLogLength );
	if ( infoLogLength ) {
		char buffer[ infoLogLength + 1 ];
		glGetProgramInfoLog( sid , infoLogLength , nullptr , buffer );
		char* start( buffer );
		char* found( strchr( buffer , '\n' ) );
		while ( found ) {
			*found = 0;
			errors.push_back( start );
			start = found + 1;
			found = strchr( start , '\n' );
		}
		if ( start < &buffer[ infoLogLength - 1 ] ) {
			errors.push_back( start );
		}
	}

	int lnk;
	glGetProgramiv( sid , GL_LINK_STATUS , &lnk );
	if ( !lnk ) {
		glDeleteProgram( sid );
		return 0;
	}

	return sid;
}


/*= T_ShaderProgram ==========================================================*/

T_ShaderProgram::T_ShaderProgram(
		__rd__ const GLenum programType ,
		__rw__ T_FilesWatcher& watcher )
	: files_( watcher , [this] { load( ); } ) ,
		programType_( programType ) , program_( 0 )
{
}

T_ShaderProgram::~T_ShaderProgram( )
{
	if ( program_ != 0 ) {
		glDeleteProgram( program_ );
	}
}

void T_ShaderProgram::addChunk(
		__rd__ std::string const& string )
{
	chunksOrFiles_.push_back( true );
	parts_.push_back( string );
}

void T_ShaderProgram::addFile(
		__rd__ std::string const& source )
{
	chunksOrFiles_.push_back( false );
	parts_.push_back( source );
}

void T_ShaderProgram::load( )
{
	const auto n( parts_.size( ) );
	errors_.clear( );
	files_.clear( );
	if ( program_ != 0 ) {
		glDeleteProgram( program_ );
		program_ = 0;
	}

	T_ShaderCode sc( n );
	printf( "LOAD PROGRAM" );
	for ( auto i = 0u ; i < n ; i ++ ) {
		if ( chunksOrFiles_[ i ] ) {
			printf( " %d:(chunk)" , i );
			sc.setPart( i , parts_[ i ].c_str( ) );
		} else {
			printf( " %d:%s" , i , parts_[ i ].c_str( ) );
			if ( sc.loadPart( i , parts_[ i ].c_str( ) , errors_ ) ) {
				files_.watch( parts_[ i ] );
			}
		}
	}
	printf( "\n" );

	if ( errors_.size( ) == 0 ) {
		program_ = sc.createProgram( programType_ , errors_ );
		if ( program_ != 0 ) {
			GLint x;
			glGetProgramInterfaceiv( program_ , GL_PROGRAM_OUTPUT ,
					GL_ACTIVE_RESOURCES , &x );
			printf( "-> LOADED (%d output(s)" , x );
			for ( int i = 0 ; i < x ; i ++ ) {
				static const GLenum query[] = {
					GL_NAME_LENGTH , GL_LOCATION
				};
				int output[ 2 ];
				glGetProgramResourceiv( program_ , GL_PROGRAM_OUTPUT ,
						i , 2 , query , 2 , nullptr ,
						output );

				char rName[ output[ 0 ] + 1 ];
				glGetProgramResourceName( program_ ,
						GL_PROGRAM_OUTPUT , i ,
						sizeof( rName ) , nullptr ,
						rName );
				printf( "%s %s@%d" , i == 0 ? ":" : "" , rName ,
						output[ 1 ] );
			}
			printf( ")\n" );
		}
	}

	if ( errors_.size( ) ) {
		printf( "\n--------------------------------------------------------------------------------\n\n" );
		for ( auto const& str : errors_ ) {
			printf( "ERR: %s\n" , str.c_str( ) );
		}
	}
}

bool T_ShaderProgram::activate( ) const
{
	if ( program_ != 0 ) {
		glUseProgram( program_ );
	}
	return program_ != 0;
}

namespace {
	std::unique_ptr< T_ShaderProgram > FsQuad_;
}

T_ShaderProgram const& T_ShaderProgram::FullscreenQuad(
		__rw__ T_FilesWatcher& watcher )
{
	if ( !FsQuad_ ) {
		FsQuad_ = std::make_unique< T_ShaderProgram >(
				GL_VERTEX_SHADER , watcher );
		FsQuad_->addFile( "fsquad.glsl" );
		FsQuad_->load( );
	}
	return *FsQuad_;
}