footnotes/class/task.php

<?php
/**
 * Includes the core function of the Plugin - Search and Replace the Footnotes.
 *
 * @filesource
 * @author Stefan Herndler
 * @since 1.5.0
 *
 * Edited for v2.0.0 and following.
 *
 * 2.0.5: Autoload / infinite scroll support added thanks to code from
 * @docteurfitness <https://wordpress.org/support/topic/auto-load-post-compatibility-update/>
 *
 * 2.0.9: DISABLED the_post HOOK  2020-11-08T1839+0100
 * 2.1.0: promoted the 'Continue reading' button from localization to customization  2020-11-08T2146+0100
 * 2.1.1: combining identical footnotes: fixed dead links  2020-11-14T2233+0100
 * 2.1.1: options fixing ref container layout and referrer vertical alignment  2020-11-16T2024+0100
 * 2.1.1: option fixing ref container relative position  2020-11-17T0254+0100
 * 2.1.2: options for the other hooks  2020-11-19T1849+0100
 * 2.1.4: fix line wrapping of URLs based on pattern, not link element  2020-11-25T0837+0100
 * 2.1.4: fix issues with link elements by making them optional   2020-11-26T1051+0100
 *
 * Last modified:  2020-11-26T1051+0100
 */

// If called directly, abort:
defined( 'ABSPATH' ) or die;

/**
 * Looks for Footnotes short codes and replaces them. Also displays the Reference Container.
 *
 * @author Stefan Herndler
 * @since 1.5.0
 */
class MCI_Footnotes_Task {

    /**
     * Contains all footnotes found on current public page.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     * @var array
     */
    public static $a_arr_Footnotes = array();

    /**
     * Flag if the display of 'LOVE FOOTNOTES' is allowed on the current public page.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     * @var bool
     */
    public static $a_bool_AllowLoveMe = true;

    /**
     * Prefix for the Footnote html element ID.
     *
     * @author Stefan Herndler
     * @since 1.5.8
     * @var string
     */
    public static $a_str_Prefix = "";

    /**
     * Register WordPress Hooks to replace Footnotes in the content of a public page.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     *
     * Edited for:
     * 2.0.5 through v2.0.7  changes to priority  2020-11-02T0330+0100..2020-11-06T1344+0100
     * 2.1.1 add setting for the_content
     * 2.1.2 add settings for 4 other hooks  2020-11-19T1248+0100
     *
     * Setting the_content priority to "10" instead of PHP_INT_MAX i.e. 9223372036854775807
     * makes the footnotes reference container display beneath the post and above other
     * features added by other plugins, e.g. related post lists and social buttons.
     * For YARPP to display related posts below the Footnotes reference container,
     * priority needs to be at least 1200.
     * Requested by users: <https://wordpress.org/support/topic/change-the-position-5/>
     * Documentation: <https://codex.wordpress.org/Plugin_API/#Hook_in_your_Filter>
     *
     * Default remains PHP_INT_MAX.
     * PHP_INT_MAX cannot be reset by leaving the number box empty. because browsers
     * (WebKit) don’t allow it, so we must resort to -1.
     */
    public function registerHooks() {

        // get values from settings:
        $p_int_TheTitlePriority    = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_EXPERT_LOOKUP_THE_TITLE_PRIORITY_LEVEL));
        $p_int_TheContentPriority  = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_EXPERT_LOOKUP_THE_CONTENT_PRIORITY_LEVEL));
        $p_int_TheExcerptPriority  = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_EXPERT_LOOKUP_THE_EXCERPT_PRIORITY_LEVEL));
        $p_int_WidgetTitlePriority = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_EXPERT_LOOKUP_WIDGET_TITLE_PRIORITY_LEVEL));
        $p_int_WidgetTextPriority  = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_EXPERT_LOOKUP_WIDGET_TEXT_PRIORITY_LEVEL));

        // PHP_INT_MAX can be set by -1:
        $p_int_TheTitlePriority    = ($p_int_TheTitlePriority    == -1) ? PHP_INT_MAX : $p_int_TheTitlePriority   ;
        $p_int_TheContentPriority  = ($p_int_TheContentPriority  == -1) ? PHP_INT_MAX : $p_int_TheContentPriority ;
        $p_int_TheExcerptPriority  = ($p_int_TheExcerptPriority  == -1) ? PHP_INT_MAX : $p_int_TheExcerptPriority ;
        $p_int_WidgetTitlePriority = ($p_int_WidgetTitlePriority == -1) ? PHP_INT_MAX : $p_int_WidgetTitlePriority;
        $p_int_WidgetTextPriority  = ($p_int_WidgetTextPriority  == -1) ? PHP_INT_MAX : $p_int_WidgetTextPriority ;


        // append custom css to the header
        add_filter('wp_head', array($this, "wp_head"), PHP_INT_MAX);

        // append the love and share me slug to the footer
        add_filter('wp_footer', array($this, "wp_footer"), PHP_INT_MAX);

        if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_EXPERT_LOOKUP_THE_TITLE))) {
            add_filter('the_title', array($this, "the_title"), $p_int_TheTitlePriority);
        }

        // custom priority level for reference container relative positioning; default PHP_INT_MAX:
        if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_EXPERT_LOOKUP_THE_CONTENT))) {
            add_filter('the_content', array($this, "the_content"), $p_int_TheContentPriority);
        }

        if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_EXPERT_LOOKUP_THE_EXCERPT))) {
             add_filter('the_excerpt', array($this, "the_excerpt"), $p_int_TheExcerptPriority);
        }
        if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_EXPERT_LOOKUP_WIDGET_TITLE))) {
            add_filter('widget_title', array($this, "widget_title"), $p_int_WidgetTitlePriority);
        }
        if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_EXPERT_LOOKUP_WIDGET_TEXT))) {
            add_filter('widget_text', array($this, "widget_text"), $p_int_WidgetTextPriority);
        }


        // REMOVED the_post HOOK  2020-11-08T1839+0100
        //
        //


        // reset stored footnotes when displaying the header
        self::$a_arr_Footnotes = array();
        self::$a_bool_AllowLoveMe = true;
    }

    /**
     * Outputs the custom css to the header of the public page.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     */
    public function wp_head() {
        $l_str_Color = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_MOUSE_OVER_BOX_COLOR);
        $l_str_Background = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_MOUSE_OVER_BOX_BACKGROUND);
        $l_int_BorderWidth = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_MOUSE_OVER_BOX_BORDER_WIDTH);
        $l_str_BorderColor = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_MOUSE_OVER_BOX_BORDER_COLOR);
        $l_int_BorderRadius = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_MOUSE_OVER_BOX_BORDER_RADIUS);
        $l_int_MaxWidth = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_MOUSE_OVER_BOX_MAX_WIDTH);
        $l_str_BoxShadowColor = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_MOUSE_OVER_BOX_SHADOW_COLOR);
        ?>
        <style type="text/css" media="screen">
            <?php

            if (!MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_REFERENCE_CONTAINER_START_PAGE_ENABLE))) {
                echo "\r\n.home .footnotes_reference_container { display: none; }\r\n";
            }

            echo '.footnote_tooltip {';
            if (!empty($l_str_Color)) {
                printf(" color: %s !important;", $l_str_Color);
            }
            if (!empty($l_str_Background)) {
                printf(" background-color: %s !important;", $l_str_Background);
            }
            if (!empty($l_int_BorderWidth) && intval($l_int_BorderWidth) > 0) {
                printf(" border-width: %dpx !important; border-style: solid !important;", $l_int_BorderWidth);
            }
            if (!empty($l_str_BorderColor)) {
                printf(" border-color: %s !important;", $l_str_BorderColor);
            }
            if (!empty($l_int_BorderRadius) && intval($l_int_BorderRadius) > 0) {
                printf(" border-radius: %dpx !important;", $l_int_BorderRadius);
            }
            if (!empty($l_int_MaxWidth) && intval($l_int_MaxWidth) > 0) {
                printf(" max-width: %dpx !important;", $l_int_MaxWidth);
            }
            if (!empty($l_str_BoxShadowColor)) {
                printf(" -webkit-box-shadow: 2px 2px 11px %s;", $l_str_BoxShadowColor);
                printf(" -moz-box-shadow: 2px 2px 11px %s;", $l_str_BoxShadowColor);
                printf(" box-shadow: 2px 2px 11px %s;", $l_str_BoxShadowColor);
            }
            echo '}';

            // set custom CSS to override settings, not conversely:
            echo MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_CUSTOM_CSS);

?>
        </style>
<?php
        if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_FOOTNOTES_MOUSE_OVER_BOX_ALTERNATIVE))) {
            echo '<script content="text/javascript">' . "\r\n";
            echo "\tfunction footnoteTooltipShow(footnoteTooltipId) {\r\n";
            echo "\t\tdocument.getElementById(footnoteTooltipId).classList.remove('hidden');\r\n";
            echo "\t\tdocument.getElementById(footnoteTooltipId).classList.add('shown');\r\n";
            echo "\t}\r\n";
            echo "\tfunction footnoteTooltipHide(footnoteTooltipId) { \r\n";
            echo "\t\tdocument.getElementById(footnoteTooltipId).classList.remove('shown');\r\n";
            echo "\t\tdocument.getElementById(footnoteTooltipId).classList.add('hidden');\r\n";
            echo "\t}\r\n";
            echo "</script>\r\n";
        };
    }

    /**
     * Displays the 'LOVE FOOTNOTES' slug if enabled.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     */
    public function wp_footer() {
        if (MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_REFERENCE_CONTAINER_POSITION) == "footer") {
            echo $this->ReferenceContainer();
        }
        // get setting for love and share this plugin
        $l_str_LoveMeIndex = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_LOVE);
        // check if the admin allows to add a link to the footer
        if (empty($l_str_LoveMeIndex) || strtolower($l_str_LoveMeIndex) == "no" || !self::$a_bool_AllowLoveMe) {
            return;
        }
        // set a hyperlink to the word "footnotes" in the Love slug
        $l_str_LinkedName = sprintf('<a href="http://wordpress.org/plugins/footnotes/" target="_blank" style="text-decoration:none;">%s</a>',MCI_Footnotes_Config::C_STR_PLUGIN_PUBLIC_NAME);
        // get random love me text
        if (strtolower($l_str_LoveMeIndex) == "random") {
            $l_str_LoveMeIndex = "text-" . rand(1,3);
        }
        switch ($l_str_LoveMeIndex) {
            case "text-1":
                $l_str_LoveMeText = sprintf(__('I %s %s', MCI_Footnotes_Config::C_STR_PLUGIN_NAME), MCI_Footnotes_Config::C_STR_LOVE_SYMBOL, $l_str_LinkedName);
                break;
            case "text-2":
                $l_str_LoveMeText = sprintf(__('this site uses the awesome %s Plugin', MCI_Footnotes_Config::C_STR_PLUGIN_NAME), $l_str_LinkedName);
                break;
            case "text-3":
            default:
                $l_str_LoveMeText = sprintf(__('extra smooth %s', MCI_Footnotes_Config::C_STR_PLUGIN_NAME), $l_str_LinkedName);
                break;
        }
        echo sprintf('<div style="text-align:center; color:#acacac;">%s</div>', $l_str_LoveMeText);
    }

    /**
     * Replaces footnotes in the post/page title.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     * @param string $p_str_Content Widget content.
     * @return string Content with replaced footnotes.
     */
    public function the_title($p_str_Content) {
        // appends the reference container if set to "post_end"
        return $this->exec($p_str_Content, false);
    }

    /**
     * Replaces footnotes in the content of the current page/post.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     * @param string $p_str_Content Page/Post content.
     * @return string Content with replaced footnotes.
     */
    public function the_content($p_str_Content) {
        // appends the reference container if set to "post_end"
        return $this->exec($p_str_Content, MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_REFERENCE_CONTAINER_POSITION) == "post_end" ? true : false);
    }

    /**
     * Replaces footnotes in the excerpt of the current page/post.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     * @param string $p_str_Content Page/Post content.
     * @return string Content with replaced footnotes.
     */
    public function the_excerpt($p_str_Content) {
        return $this->exec($p_str_Content, false, !MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_FOOTNOTES_IN_EXCERPT)));
    }

    /**
     * Replaces footnotes in the widget title.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     * @param string $p_str_Content Widget content.
     * @return string Content with replaced footnotes.
     */
    public function widget_title($p_str_Content) {
        // appends the reference container if set to "post_end"
        return $this->exec($p_str_Content, false);
    }

    /**
     * Replaces footnotes in the content of the current widget.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     * @param string $p_str_Content Widget content.
     * @return string Content with replaced footnotes.
     */
    public function widget_text($p_str_Content) {
        // appends the reference container if set to "post_end"
        return $this->exec($p_str_Content, MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_REFERENCE_CONTAINER_POSITION) == "post_end" ? true : false);
    }

    /**
     * Replaces footnotes in each Content var of the current Post object.
     *
     * @author Stefan Herndler
     * @since 1.5.4
     * @param array|WP_Post $p_mixed_Posts
     */
    public function the_post(&$p_mixed_Posts) {
        // single WP_Post object received
        if (!is_array($p_mixed_Posts)) {
            $p_mixed_Posts = $this->replacePostObject($p_mixed_Posts);
            return;
        }
        // array of WP_Post objects received
        for($l_int_Index = 0; $l_int_Index < count($p_mixed_Posts); $l_int_Index++) {
            $p_mixed_Posts[$l_int_Index] = $this->replacePostObject($p_mixed_Posts[$l_int_Index]);
        }
    }

    /**
     * Replace all Footnotes in a WP_Post object.
     *
     * @author Stefan Herndler
     * @since 1.5.6
     * @param WP_Post $p_obj_Post
     * @return WP_Post
     */
    private function replacePostObject($p_obj_Post) {
        //MCI_Footnotes_Convert::debug($p_obj_Post);
        $p_obj_Post->post_content = $this->exec($p_obj_Post->post_content);
        $p_obj_Post->post_content_filtered = $this->exec($p_obj_Post->post_content_filtered);
        $p_obj_Post->post_excerpt = $this->exec($p_obj_Post->post_excerpt);
        return $p_obj_Post;
    }

    /**
     * Replaces all footnotes that occur in the given content.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     * @param string $p_str_Content Any string that may contain footnotes to be replaced.
     * @param bool $p_bool_OutputReferences Appends the Reference Container to the output if set to true, default true.
     * @param bool $p_bool_HideFootnotesText Hide footnotes found in the string.
     * @return string
     */
    public function exec($p_str_Content, $p_bool_OutputReferences = false, $p_bool_HideFootnotesText = false) {
        // replace all footnotes in the content, settings are converted to html characters
        $p_str_Content = $this->search($p_str_Content, true, $p_bool_HideFootnotesText);
        // replace all footnotes in the content, settings are NOT converted to html characters
        $p_str_Content = $this->search($p_str_Content, false, $p_bool_HideFootnotesText);

        // append the reference container
        if ($p_bool_OutputReferences) {
            $p_str_Content = $p_str_Content . $this->ReferenceContainer();
        }

        // take a look if the LOVE ME slug should NOT be displayed on this page/post, remove the short code if found
        if (strpos($p_str_Content, MCI_Footnotes_Config::C_STR_NO_LOVE_SLUG) !== false) {
            self::$a_bool_AllowLoveMe = false;
            $p_str_Content = str_replace(MCI_Footnotes_Config::C_STR_NO_LOVE_SLUG, "", $p_str_Content);
        }
        // return the content with replaced footnotes and optional reference container append
        return $p_str_Content;
    }

    /**
     * Replaces all footnotes in the given content and appends them to the static property.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     * @param string $p_str_Content Content to be searched for footnotes.
     * @param bool $p_bool_ConvertHtmlChars html encode settings, default true.
     * @param bool $p_bool_HideFootnotesText Hide footnotes found in the string.
     * @return string
     */
    public function search($p_str_Content, $p_bool_ConvertHtmlChars, $p_bool_HideFootnotesText) {

        // post ID to make everything unique wrt infinite scroll and archive view
        global $l_int_PostId;
        $l_int_PostId = get_the_id();

        // contains the index for the next footnote on this page
        $l_int_FootnoteIndex = count(self::$a_arr_Footnotes) + 1;

        // contains the starting position for the lookup of a footnote
        $l_int_PosStart = 0;

        // get start and end tag for the footnotes short code
        $l_str_StartingTag = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_SHORT_CODE_START);
        $l_str_EndingTag = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_SHORT_CODE_END);
        if ($l_str_StartingTag == "userdefined" || $l_str_EndingTag == "userdefined") {
            $l_str_StartingTag = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_SHORT_CODE_START_USER_DEFINED);
            $l_str_EndingTag = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_SHORT_CODE_END_USER_DEFINED);
        }
        // decode html special chars
        if ($p_bool_ConvertHtmlChars) {
            $l_str_StartingTag = htmlspecialchars($l_str_StartingTag);
            $l_str_EndingTag = htmlspecialchars($l_str_EndingTag);
        }
        // if footnotes short code is empty, return the content without changes
        if (empty($l_str_StartingTag) || empty($l_str_EndingTag)) {
            return $p_str_Content;
        }

        if (!$p_bool_HideFootnotesText) {
            // load template file
            if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_FOOTNOTES_MOUSE_OVER_BOX_ALTERNATIVE))) {
                $l_obj_Template = new MCI_Footnotes_Template(MCI_Footnotes_Template::C_STR_PUBLIC, "footnote-alternative");
            } else {
                $l_obj_Template = new MCI_Footnotes_Template(MCI_Footnotes_Template::C_STR_PUBLIC, "footnote");
            }
            $l_obj_TemplateTooltip = new MCI_Footnotes_Template(MCI_Footnotes_Template::C_STR_PUBLIC, "tooltip");
        } else {
            $l_obj_Template = null;
            $l_obj_TemplateTooltip = null;
        }

        // search footnotes short codes in the content
        do {
            // get first occurrence of the footnote short code [start]
            $i_int_len_Content = strlen($p_str_Content);
            if ($l_int_PosStart > $i_int_len_Content) $l_int_PosStart = $i_int_len_Content;
            $l_int_PosStart = strpos($p_str_Content, $l_str_StartingTag, $l_int_PosStart);
            // no short code found, stop here
            if ($l_int_PosStart === false) {
                break;
            }
            // get first occurrence of a footnote short code [end]
            $l_int_PosEnd = strpos($p_str_Content, $l_str_EndingTag, $l_int_PosStart);
            // no short code found, stop here
            if ($l_int_PosEnd === false) {
                break;
            }
            // calculate the length of the footnote
            $l_int_Length = $l_int_PosEnd - $l_int_PosStart;

            // get footnote text
            $l_str_FootnoteText = substr($p_str_Content, $l_int_PosStart + strlen($l_str_StartingTag), $l_int_Length - strlen($l_str_StartingTag));

            // fix line wrapping of URLs (hyperlinked or not) based on pattern, not link element,
            // to prevent them from hanging out of the tooltip in non-Unicode-compliant user agents
            // spare however values of the href argument!
            // see public.css
            $l_str_FootnoteText = preg_replace( '#(?<!href=.)(https?://[^\\s<]+)#', '<span class="footnote_url_wrap">$1</span>', $l_str_FootnoteText );

            // Text to be displayed instead of the footnote
            $l_str_FootnoteReplaceText = "";

            // display the footnote referrers and the tooltips:
            if (!$p_bool_HideFootnotesText) {
                $l_int_Index = MCI_Footnotes_Convert::Index($l_int_FootnoteIndex, MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_COUNTER_STYLE));

                // display only an excerpt of the footnotes text if enabled
                $l_str_ExcerptText = $l_str_FootnoteText;
                $l_bool_EnableExcerpt = MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_FOOTNOTES_MOUSE_OVER_BOX_EXCERPT_ENABLED));
                $l_int_MaxLength = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_MOUSE_OVER_BOX_EXCERPT_LENGTH));

                if ($l_bool_EnableExcerpt) {
                    $l_str_DummyText = strip_tags($l_str_FootnoteText);
                    if (is_int($l_int_MaxLength) && strlen($l_str_DummyText) > $l_int_MaxLength) {
                        $l_str_ExcerptText  = substr($l_str_DummyText, 0, $l_int_MaxLength);
                        $l_str_ExcerptText  = substr($l_str_ExcerptText, 0, strrpos($l_str_ExcerptText, ' '));
                        $l_str_ExcerptText .= '&nbsp;&#x2026; ';
                        $l_str_ExcerptText .= '<span class="footnote_tooltip_continue" ';
                        $l_str_ExcerptText .= 'onclick="footnote_moveToAnchor_' . $l_int_PostId;
                        $l_str_ExcerptText .= '(\'footnote_plugin_reference_' . $l_int_PostId;
                        $l_str_ExcerptText .= '_' . $l_int_Index . '\');">';
                        $l_str_ExcerptText .= MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_TOOLTIP_READON_LABEL);
                        $l_str_ExcerptText .= '</span>';
                    }
                }

                // define the HTML element to use for the referrers:
                if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_FOOTNOTES_REFERRER_SUPERSCRIPT_TAGS))) {
                    $l_str_SupSpan = 'sup';
                } else {
                    $l_str_SupSpan = 'span';
                }

                // determine whether the link element is used, see below in ReferenceContainer()
                $l_str_LinkSpan = MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_LINK_ELEMENT_ENABLED)) ? 'a' : 'span';


                // fill in 'templates/public/footnote.html':
                $l_obj_Template->replace(
                    array(
                        "post_id"    => $l_int_PostId,
                        "id"         => $l_int_Index,
                        "link-start" => $l_str_LinkSpan == 'a' ?  '<a>' : '',
                        "link-end"   => $l_str_LinkSpan == 'a' ? '</a>' : '',
                        "sup-span"   => $l_str_SupSpan,
                        "before"     => MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_STYLING_BEFORE),
                        "index"      => $l_int_Index,
                        "after"      => MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_STYLING_AFTER),
                        "text"       => MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_FOOTNOTES_MOUSE_OVER_BOX_ENABLED)) ? $l_str_ExcerptText : "",
                    )
                );
                $l_str_FootnoteReplaceText = $l_obj_Template->getContent();

                // reset the template
                $l_obj_Template->reload();
                if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_FOOTNOTES_MOUSE_OVER_BOX_ENABLED))) {
                    $l_int_OffsetY = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_MOUSE_OVER_BOX_OFFSET_Y));
                    $l_int_OffsetX = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_MOUSE_OVER_BOX_OFFSET_X));

                    // fill in 'templates/public/tooltip.html':
                    $l_obj_TemplateTooltip->replace(
                        array(
                            "post_id"  => $l_int_PostId,
                            "id"       => $l_int_Index,
                            "position" => MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_MOUSE_OVER_BOX_POSITION),
                            "offset-y" => !empty($l_int_OffsetY) ? $l_int_OffsetY : 0,
                            "offset-x" => !empty($l_int_OffsetX) ? $l_int_OffsetX : 0,
                        )
                    );
                    if (!MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_FOOTNOTES_MOUSE_OVER_BOX_ALTERNATIVE))) {
                        $l_str_FootnoteReplaceText .= $l_obj_TemplateTooltip->getContent();
                    }
                    $l_obj_TemplateTooltip->reload();
                }
            }
            // replace the footnote with the template
            $p_str_Content = substr_replace($p_str_Content, $l_str_FootnoteReplaceText, $l_int_PosStart, $l_int_Length + strlen($l_str_EndingTag));

            // add footnote only if not empty
            if (!empty($l_str_FootnoteText)) {
                // set footnote to the output box at the end
                self::$a_arr_Footnotes[] = $l_str_FootnoteText;
                // increase footnote index
                $l_int_FootnoteIndex++;
            }
            // add offset to the new starting position
            $l_int_PosStart += $l_int_Length + strlen($l_str_EndingTag);
            $l_int_PosStart = $l_int_Length + strlen($l_str_FootnoteReplaceText);
        } while (true);

        // return content
        return $p_str_Content;
    }

    /**
     * Generates the reference container.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     * @return string
     *
     * Edited for 2.0.6: fixed line breaking behavior in footnote # clusters
     * Edited for 2.1.1: fixed fragment IDs and backlinks with combine identical turned on   2020-11-14T1808+0100
     */
    public function ReferenceContainer() {

        // no footnotes have been replaced on this page:
        if (empty(self::$a_arr_Footnotes)) {
            return "";
        }

        /**
         * INFINITE SCROLL / AUTOLOAD, ARCHIVE VIEW
         *
         * Multiple posts are appended to each other, functions and IDs must be disambiguated.
         * Contributed by @docteurfitness <https://wordpress.org/support/topic/auto-load-post-compatibility-update/>
         * @since 2.0.5
         *
         * post ID to make everything unique wrt infinite scroll and archive view:
         */
        global $l_int_PostId;
        $l_int_PostId = get_the_id();


        /**
         * OPTIONAL LINK ELEMENT FOR FOOTNOTE REFERRERS AND BACKLINKS
         *
         * STYLING:
         * Link color is preferred for referrers and backlinks.
         * Setting a global link color is a common feature in WordPress themes.
         * CSS does not support identifiers for link colors (color: link | hover | active | visited)
         * These are only supported as pseudo-classes of the link element.
         * Hence the link element must be present for styling purposes.
         * But styling these elements with the link color is not universally preferred.
         * If not, the very presence of the link elements may need to be avoided.
         *
         * FUNCTIONALITY:
         * Although widely used for that purpose, hyperlinks are disliked for footnote linking.
         * Browsers may need to be prevented from logging these clicks in the browsing history,
         * as logging compromises the usability of the 'return to previous' button in browsers.
         * For that purpose, and for scroll animation, this linking is performed by JavaScript.
         *
         * The link elements have been added and are present @since 2.0.0.
         * Then the link addresses were removed @since 2.0.4.
         * Then the presence of <a> elements was made optional
         * @since 2.1.4
         * 2020-11-25T1306+0100
         */
        $l_str_LinkSpan = MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_LINK_ELEMENT_ENABLED)) ? 'a' : 'span';


        // FOOTNOTE INDEX BACKLINK SYMBOL

        // check if arrow is enabled:
        if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_REFERENCE_CONTAINER_BACKLINK_SYMBOL_ENABLE))) {

            // get html arrow
            $l_str_Arrow = MCI_Footnotes_Convert::getArrow(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_HYPERLINK_ARROW));
            // set html arrow to the first one if invalid index defined
            if (is_array($l_str_Arrow)) {
                $l_str_Arrow = MCI_Footnotes_Convert::getArrow(0);
            }
            // get user defined arrow
            $l_str_ArrowUserDefined = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_HYPERLINK_ARROW_USER_DEFINED);
            if (!empty($l_str_ArrowUserDefined)) {
                $l_str_Arrow = $l_str_ArrowUserDefined;
            }

            // wrap the arrow in a @media print { display:hidden } span:
            $l_str_FootnoteArrow  = '<span class="footnote_index_arrow">';
            $l_str_FootnoteArrow .= $l_str_Arrow . '</span>';

        } else {

            // if it is not, set arrow to empty:
            $l_str_Arrow = "";
            $l_str_FootnoteArrow = "";

        }


        // REFERENCE CONTAINER TABLE ROW TEMPLATE LOAD

        // line breaks for source readability:
        $l_str_Body = "\r\n\r\n";

        // when combine identical is turned on, another template is needed:
        if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_COMBINE_IDENTICAL_FOOTNOTES))) {
            // In the combined template, identifiers only are clickable.
            $l_obj_Template = new MCI_Footnotes_Template(MCI_Footnotes_Template::C_STR_PUBLIC, "reference-container-body-combi");

        } else {

            // when 3-column layout is turned on (only valid if combining is turned off):
            if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_REFERENCE_CONTAINER_3COLUMN_LAYOUT_ENABLE))) {
                $l_obj_Template = new MCI_Footnotes_Template(MCI_Footnotes_Template::C_STR_PUBLIC, "reference-container-body-3column");

            } else {

                // when switch symbol and index is turned on (only valid if 3-column is disabled):
                if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_REFERENCE_CONTAINER_BACKLINK_SYMBOL_SWITCH))) {
                    $l_obj_Template = new MCI_Footnotes_Template(MCI_Footnotes_Template::C_STR_PUBLIC, "reference-container-body-switch");

                } else {

                    // default is the standard template:
                    $l_obj_Template = new MCI_Footnotes_Template(MCI_Footnotes_Template::C_STR_PUBLIC, "reference-container-body");

                }
            }
        }

        // FILL IN THE TEMPLATE

        // loop through all footnotes found in the page
        for ($l_int_Index = 0; $l_int_Index < count(self::$a_arr_Footnotes); $l_int_Index++) {

            // TEXT COLUMN

            // get footnote text
            $l_str_FootnoteText = self::$a_arr_Footnotes[$l_int_Index];
            // if footnote is empty, get to the next one
            // With combine identical turned on, identicals will be deleted and are skipped:
            if (empty($l_str_FootnoteText)) {
                continue;
            }

            // INDEX COLUMN WITH ONE BACKLINK PER TABLE ROW

            // Standard behavior appropriate for combine identical TURNED OFF

            // generate content of footnote index cell
            $l_int_FirstFootnoteIndex = ($l_int_Index + 1);

            // get the footnote index string and
            // keep supporting legacy index placeholder:
            $l_str_FootnoteIndex  = MCI_Footnotes_Convert::Index(($l_int_Index + 1),  MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_COUNTER_STYLE));



            // SUPPORT FOR COMBINE IDENTICAL: COMPOSING ENUMERATED BACKLINKS

            $l_str_FootnoteBacklinks = "";

            if ( MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_COMBINE_IDENTICAL_FOOTNOTES))) {

                $l_str_FootnoteId  = $l_str_FootnoteIndex;

                // in case the footnote is unique:
                $l_str_FootnoteReference  = "<$l_str_LinkSpan";
                $l_str_FootnoteReference .= ' id="footnote_plugin_reference_';
                $l_str_FootnoteReference .= $l_int_PostId;
                $l_str_FootnoteReference .= "_$l_str_FootnoteId\"";
                $l_str_FootnoteReference .= ' class="footnote_backlink"';

                // the click event goes in the table cell:
                $l_str_BacklinkEvent  = ' onclick="footnote_moveToAnchor_' . $l_int_PostId;
                $l_str_BacklinkEvent .= "('footnote_plugin_tooltip_$l_int_PostId";
                $l_str_BacklinkEvent .= "_$l_str_FootnoteId');\"";

                // the dedicated template enumerating backlinks uses another variable:
                $l_str_FootnoteBacklinks  = $l_str_FootnoteReference;
                $l_str_FootnoteBacklinks .= $l_str_BacklinkEvent;

                // finish both single note and notes cluster:
                $l_str_FootnoteReference .= ">$l_str_FootnoteArrow$l_str_FootnoteId</$l_str_LinkSpan>";
                $l_str_FootnoteBacklinks .= ">$l_str_FootnoteArrow$l_str_FootnoteId</$l_str_LinkSpan>";

                // If that is the only footnote with this text, we’re done.

            }


            // CHECK IF COMBINE IDENTICAL IS TURNED ON, and
            // check if it isn't the last footnote in the array:
            if ($l_int_FirstFootnoteIndex < count(self::$a_arr_Footnotes) && MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_COMBINE_IDENTICAL_FOOTNOTES))) {

                // get all footnotes that haven't passed yet:
                for ($l_int_CheckIndex = $l_int_FirstFootnoteIndex; $l_int_CheckIndex < count(self::$a_arr_Footnotes); $l_int_CheckIndex++) {

                    // check if a further footnote is the same as the actual one:
                    if ($l_str_FootnoteText == self::$a_arr_Footnotes[$l_int_CheckIndex]) {

                        // if so, set the further footnote as empty so it won't be displayed later:
                        self::$a_arr_Footnotes[$l_int_CheckIndex] = "";

                        // cancel the event altogether:
                        $l_str_BacklinkEvent = "";


                        // HERE GOES THE FRAGMENT IDENTIFIER AND THE BACKLINK TOO:
                        // add the footnote index to the actual index:

                        // update the footnote ID:
                        $l_str_FootnoteId = MCI_Footnotes_Convert::Index(($l_int_CheckIndex + 1), MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_COUNTER_STYLE));

                        // resume composing the backlinks enumeration:
                        $l_str_FootnoteBacklinks .= ", <$l_str_LinkSpan";
                        $l_str_FootnoteBacklinks .= ' id="footnote_plugin_reference_';
                        $l_str_FootnoteBacklinks .= $l_int_PostId;
                        $l_str_FootnoteBacklinks .= "_$l_str_FootnoteId";
                        $l_str_FootnoteBacklinks .= '" class="footnote_backlink" ';
                        $l_str_FootnoteBacklinks .= 'onclick="footnote_moveToAnchor_' . $l_int_PostId;
                        $l_str_FootnoteBacklinks .= "('footnote_plugin_tooltip_$l_int_PostId";
                        $l_str_FootnoteBacklinks .= "_$l_str_FootnoteId');\"";
                        $l_str_FootnoteBacklinks .= ">$l_str_FootnoteArrow$l_str_FootnoteId</$l_str_LinkSpan>";

                        // this legacy is not used:
                        //$l_str_FootnoteIndex      .= ', ' . MCI_Footnotes_Convert::Index(($l_int_CheckIndex + 1), MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_COUNTER_STYLE));

                    }
                }
            }

            // line wrapping of URLs already fixed, see:
            // $l_str_FootnoteText = preg_replace( '#(?<!href=.)(https?://[^\\s<]+)#', '<span class="footnote_url_wrap">$1</span>', $l_str_FootnoteText );

            // replace all placeholders in 'templates/public/reference-container-body.html'
            // or in 'templates/public/reference-container-body-combi.html'
            // or in 'templates/public/reference-container-body-3column.html'
            // or in 'templates/public/reference-container-body-switch.html'
            $l_obj_Template->replace(
                array(
                    // placeholder used in all templates:
                    "text"        => $l_str_FootnoteText,

                    // used in standard layout W/O COMBINED FOOTNOTES:
                    "post_id"     => $l_int_PostId,
                    "id"          => MCI_Footnotes_Convert::Index($l_int_FirstFootnoteIndex, MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_COUNTER_STYLE)),
                    "link-start"  => $l_str_LinkSpan == 'a' ?  '<a>' : '',
                    "link-end"    => $l_str_LinkSpan == 'a' ? '</a>' : '',
                    "link-span"   => $l_str_LinkSpan,

                    // used in standard layout WITH COMBINED IDENTICALS TURNED ON:
                    "pointer"     => empty($l_str_BacklinkEvent) ? '' : ' pointer',
                    "event"       => $l_str_BacklinkEvent,
                    "backlinks"   => empty($l_str_BacklinkEvent) ? $l_str_FootnoteBacklinks : $l_str_FootnoteReference,

                    // Legacy placeholders for use in legacy layout templates:
                    "arrow"       => $l_str_FootnoteArrow,
                    "index"       => $l_str_FootnoteIndex,
                )
            );

            $l_str_Body .= $l_obj_Template->getContent();

            // extra line breaks for page source readability:
            $l_str_Body .= "\r\n\r\n";

            $l_obj_Template->reload();

        }

        // load 'templates/public/reference-container.html':
        $l_obj_TemplateContainer = new MCI_Footnotes_Template(MCI_Footnotes_Template::C_STR_PUBLIC, "reference-container");
        $l_obj_TemplateContainer->replace(
            array(
                "post_id"      => $l_int_PostId,
                "label"        => MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_REFERENCE_CONTAINER_NAME),
                "button-style" => !MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_REFERENCE_CONTAINER_COLLAPSE)) ? 'display: none;' : '',
                "style"        =>  MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_REFERENCE_CONTAINER_COLLAPSE)) ? 'display: none;' : '',
                "content"      => $l_str_Body,
            )
        );

        // free all found footnotes if reference container will be displayed
        self::$a_arr_Footnotes = array();

        return $l_obj_TemplateContainer->getContent();
    }
}