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
 * @see <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, thanks to @happyches   2020-11-14T2233+0100
 * @see <https://wordpress.org/support/topic/custom-css-for-jumbled-references/>
 * 2.1.1  fix start pages by option to hide ref container, thanks to @dragon013
 * @see <https://wordpress.org/support/topic/possible-to-hide-it-from-start-page/>
 * 2.1.1  options fixing ref container layout and referrer vertical alignment  2020-11-16T2024+0100
 * 2.1.1  priority level option fixing ref container relative position, thanks to june01, @spaceling, @imeson  2020-11-17T0254+0100
 * @see <https://wordpress.org/support/topic/change-the-position-5/>
 * 2.1.2  priority level settings for all other hooks, thanks to @nikelaos  2020-11-19T1849+0100
 * @see <https://wordpress.org/support/topic/doesnt-work-any-more-11/#post-13676705>
 * 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
 * 2.1.4  support appending arrow when combining identicals is on   2020-11-26T1633+0100
 * 2.1.4  disable or select backlink separator and terminator  2020-11-28T1048+0100
 * 2.1.4  optional line breaks to stack enumerated backlinks  2020-11-28T1049+0100
 * 2.1.4  ref container column width and tooltip font size settings  2020-12-03T0954+0100
 * 2.1.4  scroll offset and duration settings  2020-12-05T0538+0100
 * 2.1.4  tooltip display duration settings  2020-12-06T1320+0100
 * 2.1.5  URL wrap: exclude image source too, thanks to @bjrnet21
 * @see <https://wordpress.org/support/topic/2-1-4-breaks-on-my-site-images-dont-show/>
 * 2.1.6  option to disable URL line wrapping   2020-12-09T1606+0100
 * 2.1.6  add catch-all exclusion to fix URL line wrapping, thanks to @a223123131   2020-12-09T1921+0100
 * @see <https://wordpress.org/support/topic/broken-layout-starting-version-2-1-4/>
 * 2.2.0  support for custom position shortcode for reference container, thanks to @hamshe  2020-12-13T2058+0100
 * @see <https://wordpress.org/support/topic/reference-container-in-elementor/>
 * 2.2.3  custom CSS from new setting in header after legacy  2020-12-15T1128+0100
 * 2.2.5  connected alternative tooltips to position and timing settings  2020-12-18T1113+0100
 * 2.2.5  delete unused position shortcode when ref container in widget or footer, thanks to @hamshe   2020-12-18T1437+0100
 * @see <https://wordpress.org/support/topic/reference-container-in-elementor/#post-13784126>
 * 2.2.5  options for label element and label bottom border, thanks to @markhillyer   2020-12-18T1447+0100
 * @see <https://wordpress.org/support/topic/how-do-i-eliminate-the-horizontal-line-beneath-the-reference-container-heading/>
 * 2.2.6  URL wrap: make the quotation mark optional in the exclusion regex, thanks to @spiralofhope2   2020-12-23T0409+0100
 * @see <https://wordpress.org/support/topic/two-links-now-breaks-footnotes-with-blogtext/>
 *
 * Last modified:  2020-12-23T1047+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 98:
        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
     *
     * Edited:
     * 2.1.1  option to hide ref container from start page
     * 2.1.1  script for alternative tooltips
     * 2.1.3  raise settings priority to override theme style sheets
     * 2.1.4  tootip font size and backlink column width settings
     * 2.2.5  options for label element and label bottom border, thanks to @markhillyer   2020-12-18T1447+0100
     * @see <https://wordpress.org/support/topic/how-do-i-eliminate-the-horizontal-line-beneath-the-reference-container-heading/>
     */
    public function wp_head() {

        // no switch out to insert start tag:
        echo "\r\n<style type=\"text/css\" media=\"all\">\r\n";

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

        // ref container label bottom border:
        if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_REFERENCE_CONTAINER_LABEL_BOTTOM_BORDER))) {
            echo ".footnote_container_prepare > ";
            echo MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_REFERENCE_CONTAINER_LABEL_ELEMENT);
            echo " {border-bottom: 1px solid #aaaaaa !important;}\r\n";
        }

        // ref container first column width and max-width:
        $l_bool_ColumnWidthEnabled = MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_BACKLINKS_COLUMN_WIDTH_ENABLED));
        $l_bool_ColumnMaxWidthEnabled = MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_BACKLINKS_COLUMN_MAX_WIDTH_ENABLED));

        if ( $l_bool_ColumnWidthEnabled || $l_bool_ColumnMaxWidthEnabled ) {
            echo ".footnote-reference-container { table-layout: fixed; }";
            echo ".footnote_plugin_index, .footnote_plugin_index_combi {";

            if ( $l_bool_ColumnWidthEnabled ) {

                $l_int_ColumnWidthScalar = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_BACKLINKS_COLUMN_WIDTH_SCALAR);
                $l_str_ColumnWidthUnit = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_BACKLINKS_COLUMN_WIDTH_UNIT);

                if (!empty($l_int_ColumnWidthScalar)) {
                    if ($l_str_ColumnWidthUnit == '%') {
                        if ($l_int_ColumnWidthScalar > 100) {
                            $l_int_ColumnWidthScalar = 100;
                        }
                    }
                } else {
                    $l_int_ColumnWidthScalar = 0;
                }

                echo " width: $l_int_ColumnWidthScalar$l_str_ColumnWidthUnit !important;";
            }

            if ( $l_bool_ColumnMaxWidthEnabled ) {

                $l_int_ColumnMaxWidthScalar = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_BACKLINKS_COLUMN_MAX_WIDTH_SCALAR);
                $l_str_ColumnMaxWidthUnit = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_BACKLINKS_COLUMN_MAX_WIDTH_UNIT);

                if (!empty($l_int_ColumnMaxWidthScalar)) {
                    if ($l_str_ColumnMaxWidthUnit == '%') {
                        if ($l_int_ColumnMaxWidthScalar > 100) {
                            $l_int_ColumnMaxWidthScalar = 100;
                        }
                    }
                } else {
                    $l_int_ColumnMaxWidthScalar = 0;
                }

                echo " max-width: $l_int_ColumnMaxWidthScalar$l_str_ColumnMaxWidthUnit !important;";

            }
        echo "}\r\n";
        }

        // tooltips:
        $l_bool_TooltipsEnabled = MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_FOOTNOTES_MOUSE_OVER_BOX_ENABLED));
        $l_bool_AlternativeTooltipsEnabled = MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_FOOTNOTES_MOUSE_OVER_BOX_ALTERNATIVE));

        if ($l_bool_TooltipsEnabled) {

            echo '.footnote_tooltip {';

            // tooltip appearance:

            // font size:
            echo ' font-size: ';
            if(MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_MOUSE_OVER_BOX_FONT_SIZE_ENABLED))) {
                echo MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_FLO_MOUSE_OVER_BOX_FONT_SIZE_SCALAR);
                echo MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_MOUSE_OVER_BOX_FONT_SIZE_UNIT);
            } else {
                echo 'inherit';
            }
            echo ' !important;';

            // text color:
            $l_str_Color = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_MOUSE_OVER_BOX_COLOR);
            if (!empty($l_str_Color)) {
                printf(" color: %s !important;", $l_str_Color);
            }

            // background color:
            $l_str_Background = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_MOUSE_OVER_BOX_BACKGROUND);
            if (!empty($l_str_Background)) {
                printf(" background-color: %s !important;", $l_str_Background);
            }

            // border width:
            $l_int_BorderWidth = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_MOUSE_OVER_BOX_BORDER_WIDTH);
            if (!empty($l_int_BorderWidth) && intval($l_int_BorderWidth) > 0) {
                printf(" border-width: %dpx !important; border-style: solid !important;", $l_int_BorderWidth);
            }

            // border color:
            $l_str_BorderColor = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_MOUSE_OVER_BOX_BORDER_COLOR);
            if (!empty($l_str_BorderColor)) {
                printf(" border-color: %s !important;", $l_str_BorderColor);
            }

            // corner radius:
            $l_int_BorderRadius = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_MOUSE_OVER_BOX_BORDER_RADIUS);
            if (!empty($l_int_BorderRadius) && intval($l_int_BorderRadius) > 0) {
                printf(" border-radius: %dpx !important;", $l_int_BorderRadius);
            }

            // shadow color:
            $l_str_BoxShadowColor = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_MOUSE_OVER_BOX_SHADOW_COLOR);
            if (!empty($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);
            }

            // alternative tooltips:
            if ( ! $l_bool_AlternativeTooltipsEnabled) {

                // tooltip position:
                $l_int_MaxWidth = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_MOUSE_OVER_BOX_MAX_WIDTH);
                if (!empty($l_int_MaxWidth) && intval($l_int_MaxWidth) > 0) {
                    printf(" max-width: %dpx !important;", $l_int_MaxWidth);
                }
                echo "}\r\n";

            } else {
                echo "}\r\n";

                // position:
                echo ".footnote_tooltip.position {";
                echo " width: " . intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_ALTERNATIVE_MOUSE_OVER_BOX_WIDTH)) . 'px;';

                $l_str_AlternativePosition = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_FOOTNOTES_ALTERNATIVE_MOUSE_OVER_BOX_POSITION);
                $l_int_OffsetX = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_ALTERNATIVE_MOUSE_OVER_BOX_OFFSET_X));

                if ($l_str_AlternativePosition == 'top left' || $l_str_AlternativePosition == 'bottom left') {
                    echo ' right: ' . ( !empty($l_int_OffsetX) ? $l_int_OffsetX : 0) . 'px;';
                } else {
                    echo ' left: ' . ( !empty($l_int_OffsetX) ? $l_int_OffsetX : 0) . 'px;';
                }

                $l_int_OffsetY = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_ALTERNATIVE_MOUSE_OVER_BOX_OFFSET_Y));

                if ($l_str_AlternativePosition == 'top left' || $l_str_AlternativePosition == 'top right') {
                    echo ' bottom: ' . ( !empty($l_int_OffsetY) ? $l_int_OffsetY : 0) . 'px;';
                } else {
                    echo ' top: ' . ( !empty($l_int_OffsetY) ? $l_int_OffsetY : 0) . 'px;';
                }
                echo "}\r\n";

                // timing:
                // jQuery tooltip timing is in templates/public/tooltip.html, filled in after line 690 below.
                echo ' .footnote_tooltip.shown {';
                $l_int_FadeInDelay     = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_MOUSE_OVER_BOX_FADE_IN_DELAY    ));
                $l_int_FadeInDuration  = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_MOUSE_OVER_BOX_FADE_IN_DURATION ));
                $l_int_FadeInDelay     = !empty($l_int_FadeInDelay    ) ? $l_int_FadeInDelay     : '0';
                $l_int_FadeInDuration  = !empty($l_int_FadeInDuration ) ? $l_int_FadeInDuration  : '0';
                echo " transition-delay: $l_int_FadeInDelay" . 'ms;';
                echo " transition-duration: $l_int_FadeInDuration" . 'ms;';

                echo '} .footnote_tooltip.hidden {';
                $l_int_FadeOutDelay    = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_MOUSE_OVER_BOX_FADE_OUT_DELAY   ));
                $l_int_FadeOutDuration = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_MOUSE_OVER_BOX_FADE_OUT_DURATION));
                $l_int_FadeOutDelay     = !empty($l_int_FadeOutDelay    ) ? $l_int_FadeOutDelay     : '0';
                $l_int_FadeOutDuration  = !empty($l_int_FadeOutDuration ) ? $l_int_FadeOutDuration  : '0';
                echo " transition-delay: $l_int_FadeOutDelay" . 'ms;';
                echo " transition-duration: $l_int_FadeOutDuration" . 'ms;';

                echo "}\r\n";

            }
        }

        // set custom CSS to override settings, not conversely:
        // if dashboard tab migration acknowledged, disable legacy in case it was not cut:
        if (!MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_CUSTOM_CSS_MIGRATED))) {
            echo MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_CUSTOM_CSS);
        }
        echo MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_CUSTOM_CSS_NEW);

        // no switch out to insert end tag:
        echo "\r\n</style>\r\n";

        // alternative tooltip script printed formatted not minified:
        if ($l_bool_AlternativeTooltipsEnabled) {
            ?>
            <script content="text/javascript">
                function footnoteTooltipShow(footnoteTooltipId) {
                    document.getElementById(footnoteTooltipId).classList.remove('hidden');
                    document.getElementById(footnoteTooltipId).classList.add('shown');
                }
                function footnoteTooltipHide(footnoteTooltipId) {
                    document.getElementById(footnoteTooltipId).classList.remove('shown');
                    document.getElementById(footnoteTooltipId).classList.add('hidden');
                }
            </script>
            <?php
        };
    }

    /**
     * Displays the 'LOVE FOOTNOTES' slug if enabled.
     *
     * @author Stefan Herndler
     * @since 1.5.0
     *
     * Edited:
     * @since 2.2.0  more options  2020-12-11T0506+0100
     */
    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
        $l_str_LinkedName = sprintf('<a href="https://wordpress.org/plugins/footnotes/" target="_blank" style="text-decoration:none;">%s</a>', MCI_Footnotes_Config::C_STR_PLUGIN_PUBLIC_NAME);
        // get random love me text
        if (strtolower($l_str_LoveMeIndex) == "random") {
            $l_str_LoveMeIndex = "text-" . rand(1,7);
        }
        switch ($l_str_LoveMeIndex) {
            // options named wrt backcompat, simplest is default:
            case "text-1": $l_str_LoveMeText = sprintf(__('I %2$s %1$s', MCI_Footnotes_Config::C_STR_PLUGIN_NAME), $l_str_LinkedName, MCI_Footnotes_Config::C_STR_LOVE_SYMBOL); break;
            case "text-2": $l_str_LoveMeText = sprintf(__('This website uses the awesome %s plugin.', MCI_Footnotes_Config::C_STR_PLUGIN_NAME), $l_str_LinkedName); break;
            case "text-4": $l_str_LoveMeText = sprintf('%s %s', $l_str_LinkedName, MCI_Footnotes_Config::C_STR_LOVE_SYMBOL); break;
            case "text-5": $l_str_LoveMeText = sprintf('%s %s', MCI_Footnotes_Config::C_STR_LOVE_SYMBOL, $l_str_LinkedName); break;
            case "text-6": $l_str_LoveMeText = sprintf(__('This website uses %s.', MCI_Footnotes_Config::C_STR_PLUGIN_NAME), $l_str_LinkedName); break;
            case "text-7": $l_str_LoveMeText = sprintf(__('This website uses the %s plugin.', MCI_Footnotes_Config::C_STR_PLUGIN_NAME), $l_str_LinkedName); break;
            case "text-3": default: $l_str_LoveMeText = sprintf('%s', $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 $p_bool_HideFootnotesText Hide footnotes found in the string.
     * @return string
     *
     * Edited:
     * @since 2.2.0  insert reference container at shortcode, thanks to @hamshe   2020-12-13T2057+0100
     * @see <https://wordpress.org/support/topic/reference-container-in-elementor/>
     *
     * @since 2.2.5  delete unused position shortcode, when position is widget or footer, thanks to @hamshe   2020-12-18T1434+0100
     * @see <https://wordpress.org/support/topic/reference-container-in-elementor/#post-13784126>
     */
    public function exec($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
        // or insert at shortcode: added for 2.2.0, thanks to @hamshe
        $l_str_ReferenceContainerPositionShortcode = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_REFERENCE_CONTAINER_POSITION_SHORTCODE);

        if ($p_bool_OutputReferences) {

            if (strpos( $p_str_Content, $l_str_ReferenceContainerPositionShortcode ) !== false ) {

                $p_str_Content = str_replace( $l_str_ReferenceContainerPositionShortcode, $this->ReferenceContainer(), $p_str_Content );

            } else {

                $p_str_Content .= $this->ReferenceContainer();

            }
        }

        // delete position shortcode should any remain e.g. when ref container is in footer, thanks to @hamshe:
        $p_str_Content = str_replace( $l_str_ReferenceContainerPositionShortcode, '', $p_str_Content );

        // 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));

            
            /**
             * URL line wrap
             * 
             * 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.
             * @see public.css
             * 
             * spare however values of the href and the src arguments!
             * @since 2.1.5  exclude image source too, thanks to @bjrnet21
             * @see <https://wordpress.org/support/topic/2-1-4-breaks-on-my-site-images-dont-show/>
             * 
             * Even ARIA labels may take a URL as value, so use \w=[\'"] as a catch-all    2020-12-10T1005+0100
             * @since 2.1.6  add catch-all exclusion to fix URL line wrapping, thanks to @a223123131   2020-12-09T1921+0100
             * @see <https://wordpress.org/support/topic/broken-layout-starting-version-2-1-4/>
             * 
             * @since 2.1.6  option to disable URL line wrapping   2020-12-09T1606+0100
             * 
             * URLs may be a query string in a URL:
             * @since 2.2.6  make the quotation mark optional in the exclusion regex, thanks to @spiralofhope2   2020-12-23T0409+0100
             * @see <https://wordpress.org/support/topic/two-links-now-breaks-footnotes-with-blogtext/>
             * @since 2.2.7  revert that change in the exclusion regex, thanks to @spiralofhope2 and @spaceling   2020-12-23T1046+0100
             * @see <https://wordpress.org/support/topic/two-links-now-breaks-footnotes-with-blogtext/>
             */
            if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_FOOTNOTE_URL_WRAP_ENABLED))) {
                $l_str_FootnoteText = preg_replace( '#(?<!\w=[\'"])(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)) &&
                    !MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_FOOTNOTES_MOUSE_OVER_BOX_ALTERNATIVE))
                ) {
                    $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));
                    $l_int_FadeInDelay     = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_MOUSE_OVER_BOX_FADE_IN_DELAY    ));
                    $l_int_FadeInDuration  = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_MOUSE_OVER_BOX_FADE_IN_DURATION ));
                    $l_int_FadeOutDelay    = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_MOUSE_OVER_BOX_FADE_OUT_DELAY   ));
                    $l_int_FadeOutDuration = intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_MOUSE_OVER_BOX_FADE_OUT_DURATION));

                    // 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) ? $l_int_OffsetX : 0,
                            "fade-in-delay"     => !empty($l_int_FadeInDelay    ) ? $l_int_FadeInDelay     : 0,
                            "fade-in-duration"  => !empty($l_int_FadeInDuration ) ? $l_int_FadeInDuration  : 0,
                            "fade-out-delay"    => !empty($l_int_FadeOutDelay   ) ? $l_int_FadeOutDelay    : 0,
                            "fade-out-duration" => !empty($l_int_FadeOutDuration) ? $l_int_FadeOutDuration : 0,
                        )
                    );
                    $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
         * @see <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.
         * 
         *
         * @since 2.0.0  the link elements have been added and are present.
         * @since 2.0.4  the link addresses were removed.
         * @since 2.1.4  the presence of <a> elements was made optional, 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
         *
         * The backlink symbol has been removed for 2.0.0 along with column 2 of the reference container.
         * On user request, an arrow is prepended @since 2.0.3, and the setting is restored @since 2.0.4.
         * @since 2.1.1 a select box allows to disable the symbol instead of customizing it to invisible.
         */
        // 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 = '';

        }


        /**
         * BACKLINK SEPARATOR
         *
         * Initially a comma was appended in this algorithm for enumerations.
         * The comma in enumerations is not generally preferred.
         * @since 2.1.4 the separator is optional, has options, and is customizable:
         */
        // check if it is even enabled:
        if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_BACKLINKS_SEPARATOR_ENABLED))) {
            // if so, check if it is customized:
            $l_str_Separator = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_BACKLINKS_SEPARATOR_CUSTOM);
            if (empty($l_str_Separator)) {
                // if it is not, check which option is on:
                $l_str_SeparatorOption = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_BACKLINKS_SEPARATOR_OPTION);
                switch ($l_str_SeparatorOption) {
                    case 'comma'    : $l_str_Separator = ',';              break;
                    case 'semicolon': $l_str_Separator = ';';              break;
                    case 'en_dash'  : $l_str_Separator = '&nbsp;&#x2013;'; break;
                }
            }
        } else {
            $l_str_Separator = '';
        }

        /**
         * BACKLINK TERMINATOR
         *
         * Initially a dot was appended in the table row template.
         * @since 2.0.6 a dot after footnote numbers is discarded as not localizable;
         * making it optional was envisaged.
         * @since 2.1.4 the terminator is optional, has options, and is customizable:
         */
        // check if it is even enabled:
        if (MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_BACKLINKS_TERMINATOR_ENABLED))) {
            // if so, check if it is customized:
            $l_str_Terminator = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_BACKLINKS_TERMINATOR_CUSTOM);
            if (empty($l_str_Terminator)) {
                // if it is not, check which option is on:
                $l_str_TerminatorOption = MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_BACKLINKS_TERMINATOR_OPTION);
                switch ($l_str_TerminatorOption) {
                    case 'period'     : $l_str_Terminator = '.'; break;
                    case 'parenthesis': $l_str_Terminator = ')'; break;
                    case 'colon'      : $l_str_Terminator = ':'; break;
                }
            }
        } else {
            $l_str_Terminator = '';
        }


        /**
         * LINE BREAKS
         *
         * The backlinks of combined footnotes are generally preferred in an enumeration.
         * But when few footnotes are identical, stacking the items in list form is better.
         * Variable number length and proportional character width require explicit line breaks.
         * Otherwise, an ordinary space character offering a line break opportunity is inserted.
         */
        $l_str_LineBreak = MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_BACKLINKS_LINE_BREAKS_ENABLED)) ? '<br />' : ' ';

        /**
         * For maintenance and support, table rows in the reference container should be
         * separated by an empty line. So we add these line breaks for source readability.
         * Before the first table row (breaks between rows are ~200 lines below):
         */
        $l_str_Body = "\r\n\r\n";


        // REFERENCE CONTAINER TABLE ROW TEMPLATE LOAD

        // when combining identical footnotes 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))) {
            // the combining template allows for backlink clusters and supports cell clicking for single notes:
            $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 available 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, and combining and 3-columns are off:
                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");

                }
            }
        }

        // SET SWITCH FLAG INDEPENDENTLY

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

            $l_bool_SymbolSwitch = true;

        } else {

            $l_bool_SymbolSwitch = false;

        }


        // 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 combining identicals 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 COMBINING IDENTICALS: COMPOSE ENUMERATED BACKLINKS

            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;

                // continue both single note and notes cluster, depending on switch option status:
                if ($l_bool_SymbolSwitch) {

                    $l_str_FootnoteReference .= ">$l_str_FootnoteId$l_str_FootnoteArrow";
                    $l_str_FootnoteBacklinks .= ">$l_str_FootnoteId$l_str_FootnoteArrow";

                } else {

                    $l_str_FootnoteReference .= ">$l_str_FootnoteArrow$l_str_FootnoteId";
                    $l_str_FootnoteBacklinks .= ">$l_str_FootnoteArrow$l_str_FootnoteId";

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


                // check if it isn't the last footnote in the array:
                if ($l_int_FirstFootnoteIndex < count(self::$a_arr_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_Separator</$l_str_LinkSpan>";
                            $l_str_FootnoteBacklinks .= "$l_str_LineBreak<$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_bool_SymbolSwitch ? '' : $l_str_FootnoteArrow;
                            $l_str_FootnoteBacklinks .= $l_str_FootnoteId;
                            $l_str_FootnoteBacklinks .= $l_bool_SymbolSwitch ? $l_str_FootnoteArrow : '';

                        }
                    }
                }

                $l_str_FootnoteReference .= "$l_str_Terminator</$l_str_LinkSpan>";
                $l_str_FootnoteBacklinks .= "$l_str_Terminator</$l_str_LinkSpan>";

            }

            // line wrapping of URLs already fixed, see above

            // 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,
                    "terminator"  => $l_str_Terminator,

                    // 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();

        }

        // streamline:
        $l_bool_CollapseDefault = MCI_Footnotes_Convert::toBool(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_BOOL_REFERENCE_CONTAINER_COLLAPSE));

        // 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"         =>  $l_int_PostId,
                "element"         =>  MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_REFERENCE_CONTAINER_LABEL_ELEMENT),
                "name"            =>  MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_STR_REFERENCE_CONTAINER_NAME),
                "button-style"    => !$l_bool_CollapseDefault ? 'display: none;' : '',
                "style"           =>  $l_bool_CollapseDefault ? 'display: none;' : '',
                "content"         =>  $l_str_Body,
                "scroll-offset"   => (intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_SCROLL_OFFSET)) / 100),
                "scroll-duration" =>  intval(MCI_Footnotes_Settings::instance()->get(MCI_Footnotes_Settings::C_INT_FOOTNOTES_SCROLL_DURATION)),
            )
        );

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

        return $l_obj_TemplateContainer->getContent();
    }
}