root/afridex/plugins/kb-linker/kb_linker.php @ 21

<?php
/*
Plugin Name: KB Linker
Plugin URI: http://adambrown.info/b/widgets/kb-linker/
Description: Looks for user-defined phrases in posts and automatically links them. Example: Link every occurrence of "Wordpress" to wordpress.org.
Author: Adam R. Brown
Version: 1.102
Author URI: http://adambrown.info/
*/

//      OPTIONAL SETTINGS
        /*special characters for foreign languages. Add any you want to the array below. Char goes on left, HTML entity on right. The German codes are here as examples.
                See http://www.w3schools.com/tags/ref_entities.asp for HTML entities.   */
        $kblinker_special_chars = array(
                                'ä' => '&#228;',
                                'Ä' => '&#196;',
                                'ö' => '&#246;',
                                'Ö' => '&#214;',
                                'ü' => '&#252;',
                                'Ü' => '&#220;',
                                'ß' => '&#223;'
        );
        /*      would you like to add title="" tags to the links with the keyword in them? true or false. */
        define( 'KBLINKER_USE_TITLES' , true );
        /*      if the preceding setting is TRUE, you can customize the text before or after the keyword below. For example, if you want titles to say "More about KEYWORD.",
                then make before = 'More about ' (note the space) and after = '.'       */
        $kblinker_title_text = array(
                'before' => 'More about ', // default: 'More about '
                'after' => ' &raquo;',  // default: '$raquo;' (an arrow pointing to the right)
        );
//      END OF SETTINGS. NO MORE EDITING REQUIRED.





/*      DEVELOPMENT NOTES

        CHANGE LOG
        1.01    initial release
        1.02    quick fix to check is_array before extracting on line 105
        1.03    - added support for German (or other) special characters
                - added support for opening links in different targets
        1.04    add 'i' tag to the tag-detection regexes (it was already in the main replacement one, causing some errors)
        1.05    bugfix
        1.06    bugfix
        1.10    - puts keyword in link's "title" tags
                - won't link the same URL more than once per post, even if multiple keywords are associated with it
                - won't link a page to itself (imperfect)
        1.101   bugfix
        1.102   bugfix

        IMPORTANT NOTE TO ANYBODY CONSIDERING ADDING THIS PLUGIN TO A WP-MU INSTALLATION:
        If you aren't sure whether you are using a WP-MU blog, then you aren't. Trust me. If this warning applies to you, then you will know it.
        For WP-MU administrators: You should not use this plugin. Your users could use it to place (potentially malicious) javascript into their blogs.
        This plugin is PERFECTLY SAFE for non-WP-MU blogs, so ignore this message if you're using regular wordpress (you probably are).

        KNOWN BUGS
        - Pre 1.04: If a tag or attribute contained the keyword, but with different capitalization than specified in options, it was replaced. That causes problems.
        - 1.04: Fixed that bug, but in return, you might find capitalization changing (within tags and attributes) to match that given in the linker's options. Sorry.
        - 1.05 Fixed the capitalization bug

        GENERAL NOTE FOR DEVELOPERS/HACKERS/ETC:
                You will notice that I've included extensive commenting in the code below. I do not have time to support this plugin. The commenting is there to make this plugin
                easy to modify. Please try making modifications on your own before posting a support question at the plugin's URI.
                That being said, you are welcome to post well-informed support questions on my site.

        DATABASE STRUCTURE
                the options->KB Linker page will create a set of matching terms and URLs that gets stored as a list.
                structure of option "kb_linker":
                        pairs => array( see below)
                        text=>  same content as pairs, but in unprocessed form (for displaying in the option's form)
                        plurals => 1, 0         if 1, we should look for variants of the keywords ending in s or es
*/

function kb_linker($content){
        global $kblinker_special_chars,$kblinker_title_text;

        $option = get_option('kb_linker');
        if (is_array($option)){
                extract($option);
        }

        // uncomment for testing (to override options):
        #$pairs = array( 'contributor'=>'http://google.com', 'a'=>'http://yahoo.com/', 'scripting'=>'scripting', 'don'=>'don', 'first post'=>'firstpost.org', 'first'=>'first.org', 'wp'=>'WP.ORG');

        // die if option isn't set yet
        if ( !is_array($pairs) )
                return $content;

        // let's make use of that special chars setting.
        if (is_array($kblinker_special_chars)){
                foreach ($kblinker_special_chars as $char => $code){
                        $content = str_replace($code,$char,$content);
                }
        }

        // needed below...
        $usedUrls = array();
        $currentUrl = 'http://' . $_SERVER["HTTP_HOST"] . $_SERVER["REQUEST_URI"]; // may not work on all hosting setups.

        // most of the action is in here.
        foreach ($pairs as $keyword => $url){
                if (in_array( $url, $usedUrls )) // don't link to the same URL more than once
                        continue;
                if (strpos( $content, $url )){ // we've already used this URL, or it was manually inserted by author into post
                        $usedUrls[] = $url;
                        continue;
                }
                if ($url == $currentUrl){ // don't link a page to itself
                        $usedUrls[] = $url;
                        continue;
                }

                // first, let's check whether we've got a "target" attribute specified.
                if (false!==strpos( $url, ' ' ) ){      // Let's not waste CPU resources unless we see a ' ' in the URL:
                        $target = trim(   substr( $url, strpos($url,' ') )   );
                        $target = ' target="'.$target.'"';
                        $url = substr( $url, 0, strpos($url,' ') );
                }else{
                        $target='';
                }
                
                // let's escape any '&' in the URL.
                $url = str_replace( '&amp;', '&', $url ); // this might seem unnecessary, but it prevents the next line from double-escaping the &
                $url = str_replace( '&', '&amp;', $url );
                
                // we don't want to link the keyword if it is already linked.
                // so let's find all instances where the keyword is in a link and precede it with &&&, which will be sufficient to avoid linking it. We use &&&, since WP would pass that
                // to us as &amp;&amp;&amp; (if it occured in a post), so it would never be in the $content on its own.
                // this has two steps. First, look for the keyword as linked text:
                $content = preg_replace( '|(<a[^>]+>)(.*)('.$keyword.')(.*)(</a[^>]*>)|Ui', '$1$2&&&$3$4$5', $content);

                // Next, look for the keyword inside tags. E.g. if they're linking every occurrence of "Google" manually, we don't want to find 
                // <a href="http://google.com"> and change it to <a href="http://<a href="http://www.google.com">.com">
                // More broadly, we don't want them linking anything that might be in a tag. (e.g. linking "strong" would screw up <strong>). 
                // if you get problems with KB linker creating links where it shouldn't, this is the regex you should tinker with, most likely. Here goes:
                $content = preg_replace( '|(<[^>]*)('.$keyword.')(.*>)|Ui', '$1&&&$2$3', $content);

                // I'm sure a true master of regular expressions wouldn't need the previous two steps, and would simply write the replacement expression (below) better. But this works for me.
        
                // set the title attribute:
                if (KBLINKER_USE_TITLES)
                        $title = ' title="'.$kblinker_title_text['before'].$keyword.$kblinker_title_text['after'].'"';
                
                // now that we've taken the keyword out of any links it appears in, let's look for the keyword elsewhere.
                if ( 1 != $plurals ){    // we do basically the same thing whether we're looking for plurals or not. Let's do non-plurals option first:
                        $content = preg_replace( '|(?<=[\s>;"\'/])('.$keyword.')(?=[\s<&.,!\'";:\-/])|i', '<a href="'.$url.'" class="kblinker"'.$target.$title.'>$1</a>', $content, 1); // that "1" at the end limits it to replacing the keyword only once per post.
                        /* some notes about that regular expression to make modifying it easier for you if you're new to these things:
                        (?<=[\s>;"\'])
                                (?<=    marks it as a lookbehind assertion
                                to ensure that we are linking only complete words, we want keyword preceded by one of space, tag (>), entity (;) or certain kinds of punctuation (escaped with \ when necessary)
                                Note that '&' is NOT one of the allowed lookbehinds (or our '&&&' trick wouldn't work)
                        (?=[\s<&.,\'";:\-])
                                (?=     marks this as a lookahead assertion
                                again, we link only complete words. Must be followed by space, tag (<), entity (&), or certain kinds of punctuation. 
                                Note that some of the punctuations are escaped with \
                        */
                }else{  // if they want us to look for plurals too:
                        // this regex is almost identical to the non-plurals one, we just add an s? where necessary:
                        $content = preg_replace( '|(?<=[\s>;"\'/])('.$keyword.'s?)(?=[\s<&.,!\'";:\-/])|i', '<a href="'.$url.'" class="kblinker"'.$target.$title.'>$1</a>', $content, 1);       // that "1" at the end limits it to replacing once per post.
                }
        }
        // get rid of our '&&&' things.
        $content = str_replace( '&&&', '', $content);
        return $content;
}


function kb_linker_options_page(){
        $sample = 'wordpress->http://wordpress.org/
google->http://www.google.com/ _blank
kb linker->http://adambrown.info/b/widgets/kb-linker/
knuckleheads->http://www.house.gov/';

        if ( $_POST['kb_linker'] ){
                $pairs = str_replace("\r", '', $_POST['kb_linker']);
                $pairs = explode("\n", $pairs);
                foreach( $pairs as $pair ){
                        $pair = trim( $pair ); // no leading or trailing spaces. Can mess with the "target" thing in function kb_linker()
                        $pair = explode( "->", $pair );
                        if ( ( '' != $pair[0] ) && ( '' != $pair[1] ) )
                                $new[ $pair[0] ] = $pair[1];
                }
                $pairs = $new;  // contains the pairs as an array for use by the filter
                $text = $_POST['kb_linker'];    // contains the pairs as entered in the form for display below
                
                $plurals = ( 1 == $_POST['kb_plurals'] ) ? 1 : 0;
                $option = array( 'pairs'=>$pairs, 'text'=>$text, 'plurals'=>$plurals ); // store both versions of the option, pairs and text
                update_option( 'kb_linker', $option );
                print '<div id="message" class="updated fade"><p><strong>KB Linker options updated.</strong> <a href="'.get_bloginfo('url').'">View site &raquo;</a></p></div>';
        }else{
                $option = get_option('kb_linker');
                if (is_array($option)){
                        extract($option);
                }else{
                        $text = $sample;
                        $plurals = 0;
                }
        }

        $checked = ( 1 == $plurals ) ? 'checked="checked"' : '' ;

        print '
        <div class="wrap">
        <h2>KB Linker</h2>
        <p>KB Linker will link phrases you specify to sites you specify. For example, you could make it so that whenever "Wordpress" occurs in a post it is automatically linked to wordpress.org.</p>
        <p>Enter your keyword-URL pairs in the box below. Each pair should appear on its own line. Separate each keyword from its respective link with "->". Look at the bottom of this page for important details. Below are a few examples to get you going. Note that the link to Google will open in a new window, since it is followed with "&nbsp;_blank" (note the space).</p>
        <blockquote><pre>'.$sample.'</pre></blockquote>
        <p>Alright, knock yourself out:</p>
        
        <form method="post" action="http://'.$_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'].'">
        <textarea id="kb_linker" name="kb_linker" rows="10" cols="45" class="widefat">'.$text.'</textarea>
        <p><input type="checkbox" '.$checked.' name="kb_plurals" id="kb_plurals" value="1" /> Also link the keyword if it ends in <i>s</i> (i.e. plurals in certain languages)</p>
        <p class="submit" style="width:420px;"><input type="submit" value="Submit &raquo;" /></p>
        </form>
        
        <p>Considerations:</p>
        <ul>
                <li>URLs should be valid (i.e. begin with http://)</li>
                <li>The same URL can appear on more than one line (i.e. with more than one keyword).</li>
                <li>Because a word can only link to one site, a keyword should not appear on more than one line. If it does, only the last instance of the keyword will be matched to its URL.</li>
                <li>If one of your keywords is a substring of the other--e.g. "download wordpress" and "wordpress"--then you should list the shorter one later than the first one.</li>
                <li>Keywords are case-insensitive (e.g. "wordpress" is the same as "WoRdPrEsS").</li>
                <li>Spaces count, so "wordpress" is not the same as "wordpress ".</li>
                <li>Keywords will be linked only if they occur in your post as a word (or phrase), not as a partial word. So if one of your keywords is "a" (for some strange reason), it will be linked only when it occurs as the word "a"--when the letter "a" occurs within a word, it will not be linked.</li>
                <li>You can use any valid target attribute, not just "_blank"--see <a href="http://www.w3schools.com/tags/tag_a.asp">W3C</a> for a list of valid targets.</li>
        </ul>
        </div>
        ';
}

function kb_linker_admin_page(){
        add_submenu_page('options-general.php', 'KB Linker', 'KB Linker', 5, 'kb_linker.php', 'kb_linker_options_page');
}

add_filter('the_content', 'kb_linker', 9); // run before Dagon Design Sitemap Generator (runs at priority 10)
add_action('admin_menu', 'kb_linker_admin_page');
?>