package base

import (
	"context"
	"crypto/rand"
	"crypto/tls"
	"errors"
	"fmt"
	"io"
	"net"
	"os"
	"os/signal"
	"sort"
	"strconv"
	"strings"
	"sync"
	"syscall"
	"time"

	"github.com/armon/go-metrics"
	"github.com/hashicorp/boundary/globals"
	"github.com/hashicorp/boundary/internal/cmd/base/logging"
	"github.com/hashicorp/boundary/internal/cmd/config"
	"github.com/hashicorp/boundary/internal/db"
	berrors "github.com/hashicorp/boundary/internal/errors"
	"github.com/hashicorp/boundary/internal/kms"
	"github.com/hashicorp/boundary/internal/observability/event"
	"github.com/hashicorp/boundary/internal/servers"
	"github.com/hashicorp/boundary/internal/types/scope"
	"github.com/hashicorp/boundary/version"
	"github.com/hashicorp/go-hclog"
	wrapping "github.com/hashicorp/go-kms-wrapping"
	"github.com/hashicorp/go-multierror"
	"github.com/hashicorp/go-secure-stdlib/configutil"
	"github.com/hashicorp/go-secure-stdlib/gatedwriter"
	"github.com/hashicorp/go-secure-stdlib/mlock"
	"github.com/hashicorp/go-secure-stdlib/parseutil"
	"github.com/hashicorp/go-secure-stdlib/reloadutil"
	"github.com/hashicorp/go-secure-stdlib/strutil"
	"github.com/jinzhu/gorm"
	"github.com/mitchellh/cli"
	"google.golang.org/grpc/grpclog"
)

const (
	// defaultStatusGracePeriod is the default status grace period, or the period
	// of time that we will go without a status report before we start
	// disconnecting and marking connections as closed. This is tied to the
	// server default liveness setting, a related value. See the servers package
	// for more details.
	defaultStatusGracePeriod = servers.DefaultLiveness

	// statusGracePeriodEnvVar is the environment variable that can be used to
	// configure the status grace period. This setting is provided in seconds,
	// and can never be lower than the default status grace period defined above.
	//
	// TODO: This value is temporary, it will be removed once we have a better
	// story/direction on attributes and system defaults.
	statusGracePeriodEnvVar = "BOUNDARY_STATUS_GRACE_PERIOD"
)

type Server struct {
	*Command

	InfoKeys []string
	Info     map[string]string

	logOutput   io.Writer
	GatedWriter *gatedwriter.Writer
	Logger      hclog.Logger
	CombineLogs bool
	LogLevel    hclog.Level

	StderrLock *sync.Mutex
	Eventer    *event.Eventer

	RootKms            wrapping.Wrapper
	WorkerAuthKms      wrapping.Wrapper
	RecoveryKms        wrapping.Wrapper
	Kms                *kms.Kms
	SecureRandomReader io.Reader

	InmemSink         *metrics.InmemSink
	PrometheusEnabled bool

	ReloadFuncsLock *sync.RWMutex
	ReloadFuncs     map[string][]reloadutil.ReloadFunc

	ShutdownFuncs []func() error

	Listeners []*ServerListener

	DevPasswordAuthMethodId          string
	DevOidcAuthMethodId              string
	DevLoginName                     string
	DevPassword                      string
	DevUserId                        string
	DevPasswordAccountId             string
	DevOidcAccountId                 string
	DevUnprivilegedLoginName         string
	DevUnprivilegedPassword          string
	DevUnprivilegedUserId            string
	DevUnprivilegedPasswordAccountId string
	DevUnprivilegedOidcAccountId     string
	DevOrgId                         string
	DevProjectId                     string
	DevHostCatalogId                 string
	DevHostSetId                     string
	DevHostId                        string
	DevTargetId                      string
	DevHostAddress                   string
	DevTargetDefaultPort             int
	DevTargetSessionMaxSeconds       int
	DevTargetSessionConnectionLimit  int

	DevOidcSetup oidcSetup

	DatabaseUrl                string
	DatabaseMaxOpenConnections int
	DevDatabaseCleanupFunc     func() error

	Database *gorm.DB

	// StatusGracePeriodDuration represents the period of time (as a
	// duration) that the controller will wait before marking
	// connections from a disconnected worker as invalid.
	StatusGracePeriodDuration time.Duration
}

func NewServer(cmd *Command) *Server {
	return &Server{
		Command:            cmd,
		InfoKeys:           make([]string, 0, 20),
		Info:               make(map[string]string),
		SecureRandomReader: rand.Reader,
		ReloadFuncsLock:    new(sync.RWMutex),
		ReloadFuncs:        make(map[string][]reloadutil.ReloadFunc),
		StderrLock:         new(sync.Mutex),
	}
}

// SetupEventing will setup the server's eventer and initialize the "system
// wide" eventer with a pointer to the same eventer
func (b *Server) SetupEventing(logger hclog.Logger, serializationLock *sync.Mutex, serverName string, opt ...Option) error {
	const op = "base.(Server).SetupEventing"

	if logger == nil {
		return berrors.New(berrors.InvalidParameter, op, "missing logger")
	}
	if serializationLock == nil {
		return berrors.New(berrors.InvalidParameter, op, "missing serialization lock")
	}
	if serverName == "" {
		return berrors.New(berrors.InvalidParameter, op, "missing server name")
	}
	opts := getOpts(opt...)
	if opts.withEventerConfig != nil {
		if err := opts.withEventerConfig.Validate(); err != nil {
			return berrors.Wrap(err, op, berrors.WithMsg("invalid eventer config"))
		}
	}
	if opts.withEventerConfig == nil {
		opts.withEventerConfig = event.DefaultEventerConfig()
	}

	if opts.withEventFlags != nil {
		if err := opts.withEventFlags.Validate(); err != nil {
			return berrors.Wrap(err, op, berrors.WithMsg("invalid event flags"))
		}
		if opts.withEventFlags.Format != "" {
			for i := 0; i < len(opts.withEventerConfig.Sinks); i++ {
				opts.withEventerConfig.Sinks[i].Format = opts.withEventFlags.Format
			}
		}
		if opts.withEventFlags.AuditEnabled != nil {
			opts.withEventerConfig.AuditEnabled = *opts.withEventFlags.AuditEnabled
		}
		if opts.withEventFlags.ObservationsEnabled != nil {
			opts.withEventerConfig.ObservationsEnabled = *opts.withEventFlags.ObservationsEnabled
		}
		if opts.withEventFlags.SysEventsEnabled != nil {
			opts.withEventerConfig.SysEventsEnabled = *opts.withEventFlags.SysEventsEnabled
		}
		if len(opts.withEventFlags.AllowFilters) > 0 {
			for i := 0; i < len(opts.withEventerConfig.Sinks); i++ {
				opts.withEventerConfig.Sinks[i].AllowFilters = opts.withEventFlags.AllowFilters
			}
		}
		if len(opts.withEventFlags.DenyFilters) > 0 {
			for i := 0; i < len(opts.withEventerConfig.Sinks); i++ {
				opts.withEventerConfig.Sinks[i].DenyFilters = opts.withEventFlags.DenyFilters
			}
		}
	}

	e, err := event.NewEventer(logger, serializationLock, serverName, *opts.withEventerConfig)
	if err != nil {
		return berrors.Wrap(err, op, berrors.WithMsg("unable to create eventer"))
	}
	b.Eventer = e

	if err := event.InitSysEventer(logger, serializationLock, serverName, event.WithEventer(e)); err != nil {
		return berrors.Wrap(err, op, berrors.WithMsg("unable to initialize system eventer"))
	}

	return nil
}

// AddEventerToContext will add the server eventer to the context provided
func (b *Server) AddEventerToContext(ctx context.Context) (context.Context, error) {
	const op = "base.(Server).AddEventerToContext"
	if b.Eventer == nil {
		return nil, berrors.New(berrors.InvalidParameter, op, "missing server eventer")
	}
	e, err := event.NewEventerContext(ctx, b.Eventer)
	if err != nil {
		return nil, berrors.Wrap(err, op, berrors.WithMsg("unable to add eventer to context"))
	}
	return e, nil
}

func (b *Server) SetupLogging(flagLogLevel, flagLogFormat, configLogLevel, configLogFormat string) error {
	b.logOutput = os.Stderr
	if b.CombineLogs {
		b.logOutput = os.Stdout
	}
	b.GatedWriter = gatedwriter.NewWriter(b.logOutput)

	// Set up logging
	logLevel, logFormat, err := ProcessLogLevelAndFormat(flagLogLevel, flagLogFormat, configLogLevel, configLogFormat)
	if err != nil {
		return err
	}
	b.Logger = hclog.New(&hclog.LoggerOptions{
		Output: b.GatedWriter,
		Level:  logLevel,
		// Note that if logFormat is either unspecified or standard, then
		// the resulting logger's format will be standard.
		JSONFormat: logFormat == logging.JSONFormat,
		Mutex:      b.StderrLock,
	})

	// create GRPC logger
	namedGRPCLogFaker := b.Logger.Named("grpclogfaker")
	grpclog.SetLogger(&GRPCLogFaker{
		Logger: namedGRPCLogFaker,
		Log:    os.Getenv("BOUNDARY_GRPC_LOGGING") != "",
	})

	b.Info["log level"] = logLevel.String()
	b.InfoKeys = append(b.InfoKeys, "log level")

	b.LogLevel = logLevel

	// log proxy settings
	// TODO: It would be good to show this but Vault has, or will soon, address
	// the fact that this can log users/passwords if they are part of the proxy
	// URL. When they change things to address that we should update the below
	// logic and re-enable.
	/*
		proxyCfg := httpproxy.FromEnvironment()
		event.WriteSysEvent(context.TODO(), op,
			"proxy environment",
			"http_proxy", proxyCfg.HTTPProxy,
			"https_proxy", proxyCfg.HTTPSProxy,
			"no_proxy",	proxyCfg.NoProxy,
		})
	*/
	// Setup gorm logging

	return nil
}

func (b *Server) ReleaseLogGate() {
	// Release the log gate.
	b.Logger.(hclog.OutputResettable).ResetOutputWithFlush(&hclog.LoggerOptions{
		Output: b.logOutput,
	}, b.GatedWriter)
}

func (b *Server) StorePidFile(pidPath string) error {
	// Quit fast if no pidfile
	if pidPath == "" {
		return nil
	}

	// Open the PID file
	pidFile, err := os.OpenFile(pidPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o644)
	if err != nil {
		return fmt.Errorf("could not open pid file: %w", err)
	}
	defer pidFile.Close()

	// Write out the PID
	pid := os.Getpid()
	_, err = pidFile.WriteString(fmt.Sprintf("%d", pid))
	if err != nil {
		return fmt.Errorf("could not write to pid file: %w", err)
	}

	b.ShutdownFuncs = append(b.ShutdownFuncs, func() error {
		if err := b.RemovePidFile(pidPath); err != nil {
			return fmt.Errorf("Error deleting the PID file: %w", err)
		}
		return nil
	})

	return nil
}

func (b *Server) RemovePidFile(pidPath string) error {
	if pidPath == "" {
		return nil
	}
	return os.Remove(pidPath)
}

func (b *Server) PrintInfo(ui cli.Ui) {
	verInfo := version.Get()
	if verInfo.Version != "" {
		b.InfoKeys = append(b.InfoKeys, "version")
		b.Info["version"] = verInfo.FullVersionNumber(false)
	}
	if verInfo.Revision != "" {
		b.Info["version sha"] = strings.Trim(verInfo.Revision, "'")
		b.InfoKeys = append(b.InfoKeys, "version sha")
	}
	b.InfoKeys = append(b.InfoKeys, "cgo")
	b.Info["cgo"] = "disabled"
	if version.CgoEnabled {
		b.Info["cgo"] = "enabled"
	}

	// Server configuration output
	padding := 0
	for _, k := range b.InfoKeys {
		currPadding := padding - len(k)
		if currPadding < 2 {
			padding = len(k) + 2
		}
	}
	sort.Strings(b.InfoKeys)
	ui.Output("==> Boundary server configuration:\n")
	for _, k := range b.InfoKeys {
		ui.Output(fmt.Sprintf(
			"%s%s: %s",
			strings.Repeat(" ", padding-len(k)),
			strings.Title(k),
			b.Info[k]))
	}
	ui.Output("")

	// Output the header that the server has started
	if !b.CombineLogs {
		ui.Output("==> Boundary server started! Log data will stream in below:\n")
	}
}

func (b *Server) SetupListeners(ui cli.Ui, config *configutil.SharedConfig, allowedPurposes []string) error {
	// Initialize the listeners
	b.Listeners = make([]*ServerListener, 0, len(config.Listeners))
	// Make sure we close everything before we exit
	// If we successfully started a controller we'll have done this anyways so
	// we ignore errors
	b.ShutdownFuncs = append(b.ShutdownFuncs, func() error {
		for _, ln := range b.Listeners {
			ln.Mux.Close()
		}
		return nil
	})

	b.ReloadFuncsLock.Lock()
	defer b.ReloadFuncsLock.Unlock()

	for i, lnConfig := range config.Listeners {
		if len(lnConfig.Purpose) != 1 {
			return fmt.Errorf("Invalid size of listener purposes (%d)", len(lnConfig.Purpose))
		}
		purpose := strings.ToLower(lnConfig.Purpose[0])
		if !strutil.StrListContains(allowedPurposes, purpose) {
			return fmt.Errorf("Unknown listener purpose %q", purpose)
		}
		lnConfig.Purpose[0] = purpose

		if lnConfig.TLSCipherSuites == nil {
			lnConfig.TLSCipherSuites = []uint16{
				// 1.3
				tls.TLS_AES_128_GCM_SHA256,
				tls.TLS_AES_256_GCM_SHA384,
				tls.TLS_CHACHA20_POLY1305_SHA256,
				// 1.2
				tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
				tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
				tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
			}
		}

		lnMux, props, reloadFunc, err := NewListener(lnConfig, b.Logger, ui)
		if err != nil {
			return fmt.Errorf("Error initializing listener of type %s: %w", lnConfig.Type, err)
		}

		// CORS props
		if purpose == "api" {
			if lnConfig.CorsEnabled != nil && *lnConfig.CorsEnabled {
				props["cors_enabled"] = "true"
				props["cors_allowed_origins"] = fmt.Sprintf("%v", lnConfig.CorsAllowedOrigins)
				props["cors_allowed_headers"] = fmt.Sprintf("%v", lnConfig.CorsAllowedHeaders)
			} else {
				props["cors_enabled"] = "false"
			}
		}

		// X-Forwarded-For props
		{
			if len(lnConfig.XForwardedForAuthorizedAddrs) > 0 {
				props["x_forwarded_for_authorized_addrs"] = fmt.Sprintf("%v", lnConfig.XForwardedForAuthorizedAddrs)
				props["x_forwarded_for_reject_not_present"] = strconv.FormatBool(lnConfig.XForwardedForRejectNotPresent)
				props["x_forwarded_for_hop_skips"] = "0"
			}

			if lnConfig.XForwardedForHopSkips > 0 {
				props["x_forwarded_for_hop_skips"] = fmt.Sprintf("%d", lnConfig.XForwardedForHopSkips)
			}
		}

		if reloadFunc != nil {
			relSlice := b.ReloadFuncs["listeners"]
			relSlice = append(relSlice, reloadFunc)
			b.ReloadFuncs["listeners"] = relSlice
		}

		if lnConfig.MaxRequestSize == 0 {
			lnConfig.MaxRequestSize = globals.DefaultMaxRequestSize
		}
		// TODO: We don't actually limit this yet.
		// props["max_request_size"] = fmt.Sprintf("%d", lnConfig.MaxRequestSize)

		if lnConfig.MaxRequestDuration == 0 {
			lnConfig.MaxRequestDuration = globals.DefaultMaxRequestDuration
		}
		props["max_request_duration"] = lnConfig.MaxRequestDuration.String()

		b.Listeners = append(b.Listeners, &ServerListener{
			Mux:    lnMux,
			Config: lnConfig,
		})

		props["purpose"] = strings.Join(lnConfig.Purpose, ",")

		// Store the listener props for output later
		key := fmt.Sprintf("listener %d", i+1)
		propsList := make([]string, 0, len(props))
		for k, v := range props {
			propsList = append(propsList, fmt.Sprintf(
				"%s: %q", k, v))
		}
		sort.Strings(propsList)
		b.InfoKeys = append(b.InfoKeys, key)
		b.Info[key] = fmt.Sprintf(
			"%s (%s)", lnConfig.Type, strings.Join(propsList, ", "))
	}

	return nil
}

func (b *Server) SetupKMSes(ui cli.Ui, config *config.Config) error {
	sharedConfig := config.SharedConfig
	for _, kms := range sharedConfig.Seals {
		for _, purpose := range kms.Purpose {
			purpose = strings.ToLower(purpose)
			switch purpose {
			case "":
				return errors.New("KMS block missing 'purpose'")
			case "root", "worker-auth", "config":
			case "recovery":
				if config.Controller != nil && config.DevRecoveryKey != "" {
					kms.Config["key"] = config.DevRecoveryKey
				}
			default:
				return fmt.Errorf("Unknown KMS purpose %q", kms.Purpose)
			}

			kmsLogger := b.Logger.ResetNamed(fmt.Sprintf("kms-%s-%s", purpose, kms.Type))

			origPurpose := kms.Purpose
			kms.Purpose = []string{purpose}
			wrapper, wrapperConfigError := configutil.ConfigureWrapper(kms, &b.InfoKeys, &b.Info, kmsLogger)
			kms.Purpose = origPurpose
			if wrapperConfigError != nil {
				return fmt.Errorf(
					"Error parsing KMS configuration: %s", wrapperConfigError)
			}
			if wrapper == nil {
				return fmt.Errorf(
					"After configuration nil KMS returned, KMS type was %s", kms.Type)
			}

			switch purpose {
			case "root":
				b.RootKms = wrapper
			case "worker-auth":
				b.WorkerAuthKms = wrapper
			case "recovery":
				b.RecoveryKms = wrapper
			case "config":
				// Do nothing, can be set in same file but not needed at runtime
			default:
				return fmt.Errorf("KMS purpose of %q is unknown", purpose)
			}

			// Ensure that the seal finalizer is called, even if using verify-only
			b.ShutdownFuncs = append(b.ShutdownFuncs, func() error {
				if err := wrapper.Finalize(context.Background()); err != nil {
					return fmt.Errorf("Error finalizing kms of type %s and purpose %s: %v", kms.Type, purpose, err)
				}

				return nil
			})
		}
	}

	// prepare a secure random reader
	var err error
	b.SecureRandomReader, err = configutil.CreateSecureRandomReaderFunc(config.SharedConfig, b.RootKms)
	if err != nil {
		return err
	}

	// This might not be the _best_ place for this but we have access to config
	// here
	b.Info["mlock"] = fmt.Sprintf(
		"supported: %v, enabled: %v",
		mlock.Supported(), !config.DisableMlock && mlock.Supported())
	b.InfoKeys = append(b.InfoKeys, "mlock")

	return nil
}

func (b *Server) RunShutdownFuncs() error {
	var mErr *multierror.Error
	for _, f := range b.ShutdownFuncs {
		if err := f(); err != nil {
			mErr = multierror.Append(mErr, err)
		}
	}
	return mErr.ErrorOrNil()
}

func (b *Server) ConnectToDatabase(dialect string) error {
	dbase, err := gorm.Open(dialect, b.DatabaseUrl)
	if err != nil {
		return fmt.Errorf("unable to create db object with dialect %s: %w", dialect, err)
	}
	if b.DatabaseMaxOpenConnections == 1 {
		return fmt.Errorf("unable to create db object with dialect %s: %s", dialect, "max_open_connections must be unlimited by setting 0 or at least 2")
	} else {
		dbase.DB().SetMaxOpenConns(b.DatabaseMaxOpenConnections)
	}
	b.Database = dbase
	if os.Getenv("BOUNDARY_DISABLE_GORM_FORMATTER") == "" {
		gorm.LogFormatter = db.GetGormLogFormatter(b.Logger)
		b.Database.SetLogger(db.GetGormLogger(b.Logger))
	}
	return nil
}

func (b *Server) CreateGlobalKmsKeys(ctx context.Context) error {
	rw := db.New(b.Database)

	kmsRepo, err := kms.NewRepository(rw, rw)
	if err != nil {
		return fmt.Errorf("error creating kms repository: %w", err)
	}
	kmsCache, err := kms.NewKms(kmsRepo)
	if err != nil {
		return fmt.Errorf("error creating kms cache: %w", err)
	}
	if err := kmsCache.AddExternalWrappers(
		kms.WithRootWrapper(b.RootKms),
	); err != nil {
		return fmt.Errorf("error adding config keys to kms: %w", err)
	}

	cancelCtx, cancel := context.WithCancel(ctx)
	defer cancel()
	go func() {
		select {
		case <-b.ShutdownCh:
			cancel()
		case <-cancelCtx.Done():
		}
	}()

	_, err = kms.CreateKeysTx(cancelCtx, rw, rw, b.RootKms, b.SecureRandomReader, scope.Global.String())
	if err != nil {
		return fmt.Errorf("error creating global scope kms keys: %w", err)
	}

	return nil
}

func (b *Server) DestroyDevDatabase() error {
	if b.Database != nil {
		b.Database.Close()
	}
	if b.DevDatabaseCleanupFunc != nil {
		return b.DevDatabaseCleanupFunc()
	}
	return nil
}

func (b *Server) SetupControllerPublicClusterAddress(conf *config.Config, flagValue string) error {
	if conf.Controller == nil {
		conf.Controller = new(config.Controller)
	}
	if flagValue != "" {
		conf.Controller.PublicClusterAddr = flagValue
	}
	if conf.Controller.PublicClusterAddr == "" {
	FindAddr:
		for _, listener := range conf.Listeners {
			for _, purpose := range listener.Purpose {
				if purpose == "cluster" {
					conf.Controller.PublicClusterAddr = listener.Address
					break FindAddr
				}
			}
		}
	} else {
		var err error
		conf.Controller.PublicClusterAddr, err = parseutil.ParsePath(conf.Controller.PublicClusterAddr)
		if err != nil && !errors.Is(err, parseutil.ErrNotAUrl) {
			return fmt.Errorf("Error parsing public cluster addr: %w", err)
		}
	}
	host, port, err := net.SplitHostPort(conf.Controller.PublicClusterAddr)
	if err != nil {
		if strings.Contains(err.Error(), "missing port") {
			port = "9201"
			host = conf.Controller.PublicClusterAddr
		} else {
			return fmt.Errorf("Error splitting public cluster adddress host/port: %w", err)
		}
	}
	conf.Controller.PublicClusterAddr = net.JoinHostPort(host, port)
	return nil
}

func (b *Server) SetupWorkerPublicAddress(conf *config.Config, flagValue string) error {
	if conf.Worker == nil {
		conf.Worker = new(config.Worker)
	}
	if flagValue != "" {
		conf.Worker.PublicAddr = flagValue
	}
	if conf.Worker.PublicAddr == "" {
	FindAddr:
		for _, listener := range conf.Listeners {
			for _, purpose := range listener.Purpose {
				if purpose == "proxy" {
					conf.Worker.PublicAddr = listener.Address
					break FindAddr
				}
			}
		}
	} else {
		var err error
		conf.Worker.PublicAddr, err = parseutil.ParsePath(conf.Worker.PublicAddr)
		if err != nil && !errors.Is(err, parseutil.ErrNotAUrl) {
			return fmt.Errorf("Error parsing public addr: %w", err)
		}
	}
	host, port, err := net.SplitHostPort(conf.Worker.PublicAddr)
	if err != nil {
		if strings.Contains(err.Error(), "missing port") {
			port = "9202"
			host = conf.Worker.PublicAddr
		} else {
			return fmt.Errorf("Error splitting public adddress host/port: %w", err)
		}
	}
	conf.Worker.PublicAddr = net.JoinHostPort(host, port)
	return nil
}

// MakeSighupCh returns a channel that can be used for SIGHUP
// reloading. This channel will send a message for every
// SIGHUP received.
func MakeSighupCh() chan struct{} {
	resultCh := make(chan struct{})

	signalCh := make(chan os.Signal, 4)
	signal.Notify(signalCh, syscall.SIGHUP)
	go func() {
		for {
			<-signalCh
			resultCh <- struct{}{}
		}
	}()
	return resultCh
}

// SetStatusGracePeriodDuration sets the value for
// StatusGracePeriodDuration.
//
// The grace period is the length of time we allow connections to run
// on a worker in the event of an error sending status updates. The
// period is defined the length of time since the last successful
// update.
//
// The setting is derived from one of the following, in order:
//
//   * Via the supplied value if non-zero.
//   * BOUNDARY_STATUS_GRACE_PERIOD, if defined, can be set to an
//   integer value to define the setting.
//   * If either of these is missing, the default is used. See the
//   defaultStatusGracePeriod value for the default value.
//
// The minimum setting for this value is the default setting. Values
// below this will be reset to the default.
func (s *Server) SetStatusGracePeriodDuration(value time.Duration) {
	const op = "base.(Server).SetStatusGracePeriodDuration"
	ctx := context.TODO()
	var result time.Duration
	switch {
	case value > 0:
		result = value
	case os.Getenv(statusGracePeriodEnvVar) != "":
		// TODO: See the description of the constant for more details on
		// this env var
		v := os.Getenv(statusGracePeriodEnvVar)
		n, err := strconv.Atoi(v)
		if err != nil {
			event.WriteError(ctx, op, err, event.WithInfoMsg("could not read status grace period setting", "envvar", statusGracePeriodEnvVar, "value", v))
			break
		}

		result = time.Second * time.Duration(n)
	}

	if result < defaultStatusGracePeriod {
		result = defaultStatusGracePeriod
	}

	s.StatusGracePeriodDuration = result
}