var typeBlacklist = ["Zone"];    /* for now, disallow all zone entities */
var center = {x: 0, y: 0, z: 0}; /* also nothing can move within 5 meters of 0,0,0 */
var radius = 5;
var epsilon = 0.01;
var aBitMore = 5 * (1 + epsilon);
var staticBounceSpeed = 0.5;     /* If edit within radius that has no velocity. */
var Vec3 = {
    distance: function distance(a, b) {
        var x = a.x - b.x,
            y = a.y - b.y,
            z = a.z - b.z;
        return Math.sqrt((x * x) + (y * y) + (z * z));
    },
    ZERO: {x: 0, y: 0, z: 0},
    length: function length(v) {
        return Vec3.distance(Vec3.ZERO, v);
    },
    multiply: function multiply(s, v) {
        return {x: s * v.x, y: s * v.y, z: s * v.z};
    },
    normalize: function normalize(v) {
        var length = Vec3.length(v);
        return Vec3.multiply(1/length, v);
    }
};

function filter(p, filterType) {
    if (p.type && (typeBlacklist.indexOf(p.type) != -1)) {
        print("filtering out " + p.type + " entity!");
        return false
    }
    if (p.position) {
        var distance = Vec3.distance(center, p.position);
        var reject = distance <= radius;
        var normal;
        if (reject) {
            print('rejecting type', filterType, 'packet near origin');
            if (filterType === Entities.ADD_FILTER_TYPE) {
                return false;
            } else { /* Others are Entities.EDIT_FILTER_TYPE and Entities.PHYSICS_FILTER_TYPE. */
                normal = Vec3.normalize(p.position);
                p.position = Vec3.multiply(aBitMore, normal);
                p.velocity = (p.velocity && Vec3.length(p.velocity) > epsilon) ?
                    Vec3.multiply(-1, p.velocity) : Vec3.multiply(staticBounceSpeed, normal);
                p.acceleration = Vec3.ZERO;
            }
        }
    }
    if (p.dimensions && (filterType !== Entities.ADD_FILTER_TYPE)) {
        if (p.dimensions.x > 11) {
            p.dimensions.x = 11;
            print('capping x dimension');
        }
        if (p.dimensions.y > 11) {
            p.dimensions.y = 11;
            print('capping y dimension');
        }
        if (p.dimensions.z > 11) {
            p.dimensions.z = 11;
            print('capping z dimension');
        }
    }
    return p;
}