class ComboGroup
{
    /**
     * Creates a new combo group for a combo-set and returns it
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int    $comboSetId
     * @param string $label
     * @param bool   $optional
     * @param bool   $enableMultiSelect
     * @return GenericError|ComboGroupType
     */
    public static function createComboGroup($comboSetId, $label = '', $optional = false, $enableMultiSelect = false) {
        global $wpdb;

        $position = 0;
        $curtime = Utils::getCurrentUTCDateTimeString();
        $csgt = Schema::getComboSetGroupsTable();

        $comboset = ComboSet::getComboSetById($comboSetId);
        if ($comboset instanceof GenericError) {
            return $comboset;
        }

        $isgitem = GroupItem::skuIsGroupItem($comboset->getSkuMetaId());
        if ($isgitem instanceof GenericError) {
            return $isgitem;
        }
        if ($isgitem === true) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::SKU_IS_COMBO_SET_GROUP_ITEM);
        }

        $position = (int)$wpdb->get_var(
            $wpdb->prepare("SELECT COUNT(ID) FROM {$csgt} WHERE combo_set_id = %d", $comboSetId)
        );

        $res = $wpdb->insert(
            $csgt,
            [
                'combo_set_id' => $comboSetId,
                'group_label' => (string)$label,
                'optional' => (int)$optional,
                'allow_multiple_selections' => (int)$enableMultiSelect,
                'position' => $position,
                'created_at' => $curtime,
                'updated_at' => $curtime,
            ],
            ['%d', '%s', '%d', '%d', '%d', '%s', '%s']
        );

        if ($res === false) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::INTERNAL_SERVER_ERROR);
        }

        return self::getComboGroupById($wpdb->insert_id);
    }

    /**
     * Updates a combo group for a combo-set and returns it
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int    $groupId
     * @param string $label
     * @param bool   $optional
     * @param bool   $enableMultiSelect
     * @return GenericError|ComboGroupType
     */
    public static function updateComboGroup($groupId, $label, $optional, $enableMultiSelect) {
        global $wpdb;

        $combogroup = self::getComboGroupById($groupId);
        if (empty($combogroup)) {
            return Master::getErrorStore()->getErrorResponse(
                ErrorStore::COMBO_GROUP_NOT_FOUND,
                [$groupId],
                [],
                [$groupId]
            );
        }

        $curtime = Utils::getCurrentUTCDateTimeString();
        $csgt = Schema::getComboSetGroupsTable();
        $res = $wpdb->update(
            $csgt,
            [
                'group_label' => (string)$label,
                'optional' => (int)$optional,
                'allow_multiple_selections' => (int)$enableMultiSelect,
                'updated_at' => $curtime,
            ],
            ['ID' => $groupId],
            ['%s', '%d', '%d', '%s'],
            ['%d']
        );

        if (empty($res)) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::INTERNAL_SERVER_ERROR);
        }

        return self::getComboGroupById($groupId);
    }

    /**
     * Duplicates a combo group
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int    $groupId
     * @param string $label
     * @return GenericError|ComboGroupType
     */
    public static function duplicateComboGroup($groupId, $label) {
        global $wpdb;

        $combogroup = self::getComboGroupById($groupId);
        if (empty($combogroup)) {
            return Master::getErrorStore()->getErrorResponse(
                ErrorStore::COMBO_GROUP_NOT_FOUND,
                [$groupId],
                [],
                [$groupId]
            );
        }

        $wpdb->query('START TRANSACTION');
        $newgroup = self::createComboGroup(
            $combogroup->getComboSetId(),
            !empty($label) ? (string)$label : '',
            $combogroup->getOptional(),
            $combogroup->getEnableMultiSelect()
        );
        if ($newgroup instanceof GenericError) {
            $wpdb->query('ROLLBACK');
            return $newgroup;
        }

        foreach ($combogroup->getItems() as $gitem) {
            $newgitem = GroupItem::createGroupItem(
                $newgroup->getId(),
                $gitem->getSkuMetaId(),
                $gitem->getPriceModifier(),
                $gitem->getItemLabel(),
                $gitem->getItemQuantity()
            );
            if ($newgitem instanceof GenericError) {
                $wpdb->query('ROLLBACK');
                return $newgitem;
            }
        }

        $wpdb->query('COMMIT');

        $dupgroup = self::getComboGroupById($newgroup->getId());
        if (empty($dupgroup)) {
            return Master::getErrorStore()->getErrorResponse(
                ErrorStore::COMBO_GROUP_NOT_FOUND,
                [$newgroup->getId()],
                [],
                [$newgroup->getId()]
            );
        }

        return $dupgroup;
    }

    /**
     * Deletes a combo group
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int $groupId
     * @return GenericError|true
     */
    public static function deleteComboGroup($groupId) {
        global $wpdb;

        $csgt = Schema::getComboSetGroupsTable();
        $res = $wpdb->delete($csgt, ['id' => $groupId], ['%d']);
        if ($res === false) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::INTERNAL_SERVER_ERROR);
        }

        return true;
    }

    /**
     * Returns an instance of `\Aivec\Welcart\Extensions\ItemComboSet\Types\ComboGroup`
     * given a group id, or `null` on failure or if not found
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int $id
     * @return null|ComboGroupType
     */
    public static function getComboGroupById($id) {
        global $wpdb;

        $csgt = Schema::getComboSetGroupsTable();
        $group = $wpdb->get_row(
            $wpdb->prepare("SELECT * FROM {$csgt} cg WHERE cg.ID = %d", $id),
            ARRAY_A
        );

        if (empty($group)) {
            return null;
        }

        $items = GroupItem::getAllGroupItemsByComboGroupId($id);
        if (empty($items)) {
            $items = [];
        }

        return new ComboGroupType(
            $group['ID'],
            $group['combo_set_id'],
            $group['group_label'],
            (bool)(int)$group['optional'],
            (bool)(int)$group['allow_multiple_selections'],
            $group['position'],
            $items,
            $group['created_at'],
            $group['updated_at']
        );
    }

    /**
     * Returns list of combo groups for a combo-set item
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int $comboSetId
     * @return ComboGroupType[]|GenericError
     */
    public static function getAllComboGroupsByComboSetId($comboSetId) {
        global $wpdb;

        $csgt = Schema::getComboSetGroupsTable();
        $groupids = $wpdb->get_results(
            $wpdb->prepare("SELECT ID FROM {$csgt} WHERE combo_set_id = %d ORDER BY position ASC", (int)$comboSetId),
            ARRAY_A
        );

        if ($groupids === null) {
            return Master::getErrorStore()->getErrorResponse(ErrorStore::INTERNAL_SERVER_ERROR);
        }

        $groups = [];
        foreach ($groupids as $groupid) {
            $group = self::getComboGroupById($groupid['ID']);
            if (!empty($group)) {
                $groups[] = $group;
            }
        }

        return $groups;
    }

    /**
     * Re-orders combo group positions for a combo-set
     *
     * @author Evan D Shaw <evandanielshaw@gmail.com>
     * @global \wpdb $wpdb
     * @param int   $comboSetId
     * @param int[] $groupIds
     * @return GenericError|bool `true` if anything was reordered, `false` otherwise
     */
    public static function reorderComboGroups($comboSetId, $groupIds) {
        global $wpdb;

        $comboSetId = (int)$comboSetId;
        $groupIds = !empty($groupIds) ? (array)$groupIds : [];

        $updated = false;
        $wpdb->query('START TRANSACTION');
        foreach ($groupIds as $position => $groupId) {
            $group = self::getComboGroupById($groupId);
            if ($group === null || $group->getComboSetId() !== $comboSetId || $group->getPosition() === $position) {
                continue;
            }

            $updated = true;
            $res = $wpdb->update(
                Schema::getComboSetGroupsTable(),
                [
                    'position' => $position,
                    'updated_at' => Utils::getCurrentUTCDateTimeString(),
                ],
                ['id' => $groupId],
                ['%d', '%s'],
                ['%d']
            );
            if ($res === false) {
                $wpdb->query('ROLLBACK');
                return Master::getErrorStore()->getErrorResponse(ErrorStore::INTERNAL_SERVER_ERROR);
            }
        }

        $wpdb->query('COMMIT');
        return $updated;
    }
}