<?php
    /**
    * Utility to build and use shortened alias URLs, useful for 
    * long URLs resulting from many layers of filters.
    */

    // header('Content-Type: text/javascript');
    
    require_once '../includes/common.php';
    require_once 'Services/JSON.php';

    // Where should stored alias records be found?
    if ( !defined('ALIASES_PATH') ) {
        define('ALIASES_PATH', '../data/aliases');
    }

    // Cheap controller: Decide what to do from here..
    if (isset($_SERVER['PATH_INFO'])) {
        // If there's a path, try to proxy the aliased URL
        processAliasGetRequest();
    } else if ($_SERVER['REQUEST_METHOD'] === 'POST') {
        // If this is a POST request, assume that it's an attempt to create a new alias.
        processAliasBuildRequest();
    } else {
        // If nothing else, show the alias build form.
        showAliasForm();
    }

    function _aliasNameToPath($alias_name) {
        $path_name = preg_replace('/\//', '_', $alias_name);
        return ALIASES_PATH . '/' . $path_name;
    }
    
    function _getRecord($alias_path) {
        // Load up the alias record.
        // TODO: Report error if problem loading up record
        $data = file_get_contents($alias_path);
        $json = new Services_JSON();
        return $json->decode($data);
    }
    
    /**
    * Handle proxying the data from an aliased URL.
    */
    function processAliasGetRequest() {
        $alias_name   = substr($_SERVER['PATH_INFO'], 1);
        $alias_record = _getRecord(_aliasNameToPath($alias_name));
        
        // Use the HTTP cache to fetch the original URL's contents.
        if (isset($_GET['direct']) && $_GET['direct']) {
            // TODO: Is using the Location: header really the best way to handle the aliases?
            header("Location: $alias_orig_url");
            return;
        } else {
            $alias_orig_url = $alias_record->{'url'};
            $cache =& new HTTPCache($alias_orig_url);
            $data  =  $cache->fetch();

            // Copy certain response headers returned in the request
            // TODO: Determine if these are sufficient headers for passthru
            $passthru_headers = array(
                'content-type', 'etag', 'date', 'expires'
            );
            if ($cache->client->headers) {
                foreach ($cache->client->headers as $header) {
                    if (strpos($header, ':') === false) {
                        error_log($header);
                        continue;
                    }
                    // Parse out the name and value of the header.
                    list($name, $value) = explode(': ', $header);
                    $lc_name = strtolower($name);
                    
                    // If this is a header to be passed through, do so.
                    if (strpos($lc_name, $passthru_headers) !== false) {
                        header($lines[0]);
                    }
                }
            }
        }

        // Finally, spew out the fetched data.
        header('Content-Type: text/xml', false);
        echo $data;
    }

    /**
    * Handle creating a new URL alias record.
    */
    function processAliasBuildRequest() {
        
        // Build the initial record for the alias.
        $alias_record = array(
            'name'        => $_POST['name'],
            'description' => $_POST['description'],
            'url'         => $_POST['original']
        );

        // Build a safe filename for this alias record.
        $path_name  = preg_replace('/\//', '_', $alias_record['name']);
        $alias_path = ALIASES_PATH . '/' . $path_name;
        
        // TODO: Report error if file not writable
        $json = new Services_JSON();
        $data = $json->encode($alias_record);
        file_put_contents($alias_path, $data);

        // Work out the URL to the newly created alias
        $alias_url  = $_SERVER['PHP_SELF'] . '/' . $alias_record['name'];

        if ($_POST['post_action'] == 'create') {
            // Redirect to the chosen alias upon creation
            header("Location: $alias_url");
        } else {
            // Return to editing form upon update.
            showAliasForm();
        }
    }
    
    /**
    * Present the URL alias construction form.
    */
    function showAliasForm() {

        if (isset($_GET['edit'])) {
            $alias_name        = $_GET['name'];
            $alias_record      = _getRecord(_aliasNameToPath($alias_name));
            $alias_name        = $alias_record->{'name'};
            $alias_url         = $alias_record->{'url'};
            $alias_description = $alias_record->{'description'};
            $post_action       = 'edit';
        } else {
            $alias_name        = '';
            $alias_url         = '';
            $alias_description = '';
            $post_action       = 'create';
        }
        
        $form_url = $_SERVER['PHP_SELF'];
        ?>
        <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
            "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
        <html xmlns="http://www.w3.org/1999/xhtml">
            <head>
                <title>FeedMagick</title>
                <script src="./js/main.js" type="text/javascript"></script>
                <link href="../css/main.css" type="text/css" rel="stylesheet" />
            </head>
            <body>
                <h1>FeedMagick URL alias builder</h1>
                <form class="fmparams" action="<?php echo $form_url ?>" method="POST">
                    
                    <input type="hidden" name="post_action" value="<?php echo $post_action ?>" />
                    
                    <label for="name">Alias name:</label>
                    <input type="text" size="30" id="name" name="name" value="<?php echo $alias_name ?>" /><br />
                    
                    <label for="description">Short description:</label>
                    <input type="text" size="70" id="description" name="description" value="<?php echo $alias_description ?>" /><br />
                    
                    <label for="original">Original URL:</label>
                    <input type="text" size="70" id="original" name="original" value="<?php echo $alias_url ?>" /><br />

                    <input type="submit" />

                </form>

                <h2>Available aliases</h2>
                <dl class="aliaslist">
        <?php
            
        // Gather up all the aliases by filename & sort.
        $dir = ALIASES_PATH;
        $dh = opendir($dir);
        $files = array();
        while (($file = readdir($dh)) !== false) {
            $path = $dir.'/'.$file;
            if (filetype($path) != 'dir') {
                array_push($files, $file);
            }
        }
        closedir($dh);
        sort($files);

        // Display all of the commands found. 
        $form_url = $_SERVER['PHP_SELF'];
        foreach ($files as $file) {
            $path   = $dir.'/'.$file;
            $record = _getRecord($path);
            ?>
                    <dt>
                        (<a href="<?php echo $form_url.'?edit=1&name='.$record->{'name'} ?>">edit</a>)
                        <a target="_new" href="<?php echo $form_url.'/'.$record->{'name'} ?>" title="<?php echo $file ?>"><?php echo $record->{'name'} ?></a>
                    </dt>
                    <dd>
                        <?php echo $record->{'description'} ?>
                    </dd>
            <?php
        }
            
        ?>
                </dl>
            </body>
        </html>
        <?php
    }
?>