/**
 * @author Eberhard Graether / http://egraether.com/
 */

THREE.TrackballControls = function ( object, domElement ) {

    var _this = this;
    var STATE = { NONE: -1, ROTATE: 0, ZOOM: 1, PAN: 2, TOUCH_ROTATE: 3, TOUCH_ZOOM: 4, TOUCH_PAN: 5 };

    this.object = object;
    this.domElement = ( domElement !== undefined ) ? domElement : document;

    // API

    this.enabled = true;

    this.screen = { left: 0, top: 0, width: 0, height: 0 };

    this.rotateSpeed = 1.0;
    this.zoomSpeed = 1.2;
    this.panSpeed = 0.3;

    this.noRotate = false;
    this.noZoom = false;
    this.noPan = false;
    this.noRoll = false;

    this.staticMoving = false;
    this.dynamicDampingFactor = 0.2;

    this.minDistance = 0;
    this.maxDistance = Infinity;

    this.keys = [ 65 /*A*/, 83 /*S*/, 68 /*D*/ ];

    // internals

    this.target = new THREE.Vector3();

    var lastPosition = new THREE.Vector3();

    var _state = STATE.NONE,
        _prevState = STATE.NONE,

        _eye = new THREE.Vector3(),

        _rotateStart = new THREE.Vector3(),
        _rotateEnd = new THREE.Vector3(),

        _zoomStart = new THREE.Vector2(),
        _zoomEnd = new THREE.Vector2(),

        _touchZoomDistanceStart = 0,
        _touchZoomDistanceEnd = 0,

        _panStart = new THREE.Vector2(),
        _panEnd = new THREE.Vector2();

    // for reset

    this.target0 = this.target.clone();
    this.position0 = this.object.position.clone();
    this.up0 = this.object.up.clone();

    // events

    var changeEvent = { type: 'change' };


    // methods

    this.handleResize = function () {

        if ( this.domElement === document ) {

            this.screen.left = 0;
            this.screen.top = 0;
            this.screen.width = window.innerWidth;
            this.screen.height = window.innerHeight;

        } else {

            this.screen = this.domElement.getBoundingClientRect();

        }

    };

    this.handleEvent = function ( event ) {

        if ( typeof this[ event.type ] == 'function' ) {

            this[ event.type ]( event );

        }

    };

    this.getMouseOnScreen = function ( clientX, clientY ) {

        return new THREE.Vector2(
            ( clientX - _this.screen.left ) / _this.screen.width,
            ( clientY - _this.screen.top ) / _this.screen.height
        );

    };

    this.getMouseProjectionOnBall = function ( clientX, clientY ) {

        var mouseOnBall = new THREE.Vector3(
            ( clientX - _this.screen.width * 0.5 - _this.screen.left ) / (_this.screen.width*.5),
            ( _this.screen.height * 0.5 + _this.screen.top - clientY ) / (_this.screen.height*.5),
            0.0
        );

        var length = mouseOnBall.length();

        if ( _this.noRoll ) {

            if ( length < Math.SQRT1_2 ) {

                mouseOnBall.z = Math.sqrt( 1.0 - length*length );

            } else {

                mouseOnBall.z = .5 / length;

            }

        } else if ( length > 1.0 ) {

            mouseOnBall.normalize();

        } else {

            mouseOnBall.z = Math.sqrt( 1.0 - length * length );

        }

        _eye.copy( _this.object.position ).sub( _this.target );

        var projection = _this.object.up.clone().setLength( mouseOnBall.y );
        projection.add( _this.object.up.clone().cross( _eye ).setLength( mouseOnBall.x ) );
        projection.add( _eye.setLength( mouseOnBall.z ) );

        return projection;

    };

    this.rotateCamera = function () {

        var angle = Math.acos( _rotateStart.dot( _rotateEnd ) / _rotateStart.length() / _rotateEnd.length() );

        if ( angle ) {

            var axis = ( new THREE.Vector3() ).crossVectors( _rotateStart, _rotateEnd ).normalize(),
                quaternion = new THREE.Quaternion();

            angle *= _this.rotateSpeed;

            quaternion.setFromAxisAngle( axis, -angle );

            _eye.applyQuaternion( quaternion );
            _this.object.up.applyQuaternion( quaternion );

            _rotateEnd.applyQuaternion( quaternion );

            if ( _this.staticMoving ) {

                _rotateStart.copy( _rotateEnd );

            } else {

                quaternion.setFromAxisAngle( axis, angle * ( _this.dynamicDampingFactor - 1.0 ) );
                _rotateStart.applyQuaternion( quaternion );

            }

        }

    };

    this.zoomCamera = function () {

        if ( _state === STATE.TOUCH_ZOOM ) {

            var factor = _touchZoomDistanceStart / _touchZoomDistanceEnd;
            _touchZoomDistanceStart = _touchZoomDistanceEnd;
            _eye.multiplyScalar( factor );

        } else {

            var factor = 1.0 + ( _zoomEnd.y - _zoomStart.y ) * _this.zoomSpeed;

            if ( factor !== 1.0 && factor > 0.0 ) {

                _eye.multiplyScalar( factor );

                if ( _this.staticMoving ) {

                    _zoomStart.copy( _zoomEnd );

                } else {

                    _zoomStart.y += ( _zoomEnd.y - _zoomStart.y ) * this.dynamicDampingFactor;

                }

            }

        }

    };

    this.panCamera = function () {

        var mouseChange = _panEnd.clone().sub( _panStart );

        if ( mouseChange.lengthSq() ) {

            mouseChange.multiplyScalar( _eye.length() * _this.panSpeed );

            var pan = _eye.clone().cross( _this.object.up ).setLength( mouseChange.x );
            pan.add( _this.object.up.clone().setLength( mouseChange.y ) );

            _this.object.position.add( pan );
            _this.target.add( pan );

            if ( _this.staticMoving ) {

                _panStart = _panEnd;

            } else {

                _panStart.add( mouseChange.subVectors( _panEnd, _panStart ).multiplyScalar( _this.dynamicDampingFactor ) );

            }

        }

    };

    this.checkDistances = function () {

        if ( !_this.noZoom || !_this.noPan ) {

            if ( _eye.lengthSq() > _this.maxDistance * _this.maxDistance ) {

                _this.object.position.addVectors( _this.target, _eye.setLength( _this.maxDistance ) );

            }

            if ( _eye.lengthSq() < _this.minDistance * _this.minDistance ) {

                _this.object.position.addVectors( _this.target, _eye.setLength( _this.minDistance ) );

            }

        }

    };

    this.update = function () {

        _eye.subVectors( _this.object.position, _this.target );

        if ( !_this.noRotate ) {

            _this.rotateCamera();

        }

        if ( !_this.noZoom ) {

            _this.zoomCamera();

        }

        if ( !_this.noPan ) {

            _this.panCamera();

        }

        _this.object.position.addVectors( _this.target, _eye );

        _this.checkDistances();

        _this.object.lookAt( _this.target );

        if ( lastPosition.distanceToSquared( _this.object.position ) > 0 ) {

            _this.dispatchEvent( changeEvent );

            lastPosition.copy( _this.object.position );

        }

    };

    this.reset = function () {

        _state = STATE.NONE;
        _prevState = STATE.NONE;

        _this.target.copy( _this.target0 );
        _this.object.position.copy( _this.position0 );
        _this.object.up.copy( _this.up0 );

        _eye.subVectors( _this.object.position, _this.target );

        _this.object.lookAt( _this.target );

        _this.dispatchEvent( changeEvent );

        lastPosition.copy( _this.object.position );

    };

    // listeners

    function keydown( event ) {

        if ( _this.enabled === false ) return;

        window.removeEventListener( 'keydown', keydown );

        _prevState = _state;

        if ( _state !== STATE.NONE ) {

            return;

        } else if ( event.keyCode === _this.keys[ STATE.ROTATE ] && !_this.noRotate ) {

            _state = STATE.ROTATE;

        } else if ( event.keyCode === _this.keys[ STATE.ZOOM ] && !_this.noZoom ) {

            _state = STATE.ZOOM;

        } else if ( event.keyCode === _this.keys[ STATE.PAN ] && !_this.noPan ) {

            _state = STATE.PAN;

        }

    }

    function keyup( event ) {

        if ( _this.enabled === false ) return;

        _state = _prevState;

        window.addEventListener( 'keydown', keydown, false );

    }

    function mousedown( event ) {

        if ( _this.enabled === false ) return;

        event.preventDefault();
        event.stopPropagation();

        if ( _state === STATE.NONE ) {

            _state = event.button;

        }

        if ( _state === STATE.ROTATE && !_this.noRotate ) {

            _rotateStart = _this.getMouseProjectionOnBall( event.clientX, event.clientY );
            _rotateEnd.copy(_rotateStart)

        } else if ( _state === STATE.ZOOM && !_this.noZoom ) {

            _zoomStart = _this.getMouseOnScreen( event.clientX, event.clientY );
            _zoomEnd.copy(_zoomStart);

        } else if ( _state === STATE.PAN && !_this.noPan ) {

            _panStart = _this.getMouseOnScreen( event.clientX, event.clientY );
            _panEnd.copy(_panStart)

        }

        document.addEventListener( 'mousemove', mousemove, false );
        document.addEventListener( 'mouseup', mouseup, false );

    }

    function mousemove( event ) {

        if ( _this.enabled === false ) return;

        event.preventDefault();
        event.stopPropagation();

        if ( _state === STATE.ROTATE && !_this.noRotate ) {

            _rotateEnd = _this.getMouseProjectionOnBall( event.clientX, event.clientY );

        } else if ( _state === STATE.ZOOM && !_this.noZoom ) {

            _zoomEnd = _this.getMouseOnScreen( event.clientX, event.clientY );

        } else if ( _state === STATE.PAN && !_this.noPan ) {

            _panEnd = _this.getMouseOnScreen( event.clientX, event.clientY );

        }

    }

    function mouseup( event ) {

        if ( _this.enabled === false ) return;

        event.preventDefault();
        event.stopPropagation();

        _state = STATE.NONE;

        document.removeEventListener( 'mousemove', mousemove );
        document.removeEventListener( 'mouseup', mouseup );

    }

    function mousewheel( event ) {

        if ( _this.enabled === false ) return;

        event.preventDefault();
        event.stopPropagation();

        var delta = 0;

        if ( event.wheelDelta ) { // WebKit / Opera / Explorer 9

            delta = event.wheelDelta / 40;

        } else if ( event.detail ) { // Firefox

            delta = - event.detail / 3;

        }

        _zoomStart.y += delta * 0.01;

    }

    function touchstart( event ) {

        if ( _this.enabled === false ) return;

        switch ( event.touches.length ) {

            case 1:
                _state = STATE.TOUCH_ROTATE;
                _rotateStart = _rotateEnd = _this.getMouseProjectionOnBall( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
                break;

            case 2:
                _state = STATE.TOUCH_ZOOM;
                var dx = event.touches[ 0 ].pageX - event.touches[ 1 ].pageX;
                var dy = event.touches[ 0 ].pageY - event.touches[ 1 ].pageY;
                _touchZoomDistanceEnd = _touchZoomDistanceStart = Math.sqrt( dx * dx + dy * dy );
                break;

            case 3:
                _state = STATE.TOUCH_PAN;
                _panStart = _panEnd = _this.getMouseOnScreen( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
                break;

            default:
                _state = STATE.NONE;

        }

    }

    function touchmove( event ) {

        if ( _this.enabled === false ) return;

        event.preventDefault();
        event.stopPropagation();

        switch ( event.touches.length ) {

            case 1:
                _rotateEnd = _this.getMouseProjectionOnBall( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
                break;

            case 2:
                var dx = event.touches[ 0 ].pageX - event.touches[ 1 ].pageX;
                var dy = event.touches[ 0 ].pageY - event.touches[ 1 ].pageY;
                _touchZoomDistanceEnd = Math.sqrt( dx * dx + dy * dy )
                break;

            case 3:
                _panEnd = _this.getMouseOnScreen( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
                break;

            default:
                _state = STATE.NONE;

        }

    }

    function touchend( event ) {

        if ( _this.enabled === false ) return;

        switch ( event.touches.length ) {

            case 1:
                _rotateStart = _rotateEnd = _this.getMouseProjectionOnBall( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
                break;

            case 2:
                _touchZoomDistanceStart = _touchZoomDistanceEnd = 0;
                break;

            case 3:
                _panStart = _panEnd = _this.getMouseOnScreen( event.touches[ 0 ].pageX, event.touches[ 0 ].pageY );
                break;

        }

        _state = STATE.NONE;

    }

    this.domElement.addEventListener( 'contextmenu', function ( event ) { event.preventDefault(); }, false );

    this.domElement.addEventListener( 'mousedown', mousedown, false );

    this.domElement.addEventListener( 'mousewheel', mousewheel, false );
    this.domElement.addEventListener( 'DOMMouseScroll', mousewheel, false ); // firefox

    this.domElement.addEventListener( 'touchstart', touchstart, false );
    this.domElement.addEventListener( 'touchend', touchend, false );
    this.domElement.addEventListener( 'touchmove', touchmove, false );

    window.addEventListener( 'keydown', keydown, false );
    window.addEventListener( 'keyup', keyup, false );

    this.handleResize();

};

THREE.TrackballControls.prototype = Object.create( THREE.EventDispatcher.prototype );