class ComboSet
{
    /**
     * Returns `true` if the SKU is a combo-set item, `false` otherwise
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int $skuMetaId
     * @return bool
     */
    public static function isComboSet($skuMetaId) {
        global $wpdb;

        $cst = Schema::getComboSetsTable();
        $exists = $wpdb->get_var(
            $wpdb->prepare(
                "SELECT COUNT(ID) FROM {$cst} WHERE sku_meta_id = %d",
                (int)$skuMetaId
            )
        );
        if ($exists === null) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::INTERNAL_SERVER_ERROR);
        }
        if ((bool)(int)$exists === true) {
            return true;
        }

        return false;
    }

    /**
     * Marks an SKU as a combo-set item
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int  $skuMetaId
     * @param bool $enableItemOptions
     * @param bool $enableMultiprice
     * @return GenericError|ComboSetType The combo-set type, on success
     */
    public static function createComboSet(
        $skuMetaId,
        $enableItemOptions = Schema::ENABLE_ITEM_OPTIONS_DEFAULT,
        $enableMultiprice = Schema::ENABLE_MULTIPRICE_DEFAULT
    ) {
        global $wpdb;

        $skuMetaId = (int)$skuMetaId;
        $postId = Utils::getSkuPostId($skuMetaId);
        if ($postId instanceof GenericError) {
            return $postId;
        }
        $exists = self::isComboSet($skuMetaId);
        if ($exists === true) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::COMBO_SET_ALREADY_EXISTS);
        }
        $isgitem = GroupItem::skuIsGroupItem($skuMetaId);
        if ($isgitem instanceof GenericError) {
            return $isgitem;
        }
        if ($isgitem === true) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::SKU_IS_COMBO_SET_GROUP_ITEM);
        }

        $curtime = Utils::getCurrentUTCDateTimeString();
        $res = $wpdb->insert(
            Schema::getComboSetsTable(),
            [
                'post_id' => (int)$postId,
                'sku_meta_id' => $skuMetaId,
                'enable_item_options' => (int)$enableItemOptions,
                'enable_multiprice' => (int)$enableMultiprice,
                'created_at' => $curtime,
                'updated_at' => $curtime,
            ],
            ['%d', '%d', '%d', '%d', '%s', '%s']
        );
        if ($res === false) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::INTERNAL_SERVER_ERROR);
        }

        return new ComboSetType(
            $wpdb->insert_id,
            $skuMetaId,
            [],
            $enableItemOptions,
            $enableMultiprice,
            $curtime,
            $curtime
        );
    }

    /**
     * Deletes all data associated with a combo-set item and unlinks from the SKU
     *
     * This method will return `0` if no combo-set exists for the `$comboSetId` provided
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int $comboSetId
     * @return GenericError|int Number of rows deleted on success
     */
    public static function deleteComboSet($comboSetId) {
        global $wpdb;

        $cst = Schema::getComboSetsTable();
        $res = $wpdb->delete($cst, ['ID' => (int)$comboSetId], ['%d']);
        if ($res === false) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::INTERNAL_SERVER_ERROR);
        }

        return (int)$res;
    }

    /**
     * Returns a `\Aivec\Welcart\Extensions\ItemComboSet\Types\ComboSet` instance given
     * its SKU meta ID
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int $skuMetaId
     * @return GenericError|ComboSetType
     */
    public static function getComboSetBySkuMetaId($skuMetaId) {
        global $wpdb;

        $postId = Utils::getSkuPostId($skuMetaId);
        if ($postId instanceof GenericError) {
            return $postId;
        }

        $cst = Schema::getComboSetsTable();
        $res = $wpdb->get_var(
            $wpdb->prepare(
                "SELECT COUNT(ID) FROM {$cst} WHERE sku_meta_id = %d",
                (int)$skuMetaId
            )
        );
        if ($res === null) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::INTERNAL_SERVER_ERROR);
        }

        if ((bool)(int)$res === false) {
            return Master::getErrorStore()->getErrorResponse(
                ErrorStore::COMBO_SET_NOT_FOUND_BY_SKU_META_ID,
                [$skuMetaId],
                [],
                [$skuMetaId]
            );
        }

        $row = $wpdb->get_row(
            $wpdb->prepare(
                "SELECT * FROM {$cst} WHERE sku_meta_id = %d",
                (int)$skuMetaId
            ),
            ARRAY_A
        );
        if ($row === null) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::INTERNAL_SERVER_ERROR);
        }

        return new ComboSetType(
            (int)$row['ID'],
            $skuMetaId,
            ComboGroup::getAllComboGroupsByComboSetId((int)$row['ID']),
            (bool)$row['enable_item_options'],
            (bool)$row['enable_multiprice'],
            $row['created_at'],
            $row['updated_at']
        );
    }

    /**
     * Returns a `\Aivec\Welcart\Extensions\ItemComboSet\Types\ComboSet` instance given
     * its ID
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int $comboSetId
     * @return GenericError|ComboSetType
     */
    public static function getComboSetById($comboSetId) {
        global $wpdb;

        $comboSetId = (int)$comboSetId;
        $cst = Schema::getComboSetsTable();
        $res = $wpdb->get_var(
            $wpdb->prepare(
                "SELECT COUNT(ID) FROM {$cst} WHERE ID = %d",
                $comboSetId
            )
        );
        if ($res === null) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::INTERNAL_SERVER_ERROR);
        }

        if ((bool)(int)$res === false) {
            return Master::getErrorStore()->getErrorResponse(
                ErrorStore::COMBO_SET_NOT_FOUND_BY_ID,
                [$comboSetId],
                [],
                [$comboSetId]
            );
        }

        $row = $wpdb->get_row(
            $wpdb->prepare(
                "SELECT * FROM {$cst} WHERE ID = %d",
                $comboSetId
            ),
            ARRAY_A
        );

        return new ComboSetType(
            (int)$row['ID'],
            (int)$row['sku_meta_id'],
            ComboGroup::getAllComboGroupsByComboSetId((int)$row['ID']),
            (bool)$row['enable_item_options'],
            (bool)$row['enable_multiprice'],
            $row['created_at'],
            $row['updated_at']
        );
    }

    /**
     * Returns instance of \Aivec\Welcart\Extensions\ItemComboSet\Types\ComboSet if found,
     * `GenericError` otherwise
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @param int    $post_id Post ID is required because SKU codes are not unique
     * @param string $sku_code **Must be decoded**
     * @return GenericError|ComboSetType
     */
    public static function getComboSetFromSkuCode($post_id, $sku_code) {
        $sets = self::getAllComboSetsForPostId($post_id);
        if (empty($sets)) {
            return Master::getErrorStore()->getErrorResponse(
                ErrorStore::COMBO_SET_NOT_FOUND_BY_SKU_CODE,
                [$post_id, $sku_code]
            );
        }

        foreach ($sets as $set) {
            if ($set === null) {
                continue;
            }
            $skudata = $set->getSkuData();
            if ($skudata['code'] === $sku_code) {
                return $set;
            }
        }

        return Master::getErrorStore()->getErrorResponse(
            ErrorStore::COMBO_SET_NOT_FOUND_BY_SKU_CODE,
            [$post_id, $sku_code]
        );
    }

    /**
     * Returns a key-value list of all combo-sets associated with a post ID where key is the SKU
     * meta ID and value is an instance of `\Aivec\Welcart\Extensions\ItemComboSet\Types\ComboSet`
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int $postId
     * @return ComboSetType[]
     */
    public static function getAllComboSetsForPostId($postId) {
        global $wpdb;

        $skust = usces_get_tablename('usces_skus');
        $skuMetaIds = $wpdb->get_results(
            $wpdb->prepare(
                "SELECT meta_id FROM {$skust} WHERE post_id = %d",
                (int)$postId
            ),
            ARRAY_N
        );
        $combos = [];
        foreach ($skuMetaIds as $metaId) {
            if (!isset($metaId[0])) {
                continue;
            }
            $skuMetaId = $metaId[0];
            $combo = self::getComboSetBySkuMetaId($skuMetaId);
            if ($combo instanceof GenericError) {
                $combo = null;
            }
            $combos[$skuMetaId] = $combo;
        }

        return $combos;
    }
}