Added Upgrader GPM class which allows to get details about the latest version of Grav available including version, release date and available assets to download

system/src/Grav/Common/GPM/Upgrader.php

@@ -0,0 +1,75 @@
+<?php
+namespace Grav\Common\GPM;
+
+use Grav\Common\Filesystem\Folder;
+use Grav\Common\GPM\Installer;
+
+class Upgrader
+{
+    /**
+     * Remote details about latest Grav version
+     * @var Packages
+     */
+    private $remote;
+
+    /**
+     * Internal cache
+     * @var Iterator
+     */
+    protected $cache;
+
+    /**
+     * Creates a new GPM instance with Local and Remote packages available
+     * @param boolean  $refresh  Applies to Remote Packages only and forces a refetch of data
+     * @param callable $callback Either a function or callback in array notation
+     */
+    public function __construct($refresh = false, $callback = null)
+    {
+        $this->remote = new Remote\Grav($refresh, $callback);
+    }
+
+    /**
+     * Returns the release date of the latest version of Grav
+     * @return string
+     */
+    public function getReleaseDate()
+    {
+        return $this->remote->getDate();
+    }
+
+    /**
+     * Returns the version of the installed Grav
+     * @return string
+     */
+    public function getLocalVersion()
+    {
+        return GRAV_VERSION;
+    }
+
+    /**
+     * Returns the version of the remotely available Grav
+     * @return string
+     */
+    public function getRemoteVersion()
+    {
+        return $this->remote->getVersion();
+    }
+
+    /**
+     * Returns an array of assets available to download remotely
+     * @return array
+     */
+    public function getAssets()
+    {
+        return $this->remote->getAssets();
+    }
+
+    /**
+     * Checks if the currently installed Grav is upgradable to a newer version
+     * @return boolean True if it's upgradable, False otherwise.
+     */
+    public function isUpgradable()
+    {
+        return version_compare($this->getLocalVersion(), $this->getRemoteVersion(), "<");
+    }
+}