module BABYLON {
    export class BoneLookController {

        private static _tmpVecs: Vector3[] = [Vector3.Zero(), Vector3.Zero(), Vector3.Zero(),Vector3.Zero(), Vector3.Zero(), Vector3.Zero(), Vector3.Zero(), Vector3.Zero(), Vector3.Zero(), Vector3.Zero()];
        private static _tmpQuat = Quaternion.Identity();
        private static _tmpMats: Matrix[] = [Matrix.Identity(), Matrix.Identity(), Matrix.Identity(), Matrix.Identity()];
        
        /**
         * The target Vector3 that the bone will look at.
         */
        public target: Vector3;

        /**
         * The mesh that the bone is attached to.
         */
        public mesh: AbstractMesh;

        /**
         * The bone that will be looking to the target.
         */
        public bone: Bone;

        /**
         * The up axis of the coordinate system that is used when the bone is rotated.
         */
        public upAxis: Vector3 = Vector3.Up();

        /**
         * The space that the up axis is in - BABYLON.Space.BONE, BABYLON.Space.LOCAL (default), or BABYLON.Space.WORLD.
         */
        public upAxisSpace: Space = Space.LOCAL;

        /**
         * Used to make an adjustment to the yaw of the bone.
         */
        public adjustYaw = 0;

        /**
         * Used to make an adjustment to the pitch of the bone.
         */
        public adjustPitch = 0;

        /**
         * Used to make an adjustment to the roll of the bone.
         */
        public adjustRoll = 0;

        /**
         * The amount to slerp (spherical linear interpolation) to the target.  Set this to a value between 0 and 1 (a value of 1 disables slerp).
         */
        public slerpAmount = 1;

        private _minYaw:number;
        private _maxYaw:number;
        private _minPitch:number;
        private _maxPitch:number;
        private _minYawSin:number;
        private _minYawCos:number;
        private _maxYawSin:number;
        private _maxYawCos:number;
        private _midYawConstraint:number;
        private _minPitchTan:number;
        private _maxPitchTan:number;
        
        private _boneQuat:Quaternion = Quaternion.Identity();
        private _slerping = false;
        private _transformYawPitch:Matrix;
        private _transformYawPitchInv:Matrix;
        private _firstFrameSkipped = false;
        private _yawRange:number;
        private _fowardAxis: Vector3 = Vector3.Forward();

        /**
         * Get/set the minimum yaw angle that the bone can look to.
         */
        get minYaw():number{
            return this._minYaw;
        }

        set minYaw(value:number){
            this._minYaw = value;
            this._minYawSin = Math.sin(value);
            this._minYawCos = Math.cos(value);
            if(this._maxYaw != null){
                this._midYawConstraint = this._getAngleDiff(this._minYaw, this._maxYaw)*.5 + this._minYaw;
                this._yawRange = this._maxYaw - this._minYaw;
            }
        }

        /**
         * Get/set the maximum yaw angle that the bone can look to.
         */
        get maxYaw():number{
            return this._maxYaw;
        }

        set maxYaw(value:number){
            this._maxYaw = value;
            this._maxYawSin = Math.sin(value);
            this._maxYawCos = Math.cos(value);
            if(this._minYaw != null){
                this._midYawConstraint = this._getAngleDiff(this._minYaw, this._maxYaw)*.5 + this._minYaw;
                this._yawRange = this._maxYaw - this._minYaw;
            }
        }

        /**
         * Get/set the minimum pitch angle that the bone can look to.
         */
        get minPitch():number{
            return this._minPitch;
        }

        set minPitch(value:number){
            this._minPitch = value;
            this._minPitchTan = Math.tan(value);
        }

        /**
         * Get/set the maximum pitch angle that the bone can look to.
         */
        get maxPitch():number{
            return this._maxPitch;
        }

        set maxPitch(value:number){
            this._maxPitch = value;
            this._maxPitchTan = Math.tan(value);
        }

        /**
         * Create a BoneLookController
         * @param mesh the mesh that the bone belongs to
         * @param bone the bone that will be looking to the target
         * @param target the target Vector3 to look at
         * @param settings optional settings:
         * - maxYaw: the maximum angle the bone will yaw to
         * - minYaw: the minimum angle the bone will yaw to
         * - maxPitch: the maximum angle the bone will pitch to
         * - minPitch: the minimum angle the bone will yaw to
         * - slerpAmount: set the between 0 and 1 to make the bone slerp to the target.
         * - upAxis: the up axis of the coordinate system
         * - upAxisSpace: the space that the up axis is in - BABYLON.Space.BONE, BABYLON.Space.LOCAL (default), or BABYLON.Space.WORLD.
         * - yawAxis: set yawAxis if the bone does not yaw on the y axis
         * - pitchAxis: set pitchAxis if the bone does not pitch on the x axis
         * - adjustYaw: used to make an adjustment to the yaw of the bone
         * - adjustPitch: used to make an adjustment to the pitch of the bone
         * - adjustRoll: used to make an adjustment to the roll of the bone
         **/
        constructor(mesh: AbstractMesh, 
                    bone: Bone, 
                    target: Vector3, 
                    options?: {
                        adjustYaw?: number, 
                        adjustPitch?: number, 
                        adjustRoll?: number, 
                        slerpAmount?: number, 
                        maxYaw?:number, 
                        minYaw?:number, 
                        maxPitch?:number, 
                        minPitch?:number,
                        upAxis?:Vector3,
                        upAxisSpace?:Space,
                        yawAxis?:Vector3,
                        pitchAxis?:Vector3,
                        showSpaceAxes?:boolean
                    }){

            this.mesh = mesh;
            this.bone = bone;
            this.target = target;

            if(options){

                if(options.adjustYaw){
                    this.adjustYaw = options.adjustYaw;
                }

                if(options.adjustPitch){
                    this.adjustPitch = options.adjustPitch;
                }

                if(options.adjustRoll){
                    this.adjustRoll = options.adjustRoll;
                }

                if(options.maxYaw != null){
                    this.maxYaw = options.maxYaw;
                }

                if(options.minYaw != null){
                    this.minYaw = options.minYaw;
                }

                if(options.maxPitch != null){
                    this.maxPitch = options.maxPitch;
                }

                if(options.minPitch != null){
                    this.minPitch = options.minPitch;
                }

                if(options.slerpAmount != null){
                    this.slerpAmount = options.slerpAmount;
                }

                if(options.upAxis != null){
                    this.upAxis = options.upAxis;
                }

                if(options.upAxisSpace != null){
                    this.upAxisSpace = options.upAxisSpace;
                }

                if(options.yawAxis != null || options.pitchAxis != null){

                    var newYawAxis = Axis.Y;
                    var newPitchAxis = Axis.X;

                    if(options.yawAxis != null){
                        newYawAxis = options.yawAxis.clone();
                        newYawAxis.normalize();
                    }

                    if(options.pitchAxis != null){
                        newPitchAxis = options.pitchAxis.clone();
                        newPitchAxis.normalize();
                    }

                    var newRollAxis = Vector3.Cross(newPitchAxis, newYawAxis);

                    this._transformYawPitch = Matrix.Identity();
                    Matrix.FromXYZAxesToRef(newPitchAxis, newYawAxis, newRollAxis, this._transformYawPitch);

                    this._transformYawPitchInv = this._transformYawPitch.clone();
                    this._transformYawPitch.invert();
                    
                }

            }

            if(!bone.getParent() && this.upAxisSpace == Space.BONE){
                this.upAxisSpace = Space.LOCAL;
            }

        }

        /**
         * Update the bone to look at the target.  This should be called before the scene is rendered (use scene.registerBeforeRender()).
         */
        public update (): void {

            //skip the first frame when slerping so that the mesh rotation is correct
            if(this.slerpAmount < 1 && !this._firstFrameSkipped){
                this._firstFrameSkipped = true;
                return;
            }

            var bone = this.bone;
            var bonePos = BoneLookController._tmpVecs[0];
            bone.getAbsolutePositionToRef(this.mesh, bonePos);

            var target = this.target;
            var _tmpMat1 = BoneLookController._tmpMats[0];
            var _tmpMat2 = BoneLookController._tmpMats[1];
            
            var mesh = this.mesh;
            var parentBone = bone.getParent();

            var upAxis = BoneLookController._tmpVecs[1];
            upAxis.copyFrom(this.upAxis);

            if(this.upAxisSpace == Space.BONE){
                if (this._transformYawPitch){
                    Vector3.TransformCoordinatesToRef(upAxis, this._transformYawPitchInv, upAxis);
                }
                parentBone.getDirectionToRef(upAxis, this.mesh, upAxis);
            }else if(this.upAxisSpace == Space.LOCAL){
                mesh.getDirectionToRef(upAxis, upAxis);
                if(mesh.scaling.x != 1 || mesh.scaling.y != 1 || mesh.scaling.z != 1){
                    upAxis.normalize();
                }
            }

            if(this._maxPitch != null || this._minPitch != null || this._maxYaw != null || this._minYaw != null){

                var _tmpMat3 = BoneLookController._tmpMats[2];
                var _tmpMat3Inv = BoneLookController._tmpMats[3];

                if(this.upAxisSpace == Space.BONE && upAxis.y == 1){

                    parentBone.getRotationMatrixToRef(Space.WORLD, this.mesh, _tmpMat3);
                    
                }else if(this.upAxisSpace == Space.LOCAL && upAxis.y == 1 && !parentBone){

                    _tmpMat3.copyFrom(mesh.getWorldMatrix());

                }else{

                    var forwardAxis = BoneLookController._tmpVecs[2];
                    forwardAxis.copyFrom(this._fowardAxis);
                    
                    if (this._transformYawPitch) {
                        Vector3.TransformCoordinatesToRef(forwardAxis, this._transformYawPitchInv, forwardAxis);
                    }

                    if(parentBone){
                        parentBone.getDirectionToRef(forwardAxis, this.mesh, forwardAxis);
                    }else{
                        mesh.getDirectionToRef(forwardAxis, forwardAxis);
                    }

                    var rightAxis = Vector3.Cross(upAxis, forwardAxis);
                    rightAxis.normalize();
                    var forwardAxis = Vector3.Cross(rightAxis, upAxis);

                    Matrix.FromXYZAxesToRef(rightAxis, upAxis, forwardAxis, _tmpMat3);
                    
                }

                _tmpMat3.invertToRef(_tmpMat3Inv);
                
                var xzlen:number;

                if(this._maxPitch != null || this._minPitch != null){
                    var localTarget = BoneLookController._tmpVecs[3];
                    Vector3.TransformCoordinatesToRef(target.subtract(bonePos), _tmpMat3Inv, localTarget);

                    var xzlen = Math.sqrt(localTarget.x * localTarget.x + localTarget.z * localTarget.z);
                    var pitch = Math.atan2(localTarget.y, xzlen);
                    var newPitch = pitch;

                    if(pitch > this._maxPitch){
                        localTarget.y = this._maxPitchTan*xzlen;
                        newPitch = this._maxPitch;
                    }else if(pitch < this._minPitch){
                        localTarget.y = this._minPitchTan*xzlen;
                        newPitch = this._minPitch;
                    }
                    
                    if(pitch != newPitch){
                        Vector3.TransformCoordinatesToRef(localTarget, _tmpMat3, localTarget);
                        localTarget.addInPlace(bonePos);
                        target = localTarget;
                    }
                }

                if(this._maxYaw != null || this._minYaw != null){
                    var localTarget = BoneLookController._tmpVecs[4];
                    Vector3.TransformCoordinatesToRef(target.subtract(bonePos), _tmpMat3Inv, localTarget);

                    var yaw = Math.atan2(localTarget.x, localTarget.z);
                    var newYaw = yaw;

                    if(yaw > this._maxYaw || yaw < this._minYaw){
                        
                        if(xzlen == null){
                            xzlen = Math.sqrt(localTarget.x * localTarget.x + localTarget.z * localTarget.z);
                        }

                        if(yaw > this._maxYaw){
                            localTarget.z = this._maxYawCos*xzlen;
                            localTarget.x = this._maxYawSin*xzlen;
                            newYaw = this._maxYaw;
                        }else if(yaw < this._minYaw){
                            localTarget.z = this._minYawCos*xzlen;
                            localTarget.x = this._minYawSin*xzlen;
                            newYaw = this._minYaw;
                        }
                    }

                    if(this._slerping && this._yawRange > Math.PI){
                        //are we going to be crossing into the min/max region
                        var _tmpVec8 = BoneLookController._tmpVecs[8];
                        _tmpVec8.copyFrom(BABYLON.Axis.Z);
                        if (this._transformYawPitch){
                            Vector3.TransformCoordinatesToRef(upAxis, this._transformYawPitchInv, upAxis);
                        }

                        var _tmpVec9 = BoneLookController._tmpVecs[9];
                        Vector3.TransformCoordinatesToRef(_tmpVec8, bone.getLocalMatrix(), _tmpVec9);
                        if (this._transformYawPitch){
                            Vector3.TransformCoordinatesToRef(upAxis, this._transformYawPitch, upAxis);
                        }

                        var boneYaw = Math.atan2(_tmpVec9.x, _tmpVec9.z);
                        var ang1 = this._getAngleBetween(boneYaw, yaw);
                        var ang2 = this._getAngleBetween(boneYaw, this._midYawConstraint);

                        if(ang1 > ang2){
                            var ang3 = this._getAngleBetween(boneYaw, this._maxYaw);
                            var ang4 = this._getAngleBetween(boneYaw, this._minYaw);

                            if(ang4 < ang3){
                                newYaw = boneYaw+Math.PI*.95;
                                localTarget.z = Math.cos(newYaw) * xzlen;
                                localTarget.x = Math.sin(newYaw) * xzlen;
                            }else{
                                newYaw = boneYaw-Math.PI*.95;
                                localTarget.z = Math.cos(newYaw) * xzlen;
                                localTarget.x = Math.sin(newYaw) * xzlen;
                            }
                        }
                    }

                    if(yaw != newYaw){
                        Vector3.TransformCoordinatesToRef(localTarget, _tmpMat3, localTarget);
                        localTarget.addInPlace(bonePos);
                        target = localTarget;
                    }
                }

            }

            var zaxis = BoneLookController._tmpVecs[5];
            var xaxis = BoneLookController._tmpVecs[6];
            var yaxis = BoneLookController._tmpVecs[7];
            var _tmpQuat = BoneLookController._tmpQuat;

            target.subtractToRef(bonePos, zaxis);
            zaxis.normalize();
            Vector3.CrossToRef(upAxis, zaxis, xaxis);
            xaxis.normalize();
            Vector3.CrossToRef(zaxis, xaxis, yaxis);
            yaxis.normalize();
            Matrix.FromXYZAxesToRef(xaxis, yaxis, zaxis, _tmpMat1);

            if(xaxis.x === 0 && xaxis.y === 0 && xaxis.z === 0){
                return;
            }

            if(yaxis.x === 0 && yaxis.y === 0 && yaxis.z === 0){
                return;
            }

            if(zaxis.x === 0 && zaxis.y === 0 && zaxis.z === 0){
                return;
            }

            if (this.adjustYaw || this.adjustPitch || this.adjustRoll) {
                Matrix.RotationYawPitchRollToRef(this.adjustYaw, this.adjustPitch, this.adjustRoll, _tmpMat2);
                _tmpMat2.multiplyToRef(_tmpMat1, _tmpMat1);
            }

            if (this.slerpAmount < 1) {
                if (!this._slerping) {
                    this.bone.getRotationQuaternionToRef(Space.WORLD, this.mesh, this._boneQuat);
                }
                if(this._transformYawPitch){
                    this._transformYawPitch.multiplyToRef(_tmpMat1, _tmpMat1);
                }
                Quaternion.FromRotationMatrixToRef(_tmpMat1, _tmpQuat);
                Quaternion.SlerpToRef(this._boneQuat, _tmpQuat, this.slerpAmount, this._boneQuat);
                
                this.bone.setRotationQuaternion(this._boneQuat, Space.WORLD, this.mesh);
                this._slerping = true;
            } else {
                if(this._transformYawPitch){
                    this._transformYawPitch.multiplyToRef(_tmpMat1, _tmpMat1);
                }
                this.bone.setRotationMatrix(_tmpMat1, Space.WORLD, this.mesh);
                this._slerping = false;
            }

        }

        private _getAngleDiff(ang1, ang2):number {

            var angDiff = ang2 - ang1;
            angDiff %= Math.PI*2;
            
            if(angDiff > Math.PI){
                angDiff -= Math.PI*2;
            }else if (angDiff < -Math.PI){
                angDiff += Math.PI*2;
            }
            
            return angDiff;
        }

        private _getAngleBetween(ang1, ang2):number {

            ang1 %= (2 * Math.PI);
            ang1 = (ang1 < 0) ? ang1 + (2 * Math.PI) : ang1;

            ang2 %= (2 * Math.PI);
            ang2 = (ang2 < 0) ? ang2 + (2 * Math.PI) : ang2;

            var ab = 0;

            if(ang1 < ang2){
                ab = ang2 - ang1;
            }else{
                ab = ang1 - ang2;
            }

            if(ab > Math.PI){
                ab = Math.PI*2 - ab;
            }

            return ab;
        }

    }
}