WC_Tax::get_matched_tax_rates PHP Method

    private static function get_matched_tax_rates($country, $state, $postcode, $city, $tax_class)
    {
        global $wpdb;
        // Query criteria - these will be ANDed
        $criteria = array();
        $criteria[] = $wpdb->prepare("tax_rate_country IN ( %s, '' )", strtoupper($country));
        $criteria[] = $wpdb->prepare("tax_rate_state IN ( %s, '' )", strtoupper($state));
        $criteria[] = $wpdb->prepare("tax_rate_class = %s", sanitize_title($tax_class));
        // Pre-query postcode ranges for PHP based matching.
        $postcode_search = wc_get_wildcard_postcodes($postcode, $country);
        $postcode_ranges = $wpdb->get_results("SELECT tax_rate_id, location_code FROM {$wpdb->prefix}woocommerce_tax_rate_locations WHERE location_type = 'postcode' AND location_code LIKE '%...%';");
        if ($postcode_ranges) {
            $matches = wc_postcode_location_matcher($postcode, $postcode_ranges, 'tax_rate_id', 'location_code', $country);
            if (!empty($matches)) {
                foreach ($matches as $matched_postcodes) {
                    $postcode_search = array_merge($postcode_search, $matched_postcodes);
                }
            }
        }
        $postcode_search = array_unique($postcode_search);
        /**
         * Location matching criteria - ORed
         * Needs to match:
         * 	- rates with no postcodes and cities
         * 	- rates with a matching postcode and city
         * 	- rates with matching postcode, no city
         * 	- rates with matching city, no postcode
         */
        $locations_criteria = array();
        $locations_criteria[] = "locations.location_type IS NULL";
        $locations_criteria[] = "\n\t\t\tlocations.location_type = 'postcode' AND locations.location_code IN ('" . implode("','", array_map('esc_sql', $postcode_search)) . "')\n\t\t\tAND (\n\t\t\t\t( locations2.location_type = 'city' AND locations2.location_code = '" . esc_sql(strtoupper($city)) . "' )\n\t\t\t\tOR NOT EXISTS (\n\t\t\t\t\tSELECT sub.tax_rate_id FROM {$wpdb->prefix}woocommerce_tax_rate_locations as sub\n\t\t\t\t\tWHERE sub.location_type = 'city'\n\t\t\t\t\tAND sub.tax_rate_id = tax_rates.tax_rate_id\n\t\t\t\t)\n\t\t\t)\n\t\t";
        $locations_criteria[] = "\n\t\t\tlocations.location_type = 'city' AND locations.location_code = '" . esc_sql(strtoupper($city)) . "'\n\t\t\tAND NOT EXISTS (\n\t\t\t\tSELECT sub.tax_rate_id FROM {$wpdb->prefix}woocommerce_tax_rate_locations as sub\n\t\t\t\tWHERE sub.location_type = 'postcode'\n\t\t\t\tAND sub.tax_rate_id = tax_rates.tax_rate_id\n\t\t\t)\n\t\t";
        $criteria[] = '( ( ' . implode(' ) OR ( ', $locations_criteria) . ' ) )';
        $found_rates = $wpdb->get_results("\n\t\t\tSELECT tax_rates.*\n\t\t\tFROM {$wpdb->prefix}woocommerce_tax_rates as tax_rates\n\t\t\tLEFT OUTER JOIN {$wpdb->prefix}woocommerce_tax_rate_locations as locations ON tax_rates.tax_rate_id = locations.tax_rate_id\n\t\t\tLEFT OUTER JOIN {$wpdb->prefix}woocommerce_tax_rate_locations as locations2 ON tax_rates.tax_rate_id = locations2.tax_rate_id\n\t\t\tWHERE 1=1 AND " . implode(' AND ', $criteria) . "\n\t\t\tGROUP BY tax_rate_id\n\t\t\tORDER BY tax_rate_priority\n\t\t");
        $found_rates = self::sort_rates($found_rates);
        $matched_tax_rates = array();
        $found_priority = array();
        foreach ($found_rates as $found_rate) {
            if (in_array($found_rate->tax_rate_priority, $found_priority)) {
                continue;
            }
            $matched_tax_rates[$found_rate->tax_rate_id] = array('rate' => $found_rate->tax_rate, 'label' => $found_rate->tax_rate_name, 'shipping' => $found_rate->tax_rate_shipping ? 'yes' : 'no', 'compound' => $found_rate->tax_rate_compound ? 'yes' : 'no');
            $found_priority[] = $found_rate->tax_rate_priority;
        }
        return apply_filters('woocommerce_matched_tax_rates', $matched_tax_rates, $country, $state, $postcode, $city, $tax_class);
    }