// Random number generator - requires a PRNG backend, e.g. prng4.js
import { prng_newstate, rng_psize } from "./prng4";
var rng_state;
var rng_pool = null;
var rng_pptr;
// Initialize the pool with junk if needed.
if (rng_pool == null) {
    rng_pool = [];
    rng_pptr = 0;
    var t = void 0;
    if (window.crypto && window.crypto.getRandomValues) {
        // Extract entropy (2048 bits) from RNG if available
        var z = new Uint32Array(256);
        window.crypto.getRandomValues(z);
        for (t = 0; t < z.length; ++t) {
            rng_pool[rng_pptr++] = z[t] & 255;
        }
    }
    // Use mouse events for entropy, if we do not have enough entropy by the time
    // we need it, entropy will be generated by Math.random.
    var count = 0;
    var onMouseMoveListener_1 = function (ev) {
        count = count || 0;
        if (count >= 256 || rng_pptr >= rng_psize) {
            if (window.removeEventListener) {
                window.removeEventListener("mousemove", onMouseMoveListener_1, false);
            }
            else if (window.detachEvent) {
                window.detachEvent("onmousemove", onMouseMoveListener_1);
            }
            return;
        }
        try {
            var mouseCoordinates = ev.x + ev.y;
            rng_pool[rng_pptr++] = mouseCoordinates & 255;
            count += 1;
        }
        catch (e) {
            // Sometimes Firefox will deny permission to access event properties for some reason. Ignore.
        }
    };
    if (window.addEventListener) {
        window.addEventListener("mousemove", onMouseMoveListener_1, false);
    }
    else if (window.attachEvent) {
        window.attachEvent("onmousemove", onMouseMoveListener_1);
    }
}
function rng_get_byte() {
    if (rng_state == null) {
        rng_state = prng_newstate();
        // At this point, we may not have collected enough entropy.  If not, fall back to Math.random
        while (rng_pptr < rng_psize) {
            var random = Math.floor(65536 * Math.random());
            rng_pool[rng_pptr++] = random & 255;
        }
        rng_state.init(rng_pool);
        for (rng_pptr = 0; rng_pptr < rng_pool.length; ++rng_pptr) {
            rng_pool[rng_pptr] = 0;
        }
        rng_pptr = 0;
    }
    // TODO: allow reseeding after first request
    return rng_state.next();
}
var SecureRandom = /** @class */ (function () {
    function SecureRandom() {
    }
    SecureRandom.prototype.nextBytes = function (ba) {
        for (var i = 0; i < ba.length; ++i) {
            ba[i] = rng_get_byte();
        }
    };
    return SecureRandom;
}());
export { SecureRandom };