func parseLexRangeItem(buf []byte) ([]byte, bool, error) {
	if len(buf) == 0 {
		return nil, false, errors.Errorf("empty lex range item")
	}

	ex := false
	var dest []byte

	switch buf[0] {
	case '+':
		if len(buf) > 1 {
			return nil, false, errors.Errorf("invalid lex range item, only +  allowed, but %s", buf)
		}
		dest = maxString
	case '-':
		if len(buf) > 1 {
			return nil, false, errors.Errorf("invalid lex range item, only - allowed, but %s", buf)
		}
		dest = minString
	case '(', '[':
		dest = buf[1:]
		if len(dest) == 0 {
			return nil, false, errors.Errorf("invalid empty lex range item %s", buf)
		}
		ex = buf[0] == '('
	default:
		return nil, false, errors.Errorf("invalid lex range item at first byte, %s", buf)
	}

	return dest, ex, nil
}

func (h *EventHeader) Decode(data []byte) error {
	if len(data) < EventHeaderSize {
		return errors.Errorf("header size too short %d, must 19", len(data))
	}

	pos := 0

	h.Timestamp = binary.LittleEndian.Uint32(data[pos:])
	pos += 4

	h.EventType = EventType(data[pos])
	pos++

	h.ServerID = binary.LittleEndian.Uint32(data[pos:])
	pos += 4

	h.EventSize = binary.LittleEndian.Uint32(data[pos:])
	pos += 4

	h.LogPos = binary.LittleEndian.Uint32(data[pos:])
	pos += 4

	h.Flags = binary.LittleEndian.Uint16(data[pos:])
	pos += 2

	if h.EventSize < uint32(EventHeaderSize) {
		return errors.Errorf("invalid event size %d, must >= 19", h.EventSize)
	}

	return nil
}

// ValidateVolumeParams is specified on the storage.VolumeSource interface.
func (v *ebsVolumeSource) ValidateVolumeParams(params storage.VolumeParams) error {
	vol, err := parseVolumeOptions(params.Size, params.Attributes)
	if err != nil {
		return err
	}
	var minVolumeSize, maxVolumeSize int
	switch vol.VolumeType {
	case volumeTypeStandard:
		minVolumeSize = minMagneticVolumeSizeGiB
		maxVolumeSize = maxMagneticVolumeSizeGiB
	case volumeTypeGp2:
		minVolumeSize = minSsdVolumeSizeGiB
		maxVolumeSize = maxSsdVolumeSizeGiB
	case volumeTypeIo1:
		minVolumeSize = minProvisionedIopsVolumeSizeGiB
		maxVolumeSize = maxProvisionedIopsVolumeSizeGiB
	}
	if vol.VolumeSize < minVolumeSize {
		return errors.Errorf(
			"volume size is %d GiB, must be at least %d GiB",
			vol.VolumeSize, minVolumeSize,
		)
	}
	if vol.VolumeSize > maxVolumeSize {
		return errors.Errorf(
			"volume size %d GiB exceeds the maximum of %d GiB",
			vol.VolumeSize, maxVolumeSize,
		)
	}
	return nil
}

// Compose update stmt assignment list for column scope privilege update.
func composeColumnPrivUpdate(ctx context.Context, priv mysql.PrivilegeType, name string, host string, db string, tbl string, col string) (string, error) {
	newColumnPriv := ""
	if priv == mysql.AllPriv {
		for _, p := range mysql.AllColumnPrivs {
			v, ok := mysql.Priv2SetStr[p]
			if !ok {
				return "", errors.Errorf("Unknown column privilege %v", p)
			}
			if len(newColumnPriv) == 0 {
				newColumnPriv = v
			} else {
				newColumnPriv = fmt.Sprintf("%s,%s", newColumnPriv, v)
			}
		}
	} else {
		currColumnPriv, err := getColumnPriv(ctx, name, host, db, tbl, col)
		if err != nil {
			return "", errors.Trace(err)
		}
		p, ok := mysql.Priv2SetStr[priv]
		if !ok {
			return "", errors.Errorf("Unknown priv: %v", priv)
		}
		if len(currColumnPriv) == 0 {
			newColumnPriv = p
		} else {
			newColumnPriv = fmt.Sprintf("%s,%s", currColumnPriv, p)
		}
	}
	return fmt.Sprintf(`Column_priv="%s"`, newColumnPriv), nil
}

// CheckCIDRs parses the list of strings as CIDRs, checking for
// correct formatting, no duplication and no overlaps. Returns error
// if no CIDRs are provided, unless cidrsOptional is true.
func CheckCIDRs(args []string, cidrsOptional bool) (set.Strings, error) {
	// Validate any given CIDRs.
	CIDRs := set.NewStrings()
	for _, arg := range args {
		_, ipNet, err := net.ParseCIDR(arg)
		if err != nil {
			logger.Debugf("cannot parse %q: %v", arg, err)
			return CIDRs, errors.Errorf("%q is not a valid CIDR", arg)
		}
		cidr := ipNet.String()
		if CIDRs.Contains(cidr) {
			if cidr == arg {
				return CIDRs, errors.Errorf("duplicate subnet %q specified", cidr)
			}
			return CIDRs, errors.Errorf("subnet %q overlaps with %q", arg, cidr)
		}
		CIDRs.Add(cidr)
	}

	if CIDRs.IsEmpty() && !cidrsOptional {
		return CIDRs, errors.New("CIDRs required but not provided")
	}

	return CIDRs, nil
}

// decorateAndWriteInfo decorates the info struct with information
// from the given cfg, and the writes that out to the filesystem.
func decorateAndWriteInfo(info configstore.EnvironInfo, cfg *config.Config) error {

	// Sanity check our config.
	var endpoint configstore.APIEndpoint
	if cert, ok := cfg.CACert(); !ok {
		return errors.Errorf("CACert is not set")
	} else if uuid, ok := cfg.UUID(); !ok {
		return errors.Errorf("UUID is not set")
	} else if adminSecret := cfg.AdminSecret(); adminSecret == "" {
		return errors.Errorf("admin-secret is not set")
	} else {
		endpoint = configstore.APIEndpoint{
			CACert:      cert,
			EnvironUUID: uuid,
		}
	}

	creds := configstore.APICredentials{
		User:     "admin", // TODO(waigani) [email protected] once we have that set
		Password: cfg.AdminSecret(),
	}
	info.SetAPICredentials(creds)
	info.SetAPIEndpoint(endpoint)
	info.SetBootstrapConfig(cfg.AllAttrs())

	if err := info.Write(); err != nil {
		return errors.Annotatef(err, "cannot create environment info %q", cfg.Name())
	}

	return nil
}

func ensureUpgradeInfoUpdated(st *State, machineId string, previousVersion, targetVersion version.Number) (*UpgradeInfo, error) {
	var doc upgradeInfoDoc
	if pdoc, err := currentUpgradeInfoDoc(st); err != nil {
		return nil, errors.Trace(err)
	} else {
		doc = *pdoc
	}

	if doc.PreviousVersion != previousVersion {
		return nil, errors.Errorf(
			"current upgrade info mismatch: expected previous version %s, got %s",
			previousVersion, doc.PreviousVersion)
	}
	if doc.TargetVersion != targetVersion {
		return nil, errors.Errorf(
			"current upgrade info mismatch: expected target version %s, got %s",
			targetVersion, doc.TargetVersion)
	}

	controllersReady := set.NewStrings(doc.ControllersReady...)
	if !controllersReady.Contains(machineId) {
		return nil, errors.Trace(errUpgradeInfoNotUpdated)
	}
	return &UpgradeInfo{st: st, doc: doc}, nil
}

// requestStart invokes a runWorker goroutine for the manifold with the supplied
// name. It must only be called from the loop goroutine.
func (engine *engine) requestStart(name string, delay time.Duration) {

	// Check preconditions.
	manifold, found := engine.manifolds[name]
	if !found {
		engine.tomb.Kill(errors.Errorf("fatal: unknown manifold %q", name))
	}

	// Copy current info and check more preconditions.
	info := engine.current[name]
	if !info.stopped() {
		engine.tomb.Kill(errors.Errorf("fatal: trying to start a second %q manifold worker", name))
	}

	// Final check that we're not shutting down yet...
	if engine.isDying() {
		logger.Tracef("not starting %q manifold worker (shutting down)", name)
		return
	}

	// ...then update the info, copy it back to the engine, and start a worker
	// goroutine based on current known state.
	info.starting = true
	engine.current[name] = info
	resourceGetter := engine.resourceGetter(name, manifold.Inputs)
	go engine.runWorker(name, delay, manifold.Start, resourceGetter)
}

// fetchResult queries the given API for the given Action ID prefix, and
// makes sure the results are acceptable, returning an error if they are not.
func fetchResult(api APIClient, requestedId string) (params.ActionResult, error) {
	none := params.ActionResult{}

	actionTag, err := getActionTagByPrefix(api, requestedId)
	if err != nil {
		return none, err
	}

	actions, err := api.Actions(params.Entities{
		Entities: []params.Entity{{actionTag.String()}},
	})
	if err != nil {
		return none, err
	}
	actionResults := actions.Results
	numActionResults := len(actionResults)
	if numActionResults == 0 {
		return none, errors.Errorf("no results for action %s", requestedId)
	}
	if numActionResults != 1 {
		return none, errors.Errorf("too many results for action %s", requestedId)
	}

	result := actionResults[0]
	if result.Error != nil {
		return none, result.Error
	}

	return result, nil
}

func (r *JoinRset) checkTableDuplicate(t *TableSource, tr *TableRset) error {
	if len(t.Name) > 0 {
		// use alias name
		_, ok := r.tableNames[t.Name]
		if ok {
			return errors.Errorf("%s: duplicate name %s", r, t.Name)
		}
		r.tableNames[t.Name] = struct{}{}
		return nil
	}

	// first check ident name
	identName := t.String()
	_, ok := r.tableNames[identName]
	if ok {
		return errors.Errorf("%s: duplicate name %s", r, identName)
	}
	r.tableNames[identName] = struct{}{}

	qualifiedName := tr.Schema + "." + tr.Name
	// we should check qualifed name too, e,g select * form t1 join test.t1
	if identName != qualifiedName {
		_, ok = r.tableNames[qualifiedName]
		if ok {
			return errors.Errorf("%s: duplicate name %s", r, identName)
		}
		r.tableNames[qualifiedName] = struct{}{}
	}

	return nil
}

func (o *setRow) getMembers(r storeReader, count int64) ([][]byte, error) {
	it := r.getIterator()
	defer r.putIterator(it)
	var members [][]byte
	for pfx := it.SeekTo(o.DataKeyPrefix()); count > 0 && it.Valid(); it.Next() {
		key := it.Key()
		if !bytes.HasPrefix(key, pfx) {
			break
		}
		sfx := key[len(pfx):]
		if err := o.ParseDataKeySuffix(sfx); err != nil {
			return nil, err
		}
		if err := o.ParseDataValue(it.Value()); err != nil {
			return nil, err
		}
		if len(o.Member) == 0 {
			return nil, errors.Errorf("len(member) = %d", len(o.Member))
		}
		members = append(members, o.Member)
		count--
	}
	if err := it.Error(); err != nil {
		return nil, err
	}
	if len(members) == 0 {
		return nil, errors.Errorf("len(members) = %d, set.size = %d", len(members), o.Size)
	}
	return members, nil
}

func buildIndexInfo(tblInfo *model.TableInfo, unique bool, indexName model.CIStr, indexID int64, idxColNames []*coldef.IndexColName) (*model.IndexInfo, error) {
	for _, col := range tblInfo.Columns {
		if col.Name.L == indexName.L {
			return nil, errors.Errorf("CREATE INDEX: index name collision with existing column: %s", indexName)
		}
	}

	// build offsets
	idxColumns := make([]*model.IndexColumn, 0, len(idxColNames))
	for _, ic := range idxColNames {
		col := findCol(tblInfo.Columns, ic.ColumnName)
		if col == nil {
			return nil, errors.Errorf("CREATE INDEX: column does not exist: %s", ic.ColumnName)
		}

		idxColumns = append(idxColumns, &model.IndexColumn{
			Name:   col.Name,
			Offset: col.Offset,
			Length: ic.Length,
		})
	}
	// create index info
	idxInfo := &model.IndexInfo{
		ID:      indexID,
		Name:    indexName,
		Columns: idxColumns,
		Unique:  unique,
		State:   model.StateNone,
	}
	return idxInfo, nil
}

// We don't support multi source replication, so the mariadb gtid set may have only domain-server-sequence
func ParseMariadbGTIDSet(str string) (GTIDSet, error) {
	if len(str) == 0 {
		return MariadbGTID{0, 0, 0}, nil
	}

	seps := strings.Split(str, "-")

	var gtid MariadbGTID

	if len(seps) != 3 {
		return gtid, errors.Errorf("invalid Mariadb GTID %v, must domain-server-sequence", str)
	}

	domainID, err := strconv.ParseUint(seps[0], 10, 32)
	if err != nil {
		return gtid, errors.Errorf("invalid MariaDB GTID Domain ID (%v): %v", seps[0], err)
	}

	serverID, err := strconv.ParseUint(seps[1], 10, 32)
	if err != nil {
		return gtid, errors.Errorf("invalid MariaDB GTID Server ID (%v): %v", seps[1], err)
	}

	sequenceID, err := strconv.ParseUint(seps[2], 10, 64)
	if err != nil {
		return gtid, errors.Errorf("invalid MariaDB GTID Sequence number (%v): %v", seps[2], err)
	}

	return MariadbGTID{
		DomainID:       uint32(domainID),
		ServerID:       uint32(serverID),
		SequenceNumber: sequenceID}, nil
}

func (b *planBuilder) buildUpdateLists(list []*ast.Assignment, p LogicalPlan) ([]*expression.Assignment, LogicalPlan) {
	schema := p.GetSchema()
	newList := make([]*expression.Assignment, len(schema))
	for _, assign := range list {
		col, err := schema.FindColumn(assign.Column)
		if err != nil {
			b.err = errors.Trace(err)
			return nil, nil
		}
		if col == nil {
			b.err = errors.Trace(errors.Errorf("column %s not found", assign.Column.Name.O))
			return nil, nil
		}
		offset := schema.GetIndex(col)
		if offset == -1 {
			b.err = errors.Trace(errors.Errorf("could not find column %s.%s", col.TblName, col.ColName))
		}
		newExpr, np, _, err := b.rewrite(assign.Expr, p, nil, false)
		if err != nil {
			b.err = errors.Trace(err)
			return nil, nil
		}
		p = np
		newList[offset] = &expression.Assignment{Col: col, Expr: newExpr}
	}
	return newList, p
}

// GetColDefaultValue gets default value of the column.
func GetColDefaultValue(ctx context.Context, col *model.ColumnInfo) (interface{}, bool, error) {
	// Check no default value flag.
	if mysql.HasNoDefaultValueFlag(col.Flag) && col.Tp != mysql.TypeEnum {
		return nil, false, errors.Errorf("Field '%s' doesn't have a default value", col.Name)
	}

	// Check and get timestamp/datetime default value.
	if col.Tp == mysql.TypeTimestamp || col.Tp == mysql.TypeDatetime {
		if col.DefaultValue == nil {
			return nil, true, nil
		}

		value, err := expression.GetTimeValue(ctx, col.DefaultValue, col.Tp, col.Decimal)
		if err != nil {
			return nil, true, errors.Errorf("Field '%s' get default value fail - %s", col.Name, errors.Trace(err))
		}

		return value, true, nil
	} else if col.Tp == mysql.TypeEnum {
		// For enum type, if no default value and not null is set,
		// the default value is the first element of the enum list
		if col.DefaultValue == nil && mysql.HasNotNullFlag(col.Flag) {
			return col.FieldType.Elems[0], true, nil
		}
	}

	return col.DefaultValue, true, nil
}

func (c *addCloudCommand) Run(ctxt *cmd.Context) error {
	specifiedClouds, err := cloud.ParseCloudMetadataFile(c.CloudFile)
	if err != nil {
		return err
	}
	if specifiedClouds == nil {
		return errors.New("no personal clouds are defined")
	}
	newCloud, ok := specifiedClouds[c.Cloud]
	if !ok {
		return errors.Errorf("cloud %q not found in file %q", c.Cloud, c.CloudFile)
	}
	personalClouds, err := cloud.PersonalCloudMetadata()
	if err != nil {
		return err
	}
	if _, ok = personalClouds[c.Cloud]; ok && !c.Replace {
		return errors.Errorf("cloud called %q already exists; use --replace to replace this existing cloud", c.Cloud)
	}
	if personalClouds == nil {
		personalClouds = make(map[string]cloud.Cloud)
	}
	personalClouds[c.Cloud] = newCloud
	return cloud.WritePersonalCloudMetadata(personalClouds)
}

// DecodeRecordKey decodes the key and gets the tableID, handle and columnID.
func DecodeRecordKey(key kv.Key) (tableID int64, handle int64, columnID int64, err error) {
	k := key
	if !key.HasPrefix(TablePrefix) {
		return 0, 0, 0, errors.Errorf("invalid record key - %q", k)
	}

	key = key[len(TablePrefix):]
	key, tableID, err = codec.DecodeInt(key)
	if err != nil {
		return 0, 0, 0, errors.Trace(err)
	}

	if !key.HasPrefix(recordPrefixSep) {
		return 0, 0, 0, errors.Errorf("invalid record key - %q", k)
	}

	key = key[len(recordPrefixSep):]

	key, handle, err = codec.DecodeInt(key)
	if err != nil {
		return 0, 0, 0, errors.Trace(err)
	}
	if len(key) == 0 {
		return
	}

	key, columnID, err = codec.DecodeInt(key)
	if err != nil {
		return 0, 0, 0, errors.Trace(err)
	}

	return
}

func (o *hashRow) getAllFields(r storeReader) ([][]byte, error) {
	it := r.getIterator()
	defer r.putIterator(it)
	var fields [][]byte
	for pfx := it.SeekTo(o.DataKeyPrefix()); it.Valid(); it.Next() {
		key := it.Key()
		if !bytes.HasPrefix(key, pfx) {
			break
		}
		sfx := key[len(pfx):]
		if err := o.ParseDataKeySuffix(sfx); err != nil {
			return nil, errors.Trace(err)
		}
		if len(o.Field) == 0 {
			return nil, errors.Errorf("len(field) = %d", len(o.Field))
		}
		fields = append(fields, o.Field)
	}
	if err := it.Error(); err != nil {
		return nil, errors.Trace(err)
	}
	if len(fields) == 0 || int64(len(fields)) != o.Size {
		return nil, errors.Errorf("len(fields) = %d, hash.size = %d", len(fields), o.Size)
	}
	return fields, nil
}

func checkUnits(app PrecheckApplication, modelVersion version.Number) error {
	units, err := app.AllUnits()
	if err != nil {
		return errors.Annotatef(err, "retrieving units for %s", app.Name())
	}
	if len(units) < app.MinUnits() {
		return errors.Errorf("application %s is below its minimum units threshold", app.Name())
	}

	appCharmURL, _ := app.CharmURL()

	for _, unit := range units {
		if unit.Life() != state.Alive {
			return errors.Errorf("unit %s is %s", unit.Name(), unit.Life())
		}

		if err := checkUnitAgentStatus(unit); err != nil {
			return errors.Trace(err)
		}

		if err := checkAgentTools(modelVersion, unit, "unit "+unit.Name()); err != nil {
			return errors.Trace(err)
		}

		unitCharmURL, _ := unit.CharmURL()
		if appCharmURL.String() != unitCharmURL.String() {
			return errors.Errorf("unit %s is upgrading", unit.Name())
		}
	}
	return nil
}

func (o *hashRow) getAllValues(r storeReader) ([][]byte, error) {
	it := r.getIterator()
	defer r.putIterator(it)
	var values [][]byte
	for pfx := it.SeekTo(o.DataKeyPrefix()); it.Valid(); it.Next() {
		key := it.Key()
		if !bytes.HasPrefix(key, pfx) {
			break
		}
		if err := o.ParseDataValue(it.Value()); err != nil {
			return nil, errors.Trace(err)
		}
		if len(o.Value) == 0 {
			return nil, errors.Errorf("len(value) = %d", len(o.Value))
		}
		values = append(values, o.Value)
	}
	if err := it.Error(); err != nil {
		return nil, errors.Trace(err)
	}
	if len(values) == 0 || int64(len(values)) != o.Size {
		return nil, errors.Errorf("len(values) = %d, hash.size = %d", len(values), o.Size)
	}
	return values, nil
}