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 d136b39011
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 1e1c851ff3
Author: Evan Prodromou <evan@status.net>
Date:   Mon Apr 26 02:38:40 2010 -0400

    add a method to force shortening URLs

commit 4d29ca0b91
Author: Evan Prodromou <evan@status.net>
Date:   Mon Apr 26 02:37:41 2010 -0400

    static method for getting best URL shortening service

commit a9c6a3bace
Author: Evan Prodromou <evan@status.net>
Date:   Mon Apr 26 02:37:11 2010 -0400

    allow 0 in numeric entries in othersettings

commit 767ff2f7ec
Author: Evan Prodromou <evan@status.net>
Date:   Mon Apr 26 02:36:46 2010 -0400

    allow 0 or blank string in inputs

commit 1e21af42a6
Author: Evan Prodromou <evan@status.net>
Date:   Mon Apr 26 02:01:11 2010 -0400

    add more URL-shortening options to othersettings

commit 869a6be0f5
Author: Evan Prodromou <evan@status.net>
Date:   Sat Apr 24 14:22:51 2010 -0400

    move url shortener superclass to lib from plugin

commit 9c0c9863d5
Author: Evan Prodromou <evan@status.net>
Date:   Sat Apr 24 14:20:28 2010 -0400

    documentation and whitespace on UrlShortenerPlugin

commit 7a1dd5798f
Author: Evan Prodromou <evan@status.net>
Date:   Sat Apr 24 14:05:46 2010 -0400

    add defaults for URL shortening

commit d259c37ad2
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.

lib/util.php

@@ -828,9 +828,21 @@ function common_linkify($url) {
 
 function common_shorten_links($text)
 {
-    $maxLength = Notice::maxContent();
-    if ($maxLength == 0 || mb_strlen($text) <= $maxLength) return $text;
-    return common_replace_urls_callback($text, array('File_redirection', 'makeShort'));
+    common_debug("common_shorten_links() called");
+
+    $user = common_current_user();
+
+    $maxLength = User_urlshortener_prefs::maxNoticeLength($user);
+
+    common_debug("maxLength = $maxLength");
+
+    if (mb_strlen($text) > $maxLength) {
+        common_debug("Forcing shortening");
+        return common_replace_urls_callback($text, array('File_redirection', 'forceShort'));
+    } else {
+        common_debug("Not forcing shortening");
+        return common_replace_urls_callback($text, array('File_redirection', 'makeShort'));
+    }
 }
 
 function common_xml_safe_str($str)
@@ -1392,7 +1404,7 @@ function common_valid_tag($tag)
  * Determine if given domain or address literal is valid
  * eg for use in JIDs and URLs. Does not check if the domain
  * exists!
- * 
+ *
  * @param string $domain
  * @return boolean valid or not
  */
@@ -1734,30 +1746,42 @@ function common_database_tablename($tablename)
 /**
  * Shorten a URL with the current user's configured shortening service,
  * or ur1.ca if configured, or not at all if no shortening is set up.
- * Length is not considered.
  *
- * @param string $long_url
+ * @param string  $long_url original URL
+ * @param boolean $force    Force shortening (used when notice is too long)
+ *
  * @return string may return the original URL if shortening failed
  *
  * @fixme provide a way to specify a particular shortener
  * @fixme provide a way to specify to use a given user's shortening preferences
  */
-function common_shorten_url($long_url)
+
+function common_shorten_url($long_url, $force = false)
 {
+    common_debug("Shortening URL '$long_url' (force = $force)");
+
     $long_url = trim($long_url);
+
     $user = common_current_user();
-    if (empty($user)) {
-        // common current user does not find a user when called from the XMPP daemon
-        // therefore we'll set one here fix, so that XMPP given URLs may be shortened
-        $shortenerName = 'ur1.ca';
-    } else {
-        $shortenerName = $user->urlshorteningservice;
+
+    $maxUrlLength = User_urlshortener_prefs::maxUrlLength($user);
+    common_debug("maxUrlLength = $maxUrlLength");
+
+    // $force forces shortening even if it's not strictly needed
+
+    if (mb_strlen($long_url) < $maxUrlLength && !$force) {
+        common_debug("Skipped shortening URL.");
+        return $long_url;
     }
 
-    if(Event::handle('StartShortenUrl', array($long_url,$shortenerName,&$shortenedUrl))){
+    $shortenerName = User_urlshortener_prefs::urlShorteningService($user);
+
+    common_debug("Shortener name = '$shortenerName'");
+
+    if (Event::handle('StartShortenUrl', array($long_url, $shortenerName, &$shortenedUrl))) {
         //URL wasn't shortened, so return the long url
         return $long_url;
-    }else{
+    } else {
         //URL was shortened, so return the result
         return trim($shortenedUrl);
     }