(function() {
    var LOOKAT_MIX_ALPHA = 0.15;
    var lookAtPoint = undefined;
    var lookingAtAvatarID = undefined;
    var lookingAvatarJointIndex = undefined;
    var getNormalizedLookAtPoint = function(worldLookAtPoint) {
        return Vec3.sum(MyAvatar.getHeadPosition(), Vec3.normalize(Vec3.subtract(worldLookAtPoint, MyAvatar.getHeadPosition())));
    }
    var interpolatedLookAt = getNormalizedLookAtPoint(MyAvatar.getHeadLookAt());
    var mousePressEvent = function(event) {
        if (!event.isLeftButton) return;
        var pickRay = Camera.computePickRay(event.x, event.y);
        var intersection = AvatarManager.findRayIntersection({origin: pickRay.origin, direction: pickRay.direction}, [], [MyAvatar.sessionUUID], false);
        lookingAtAvatarID = intersection.intersects ? intersection.avatarID : undefined;
        if (!lookingAtAvatarID) {
            intersection = Entities.findRayIntersection({origin: pickRay.origin, direction: pickRay.direction}, true);
            lookAtPoint = intersection.intersection;
        } else {
            var avatar = AvatarList.getAvatar(lookingAtAvatarID);
            console.log("Looking at avatar: " + avatar.displayName);
            lookingAvatarJointIndex = intersection.jointIndex;
        }
    }
    
    Script.update.connect(function() {
        if (lookAtPoint || lookingAtAvatarID) {
            if (lookingAtAvatarID) {
                lookAtPoint = AvatarList.getAvatar(lookingAtAvatarID).getJointPosition(lookingAvatarJointIndex);
            }
            var normalizedLookAt = getNormalizedLookAtPoint(lookAtPoint);
            interpolatedLookAt = Vec3.mix(interpolatedLookAt, normalizedLookAt, LOOKAT_MIX_ALPHA);
            MyAvatar.setHeadLookAt(interpolatedLookAt);
        }
    });
    
    Controller.mousePressEvent.connect(mousePressEvent);
})();