function createRenderStep(runNextFrame) {
    var toRun = [];
    var toRunNextFrame = [];
    var numToRun = 0;
    var isProcessing = false;
    var toKeepAlive = new WeakSet();
    var step = {
        schedule: function (callback, keepAlive, immediate) {
            if (keepAlive === void 0) { keepAlive = false; }
            if (immediate === void 0) { immediate = false; }
            var addToCurrentFrame = immediate && isProcessing;
            var buffer = addToCurrentFrame ? toRun : toRunNextFrame;
            if (keepAlive)
                toKeepAlive.add(callback);
            if (buffer.indexOf(callback) === -1) {
                buffer.push(callback);
                if (addToCurrentFrame && isProcessing)
                    numToRun = toRun.length;
            }
            return callback;
        },
        cancel: function (callback) {
            var index = toRunNextFrame.indexOf(callback);
            if (index !== -1)
                toRunNextFrame.splice(index, 1);
            toKeepAlive.delete(callback);
        },
        process: function (frameData) {
            var _a;
            isProcessing = true;
            _a = [toRunNextFrame, toRun], toRun = _a[0], toRunNextFrame = _a[1];
            toRunNextFrame.length = 0;
            numToRun = toRun.length;
            if (numToRun) {
                for (var i = 0; i < numToRun; i++) {
                    var callback = toRun[i];
                    callback(frameData);
                    if (toKeepAlive.has(callback)) {
                        step.schedule(callback);
                        runNextFrame();
                    }
                }
            }
            isProcessing = false;
        },
    };
    return step;
}

export { createRenderStep };