<?php
/**
 * Server-side rendering of the `core/categories` block.
 *
 * @package WordPress
 */

/**
 * Renders the `core/categories` block on server.
 *
 * @since 5.0.0
 * @since 6.7.0 Enable client-side rendering if enhancedPagination context is true.
 *
 * @param array    $attributes The block attributes.
 * @param string   $content    Block default content.
 * @param WP_Block $block      Block instance.
 *
 * @return string Returns the categories list/dropdown markup.
 */
function render_block_core_categories( $attributes, $content, $block ) {
    static $block_id = 0;
    ++$block_id;

    $taxonomy = get_taxonomy( $attributes['taxonomy'] );

    $args = array(
        'echo'         => false,
        'hierarchical' => ! empty( $attributes['showHierarchy'] ),
        'orderby'      => 'name',
        'show_count'   => ! empty( $attributes['showPostCounts'] ),
        'taxonomy'     => $attributes['taxonomy'],
        'title_li'     => '',
        'hide_empty'   => empty( $attributes['showEmpty'] ),
    );
    if ( ! empty( $attributes['showOnlyTopLevel'] ) && $attributes['showOnlyTopLevel'] ) {
        $args['parent'] = 0;
    }

    if ( ! empty( $attributes['displayAsDropdown'] ) ) {
        $id                       = 'wp-block-categories-' . $block_id;
        $args['id']               = $id;
        $args['name']             = $taxonomy->query_var;
        $args['value_field']      = 'slug';
        $args['show_option_none'] = sprintf(
            /* translators: %s: taxonomy's singular name */
            __( 'Select %s' ),
            $taxonomy->labels->singular_name
        );

        // Pre-select the current term using query var.
        $args['selected'] = get_query_var( $taxonomy->query_var );

        $show_label     = empty( $attributes['showLabel'] ) ? ' screen-reader-text' : '';
        $default_label  = $taxonomy->label;
        $label_text     = ! empty( $attributes['label'] ) ? wp_kses_post( $attributes['label'] ) : $default_label;
        $wrapper_markup = '<div %1$s><label class="wp-block-categories__label' . $show_label . '" for="' . esc_attr( $id ) . '">' . $label_text . '</label>%2$s</div>';
        $items_markup   = wp_dropdown_categories( $args );
        $type           = 'dropdown';

        if ( ! is_admin() ) {
            // Inject the dropdown script immediately after the select dropdown.
            $items_markup = preg_replace(
                '#(?<=</select>)#',
                build_dropdown_script_block_core_categories( $id ),
                $items_markup,
                1
            );
        }
    } else {
        $args['show_option_none'] = $taxonomy->labels->no_terms;

        $wrapper_markup = '<ul %1$s>%2$s</ul>';
        $items_markup   = wp_list_categories( $args );
        $type           = 'list';

        if ( ! empty( $block->context['enhancedPagination'] ) ) {
            $p = new WP_HTML_Tag_Processor( $items_markup );
            while ( $p->next_tag( 'a' ) ) {
                $p->set_attribute( 'data-wp-on--click', 'core/query::actions.navigate' );
            }
            $items_markup = $p->get_updated_html();
        }
    }

    $wrapper_attributes = get_block_wrapper_attributes( array( 'class' => "wp-block-categories-{$type} wp-block-categories-taxonomy-{$attributes['taxonomy']}" ) );

    return sprintf(
        $wrapper_markup,
        $wrapper_attributes,
        $items_markup
    );
}

/**
 * Generates the inline script for a categories dropdown field.
 *
 * @since 5.0.0
 *
 * @param string $dropdown_id ID of the dropdown field.
 *
 * @return string Returns the dropdown onChange redirection script.
 */
function build_dropdown_script_block_core_categories( $dropdown_id ) {
    ob_start();

    $exports = array( $dropdown_id, home_url() );
    ?>
    <script>
    ( ( [ dropdownId, homeUrl ] ) => {
        const dropdown = document.getElementById( dropdownId );
        function onSelectChange() {
            setTimeout( () => {
                if ( 'escape' === dropdown.dataset.lastkey ) {
                    return;
                }
                // Only navigate if a valid term is selected (not the default "Select [taxonomy]" option)
                if ( dropdown.value && dropdown.value !== '-1' && dropdown instanceof HTMLSelectElement ) {
                    const url = new URL( homeUrl );
                    url.searchParams.set( dropdown.name, dropdown.value );
                    location.href = url.href;
                }
            }, 250 );
        }
        function onKeyUp( event ) {
            if ( 'Escape' === event.key ) {
                dropdown.dataset.lastkey = 'escape';
            } else {
                delete dropdown.dataset.lastkey;
            }
        }
        function onClick() {
            delete dropdown.dataset.lastkey;
        }
        dropdown.addEventListener( 'keyup', onKeyUp );
        dropdown.addEventListener( 'click', onClick );
        dropdown.addEventListener( 'change', onSelectChange );
    } )( <?php echo wp_json_encode( $exports, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES ); ?> );
    </script>
    <?php
    return wp_get_inline_script_tag(
        trim( str_replace( array( '<script>', '</script>' ), '', ob_get_clean() ) ) .
        "\n//# sourceURL=" . rawurlencode( __FUNCTION__ )
    );
}

/**
 * Registers the `core/categories` block on server.
 *
 * @since 5.0.0
 */
function register_block_core_categories() {
    register_block_type_from_metadata(
        __DIR__ . '/categories',
        array(
            'render_callback' => 'render_block_core_categories',
        )
    );
}
add_action( 'init', 'register_block_core_categories' );