// Limit cache size, LRU (least recently used) algorithm.

"use strict";

var toPosInteger = require("es5-ext/number/to-pos-integer")
  , lruQueue     = require("lru-queue")
  , extensions   = require("../lib/registered-extensions");

extensions.max = function (max, conf, options) {
	var postfix, queue, hit;

	max = toPosInteger(max);
	if (!max) return;

	queue = lruQueue(max);
	postfix = (options.async && extensions.async) || (options.promise && extensions.promise)
		? "async" : "";

	conf.on("set" + postfix, hit = function (id) {
		id = queue.hit(id);
		if (id === undefined) return;
		conf.delete(id);
	});
	conf.on("get" + postfix, hit);
	conf.on("delete" + postfix, queue.delete);
	conf.on("clear" + postfix, queue.clear);
};