'compare' => 'NOT IN',
            );
        }
        return $meta_query;
    }

    /**
     * Get tax query
     * For WooCommerce >= 3.0
     *
     * return array
     */
    private function getTaxQuery() {
        $product_visibility_term_ids = wc_get_product_visibility_term_ids();
        $tax_query = array(
            'relation' => 'AND',
        );
        $tax_query[] = array(
            'taxonomy' => 'product_visibility',
            'field'    => 'term_taxonomy_id',
            'terms'    => $product_visibility_term_ids['exclude-from-search'],
            'operator' => 'NOT IN',
        );
        // Exclude out of stock products from suggestions
        if ( DGWT_WCAS()->settings->getOption( 'exclude_out_of_stock' ) === 'on' ) {
            $tax_query[] = array(
                'taxonomy' => 'product_visibility',
                'field'    => 'term_taxonomy_id',
                'terms'    => $product_visibility_term_ids['outofstock'],
                'operator' => 'NOT IN',
            );
        }
        return $tax_query;
    }

    /**
     * Search for matching category
     *
     * @param string $keyword
     * @param int $limit
     *
     * @return array
     */
    public function getCategories( $keyword, $limit = 3 ) {
        $results = array(
            'total' => 0,
            'items' => array(),
        );
        $args = array(
            'taxonomy' => 'product_cat',
        );
        $productCategories = get_terms( 'product_cat', apply_filters( 'dgwt/wcas/search/product_cat/args', $args ) );
        $keywordUnslashed = wp_unslash( $keyword );
        // Compare keyword and term name
        $i = 0;
        foreach ( $productCategories as $cat ) {
            if ( $i < $limit ) {
                $catName = html_entity_decode( $cat->name );
                $pos = strpos( mb_strtolower( remove_accents( Helpers::removeGreekAccents( $catName ) ) ), mb_strtolower( remove_accents( Helpers::removeGreekAccents( $keywordUnslashed ) ) ) );
                if ( $pos !== false ) {
                    $results['total']++;
                    $termLang = Multilingual::getTermLang( $cat->term_id, 'product_cat' );
                    $results['items'][$i] = array(
                        'term_id'     => $cat->term_id,
                        'taxonomy'    => 'product_cat',
                        'value'       => $catName,
                        'url'         => get_term_link( $cat, 'product_cat' ),
                        'breadcrumbs' => Helpers::getTermBreadcrumbs(
                            $cat->term_id,
                            'product_cat',
                            array(),
                            $termLang,
                            array($cat->term_id)
                        ),
                        'type'        => 'taxonomy',
                    );
                    // Fix: Remove last separator
                    if ( !empty( $results['items'][$i]['breadcrumbs'] ) ) {
                        $results['items'][$i]['breadcrumbs'] = mb_substr( $results['items'][$i]['breadcrumbs'], 0, -3 );
                    }
                    $i++;
                }
            }
        }
        return $results;
    }

    /**
     * Extend research in the Woo tags
     *
     * @param strong $keyword
     * @param int $limit
     *
     * @return array
     */
    public function getTags( $keyword, $limit = 3 ) {
        $results = array(
            'total' => 0,
            'items' => array(),
        );
        $args = array(
            'taxonomy' => 'product_tag',
        );
        $productTags = get_terms( 'product_tag', apply_filters( 'dgwt/wcas/search/product_tag/args', $args ) );
        $keywordUnslashed = wp_unslash( $keyword );
        // Compare keyword and term name
        $i = 0;
        foreach ( $productTags as $tag ) {
            if ( $i < $limit ) {
                $tagName = html_entity_decode( $tag->name );
                $pos = strpos( mb_strtolower( remove_accents( Helpers::removeGreekAccents( $tagName ) ) ), mb_strtolower( remove_accents( Helpers::removeGreekAccents( $keywordUnslashed ) ) ) );
                if ( $pos !== false ) {
                    $results['total']++;
                    $results['items'][$i] = array(
                        'term_id'  => $tag->term_id,
                        'taxonomy' => 'product_tag',
                        'value'    => $tagName,
                        'url'      => get_term_link( $tag, 'product_tag' ),
                        'parents'  => '',
                        'type'     => 'taxonomy',
                    );
                    $i++;
                }
            }
        }
        return $results;
    }

    /**
     * Search in extra fields
     *
     * @param string $search SQL
     *
     * @return string prepared SQL
     */
    public function searchFilters( $search, $wp_query ) {
        global $wpdb;
        if ( empty( $search ) ) {
            return $search;
            // skip processing - there is no keyword
        }
        if ( $this->isAjaxSearch() ) {
            $q = $wp_query->query_vars;
            if ( $q['post_type'] !== 'product' ) {
                return $search;
                // skip processing
            }
            $n = ( !empty( $q['exact'] ) ? '' : '%' );
            $search = $searchand = '';
            if ( !empty( $q['search_terms'] ) ) {
                foreach ( (array) $q['search_terms'] as $term ) {
                    $like = $n . $wpdb->esc_like( $term ) . $n;
                    $search .= "{$searchand} (";
                    // Search in title
                    if ( in_array( 'title', $this->searchIn ) ) {
                        $search .= $wpdb->prepare( "({$wpdb->posts}.post_title LIKE %s)", $like );
                    } else {
                        $search .= "(0 = 1)";
                    }
                    // Search in content
                    if ( DGWT_WCAS()->settings->getOption( 'search_in_product_content' ) === 'on' && in_array( 'content', $this->searchIn ) ) {
                        $search .= $wpdb->prepare( " OR ({$wpdb->posts}.post_content LIKE %s)", $like );
                    }
                    // Search in excerpt
                    if ( DGWT_WCAS()->settings->getOption( 'search_in_product_excerpt' ) === 'on' && in_array( 'excerpt', $this->searchIn ) ) {
                        $search .= $wpdb->prepare( " OR ({$wpdb->posts}.post_excerpt LIKE %s)", $like );
                    }
                    // Search in SKU
                    if ( DGWT_WCAS()->settings->getOption( 'search_in_product_sku' ) === 'on' && in_array( 'sku', $this->searchIn ) ) {
                        $search .= $wpdb->prepare( " OR (dgwt_wcasmsku.meta_key='_sku' AND dgwt_wcasmsku.meta_value LIKE %s)", $like );
                    }
                    $search = apply_filters(
                        'dgwt/wcas/native/search_query/search_or',
                        $search,
                        $like,
                        $this
                    );
                    $search .= ")";
                    $searchand = ' AND ';
                }
            }
            if ( !empty( $search ) ) {
                $search = " AND ({$search}) ";
                if ( !is_user_logged_in() ) {
                    $search .= " AND ({$wpdb->posts}.post_password = '') ";
                }
            }
        }
        return $search;
    }

    /**
     * @param $where
     *
     * @return string
     */
    public function searchDistinct( $where ) {
        if ( $this->isAjaxSearch() ) {
            return 'DISTINCT';
        }
        return $where;
    }

    /**
     * Join the postmeta column in the search posts SQL
     */
    public function searchFiltersJoin( $join, $query ) {
        global $wpdb;
        if ( empty( $query->query_vars['post_type'] ) || $query->query_vars['post_type'] !== 'product' ) {
            return $join;
            // skip processing
        }
        if ( $this->isAjaxSearch() ) {
            if ( DGWT_WCAS()->settings->getOption( 'search_in_product_sku' ) === 'on' && in_array( 'sku', $this->searchIn ) ) {
                $join .= " INNER JOIN {$wpdb->postmeta} AS dgwt_wcasmsku ON ( {$wpdb->posts}.ID = dgwt_wcasmsku.post_id )";
            }
            $join = apply_filters( 'dgwt/wcas/native/search_query/join', $join );
        }
        return $join;
    }

    /**
     * Corrects the search by excerpt if necessary.
     * WooCommerce adds search in excerpt by defaults and this should be corrected.
     *
     * @param string $where
     *
     * @return string
     * @since 1.1.4
     *
     */
    public function fixWooExcerptSearch( $where ) {
        global $wp_the_query;
        // If this is not a WC Query, do not modify the query
        if ( empty( $wp_the_query->query_vars['wc_query'] ) || empty( $wp_the_query->query_vars['s'] ) ) {
            return $where;
        }
        if ( DGWT_WCAS()->settings->getOption( 'search_in_product_excerpt' ) !== 'on' && in_array( 'excerpt', $this->searchIn ) ) {
            $where = preg_replace( "/OR \\(post_excerpt\\s+LIKE\\s*(\\'\\%[^\\%]+\\%\\')\\)/", "", $where );
        }
        return $where;
    }

    /**
     * Disable cache results and narrowing search results to those from our engine
     *
     * @param \WP_Query $query
     */
    public function overwriteSearchPage( $query ) {
        if ( !Helpers::isSearchQuery( $query ) ) {
            return;
        }
        if ( $this->hooked ) {
            return;
        }
        /**
         * Allowing hook WP_Query more then once
         *
         * @since 1.26.0
         */
        if ( apply_filters( 'dgwt/wcas/native/hook_query_once', true ) ) {
            $this->hooked = true;
        }
        /**
         * Disable cache: `cache_results` defaults to false but can be enabled
         */
        $query->set( 'cache_results', false );
        if ( !empty( $query->query['cache_results'] ) ) {
            $query->set( 'cache_results', true );
        }
        $query->set( 'dgwt_wcas', $query->query_vars['s'] );
        $phrase = $query->query_vars['s'];
        // Break early if keyword contains blacklisted phrase.
        if ( Helpers::phraseContainsBlacklistedTerm( $phrase ) ) {
            header( 'X-Robots-Tag: noindex' );
            http_response_code( 400 );
            exit;
        }
        $orderby = 'post__in';
        $order = 'desc';
        if ( !empty( $query->query_vars['orderby'] ) ) {
            $orderby = ( $query->query_vars['orderby'] === 'relevance' ? 'post__in' : $query->query_vars['orderby'] );
        }
        if ( !empty( $query->query_vars['order'] ) ) {
            $order = strtolower( $query->query_vars['order'] );
        }
        $postIn = array();
        $searchResults = $this->getSearchResults( $phrase, true, 'product-ids' );
        foreach ( $searchResults['suggestions'] as $suggestion ) {
            $postIn[] = $suggestion->ID;
        }
        // Integration with FiboFilters.
        if ( $query->get( 'fibofilters' ) ) {
            $postIn = array_intersect( $query->get( 'post__in' ), $postIn );
        }
        // Save for later use
        $this->postsIDsBuffer = $postIn;
        $query->set( 'orderby', $orderby );
        $query->set( 'order', $order );
        $query->set( 'post__in', $postIn );
        // Resetting the key 's' to disable the default search logic.
        $query->set( 's', '' );
    }

    /**
     * Check if is ajax search processing
     *
     * @return bool
     * @since 1.1.3
     *
     */
    public function isAjaxSearch() {
        if ( defined( 'DGWT_WCAS_AJAX' ) && DGWT_WCAS_AJAX ) {
            return true;
        }
        return false;
    }

    /**
     * Headline output structure
     *
     * @return array
     */
    public function headlineBody( $headline ) {
        return array(
            'value' => $headline,
            'type'  => 'headline',
        );
    }

    /**
     * Check if the query retuns resutls
     *
     * @return bool
     */
    public function hasResults() {
        $hasResults = false;
        foreach ( $this->groups as $group ) {
            if ( !empty( $group['results'] ) ) {
                $hasResults = true;
                break;
            }
        }
        return $hasResults;
    }

    /**
     * Calc free slots
     *
     * @return int
     */
    public function calcFreeSlots() {
        $slots = 0;
        foreach ( $this->groups as $key => $group ) {
            if ( !empty( $group['limit'] ) ) {
                $slots = $slots + absint( $group['limit'] );
            }
        }
        return $slots;
    }

    /**
     * Apply flexible limits
     *
     * @return void
     */
    public function applyFlexibleLimits() {
        $slots = $this->totalLimit;
        $total = 0;
        $groups = 0;
        foreach ( $this->groups as $key => $group ) {
            if ( !empty( $this->groups[$key]['results'] ) ) {
                $total = $total + count( $this->groups[$key]['results'] );
                $groups++;
            }
        }
        $toRemove = ( $total >= $slots ? $total - $slots : 0 );
        if ( $toRemove > 0 ) {
            for ($i = 0; $i < $toRemove; $i++) {
                $largestGroupCount = 0;
                $largestGroupKey = 'product';
                foreach ( $this->groups as $key => $group ) {
                    if ( !empty( $this->groups[$key]['results'] ) ) {
                        $thisGroupTotal = count( $this->groups[$key]['results'] );
                        if ( $thisGroupTotal > $largestGroupCount ) {
                            $largestGroupCount = $thisGroupTotal;
                            $largestGroupKey = $key;
                        }
                    }
                }
                $last = count( $this->groups[$largestGroupKey]['results'] ) - 1;
                if ( isset( $this->groups[$largestGroupKey]['results'][$last] ) ) {
                    unset($this->groups[$largestGroupKey]['results'][$last]);
                }
            }
        }
    }

    /**
     * Prepare suggestions based on groups
     *
     * @return array
     */
    public function convertGroupsToSuggestions() {
        $suggestions = array();
        $totalHeadlines = 0;
        foreach ( $this->groups as $key => $group ) {
            if ( !empty( $group['results'] ) ) {
                if ( $this->showHeadings ) {
                    $suggestions[] = $this->headlineBody( $key );
                    $totalHeadlines++;
                }
                foreach ( $group['results'] as $result ) {
                    $suggestions[] = $result;
                }
            }
        }
        // Remove products headline when there are only product type suggestion
        if ( $totalHeadlines === 1 ) {
            $i = 0;
            $unset = false;
            foreach ( $suggestions as $key => $suggestion ) {
                if ( !empty( $suggestion['type'] ) && $suggestion['type'] === 'headline' && $suggestion['value'] === 'product' ) {
                    unset($suggestions[$i]);
                    $unset = true;
                    break;
                }
                $i++;
            }
            if ( $unset ) {
                $suggestions = array_values( $suggestions );
            }
        }
        return $suggestions;
    }

    /**
     * Order of the search resutls groups
     *
     * @return array
     */
    public function searchResultsGroups() {
        $groups = array();
        if ( DGWT_WCAS()->settings->getOption( 'show_product_tax_product_cat' ) === 'on' ) {
            $groups['tax_product_cat'] = array(
                'limit' => 3,
            );
        }
        if ( DGWT_WCAS()->settings->getOption( 'show_product_tax_product_tag' ) === 'on' ) {
            $groups['tax_product_tag'] = array(
                'limit' => 3,
            );
        }
        $groups['product'] = array(
            'limit' => 7,
        );
        return apply_filters( 'dgwt/wcas/search_groups', $groups );
    }

    /**
     * Allow to get the ID of products that have been found
     *
     * @param integer[] $postsIDs
     *
     * @return mixed
     */
    public function getProductIds( $postsIDs ) {
        if ( $this->postsIDsBuffer !== null ) {
            return $this->postsIDsBuffer;
        }
        return $postsIDs;
    }

    /**
     * Add taxonomies labels
     *
     * @param array $labels Labels used at frontend
     *
     * @return array
     */
    public function setTaxonomiesLabels( $labels ) {
        $labels['tax_product_cat_plu'] = __( 'Categories', 'woocommerce' );
        $labels['tax_product_cat'] = __( 'Category', 'woocommerce' );
        $labels['tax_product_tag_plu'] = __( 'Tags' );
        $labels['tax_product_tag'] = __( 'Tag' );
        return $labels;
    }

    /**
     * Backward compatibility for labels
     *
     * Full taxonomy names for categories and tags. All with prefix 'tax_'.
     *
     * @param array $labels Labels used at frontend
     *
     * @return array
     */
    public function fixTaxonomiesLabels( $labels ) {
        // Product category. Old: 'category', 'product_cat_plu'.
        if ( isset( $labels['category'] ) ) {
            $labels['tax_product_cat'] = $labels['category'];
            unset($labels['category']);
        }
        if ( isset( $labels['product_cat_plu'] ) ) {
            $labels['tax_product_cat_plu'] = $labels['product_cat_plu'];
            unset($labels['product_cat_plu']);
        }
        // Product tag. Old: 'tag', 'product_tag_plu'.
        if ( isset( $labels['tag'] ) ) {
            $labels['tax_product_tag'] = $labels['tag'];
            unset($labels['tag']);
        }
        if ( isset( $labels['product_tag_plu'] ) ) {
            $labels['tax_product_tag_plu'] = $labels['product_tag_plu'];
            unset($labels['product_tag_plu']);
        }
        return $labels;
    }

    /**
     * Add language to WC endpoint if Polylang is active
     *
     * @param $url
     * @param $request
     *
     * @return string
     * @see polylang-wc/frontend/frontend.php:306
     */
    public function fixPolylangWooEndpoint( $url, $request ) {
        if ( PLL() instanceof \PLL_Frontend ) {
            // Remove wc-ajax to avoid the value %%endpoint%% to be encoded by add_query_arg (used in plain permalinks).
            $url = remove_query_arg( 'wc-ajax', $url );
            $url = PLL()->links_model->switch_language_in_link( $url, PLL()->curlang );
            return add_query_arg( 'wc-ajax', $request, $url );
        }
        return $url;
    }

    /**
     * Get empty search output
     *
     * @return array
     */
    private function getEmptyOutput() {
        $output = array(
            'engine'      => 'free',
            'suggestions' => array(),
            'time'        => '0 sec',
            'total'       => 0,
            'v'           => DGWT_WCAS_VERSION,
        );
        return $output;
    }

}