module BABYLON {
    export class TargetCamera extends Camera {

        public cameraDirection = new Vector3(0, 0, 0);
        public cameraRotation = new Vector2(0, 0);

        @serializeAsVector3()
        public rotation = new Vector3(0, 0, 0);

        @serialize()
        public speed = 2.0;

        public noRotationConstraint = false;

        @serializeAsMeshReference("lockedTargetId")
        public lockedTarget = null;

        public _currentTarget = Vector3.Zero();
        public _viewMatrix = Matrix.Zero();
        public _camMatrix = Matrix.Zero();
        public _cameraTransformMatrix = Matrix.Zero();
        public _cameraRotationMatrix = Matrix.Zero();
        private _rigCamTransformMatrix: Matrix;

        public _referencePoint = new Vector3(0, 0, 1);
        public _transformedReferencePoint = Vector3.Zero();
        public _lookAtTemp = Matrix.Zero();
        public _tempMatrix = Matrix.Zero();

        public _reset: () => void;

        constructor(name: string, position: Vector3, scene: Scene) {
            super(name, position, scene);
        }

        public getFrontPosition(distance: number): Vector3 {
            var direction = this.getTarget().subtract(this.position);
            direction.normalize();
            direction.scaleInPlace(distance);
            return this.globalPosition.add(direction);
        }

        public _getLockedTargetPosition(): Vector3 {
            if (!this.lockedTarget) {
                return null;
            }

            return this.lockedTarget.position || this.lockedTarget;
        }

        // Cache
        public _initCache() {
            super._initCache();
            this._cache.lockedTarget = new Vector3(Number.MAX_VALUE, Number.MAX_VALUE, Number.MAX_VALUE);
            this._cache.rotation = new Vector3(Number.MAX_VALUE, Number.MAX_VALUE, Number.MAX_VALUE);
        }

        public _updateCache(ignoreParentClass?: boolean): void {
            if (!ignoreParentClass) {
                super._updateCache();
            }

            var lockedTargetPosition = this._getLockedTargetPosition();
            if (!lockedTargetPosition) {
                this._cache.lockedTarget = null;
            }
            else {
                if (!this._cache.lockedTarget) {
                    this._cache.lockedTarget = lockedTargetPosition.clone();
                }
                else {
                    this._cache.lockedTarget.copyFrom(lockedTargetPosition);
                }
            }

            this._cache.rotation.copyFrom(this.rotation);
        }

        // Synchronized
        public _isSynchronizedViewMatrix(): boolean {
            if (!super._isSynchronizedViewMatrix()) {
                return false;
            }

            var lockedTargetPosition = this._getLockedTargetPosition();

            return (this._cache.lockedTarget ? this._cache.lockedTarget.equals(lockedTargetPosition) : !lockedTargetPosition)
                && this._cache.rotation.equals(this.rotation);
        }

        // Methods
        public _computeLocalCameraSpeed(): number {
            var engine = this.getEngine();
            return this.speed * ((engine.getDeltaTime() / (engine.getFps() * 10.0)));
        }

        // Target
        public setTarget(target: Vector3): void {
            this.upVector.normalize();

            Matrix.LookAtLHToRef(this.position, target, this.upVector, this._camMatrix);
            this._camMatrix.invert();

            this.rotation.x = Math.atan(this._camMatrix.m[6] / this._camMatrix.m[10]);

            var vDir = target.subtract(this.position);

            if (vDir.x >= 0.0) {
                this.rotation.y = (-Math.atan(vDir.z / vDir.x) + Math.PI / 2.0);
            } else {
                this.rotation.y = (-Math.atan(vDir.z / vDir.x) - Math.PI / 2.0);
            }

            this.rotation.z = -Math.acos(Vector3.Dot(new Vector3(0, 1.0, 0), this.upVector));

            if (isNaN(this.rotation.x)) {
                this.rotation.x = 0;
            }

            if (isNaN(this.rotation.y)) {
                this.rotation.y = 0;
            }

            if (isNaN(this.rotation.z)) {
                this.rotation.z = 0;
            }
        }

        public getTarget(): Vector3 {
            return this._currentTarget;
        }


        public _decideIfNeedsToMove(): boolean {
            return Math.abs(this.cameraDirection.x) > 0 || Math.abs(this.cameraDirection.y) > 0 || Math.abs(this.cameraDirection.z) > 0;
        }

        public _updatePosition(): void {
            this.position.addInPlace(this.cameraDirection);
        }
        public _checkInputs(): void {
            var needToMove = this._decideIfNeedsToMove();
            var needToRotate = Math.abs(this.cameraRotation.x) > 0 || Math.abs(this.cameraRotation.y) > 0;

            // Move
            if (needToMove) {
                this._updatePosition();
            }

            // Rotate
            if (needToRotate) {
                this.rotation.x += this.cameraRotation.x;
                this.rotation.y += this.cameraRotation.y;


                if (!this.noRotationConstraint) {
                    var limit = (Math.PI / 2) * 0.95;


                    if (this.rotation.x > limit)
                        this.rotation.x = limit;
                    if (this.rotation.x < -limit)
                        this.rotation.x = -limit;
                }
            }

            // Inertia
            if (needToMove) {
                if (Math.abs(this.cameraDirection.x) < Epsilon) {
                    this.cameraDirection.x = 0;
                }

                if (Math.abs(this.cameraDirection.y) < Epsilon) {
                    this.cameraDirection.y = 0;
                }

                if (Math.abs(this.cameraDirection.z) < Epsilon) {
                    this.cameraDirection.z = 0;
                }

                this.cameraDirection.scaleInPlace(this.inertia);
            }
            if (needToRotate) {
                if (Math.abs(this.cameraRotation.x) < Epsilon) {
                    this.cameraRotation.x = 0;
                }

                if (Math.abs(this.cameraRotation.y) < Epsilon) {
                    this.cameraRotation.y = 0;
                }
                this.cameraRotation.scaleInPlace(this.inertia);
            }

            super._checkInputs();
        }


        public _getViewMatrix(): Matrix {
            if (!this.lockedTarget) {
                // Compute
                if (this.upVector.x !== 0 || this.upVector.y !== 1.0 || this.upVector.z !== 0) {
                    Matrix.LookAtLHToRef(Vector3.Zero(), this._referencePoint, this.upVector, this._lookAtTemp);
                    Matrix.RotationYawPitchRollToRef(this.rotation.y, this.rotation.x, this.rotation.z, this._cameraRotationMatrix);


                    this._lookAtTemp.multiplyToRef(this._cameraRotationMatrix, this._tempMatrix);
                    this._lookAtTemp.invert();
                    this._tempMatrix.multiplyToRef(this._lookAtTemp, this._cameraRotationMatrix);
                } else {
                    Matrix.RotationYawPitchRollToRef(this.rotation.y, this.rotation.x, this.rotation.z, this._cameraRotationMatrix);
                }

                Vector3.TransformCoordinatesToRef(this._referencePoint, this._cameraRotationMatrix, this._transformedReferencePoint);

                // Computing target and final matrix
                this.position.addToRef(this._transformedReferencePoint, this._currentTarget);
            } else {
                this._currentTarget.copyFrom(this._getLockedTargetPosition());
            }

            Matrix.LookAtLHToRef(this.position, this._currentTarget, this.upVector, this._viewMatrix);
            return this._viewMatrix;
        }

        public _getVRViewMatrix(): Matrix {
            Matrix.RotationYawPitchRollToRef(this.rotation.y, this.rotation.x, this.rotation.z, this._cameraRotationMatrix);

            Vector3.TransformCoordinatesToRef(this._referencePoint, this._cameraRotationMatrix, this._transformedReferencePoint);
            Vector3.TransformNormalToRef(this.upVector, this._cameraRotationMatrix, this._cameraRigParams.vrActualUp);

            // Computing target and final matrix
            this.position.addToRef(this._transformedReferencePoint, this._currentTarget);

            Matrix.LookAtLHToRef(this.position, this._currentTarget, this._cameraRigParams.vrActualUp, this._cameraRigParams.vrWorkMatrix);

            this._cameraRigParams.vrWorkMatrix.multiplyToRef(this._cameraRigParams.vrPreViewMatrix, this._viewMatrix);
            return this._viewMatrix;
        }
        
        /**
         * @override
         * Override Camera.createRigCamera
         */
        public createRigCamera(name: string, cameraIndex: number): Camera {
            if (this.cameraRigMode !== Camera.RIG_MODE_NONE) {
                var rigCamera = new TargetCamera(name, this.position.clone(), this.getScene());
                if (this.cameraRigMode === Camera.RIG_MODE_VR) {
                    rigCamera._cameraRigParams = {};
                    rigCamera._cameraRigParams.vrActualUp = new Vector3(0, 0, 0);
                    rigCamera._getViewMatrix = rigCamera._getVRViewMatrix;
                }
                return rigCamera;
            }
            return null;
        }
        
        /**
         * @override
         * Override Camera._updateRigCameras
         */
        public _updateRigCameras() {
            switch (this.cameraRigMode) {
                case Camera.RIG_MODE_STEREOSCOPIC_ANAGLYPH:
                case Camera.RIG_MODE_STEREOSCOPIC_SIDEBYSIDE_PARALLEL:
                case Camera.RIG_MODE_STEREOSCOPIC_SIDEBYSIDE_CROSSEYED:
                case Camera.RIG_MODE_STEREOSCOPIC_OVERUNDER:
                case Camera.RIG_MODE_VR:
                    var camLeft = <TargetCamera>this._rigCameras[0];
                    var camRight = <TargetCamera>this._rigCameras[1];

                    if (this.cameraRigMode === Camera.RIG_MODE_VR) {
                        camLeft.rotation.x = camRight.rotation.x = this.rotation.x;
                        camLeft.rotation.y = camRight.rotation.y = this.rotation.y;
                        camLeft.rotation.z = camRight.rotation.z = this.rotation.z;

                        camLeft.position.copyFrom(this.position);
                        camRight.position.copyFrom(this.position);

                    } else {
                        //provisionnaly using _cameraRigParams.stereoHalfAngle instead of calculations based on _cameraRigParams.interaxialDistance:
                        this._getRigCamPosition(-this._cameraRigParams.stereoHalfAngle, camLeft.position);
                        this._getRigCamPosition(this._cameraRigParams.stereoHalfAngle, camRight.position);

                        camLeft.setTarget(this.getTarget());
                        camRight.setTarget(this.getTarget());
                    }
                    break;
            }
            super._updateRigCameras();
        }

        private _getRigCamPosition(halfSpace: number, result: Vector3) {
            if (!this._rigCamTransformMatrix) {
                this._rigCamTransformMatrix = new Matrix();
            }
            var target = this.getTarget();
            Matrix.Translation(-target.x, -target.y, -target.z).multiplyToRef(Matrix.RotationY(halfSpace), this._rigCamTransformMatrix);

            this._rigCamTransformMatrix = this._rigCamTransformMatrix.multiply(Matrix.Translation(target.x, target.y, target.z));

            Vector3.TransformCoordinatesToRef(this.position, this._rigCamTransformMatrix, result);
        }

        public getTypeName(): string {
            return "TargetCamera";
        }
    }
}