Give users more control over URL shortening

Users and administrators can set how long an URL can be before it's
shortened, and how long a notice can be before all its URLs are
shortened. They can also turn off shortening altogether.

Squashed commit of the following:

commit d136b390115829c4391b3666bb1967f190a0de35
Author: Evan Prodromou <evan@status.net>
Date:   Mon Apr 26 02:39:00 2010 -0400

    use site and user settings to determine when to shorten URLs

commit 1e1c851ff3cb2da5e0dc3a0b06239a9d9c618488
Author: Evan Prodromou <evan@status.net>
Date:   Mon Apr 26 02:38:40 2010 -0400

    add a method to force shortening URLs

commit 4d29ca0b91201f6df42940297ed5b64b070efe49
Author: Evan Prodromou <evan@status.net>
Date:   Mon Apr 26 02:37:41 2010 -0400

    static method for getting best URL shortening service

commit a9c6a3bace0af44bcf38d1c790425a7be9c72147
Author: Evan Prodromou <evan@status.net>
Date:   Mon Apr 26 02:37:11 2010 -0400

    allow 0 in numeric entries in othersettings

commit 767ff2f7ecfd7e76e8418fc79d45e61898f09382
Author: Evan Prodromou <evan@status.net>
Date:   Mon Apr 26 02:36:46 2010 -0400

    allow 0 or blank string in inputs

commit 1e21af42a685f600f4a53f49a194013e78b12f20
Author: Evan Prodromou <evan@status.net>
Date:   Mon Apr 26 02:01:11 2010 -0400

    add more URL-shortening options to othersettings

commit 869a6be0f5779aff69018d02f9ac0273946040d9
Author: Evan Prodromou <evan@status.net>
Date:   Sat Apr 24 14:22:51 2010 -0400

    move url shortener superclass to lib from plugin

commit 9c0c9863d532942b99184f14e923fc3c050f8177
Author: Evan Prodromou <evan@status.net>
Date:   Sat Apr 24 14:20:28 2010 -0400

    documentation and whitespace on UrlShortenerPlugin

commit 7a1dd5798f0fcf2c03d1257a18ddcb9008879de0
Author: Evan Prodromou <evan@status.net>
Date:   Sat Apr 24 14:05:46 2010 -0400

    add defaults for URL shortening

commit d259c37ad231ca0010c60e5cfd397bb1732874a4
Author: Evan Prodromou <evan@status.net>
Date:   Sat Apr 24 13:40:10 2010 -0400

    Add User_urlshortener_prefs

    Add a table for URL shortener prefs, a corresponding class, and the
    correct mumbo-jumbo in statusnet.ini to make everything work.

1 files changed, 155 insertions, 0 deletions

diff --git a/lib/urlshortenerplugin.php b/lib/urlshortenerplugin.php
new file mode 100644
index 000000000..8acfac26f
--- /dev/null
+++ b/lib/urlshortenerplugin.php
@@ -0,0 +1,155 @@
+<?php
+/**
+ * StatusNet, the distributed open-source microblogging tool
+ *
+ * Superclass for plugins that do URL shortening
+ *
+ * PHP version 5
+ *
+ * LICENCE: This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @category Plugin
+ * @package  StatusNet
+ * @author   Craig Andrews <candrews@integralblue.com>
+ * @license  http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link     http://status.net/
+ */
+
+if (!defined('STATUSNET') && !defined('LACONICA')) {
+    exit(1);
+}
+
+/**
+ * Superclass for plugins that do URL shortening
+ *
+ * @category Plugin
+ * @package  StatusNet
+ * @author   Craig Andrews <candrews@integralblue.com>
+ * @license  http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link     http://status.net/
+ */
+
+abstract class UrlShortenerPlugin extends Plugin
+{
+    public $shortenerName;
+    public $freeService = false;
+
+    // Url Shortener plugins should implement some (or all)
+    // of these methods
+
+    /**
+     * Make an URL shorter.
+     *
+     * @param string $url URL to shorten
+     *
+     * @return string shortened version of the url, or null on failure
+     */
+
+    protected abstract function shorten($url);
+
+    /**
+     * Utility to get the data at an URL
+     *
+     * @param string $url URL to fetch
+     *
+     * @return string response body
+     *
+     * @todo rename to code-standard camelCase httpGet()
+     */
+
+    protected function http_get($url)
+    {
+        $request  = HTTPClient::start();
+        $response = $request->get($url);
+        return $response->getBody();
+    }
+
+    /**
+     * Utility to post a request and get a response URL
+     *
+     * @param string $url  URL to fetch
+     * @param array  $data post parameters
+     *
+     * @return string response body
+     *
+     * @todo rename to code-standard httpPost()
+     */
+
+    protected function http_post($url, $data)
+    {
+        $request  = HTTPClient::start();
+        $response = $request->post($url, null, $data);
+        return $response->getBody();
+    }
+
+    // Hook handlers
+
+    /**
+     * Called when all plugins have been initialized
+     *
+     * @return boolean hook value
+     */
+
+    function onInitializePlugin()
+    {
+        if (!isset($this->shortenerName)) {
+            throw new Exception("must specify a shortenerName");
+        }
+        return true;
+    }
+
+    /**
+     * Called when a showing the URL shortener drop-down box
+     *
+     * Properties of the shortening service currently only
+     * include whether it's a free service.
+     *
+     * @param array &$shorteners array mapping shortener name to properties
+     *
+     * @return boolean hook value
+     */
+
+    function onGetUrlShorteners(&$shorteners)
+    {
+        $shorteners[$this->shortenerName] =
+          array('freeService' => $this->freeService);
+        return true;
+    }
+
+    /**
+     * Called to shorten an URL
+     *
+     * @param string $url           URL to shorten
+     * @param string $shortenerName Shortening service. Don't handle if it's
+     *                              not you!
+     * @param string &$shortenedUrl URL after shortening; out param.
+     *
+     * @return boolean hook value
+     */
+
+    function onStartShortenUrl($url, $shortenerName, &$shortenedUrl)
+    {
+        if ($shortenerName == $this->shortenerName) {
+            $result = $this->shorten($url);
+            if (isset($result) && $result != null && $result !== false) {
+                $shortenedUrl = $result;
+                common_log(LOG_INFO,
+                           __CLASS__ . ": $this->shortenerName ".
+                           "shortened $url to $shortenedUrl");
+                return false;
+            }
+        }
+        return true;
+    }
+}