Add support for WireCache + make cache method and TTL configurable

MarkupSitemap.info.json

 {
     "title": "Sitemap",
-    "version": "0.4.1",
+    "version": "0.5.0",
     "author": "Mike Rockett",
     "summary": "Renders a sitemap for your ProcessWire powered site. Supports multi-language, multi-site, and image sub-elements. Adapted from MarkupSitemapXML.",
     "href": "http://github.com/rockettpw/markup-sitemap",

MarkupSitemap.module.php

@@ -219,8 +219,9 @@ class MarkupSitemap extends WireData implements Module
    * consideration to multi-site setups) and passing it to the
    * first/parent recursive render-method (addPages).
    *
-   * MarkupCache is used to cache the entire sitemap, and the cache
-   * is destroyed when settings are saved and, if set up, a page is saved.
+   * Depending on config settings entire sitemap is cached using MarkupCache or
+   * WireCache, and the cache is destroyed when settings are saved and, if set
+   * up, a page is saved.
    *
    * @param HookEvent $event
    */
@@ -239,21 +240,10 @@ class MarkupSitemap extends WireData implements Module
 
     // Make sure that the root page exists.
     if (!$this->pages->get($rootPage) instanceof NullPage) {
-      // Check for cached sitemap or regenerate if it doesn't exist
-      $markupCache = $this->modules->MarkupCache;
-
-      if ((!$output = $markupCache->get('MarkupSitemap', 3600)) || $this->config->debug) {
-        $output = $this->buildNewSitemap($rootPage);
-        $markupCache->save($output);
-        header('X-Cached-Sitemap: no');
-      } else {
-        header('X-Cached-Sitemap: yes');
-      }
-
+      // Get cached sitemap
+      $event->return = $this->getCached($rootPage);
       header('Content-Type: application/xml', true, 200);
 
-      $event->return = $output;
-
       // Prevent further hooks. This stops
       // SystemNotifications from displaying a 404 event
       // when /sitemap.xml is requested. Additionally,
@@ -263,6 +253,45 @@ class MarkupSitemap extends WireData implements Module
     }
   }
 
+  /**
+   * Get cached sitemap markup
+   *
+   * @param string $rootPage
+   * @return string
+   */
+  protected function getCached($rootPage)
+  {
+    // Bail out early if debug mode is enabled
+    if ($this->config->debug) {
+      header('X-Cached-Sitemap: no');
+      return $this->buildNewSitemap($rootPage);
+    }
+
+    // Cache settings
+    $cacheTTL = $this->cache_ttl ?: 3600;
+    $cacheKey = 'MarkupSitemap';
+    $cacheMethod = $this->cache_method ?: 'MarkupCache';
+
+    // Attempt to fetch sitemap from cache
+    $cache = $cacheMethod == 'WireCache' ? $this->cache : $this->modules->MarkupCache;
+    $output = $cache->get($cacheKey, $cacheTTL);
+
+    // If output is empty, generate and cache new sitemap
+    if (empty($output)) {
+      header('X-Cached-Sitemap: no');
+      $output = $this->buildNewSitemap($rootPage);
+      if ($cacheMethod == 'WireCache') {
+        $cache->save($cacheKey, $output, $cacheTTL);
+      } else {
+        $cache->save($output);
+      }
+      return $output;
+    }
+
+    header('X-Cached-Sitemap: yes');
+    return $output;
+  }
+
   /**
    * Add sitemap fields to the Settings tab.
    * Responds to ProcessPageEdit::buildFormSettings hook

MarkupSitemapConfig.php

@@ -28,6 +28,8 @@ class MarkupSitemapConfig extends ModuleConfig
       'sitemap_stylesheet' => true,
       'sitemap_exclude_templates' => [],
       'sitemap_include_hidden' => false,
+      'cache_method' => 'MarkupCache',
+      'cache_ttl' => 3600,
     ];
   }
 
@@ -150,6 +152,39 @@ class MarkupSitemapConfig extends ModuleConfig
     // Add the stylesheet fieldset to the inputfields
     $inputfields->add($stylesheetFieldset);
 
+    // Create the cache fieldset
+    $cacheFieldset = $this->buildInputField('Fieldset', [
+      'label' => $this->_('Cache'),
+      'collapsed' => Inputfield::collapsedBlank,
+      'icon' => 'database',
+    ]);
+
+    // Add the cache method select field
+    $cacheFieldset->add($this->buildInputField('Select', [
+      'name+id' => 'cache_method',
+      'label' => $this->_('Choose the cache method'),
+      'description' => $this->_('MarkupCache (default) stores cached content as files on disk. WireCache stores cached content into database.'),
+      'icon' => 'floppy-o',
+      'options' => [
+          'MarkupCache' => 'MarkupCache',
+          'WireCache' => 'WireCache',
+      ],
+    ]));
+
+    // Add the cache expire time (TTL) input
+    $cacheFieldset->add($this->buildInputField('Integer', [
+      'name+id' => 'cache_ttl',
+      'label' => $this->_('Cache expire time (TTL)'),
+      'description' => $this->_('Type in the expire time for the cache as a number of seconds.'),
+      'notes' => $this->_('The default value is **3600**.'),
+      'min' => 1,
+      'icon' => 'clock-o',
+      'collapsed' => Inputfield::collapsedBlank,
+    ]));
+
+    // Add the stylesheet fieldset to the inputfields
+    $inputfields->add($cacheFieldset);
+
     // Add the support-development markup field
     $supportText = $this->wire('sanitizer')->entitiesMarkdown($this->_('Sitemap is proudly [open-source](http://opensource.com/resources/what-open-source) and is [free to use](https://en.wikipedia.org/wiki/Free_software) for personal and commercial projects. Please consider [making a small donation](https://rockett.pw/donate) in support of the development of MarkupSitemap and other modules.'), ['fullMarkdown' => true]);
     $inputfields->add($this->buildInputField('Markup', [