( function () {

	const _changeEvent = {
		type: 'change'
	};

	class FlyControls extends THREE.EventDispatcher {

		constructor( object, domElement ) {

			super();

			if ( domElement === undefined ) {

				console.warn( 'THREE.FlyControls: The second parameter "domElement" is now mandatory.' );
				domElement = document;

			}

			this.object = object;
			this.domElement = domElement; // API

			this.movementSpeed = 1.0;
			this.rollSpeed = 0.005;
			this.dragToLook = false;
			this.autoForward = false; // disable default target object behavior
			// internals

			const scope = this;
			const EPS = 0.000001;
			const lastQuaternion = new THREE.Quaternion();
			const lastPosition = new THREE.Vector3();
			this.tmpQuaternion = new THREE.Quaternion();
			this.mouseStatus = 0;
			this.moveState = {
				up: 0,
				down: 0,
				left: 0,
				right: 0,
				forward: 0,
				back: 0,
				pitchUp: 0,
				pitchDown: 0,
				yawLeft: 0,
				yawRight: 0,
				rollLeft: 0,
				rollRight: 0
			};
			this.moveVector = new THREE.Vector3( 0, 0, 0 );
			this.rotationVector = new THREE.Vector3( 0, 0, 0 );

			this.keydown = function ( event ) {

				if ( event.altKey ) {

					return;

				}

				switch ( event.code ) {

					case 'ShiftLeft':
					case 'ShiftRight':
						this.movementSpeedMultiplier = .1;
						break;

					case 'KeyW':
						this.moveState.forward = 1;
						break;

					case 'KeyS':
						this.moveState.back = 1;
						break;

					case 'KeyA':
						this.moveState.left = 1;
						break;

					case 'KeyD':
						this.moveState.right = 1;
						break;

					case 'KeyR':
						this.moveState.up = 1;
						break;

					case 'KeyF':
						this.moveState.down = 1;
						break;

					case 'ArrowUp':
						this.moveState.pitchUp = 1;
						break;

					case 'ArrowDown':
						this.moveState.pitchDown = 1;
						break;

					case 'ArrowLeft':
						this.moveState.yawLeft = 1;
						break;

					case 'ArrowRight':
						this.moveState.yawRight = 1;
						break;

					case 'KeyQ':
						this.moveState.rollLeft = 1;
						break;

					case 'KeyE':
						this.moveState.rollRight = 1;
						break;

				}

				this.updateMovementVector();
				this.updateRotationVector();

			};

			this.keyup = function ( event ) {

				switch ( event.code ) {

					case 'ShiftLeft':
					case 'ShiftRight':
						this.movementSpeedMultiplier = 1;
						break;

					case 'KeyW':
						this.moveState.forward = 0;
						break;

					case 'KeyS':
						this.moveState.back = 0;
						break;

					case 'KeyA':
						this.moveState.left = 0;
						break;

					case 'KeyD':
						this.moveState.right = 0;
						break;

					case 'KeyR':
						this.moveState.up = 0;
						break;

					case 'KeyF':
						this.moveState.down = 0;
						break;

					case 'ArrowUp':
						this.moveState.pitchUp = 0;
						break;

					case 'ArrowDown':
						this.moveState.pitchDown = 0;
						break;

					case 'ArrowLeft':
						this.moveState.yawLeft = 0;
						break;

					case 'ArrowRight':
						this.moveState.yawRight = 0;
						break;

					case 'KeyQ':
						this.moveState.rollLeft = 0;
						break;

					case 'KeyE':
						this.moveState.rollRight = 0;
						break;

				}

				this.updateMovementVector();
				this.updateRotationVector();

			};

			this.mousedown = function ( event ) {

				if ( this.dragToLook ) {

					this.mouseStatus ++;

				} else {

					switch ( event.button ) {

						case 0:
							this.moveState.forward = 1;
							break;

						case 2:
							this.moveState.back = 1;
							break;

					}

					this.updateMovementVector();

				}

			};

			this.mousemove = function ( event ) {

				if ( ! this.dragToLook || this.mouseStatus > 0 ) {

					const container = this.getContainerDimensions();
					const halfWidth = container.size[ 0 ] / 2;
					const halfHeight = container.size[ 1 ] / 2;
					this.moveState.yawLeft = - ( event.pageX - container.offset[ 0 ] - halfWidth ) / halfWidth;
					this.moveState.pitchDown = ( event.pageY - container.offset[ 1 ] - halfHeight ) / halfHeight;
					this.updateRotationVector();

				}

			};

			this.mouseup = function ( event ) {

				if ( this.dragToLook ) {

					this.mouseStatus --;
					this.moveState.yawLeft = this.moveState.pitchDown = 0;

				} else {

					switch ( event.button ) {

						case 0:
							this.moveState.forward = 0;
							break;

						case 2:
							this.moveState.back = 0;
							break;

					}

					this.updateMovementVector();

				}

				this.updateRotationVector();

			};

			this.update = function ( delta ) {

				const moveMult = delta * scope.movementSpeed;
				const rotMult = delta * scope.rollSpeed;
				scope.object.translateX( scope.moveVector.x * moveMult );
				scope.object.translateY( scope.moveVector.y * moveMult );
				scope.object.translateZ( scope.moveVector.z * moveMult );
				scope.tmpQuaternion.set( scope.rotationVector.x * rotMult, scope.rotationVector.y * rotMult, scope.rotationVector.z * rotMult, 1 ).normalize();
				scope.object.quaternion.multiply( scope.tmpQuaternion );

				if ( lastPosition.distanceToSquared( scope.object.position ) > EPS || 8 * ( 1 - lastQuaternion.dot( scope.object.quaternion ) ) > EPS ) {

					scope.dispatchEvent( _changeEvent );
					lastQuaternion.copy( scope.object.quaternion );
					lastPosition.copy( scope.object.position );

				}

			};

			this.updateMovementVector = function () {

				const forward = this.moveState.forward || this.autoForward && ! this.moveState.back ? 1 : 0;
				this.moveVector.x = - this.moveState.left + this.moveState.right;
				this.moveVector.y = - this.moveState.down + this.moveState.up;
				this.moveVector.z = - forward + this.moveState.back; //console.log( 'move:', [ this.moveVector.x, this.moveVector.y, this.moveVector.z ] );

			};

			this.updateRotationVector = function () {

				this.rotationVector.x = - this.moveState.pitchDown + this.moveState.pitchUp;
				this.rotationVector.y = - this.moveState.yawRight + this.moveState.yawLeft;
				this.rotationVector.z = - this.moveState.rollRight + this.moveState.rollLeft; //console.log( 'rotate:', [ this.rotationVector.x, this.rotationVector.y, this.rotationVector.z ] );

			};

			this.getContainerDimensions = function () {

				if ( this.domElement != document ) {

					return {
						size: [ this.domElement.offsetWidth, this.domElement.offsetHeight ],
						offset: [ this.domElement.offsetLeft, this.domElement.offsetTop ]
					};

				} else {

					return {
						size: [ window.innerWidth, window.innerHeight ],
						offset: [ 0, 0 ]
					};

				}

			};

			this.dispose = function () {

				this.domElement.removeEventListener( 'contextmenu', contextmenu );
				this.domElement.removeEventListener( 'mousedown', _mousedown );
				this.domElement.removeEventListener( 'mousemove', _mousemove );
				this.domElement.removeEventListener( 'mouseup', _mouseup );
				window.removeEventListener( 'keydown', _keydown );
				window.removeEventListener( 'keyup', _keyup );

			};

			const _mousemove = this.mousemove.bind( this );

			const _mousedown = this.mousedown.bind( this );

			const _mouseup = this.mouseup.bind( this );

			const _keydown = this.keydown.bind( this );

			const _keyup = this.keyup.bind( this );

			this.domElement.addEventListener( 'contextmenu', contextmenu );
			this.domElement.addEventListener( 'mousemove', _mousemove );
			this.domElement.addEventListener( 'mousedown', _mousedown );
			this.domElement.addEventListener( 'mouseup', _mouseup );
			window.addEventListener( 'keydown', _keydown );
			window.addEventListener( 'keyup', _keyup );
			this.updateMovementVector();
			this.updateRotationVector();

		}

	}

	function contextmenu( event ) {

		event.preventDefault();

	}

	THREE.FlyControls = FlyControls;

} )();