[Plugin: Now Reading Reloaded] How to add a new template file

I figured it out. The Now Reading (Reloaded) functions require a URL string of something like; blog/index.php?now_reading_<blahtype>=<blahvalue>. Where blahtype is something like library, tag, author etc. and blahvalue relates to the type (e.g now_reading_library=1, now_reading_tag=Doctor).

So to add a new template file you need to extend everything that plays with the URL and query strings…. For example, I decided to add a “now_reading_page=favourites.php” so I could add multiple pages with one set of plugin changes.

The files I had to modify were:
1. url.php: this module processes the URL’s that use the mod_rewrite function. I had to modify the
1a. the nr_query_vars function to add a new variable (now_reading_page)…

function nr_query_vars( $vars ) {
    $vars[] = 'now_reading_library';
    $vars[] = 'now_reading_id';
    $vars[] = 'now_reading_tag';
    $vars[] = 'now_reading_page';
    $vars[] = 'now_reading_search';
    $vars[] = 'now_reading_title';
    $vars[] = 'now_reading_author';
    $vars[] = 'now_reading_reader'; //in order to filter books by reader
    return $vars;
}

1b. the nr_mod_rewrite function to add a new mod_rewrite rule for URL’s of the format library/page/favourites.php…

function nr_mod_rewrite( $rules ) {
    $options = get_option('nowReadingOptions');
    add_rewrite_rule(preg_quote($options['permalinkBase']) . '([0-9]+)/?$', 'index.php?now_reading_id=$matches[1]', 'top');
    add_rewrite_rule(preg_quote($options['permalinkBase']) . 'tag/([^/]+)/?$', 'index.php?now_reading_tag=$matches[1]', 'top');
    add_rewrite_rule(preg_quote($options['permalinkBase']) . 'page/([^/]+)/?$', 'index.php?now_reading_page=$matches[1]', 'top');
    add_rewrite_rule(preg_quote($options['permalinkBase']) . 'search/?$', 'index.php?now_reading_search=true', 'top');
    add_rewrite_rule(preg_quote($options['permalinkBase']) . 'reader/([^/]+)/?$', 'index.php?now_reading_library=1&now_reading_reader=$matches[1]', 'top');
    add_rewrite_rule(preg_quote($options['permalinkBase']) . '([^/]+)/([^/]+)/?$', 'index.php?now_reading_author=$matches[1]&now_reading_title=$matches[2]', 'top');
    add_rewrite_rule(preg_quote($options['permalinkBase']) . '([^/]+)/?$', 'index.php?now_reading_author=$matches[1]', 'top');
    add_rewrite_rule(preg_quote($options['permalinkBase']) . '?$', 'index.php?now_reading_library=1', 'top');
}

1c. The is_now_reading_page function to make the new query string register as a now_reading page…

function is_now_reading_page() {
    global $wp;
    $wp->parse_request();

    return (
    get_query_var('now_reading_library') ||
        get_query_var('now_reading_search')  ||
        get_query_var('now_reading_id')      ||
        get_query_var('now_reading_tag')     ||
        get_query_var('now_reading_page')    ||
        get_query_var('now_reading_title')   ||
        get_query_var('now_reading_author')
    );
}

2. now-reading.php: the main file in the library_init() function to add a new check:

if ( get_query_var('now_reading_page') ) {
    // get page name from query string:
        $nrr_page = get_query_var('now_reading_page');

        $load = nr_load_template($nrr_page);
        if ( is_wp_error($load) )
            echo $load->get_error_message();

        die;
    }

3. I also had to create a new function in template-functions.php to return either a normal or mod_rewrite URL…

/**
 * Returns a URL to the permalink for a given (custom) page.
 * @param string $page Page name (e.g. custom.php) to create URL for.
 * @param bool $echo Whether or not to echo the results.
 */
function library_page_url( $page, $echo = true ) {
    $options = get_option('nowReadingOptions');

    if ( $options['useModRewrite'] )
        $url = get_option('home') . "/" . preg_replace("/^\/|\/+$/", "", $options['permalinkBase']) . "/page/" . urlencode($page);
    else
        $url = get_option('home') . '/index.php?now_reading_page=' . urlencode($page);

    $url = apply_filters('library_page_url', $url);

    if ( $echo )
        echo $url;
    return $url;
}

I have no idea what the apply_filters function is doing.