/**
 * Entities with LookAt component looks to targetPosition (default up is 0,1,0)
 * @param graphics R3.GraphicsRuntime
 * @param apiLookAt R3.D3.API.LookAt
 * @constructor
 */
R3.D3.LookAt = function (
    graphics,
    apiLookAt
) {
    this.graphics = graphics;
    this.graphics.isNotThreeThrow();

    if (R3.Utils.UndefinedOrNull(apiLookAt)) {
        apiLookAt = {};
    }

	if (apiLookAt instanceof R3.D3.LookAt) {
		return apiLookAt;
	}

    R3.D3.API.LookAt.call(
        this,
        apiLookAt.id,
        apiLookAt.name,
        apiLookAt.currentComponent,
        apiLookAt.targetComponent,
        apiLookAt.targetPositionOffset,
        apiLookAt.rotationSpeed,
        apiLookAt.parentEntity
    );

    this.targetPositionOffset = new R3.Vector3(
        this.graphics,
        this.targetPositionOffset,
        this
    );

    this.lookAtMatrix = new R3.Matrix4(
        this.graphics,
        this.lookAtMatrix,
        this
    );

    this.up = new R3.Vector3(
        this.graphics,
        this.up,
        this
    );

    this.currentRotation = new R3.Quaternion(
        this.graphics,
        this.currentRotation,
        this
    );

    this.targetPosition = new R3.Vector3(
        this.graphics,
        this.targetPosition,
        this
    );

    R3.Component.call(
        this,
        R3.Component.COMPONENT_LOOK_AT,
        {
            'currentComponent' : R3.Component,
            'targetComponent' : R3.Component
        }
    );
};

R3.D3.LookAt.prototype = Object.create(R3.D3.API.LookAt.prototype);
R3.D3.LookAt.prototype.constructor = R3.D3.LookAt;

R3.D3.LookAt.prototype.createInstance = function() {
    this.instance = true;
    R3.Component.prototype.createInstance.call(this);
};

R3.D3.LookAt.prototype.updateInstance = function() {
};

/**
 * to API object
 * @returns {R3.D3.API.LookAt}
 */
R3.D3.LookAt.prototype.toApiObject = function() {

    var apiLookAt = new R3.D3.API.LookAt(
        this.id,
        this.name,
        R3.Utils.IdOrNull(this.currentComponent),
        R3.Utils.IdOrNull(this.targetComponent),
        this.targetPositionOffset.toApiObject(),
        this.rotationSpeed,
        R3.Utils.IdOrNull(this.parentEntity)
    );

    return apiLookAt;
};

R3.D3.LookAt.FromObject = function(graphics, objectComponent) {

    var apiLookAt = R3.D3.API.LookAt.FromObject(objectComponent);

    return new R3.D3.LookAt(
        graphics,
        apiLookAt
    );
};

/**
 * Looks at using time
 * @param deltaTime
 */
R3.D3.LookAt.prototype.update = function(deltaTime) {

    if (this.currentComponent && this.targetComponent) {

        this.targetPosition.x = this.targetComponent.position.x + this.targetPositionOffset.x;
        this.targetPosition.y = this.targetComponent.position.y + this.targetPositionOffset.y;
        this.targetPosition.z = this.targetComponent.position.z + this.targetPositionOffset.z;

        this.targetPosition.updateInstance();

        // this.lookAtMatrix.lookAt(
        //     this.currentComponent.position,
        //     this.targetPosition,
        //     this.up
        // );
        //
        // this.currentRotation = new R3.Quaternion(this.graphics, this, new R3.API.Quaternion());
        //
        // this.currentRotation.setFromRotationMatrix(this.lookAtMatrix);

        // var t = deltaTime * this.rotationSpeed;
        // t = t * t * t * (t * (6.0 * t - 15.0) + 10.0);

       // this.currentRotation.slerp(this.currentRotation, t);

        // this.currentRotation.normalize();
        //
        // this.currentComponent.quaternion.x = this.currentRotation.x;
        // this.currentComponent.quaternion.y = this.currentRotation.y;
        // this.currentComponent.quaternion.z = this.currentRotation.z;
        // this.currentComponent.quaternion.w = this.currentRotation.w;
        //
        this.currentComponent.lookAt.x = this.targetPosition.x;
        this.currentComponent.lookAt.y = this.targetPosition.y;
        this.currentComponent.lookAt.z = this.targetPosition.z;

        this.currentComponent.lookAt.updateInstance();
    }

};