/*

YUI 3.10.3 (build 2fb5187)

Copyright 2013 Yahoo! Inc. All rights reserved.

Licensed under the BSD License.

http://yuilibrary.com/license/

*/

YUI.add('cache-base', function (Y, NAME) {

/**

 * The Cache utility provides a common configurable interface for components to

 * cache and retrieve data from a local JavaScript struct.

 *

 * @module cache

 * @main

 */

/**

 * Provides the base class for the YUI Cache utility.

 *

 * @submodule cache-base

 */

var LANG = Y.Lang,

    isDate = Y.Lang.isDate,

/**

 * Base class for the YUI Cache utility.

 * @class Cache

 * @extends Base

 * @constructor

 */

Cache = function() {

    Cache.superclass.constructor.apply(this, arguments);

};

    /////////////////////////////////////////////////////////////////////////////

    //

    // Cache static properties

    //

    /////////////////////////////////////////////////////////////////////////////

Y.mix(Cache, {

    /**

     * Class name.

     *

     * @property NAME

     * @type String

     * @static

     * @final

     * @value "cache"

     */

    NAME: "cache",

    ATTRS: {

        /////////////////////////////////////////////////////////////////////////////

        //

        // Cache Attributes

        //

        /////////////////////////////////////////////////////////////////////////////

        /**

        * @attribute max

        * @description Maximum number of entries the Cache can hold.

        * Set to 0 to turn off caching.

        * @type Number

        * @default 0

        */

        max: {

            value: 0,

            setter: "_setMax"

        },

        /**

        * @attribute size

        * @description Number of entries currently cached.

        * @type Number

        */

        size: {

            readOnly: true,

            getter: "_getSize"

        },

        /**

        * @attribute uniqueKeys

        * @description Validate uniqueness of stored keys. Default is false and

        * is more performant.

        * @type Boolean

        */

        uniqueKeys: {

            value: false

        },

        /**

        * @attribute expires

        * @description Absolute Date when data expires or

        * relative number of milliseconds. Zero disables expiration.

        * @type Date | Number

        * @default 0

        */

        expires: {

            value: 0,

            validator: function(v) {

                return Y.Lang.isDate(v) || (Y.Lang.isNumber(v) && v >= 0);

            }

        },

        /**

         * @attribute entries

         * @description Cached entries.

         * @type Array

         */

        entries: {

            readOnly: true,

            getter: "_getEntries"

        }

    }

});

Y.extend(Cache, Y.Base, {

    /////////////////////////////////////////////////////////////////////////////

    //

    // Cache private properties

    //

    /////////////////////////////////////////////////////////////////////////////

    /**

     * Array of request/response objects indexed chronologically.

     *

     * @property _entries

     * @type Object[]

     * @private

     */

    _entries: null,

    /////////////////////////////////////////////////////////////////////////////

    //

    // Cache private methods

    //

    /////////////////////////////////////////////////////////////////////////////

    /**

    * @method initializer

    * @description Internal init() handler.

    * @param config {Object} Config object.

    * @private

    */

    initializer: function(config) {

        /**

        * @event add

        * @description Fired when an entry is added.

        * @param e {Event.Facade} Event Facade with the following properties:

         * <dl>

         * <dt>entry (Object)</dt> <dd>The cached entry.</dd>

         * </dl>

        * @preventable _defAddFn

        */

        this.publish("add", {defaultFn: this._defAddFn});

        /**

        * @event flush

        * @description Fired when the cache is flushed.

        * @param e {Event.Facade} Event Facade object.

        * @preventable _defFlushFn

        */

        this.publish("flush", {defaultFn: this._defFlushFn});

        /**

        * @event request

        * @description Fired when an entry is requested from the cache.

        * @param e {Event.Facade} Event Facade with the following properties:

        * <dl>

        * <dt>request (Object)</dt> <dd>The request object.</dd>

        * </dl>

        */

        /**

        * @event retrieve

        * @description Fired when an entry is retrieved from the cache.

        * @param e {Event.Facade} Event Facade with the following properties:

        * <dl>

        * <dt>entry (Object)</dt> <dd>The retrieved entry.</dd>

        * </dl>

        */

        // Initialize internal values

        this._entries = [];

    },

    /**

    * @method destructor

    * @description Internal destroy() handler.

    * @private

    */

    destructor: function() {

        this._entries = [];

    },

    /////////////////////////////////////////////////////////////////////////////

    //

    // Cache protected methods

    //

    /////////////////////////////////////////////////////////////////////////////

    /**

     * Sets max.

     *

     * @method _setMax

     * @protected

     */

    _setMax: function(value) {

        // If the cache is full, make room by removing stalest element (index=0)

        var entries = this._entries;

        if(value > 0) {

            if(entries) {

                while(entries.length > value) {

                    entries.shift();

                }

            }

        }

        else {

            value = 0;

            this._entries = [];

        }

        return value;

    },

    /**

     * Gets size.

     *

     * @method _getSize

     * @protected

     */

    _getSize: function() {

        return this._entries.length;

    },

    /**

     * Gets all entries.

     *

     * @method _getEntries

     * @protected

     */

    _getEntries: function() {

        return this._entries;

    },

    /**

     * Adds entry to cache.

     *

     * @method _defAddFn

     * @param e {Event.Facade} Event Facade with the following properties:

     * <dl>

     * <dt>entry (Object)</dt> <dd>The cached entry.</dd>

     * </dl>

     * @protected

     */

    _defAddFn: function(e) {

        var entries = this._entries,

            entry   = e.entry,

            max     = this.get("max"),

            pos;

        // If uniqueKeys is true and item exists with this key, then remove it.

        if (this.get("uniqueKeys")) {

            pos = this._position(e.entry.request);

            if (LANG.isValue(pos)) {

                entries.splice(pos, 1);

            }

        }

        // If the cache at or over capacity, make room by removing stalest

        // element(s) starting at index-0.

        while (max && entries.length >= max) {

            entries.shift();

        }

        // Add entry to cache in the newest position, at the end of the array

        entries[entries.length] = entry;

    },

    /**

     * Flushes cache.

     *

     * @method _defFlushFn

     * @param e {Event.Facade} Event Facade object.

     * @protected

     */

    _defFlushFn: function(e) {

        var entries = this._entries,

            details = e.details[0],

            pos;

        //passed an item, flush only that

        if(details && LANG.isValue(details.request)) {

            pos = this._position(details.request);

            if(LANG.isValue(pos)) {

                entries.splice(pos,1);

            }

        }

        //no item, flush everything

        else {

            this._entries = [];

        }

    },

    /**

     * Default overridable method compares current request with given cache entry.

     * Returns true if current request matches the cached request, otherwise

     * false. Implementers should override this method to customize the

     * cache-matching algorithm.

     *

     * @method _isMatch

     * @param request {Object} Request object.

     * @param entry {Object} Cached entry.

     * @return {Boolean} True if current request matches given cached request, false otherwise.

     * @protected

     */

    _isMatch: function(request, entry) {

        if(!entry.expires || new Date() < entry.expires) {

            return (request === entry.request);

        }

        return false;

    },

    /**

     * Returns position of a request in the entries array, otherwise null.

     *

     * @method _position

     * @param request {Object} Request object.

     * @return {Number} Array position if found, null otherwise.

     * @protected

     */

    _position: function(request) {

        // If cache is enabled...

        var entries = this._entries,

            length = entries.length,

            i = length-1;

        if((this.get("max") === null) || this.get("max") > 0) {

            // Loop through each cached entry starting from the newest

            for(; i >= 0; i--) {

                // Execute matching function

                if(this._isMatch(request, entries[i])) {

                    return i;

                }

            }

        }

        return null;

    },

    /////////////////////////////////////////////////////////////////////////////

    //

    // Cache public methods

    //

    /////////////////////////////////////////////////////////////////////////////

    /**

     * Adds a new entry to the cache of the format

     * {request:request, response:response, cached:cached, expires:expires}.

     * If cache is full, evicts the stalest entry before adding the new one.

     *

     * @method add

     * @param request {Object} Request value.

     * @param response {Object} Response value.

     */

    add: function(request, response) {

        var expires = this.get("expires");

        if(this.get("initialized") && ((this.get("max") === null) || this.get("max") > 0) &&

                (LANG.isValue(request) || LANG.isNull(request) || LANG.isUndefined(request))) {

            this.fire("add", {entry: {

                request:request,

                response:response,

                cached: new Date(),

                expires: isDate(expires) ? expires :

            (expires ? new Date(new Date().getTime() + this.get("expires")) : null)

            }});

        }

        else {

        }

    },

    /**

     * Flushes cache.

     *

     * @method flush

     */

    flush: function(request) {

        this.fire("flush", { request: (LANG.isValue(request) ? request : null) });

    },

    /**

     * Retrieves cached object for given request, if available, and refreshes

     * entry in the cache. Returns null if there is no cache match.

     *

     * @method retrieve

     * @param request {Object} Request object.

     * @return {Object} Cached object with the properties request and response, or null.

     */

    retrieve: function(request) {

        // If cache is enabled...

        var entries = this._entries,

            length = entries.length,

            entry = null,

            pos;

        if((length > 0) && ((this.get("max") === null) || (this.get("max") > 0))) {

            this.fire("request", {request: request});

            pos = this._position(request);

            if(LANG.isValue(pos)) {

                entry = entries[pos];

                this.fire("retrieve", {entry: entry});

                // Refresh the position of the cache hit

                if(pos < length-1) {

                    // Remove element from its original location

                    entries.splice(pos,1);

                    // Add as newest

                    entries[entries.length] = entry;