New method Service.Cache()

…for auto-caching with date pattern.

src/Lungo.Service.js

@@ -11,6 +11,13 @@
 
 LUNGO.Service = (function(lng, $$, undefined) {
 
+    var URL_CACHE_INDEX_KEY = 'lungojs_service_cache';
+    var DATE_PATTERN = {
+        MINUTE: 'minute',
+        HOUR: 'hour',
+        DAY: 'day'
+    };
+
     /**
      * Load data from the server using a HTTP GET request.
      *
@@ -52,10 +59,84 @@ LUNGO.Service = (function(lng, $$, undefined) {
         return $$.json(url, data, success);
     };
 
+    /**
+     * Auto-caching system with date pattern.
+     *
+     * @method cache
+     *
+     * @param  {string} Containing the URL to which the request is sent
+     * @param  {object} A map or string that is sent to the server with the request
+     * @param  {string} Date pattern (example: 15 minutes, 1 hour, 3 days)
+     * @param  {Function} [OPTIONAL] Callback function after the request
+     * @param  {string} Mime-Type: json, xml, html, or text [OPTIONAL]
+     */
+    var cache = function(url, data, date_pattern, success, dataType) {
+        var url_key = url + $$.serializeParameters(data);
+
+        if (_urlCached(url_key, date_pattern)) {
+            var value = lng.Data.Storage.persistent(url_key);
+            if (value) {
+                return success.call(success, value);
+            }
+        } else {
+            return $$.get(url, data, function(result) {
+                _saveServiceInCache(url_key, result);
+                success.call(success, result);
+            }, dataType);
+        }
+    };
+
+    var _urlCached = function(url, date_pattern) {
+        var in_cache = false;
+
+        var url_cache_index = lng.Data.Storage.persistent(URL_CACHE_INDEX_KEY);
+        if (url_cache_index) {
+            var time_between = calculateTimeSpent(url_cache_index[url]);
+            in_cache = _checkIsValidPattern(time_between, date_pattern);
+        }
+
+        return in_cache;
+    };
+
+    var calculateTimeSpent = function(url_last_access) {
+        var now = new Date().getTime();
+        var service_last_access = new Date(url_last_access).getTime();
+
+        return now - service_last_access;
+    };
+
+    var _checkIsValidPattern = function(time_between, date_pattern) {
+        var pattern = date_pattern.split(' ');
+        var diference_time = _calculateDiferenceTime(pattern[1], time_between);
+
+        return (diference_time < pattern[0]) ? true : false;
+    };
+
+    var _calculateDiferenceTime = function(pattern_name, time_between) {
+        var diference = (time_between / 1000) / 60;
+
+        if (pattern_name.indexOf(DATE_PATTERN.HOUR) >= 0) {
+            diference = diference / 60;
+        } else if (pattern_name.indexOf(DATE_PATTERN.DAY) >= 0) {
+            diference = (diference / 60) / 24;
+        }
+
+        return diference;
+    };
+
+    var _saveServiceInCache = function(url, result) {
+        var service_cache_index = lng.Data.Storage.persistent(URL_CACHE_INDEX_KEY) || {};
+        service_cache_index[url] = new Date();
+
+        lng.Data.Storage.persistent(URL_CACHE_INDEX_KEY, service_cache_index);
+        lng.Data.Storage.persistent(url, result);
+    };
+
     return {
         get: get,
         post: post,
         json: json,
+        cache: cache,
         Settings: $$.ajaxSettings
     };