#include "externals.hh"
#include "utilities.hh"


void disableButton( )
{
	ImGui::PushStyleColor( ImGuiCol_Button , ImColor( .3f , .3f , .3f ) );
	ImGui::PushStyleColor( ImGuiCol_ButtonHovered , ImColor( .3f , .3f , .3f ) );
	ImGui::PushStyleColor( ImGuiCol_ButtonActive , ImColor( .3f , .3f , .3f ) );
}

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

void updateAngle(
		__rw__	float& initial ,
		__rd__	const float delta
	)
{
	initial = fmod( initial + delta + 540 , 360 ) - 180;
}

void anglesToMatrix(
		__rd__	float const* angles ,
		__wr__	float* matrix )
{
	float c[3] , s[3];
	for ( int i = 0 ; i < 3 ; i ++ ) {
		const float a = M_PI * angles[ i ] / 180;
		c[i] = cos( a );
		s[i] = sin( a );
	}
	matrix[0] = c[1]*c[2];
	matrix[1] = s[0]*s[1]*c[2] - c[0]*s[2];
	matrix[2] = s[0]*s[2] + c[0]*s[1]*c[2];
	matrix[3] = c[1]*s[2];
	matrix[4] = c[0]*c[2] + s[0]*s[1]*s[2];
	matrix[5] = c[0]*s[1]*s[2] - s[0]*c[2];
	matrix[6] = -s[1];
	matrix[7] = s[0]*c[1];
	matrix[8] = c[0]*c[1];
}


/*= T_FilesWatcher ===========================================================*/

T_FilesWatcher::T_FilesWatcher( )
	: fd( inotify_init1( O_NONBLOCK ) )
{ }

T_FilesWatcher::T_FilesWatcher( T_FilesWatcher&& other ) noexcept
	: fd( 0 ) , watched( std::move( other.watched ) )
{
	std::swap( fd , other.fd );
	other.watched.clear( );
	for ( T_WatchedFiles* wf : watched ) {
		if ( wf ) {
			wf->watcher = this;
		}
	}
}

T_FilesWatcher::~T_FilesWatcher( )
{
	if ( fd ) {
		close( fd );
	}
	for ( T_WatchedFiles* wf : watched ) {
		if ( wf ) {
			wf->watcher = nullptr;
		}
	}
}

void T_FilesWatcher::check( )
{
	for ( T_WatchedFiles* wf : watched ) {
		if ( wf ) {
			wf->triggered = false;
		}
	}

	inotify_event ie;
	while ( read( fd , &ie , sizeof( ie ) ) == sizeof( ie ) ) {
		if ( ( ie.mask & ( IN_CLOSE_WRITE | IN_DELETE_SELF ) ) == 0 ) {
			continue;
		}

		for ( T_WatchedFiles* wf : watched ) {
			if ( !wf || wf->triggered ) {
				continue;
			}
			auto const& idl( wf->identifiers );
			if ( find( idl , ie.wd ) != idl.end( ) ) {
				wf->triggered = true;
				wf->callback( );
			}
		}
	}
}

/*= T_WatchedFiles ===========================================================*/

T_WatchedFiles::T_WatchedFiles( T_WatchedFiles&& other ) noexcept
	: watcher( other.watcher ) , callback( other.callback ) ,
		triggered( other.triggered ) ,
		identifiers( std::move( other.identifiers ) )
{
	if ( watcher ) {
		other.watcher = nullptr;
		*( find( watcher->watched , &other ) ) = this;
	}
}

T_WatchedFiles::T_WatchedFiles(
		__rw__	T_FilesWatcher& watcher ,
		__rd__	const F_OnFileChanges callback )
	: watcher( &watcher ) , callback( callback ) , triggered( false )
{
	watcher.watched.push_back( this );
}

T_WatchedFiles::~T_WatchedFiles( )
{
	clear( );
	if ( watcher ) {
		watcher->watched.erase( find( watcher->watched , this ) );
	}
}

void T_WatchedFiles::clear( )
{
	if ( watcher ) {
		const auto fd( watcher->fd );
		for ( int wd : identifiers ) {
			inotify_rm_watch( fd , wd );
		}
	}
	identifiers.clear( );
}

bool T_WatchedFiles::watch(
		__rd__	std::string const& file )
{
	static constexpr auto inFlags( IN_CLOSE_WRITE | IN_DELETE_SELF );
	if ( watcher ) {
		const auto wd( inotify_add_watch( watcher->fd ,
					file.c_str( ) , inFlags ) );
		if ( wd == -1 ) {
			return false;
		}
		if ( find( identifiers , wd ) == identifiers.end( ) ) {
			identifiers.push_back( wd );
		}
		return true;
	}
	return false;
}


/*= 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 );

	FILE * f = fopen( source.c_str( ) , "r" );
	if ( !f ) {
		std::string error( "File not found: " );
		error += source;
		errors.push_back( error );
		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_Camera =================================================================*/

void T_Camera::handleDND(
		__rd__	ImVec2 const& move ,
		__rd__	const bool hasCtrl ,
		__rd__	const bool hasShift ,
		__rd__	const bool lmb		// Left mouse button
	)
{
	if ( move.x == 0 || move.y == 0 ) {
		return;
	}

	const float fdx( move.x * .1f * ( hasCtrl ? 1.f : .1f ) );
	const float fdy( move.y * .1f * ( hasCtrl ? 1.f : .1f ) );

	if ( lmb && hasShift ) {
		// Left mouse button, shift - move camera
		const auto side( glm::normalize( glm::cross( up , dir ) ) );
		lookAt += .01f * ( side * fdx + up * fdy );
	} else if ( lmb ) {
		// Left mouse button, no shift - change yaw/pitch
		updateAngle( angles.y , fdx );
		updateAngle( angles.x , fdy );
	} else {
		// Right mouse button - change roll
		updateAngle( angles.z , fdx );
	}
	update( );
}

void T_Camera::handleWheel(
		__rd__	const float wheel ,
		__rd__	const bool hasCtrl ,
		__rd__	const bool hasShift
	)
{
	const float delta( wheel * ( hasCtrl ? 1.f : .1f) );
	if ( hasShift ) {
		fov = std::max( 1.f , std::min( 179.f , fov + delta ) );
	} else {
		distance = std::max( .01f , distance - delta );
	}
	update( );
}

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

void T_Camera::makeUI( )
{
	if ( !ImGui::CollapsingHeader( "Camera" ) ) {
		return;
	}

	const bool changed[] = {
		ImGui::DragFloat3( "Look at" , &lookAt.x ) ,
		ImGui::DragFloat( "Distance" , &distance , .1f ,
				.1f , 1e8 , "%.1f" ) ,
		ImGui::DragFloat3( "Angles" , &angles.x , .01f , -180 , 180 ) ,
		ImGui::DragFloat( "FoV" , &fov , .01f , .01f , 179.9f )
	};

	for ( unsigned i = 0 ; i < sizeof( changed ) / sizeof( bool ) ; i ++ ) {
		if ( changed[ i ] ) {
			update( );
			break;
		}
	}
}

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

void T_Camera::update( )
{
	anglesToMatrix( &angles.x , &rotMat[ 0 ].x );
	dir = glm::vec3( 0 , 0 , -distance ) * rotMat;
	up = glm::vec3( 0 , 1 , 0 ) * rotMat;
	pos = lookAt - dir;
	np = 2 * tan( M_PI * ( 180. - fov ) / 360. );
}