// PrivateAddress implements the server side of Client.PrivateAddress.
func (c *Client) PrivateAddress(p params.PrivateAddress) (results params.PrivateAddressResults, err error) {
	switch {
	case names.IsValidMachine(p.Target):
		machine, err := c.api.stateAccessor.Machine(p.Target)
		if err != nil {
			return results, err
		}
		addr, err := machine.PrivateAddress()
		if err != nil {
			return results, errors.Annotatef(err, "error fetching address for machine %q", machine)
		}
		return params.PrivateAddressResults{PrivateAddress: addr.Value}, nil

	case names.IsValidUnit(p.Target):
		unit, err := c.api.stateAccessor.Unit(p.Target)
		if err != nil {
			return results, err
		}
		addr, err := unit.PrivateAddress()
		if err != nil {
			return results, errors.Annotatef(err, "error fetching address for unit %q", unit)
		}
		return params.PrivateAddressResults{PrivateAddress: addr.Value}, nil
	}
	return results, fmt.Errorf("unknown unit or machine %q", p.Target)

}

func (c *RunCommand) Init(args []string) error {
	// make sure we aren't in an existing hook context
	if contextId, err := getenv("JUJU_CONTEXT_ID"); err == nil && contextId != "" {
		return fmt.Errorf("juju-run cannot be called from within a hook, have context %q", contextId)
	}
	if !c.noContext {
		if len(args) < 1 {
			return fmt.Errorf("missing unit-name")
		}
		var unitName string
		unitName, args = args[0], args[1:]
		// If the command line param is a unit id (like service/2) we need to
		// change it to the unit tag as that is the format of the agent directory
		// on disk (unit-service-2).
		if names.IsValidUnit(unitName) {
			c.unit = names.NewUnitTag(unitName)
		} else {
			var err error
			c.unit, err = names.ParseUnitTag(unitName)
			if err != nil {
				return errors.Trace(err)
			}
		}
	}
	if len(args) < 1 {
		return fmt.Errorf("missing commands")
	}
	c.commands, args = args[0], args[1:]
	return cmd.CheckEmpty(args)
}

// PrivateAddress implements the server side of Client.PrivateAddress.
func (c *Client) PrivateAddress(p params.PrivateAddress) (results params.PrivateAddressResults, err error) {
	switch {
	case names.IsValidMachine(p.Target):
		machine, err := c.api.state.Machine(p.Target)
		if err != nil {
			return results, err
		}
		addr := network.SelectInternalAddress(machine.Addresses(), false)
		if addr == "" {
			return results, fmt.Errorf("machine %q has no internal address", machine)
		}
		return params.PrivateAddressResults{PrivateAddress: addr}, nil

	case names.IsValidUnit(p.Target):
		unit, err := c.api.state.Unit(p.Target)
		if err != nil {
			return results, err
		}
		addr, ok := unit.PrivateAddress()
		if !ok {
			return results, fmt.Errorf("unit %q has no internal address", unit)
		}
		return params.PrivateAddressResults{PrivateAddress: addr}, nil
	}
	return results, fmt.Errorf("unknown unit or machine %q", p.Target)
}

// Init initializes the command for running.
func (a *UnitAgent) Init(args []string) error {
	if a.UnitName == "" {
		return cmdutil.RequiredError("unit-name")
	}
	if !names.IsValidUnit(a.UnitName) {
		return fmt.Errorf(`--unit-name option expects "<service>/<n>" argument`)
	}
	if err := a.AgentConf.CheckArgs(args); err != nil {
		return err
	}
	a.runner = worker.NewRunner(cmdutil.IsFatal, cmdutil.MoreImportant, worker.RestartDelay)

	if !a.logToStdErr {
		if err := a.ReadConfig(a.Tag().String()); err != nil {
			return err
		}
		agentConfig := a.CurrentConfig()

		// the writer in ctx.stderr gets set as the loggo writer in github.com/juju/cmd/logging.go
		a.ctx.Stderr = &lumberjack.Logger{
			Filename:   agent.LogFilename(agentConfig),
			MaxSize:    300, // megabytes
			MaxBackups: 2,
		}

	}

	return nil
}

// ReadSettings returns a map holding the settings of the unit with the
// supplied name within this relation. An error will be returned if the
// relation no longer exists, or if the unit's service is not part of the
// relation, or the settings are invalid; but mere non-existence of the
// unit is not grounds for an error, because the unit settings are
// guaranteed to persist for the lifetime of the relation, regardless
// of the lifetime of the unit.
func (ru *RelationUnit) ReadSettings(uname string) (params.RelationSettings, error) {
	if !names.IsValidUnit(uname) {
		return nil, errors.Errorf("%q is not a valid unit", uname)
	}
	tag := names.NewUnitTag(uname)
	var results params.RelationSettingsResults
	args := params.RelationUnitPairs{
		RelationUnitPairs: []params.RelationUnitPair{{
			Relation:   ru.relation.tag.String(),
			LocalUnit:  ru.unit.tag.String(),
			RemoteUnit: tag.String(),
		}},
	}
	err := ru.st.facade.FacadeCall("ReadRemoteSettings", args, &results)
	if err != nil {
		return nil, err
	}
	if len(results.Results) != 1 {
		return nil, fmt.Errorf("expected 1 result, got %d", len(results.Results))
	}
	result := results.Results[0]
	if result.Error != nil {
		return nil, result.Error
	}
	return result.Settings, nil
}

func (c *SSHCommon) hostFromTarget(target string) (string, error) {
	// If the target is neither a machine nor a unit,
	// assume it's a hostname and try it directly.
	if !names.IsValidMachine(target) && !names.IsValidUnit(target) {
		return target, nil
	}
	// A target may not initially have an address (e.g. the
	// address updater hasn't yet run), so we must do this in
	// a loop.
	if _, err := c.ensureAPIClient(); err != nil {
		return "", err
	}
	var err error
	for a := sshHostFromTargetAttemptStrategy.Start(); a.Next(); {
		var addr string
		if c.proxy {
			addr, err = c.apiClient.PrivateAddress(target)
		} else {
			addr, err = c.apiClient.PublicAddress(target)
		}
		if err == nil {
			return addr, nil
		}
	}
	return "", err
}

func (s *serviceSuite) TestServiceNameFormats(c *gc.C) {
	assertService := func(s string, expect bool) {
		c.Assert(names.IsValidService(s), gc.Equals, expect)
		// Check that anything that is considered a valid service name
		// is also (in)valid if a(n) (in)valid unit designator is added
		// to it.
		c.Assert(names.IsValidUnit(s+"/0"), gc.Equals, expect)
		c.Assert(names.IsValidUnit(s+"/99"), gc.Equals, expect)
		c.Assert(names.IsValidUnit(s+"/-1"), gc.Equals, false)
		c.Assert(names.IsValidUnit(s+"/blah"), gc.Equals, false)
		c.Assert(names.IsValidUnit(s+"/"), gc.Equals, false)
	}

	for i, test := range serviceNameTests {
		c.Logf("test %d: %q", i, test.pattern)
		assertService(test.pattern, test.valid)
	}
}

// IsValid checks if the port range is valid.
func (p PortRange) IsValid() bool {
	proto := strings.ToLower(p.Protocol)
	if proto != "tcp" && proto != "udp" {
		return false
	}
	if !names.IsValidUnit(p.UnitName) {
		return false
	}
	return p.FromPort <= p.ToPort
}

// Unit returns the service's unit with name.
func (s *Service) Unit(name string) (*Unit, error) {
	if !names.IsValidUnit(name) {
		return nil, fmt.Errorf("%q is not a valid unit name", name)
	}
	udoc := &unitDoc{}
	sel := bson.D{{"_id", name}, {"service", s.doc.Name}}
	if err := s.st.units.Find(sel).One(udoc); err != nil {
		return nil, fmt.Errorf("cannot get unit %q from service %q: %v", name, s.doc.Name, err)
	}
	return newUnit(s.st, udoc), nil
}

// resolveMachine returns the machine id resolving the given unit or machine
// placeholder.
func (h *bundleHandler) resolveMachine(placeholder string) (string, error) {
	machineOrUnit := resolve(placeholder, h.results)
	if !names.IsValidUnit(machineOrUnit) {
		return machineOrUnit, nil
	}
	for h.unitStatus[machineOrUnit] == "" {
		if err := h.updateUnitStatus(); err != nil {
			return "", errors.Annotate(err, "cannot resolve machine")
		}
	}
	return h.unitStatus[machineOrUnit], nil
}

func (c *RemoveUnitCommand) Init(args []string) error {
	c.UnitNames = args
	if len(c.UnitNames) == 0 {
		return fmt.Errorf("no units specified")
	}
	for _, name := range c.UnitNames {
		if !names.IsValidUnit(name) {
			return fmt.Errorf("invalid unit name %q", name)
		}
	}
	return nil
}

func (c *resolvedCommand) Init(args []string) error {
	if len(args) > 0 {
		c.UnitName = args[0]
		if !names.IsValidUnit(c.UnitName) {
			return fmt.Errorf("invalid unit name %q", c.UnitName)
		}
		args = args[1:]
	} else {
		return fmt.Errorf("no unit specified")
	}
	return cmd.CheckEmpty(args)
}

func (u unitAssigner) Handle(ids []string) error {
	logger.Tracef("Handling unit assignments: %q", ids)
	if len(ids) == 0 {
		return nil
	}

	units := make([]names.UnitTag, len(ids))
	for i, id := range ids {
		if !names.IsValidUnit(id) {
			return errors.Errorf("%q is not a valid unit id", id)
		}
		units[i] = names.NewUnitTag(id)
	}

	results, err := u.api.AssignUnits(units)
	if err != nil {
		return err
	}

	failures := map[string]error{}

	logger.Tracef("Unit assignment results: %q", results)
	// errors are returned in the same order as the ids given. Any errors from
	// the assign units call must be reported as error statuses on the
	// respective units (though the assignments will be retried).  Not found
	// errors indicate that the unit was removed before the assignment was
	// requested, which can be safely ignored.
	for i, err := range results {
		if err != nil && !errors.IsNotFound(err) {
			failures[units[i].String()] = err
		}
	}

	if len(failures) > 0 {
		args := params.SetStatus{
			Entities: make([]params.EntityStatusArgs, len(failures)),
		}

		x := 0
		for unit, err := range failures {
			args.Entities[x] = params.EntityStatusArgs{
				Tag:    unit,
				Status: params.StatusError,
				Info:   err.Error(),
			}
			x++
		}

		return u.api.SetAgentStatus(args)
	}
	return nil
}

// IsValid checks if the port range is valid.
func (p PortRange) Validate() error {
	proto := strings.ToLower(p.Protocol)
	if proto != "tcp" && proto != "udp" {
		return errors.Errorf("invalid protocol %q", proto)
	}
	if !names.IsValidUnit(p.UnitName) {
		return errors.Errorf("invalid unit %q", p.UnitName)
	}
	if p.FromPort > p.ToPort {
		return errors.Errorf("invalid port range %d-%d", p.FromPort, p.ToPort)
	}
	return nil
}

// Init initializes the command for running.
func (a *UnitAgent) Init(args []string) error {
	if a.UnitName == "" {
		return requiredError("unit-name")
	}
	if !names.IsValidUnit(a.UnitName) {
		return fmt.Errorf(`--unit-name option expects "<service>/<n>" argument`)
	}
	if err := a.AgentConf.CheckArgs(args); err != nil {
		return err
	}
	a.runner = worker.NewRunner(isFatal, moreImportant)
	return nil
}

// Init implements Command.Init.
func (c *addCommand) Init(args []string) (err error) {
	if len(args) < 2 {
		return errors.New("storage add requires a unit and a storage directive")
	}

	u := args[0]
	if !names.IsValidUnit(u) {
		return errors.NotValidf("unit name %q", u)
	}
	c.unitTag = names.NewUnitTag(u).String()

	c.storageCons, err = storage.ParseConstraintsMap(args[1:], false)
	return
}

// Unit returns a unit by name.
func (st *State) Unit(name string) (*Unit, error) {
	if !names.IsValidUnit(name) {
		return nil, fmt.Errorf("%q is not a valid unit name", name)
	}
	doc := unitDoc{}
	err := st.units.FindId(name).One(&doc)
	if err == mgo.ErrNotFound {
		return nil, errors.NotFoundf("unit %q", name)
	}
	if err != nil {
		return nil, fmt.Errorf("cannot get unit %q: %v", name, err)
	}
	return newUnit(st, &doc), nil
}

// validate returns an error if any fields are invalid or missing.
func (c check) validate() error {
	if !names.IsValidService(c.serviceName) {
		return errors.Errorf("invalid service name %q", c.serviceName)
	}
	if !names.IsValidUnit(c.unitName) {
		return errors.Errorf("invalid unit name %q", c.unitName)
	}
	if c.response == nil {
		return errors.New("missing response channel")
	}
	if c.abort == nil {
		return errors.New("missing abort channel")
	}
	return nil
}

// ReadSettings returns a map holding the settings of the unit with the
// supplied name within this relation. An error will be returned if the
// relation no longer exists, or if the unit's service is not part of the
// relation, or the settings are invalid; but mere non-existence of the
// unit is not grounds for an error, because the unit settings are
// guaranteed to persist for the lifetime of the relation, regardless
// of the lifetime of the unit.
func (ru *RelationUnit) ReadSettings(uname string) (m map[string]interface{}, err error) {
	defer errors.Maskf(&err, "cannot read settings for unit %q in relation %q", uname, ru.relation)
	if !names.IsValidUnit(uname) {
		return nil, fmt.Errorf("%q is not a valid unit name", uname)
	}
	key, err := ru.key(uname)
	if err != nil {
		return nil, err
	}
	node, err := readSettings(ru.st, key)
	if err != nil {
		return nil, err
	}
	return node.Map(), nil
}

// Init reads and verifies the cli arguments for the collectMetricsCommand
func (c *collectMetricsCommand) Init(args []string) error {
	if len(args) == 0 {
		return errors.New("you need to specify a unit or service.")
	}
	if names.IsValidUnit(args[0]) {
		c.units = []string{args[0]}
	} else if names.IsValidService(args[0]) {
		c.services = []string{args[0]}
	} else {
		return errors.Errorf("%q is not a valid unit or service", args[0])
	}
	if err := cmd.CheckEmpty(args[1:]); err != nil {
		return errors.Errorf("unknown command line arguments: " + strings.Join(args, ","))
	}
	return nil
}