/**
 *
 * @param id
 * @param name
 * @param splineCurve3
 * @param accel
 * @param maxSpeed
 * @param baseOffset
 * @constructor
 */
GameLib.D3.ComponentPathFollowing = function ComponentPathFollowing(
    id,
    name,
    splineCurve3,
    accel,
    maxSpeed,
    baseOffset
) {
    this.id = id || GameLib.D3.Tools.RandomId();

    if (typeof name == 'undefined') {
        name = this.constructor.name;
    }

    this.name = name;
    this.parentEntity = null;
    this.splineCurve3 = splineCurve3;
    this.maxSpeed = maxSpeed || 10.0;
    this.accel = accel || 2.0;
    this.baseOffset = baseOffset || new GameLib.D3.Vector3();


    // runtime code
    this.currentPathValue = 0.0;
    this.offset = new GameLib.D3.Vector3();
    this.currentSpeed = 0.0;
    this.direction = 0;


    GameLib.D3.Utils.Extend(GameLib.D3.ComponentPathFollowing, GameLib.D3.ComponentInterface);
};

///////////////////////// Methods to override //////////////////////////
GameLib.D3.ComponentPathFollowing.prototype.onUpdate = function(
    deltaTime,
    parentEntity
) {

    if(this.splineCurve3) {

        if(this.currentPathValue >= 1 || this.currentPathValue < 0) {
            this.currentPathValue = 0;
        }

        //To maintain a constant speed, you use .getPointAt( t ) instead of .getPoint( t ).
        //http://stackoverflow.com/questions/18400667/three-js-object-following-a-spline-path-rotation-tanget-issues-constant-sp

        var position = this.splineCurve3.getPointAt(this.currentPathValue);
        var rotation = this.splineCurve3.getTangentAt(this.currentPathValue).normalize();

        var up = new THREE.Vector3(-1, 0, 0);

        var axis = new THREE.Vector3();
            axis.crossVectors(up, rotation).normalize();
        var radians = Math.acos(up.dot(rotation));
        var quaternion = new THREE.Quaternion().setFromAxisAngle( axis, radians );

        // move the entity
        var t = deltaTime * this.accel;
        t = t * t * t * (t * (6.0 * t - 15.0) + 10.0);
        this.currentSpeed = this.currentSpeed + (this.maxSpeed * this.direction - this.currentSpeed) * t;

        var transformedOffset = new THREE.Vector3(
            this.baseOffset.x + this.offset.x,
            this.baseOffset.y + this.offset.y,
            this.baseOffset.z + this.offset.z
        ).applyQuaternion(quaternion);

        // apply to parent rigidbody instead of direclty to the mesh.
        parentEntity.position.x = position.x + transformedOffset.x;
        parentEntity.position.y = position.y + transformedOffset.y;
        parentEntity.position.z = position.z + transformedOffset.z;

        parentEntity.quaternion.x = quaternion.x;
        parentEntity.quaternion.y = quaternion.y;
        parentEntity.quaternion.z = quaternion.z;
        parentEntity.quaternion.w = quaternion.w;

        console.log("this.currentSpeed", this.currentSpeed);

        this.currentPathValue += (this.currentSpeed);

        if(this.currentSpeed >= this.maxSpeed) {
            this.currentSpeed = this.maxSpeed;
        } else if (this.currentSpeed <= 0) {
            this.currentSpeed = 0.0;
        }

    }
};

GameLib.D3.ComponentPathFollowing.prototype.onSetParentEntity = function(
    parentScene,
    parentEntity
) {
    if(!this.splineCurve3) {
        console.error("NO PATH GIVEN");
    }
};