package edge

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"math/rand/v2"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"github.com/carlosframework/platform/internal/geo"
	"github.com/carlosframework/platform/internal/geoip"
	"github.com/carlosframework/platform/internal/release"
)

// The GeoIP mirror (geoip spec §5): poll control/geoip/current.json, fetch
// the content-addressed blob it names into an immutable local generation,
// and hot-swap the edge's reader. genMu serialises everything that chooses,
// expires or deletes a generation (codex R3-1); network I/O stays outside it.

var (
	// geoPointerReadTimeout bounds every pointer read on its own, so a
	// slow store cannot stretch the off bound past interval+jitter+this
	// (codex R9 on R8-2).
	geoPointerReadTimeout = 30 * time.Second
	geoMirrorInterval     = 10 * time.Minute
	geoMirrorJitter       = time.Minute
	geoMirrorDeadline     = 10 * time.Minute
	geoExpiryInterval     = time.Minute
)

// geoCurrent is the shared local format (geoip.LocalCurrent), so the
// console's follower reads exactly what this mirror writes.
type geoCurrent = geoip.LocalCurrent

type geoMirror struct {
	store    release.Store
	dir      string
	sw       *geo.Swappable
	now      func() time.Time
	maxBytes int64

	genMu       sync.Mutex
	loadedSHA   string
	loadedType  string
	loadedBuild time.Time
	skipSHA     map[string]string     // sha -> why (rejected | expired); cleared whenever the observed pointer changes
	pointerSHA  string                // the sha the last readable pointer named; "" for none
	syncPending bool                  // the last `current` rename is not known durable
	unsynced    map[string]geoCurrent // every generation a crash could bring back while syncPending; kept until a sync succeeds or it expires

	// The alert's inputs (geoip spec §10.4). The pointer's metadata is
	// kept after the reader is dropped, so an expired pointer still reads
	// as expired by the clock before the console marks it (codex R11-1).
	pointerPresent bool
	pointerType    string
	pointerBuild   time.Time
	pointerMarked  bool
	wantSince      time.Time // a live pointer has named a sha not loaded here since then
	feedFailing    bool
	feedBox        string
	// pointerKnown and feedKnown are false until a read has succeeded or
	// confirmed absence: until then the alert's reading is unknown (nil),
	// so a restart cannot clear an alert the last process raised (code
	// review R4-2).
	pointerKnown bool
	feedKnown    bool
	lastErr      string // last poll's error category, "" when healthy
	failingAt    time.Time
	lastFailLog  time.Time
}

func newGeoMirror(store release.Store, dir string, sw *geo.Swappable) *geoMirror {
	return &geoMirror{store: store, dir: dir, sw: sw, now: time.Now, maxBytes: geoip.MaxBlobBytes, skipSHA: map[string]string{}}
}

// GeoIPState is the heartbeat's view of this edge's GeoIP (spec §5.5).
type GeoIPState struct {
	Mode   string `json:"mode"` // mirror | tunnel | none
	SHA256 string `json:"sha256,omitempty"`
	Type   string `json:"type,omitempty"`
	Error  string `json:"error,omitempty"`
}

func (m *geoMirror) State() GeoIPState {
	m.genMu.Lock()
	defer m.genMu.Unlock()
	return GeoIPState{Mode: "mirror", SHA256: m.loadedSHA, Type: m.loadedType, Error: m.lastErr}
}

func (m *geoMirror) path(sha string) string { return filepath.Join(m.dir, sha+".mmdb") }

// Boot installs the local generation `current` names, if any, without
// touching the bucket, and clears everything else (spec §5.3 "At boot").
func (m *geoMirror) Boot() {
	if err := os.MkdirAll(m.dir, 0o755); err != nil {
		log.Printf("edge: geoip directory unusable; GeoIP stays off until it is: %v", err)
		return
	}
	os.Chmod(m.dir, 0o755)
	m.genMu.Lock()
	defer m.genMu.Unlock()
	cur, err := m.readCurrent()
	keep := ""
	switch {
	case err != nil && !errors.Is(err, os.ErrNotExist):
		log.Printf("edge: geoip local state unreadable; starting with no database")
		os.Remove(filepath.Join(m.dir, "current"))
	case cur.SHA256 == "":
	case geoip.Expired(cur.DatabaseType, time.Unix(cur.BuildEpoch, 0), m.now()):
		log.Printf("edge: geoip database %s expired (GeoLite2, 30 days after build) and was removed", short(cur.SHA256))
		m.writeCurrentLocked(geoCurrent{})
	default:
		db, err := geo.OpenMMDBTrusted(m.path(cur.SHA256))
		if err != nil {
			log.Printf("edge: geoip local generation %s unopenable; starting with no database", short(cur.SHA256))
			os.Remove(filepath.Join(m.dir, "current"))
			break
		}
		m.sw.Swap(db)
		m.loadedSHA, m.loadedType, m.loadedBuild = cur.SHA256, db.Source(), db.BuildEpoch()
		keep = cur.SHA256
		log.Printf("edge: geoip database %s (%s, built %s) loaded", short(cur.SHA256), db.Source(), db.BuildEpoch().Format("2006-01-02"))
	}
	m.cleanLocked(keep, true)
}

func short(sha string) string {
	if len(sha) > 8 {
		return sha[:8]
	}
	return sha
}

func (m *geoMirror) readCurrent() (geoCurrent, error) {
	var c geoCurrent
	b, err := os.ReadFile(filepath.Join(m.dir, geoip.LocalCurrentFile))
	if err != nil {
		return c, err
	}
	return geoip.ParseLocalCurrent(b)
}

// writeCurrentLocked replaces `current` atomically: temp, fsync, rename,
// fsync the directory (spec §5.2).
func (m *geoMirror) writeCurrentLocked(c geoCurrent) error {
	b, _ := json.Marshal(c)
	tmp, err := os.CreateTemp(m.dir, ".current-*")
	if err != nil {
		return err
	}
	defer os.Remove(tmp.Name())
	if _, err := tmp.Write(b); err != nil {
		tmp.Close()
		return err
	}
	if err := tmp.Sync(); err != nil {
		tmp.Close()
		return err
	}
	if err := tmp.Close(); err != nil {
		return err
	}
	if err := os.Chmod(tmp.Name(), 0o644); err != nil {
		return err
	}
	if err := os.Rename(tmp.Name(), filepath.Join(m.dir, "current")); err != nil {
		return err
	}
	// After the rename `current` already names the new generation, so a
	// failed directory fsync must not make the caller delete it (plan review
	// R1-4): it is logged, and the rename stands. But the rename is not
	// durable either: a crash could bring back the PREVIOUS `current`, so
	// m.syncPending tells install to keep the previous generation too until
	// a later write is durable (code review R1-4).
	if err := syncDirFn(m.dir); err != nil {
		log.Printf("edge: geoip directory sync failed after selecting a generation; keeping the earlier ones until it succeeds")
		m.syncPending = true
		return nil
	}
	m.syncPending, m.unsynced = false, nil
	return nil
}

// syncDirFn is syncDir, a variable so a test can inject a failure.
var syncDirFn = syncDir

func syncDir(dir string) error {
	d, err := os.Open(dir)
	if err != nil {
		return err
	}
	defer d.Close()
	return d.Sync()
}

// cleanLocked deletes every generation but keep and every stray
// .current-*. Downloads (.incoming-*) are deleted only at boot: at any other
// time one may be in progress outside genMu, and unlinking it would break
// a replacement that an expiry tick happened to race (plan review R1-3).
func (m *geoMirror) cleanLocked(keep string, atBoot bool) {
	m.cleanLockedKeeping(atBoot, keep)
}

// cleanLockedKeeping is cleanLocked with any number of generations kept.
func (m *geoMirror) cleanLockedKeeping(atBoot bool, keep ...string) {
	kept := map[string]bool{}
	for _, k := range keep {
		if k != "" {
			kept[k+".mmdb"] = true
		}
	}
	entries, _ := os.ReadDir(m.dir)
	for _, e := range entries {
		n := e.Name()
		if n == "current" || kept[n] {
			continue
		}
		if strings.HasSuffix(n, ".mmdb") || strings.HasPrefix(n, ".current-") || (atBoot && strings.HasPrefix(n, ".incoming-")) {
			os.Remove(filepath.Join(m.dir, n))
		}
	}
}

// clearLocked turns GeoIP off on this box: empty current, nil reader, no
// generations.
func (m *geoMirror) clearLocked() {
	if err := m.writeCurrentLocked(geoCurrent{}); err != nil {
		os.Remove(filepath.Join(m.dir, "current"))
	}
	m.sw.Swap(nil)
	m.loadedSHA, m.loadedType, m.loadedBuild = "", "", time.Time{}
	m.cleanLocked("", false)
}

// Poll is one pass (spec §5.3). The caller bounds ctx by geoMirrorDeadline.
func (m *geoMirror) Poll(ctx context.Context) error { return m.poll(ctx, true) }

// poll is one pass; recheck allows ONE immediate re-run when a finished
// download turns out to be superseded, so an `off` or a newer publish that
// landed during a long download takes effect now, not a whole interval later
// (codex R8-2).
func (m *geoMirror) poll(ctx context.Context, recheck bool) error {
	// The control-plane state (feed, pointer) is read whatever the local
	// directory's health, so the alert sees a published database this box
	// cannot install (code review R2-4).
	m.readFeedStatus(ctx)
	raw, err := m.readPointer(ctx)
	var p geoip.Pointer
	if err == nil {
		p, err = geoip.ParsePointer(raw)
	}
	if errors.Is(err, os.ErrNotExist) || errors.Is(err, geoip.ErrUnknownVersion) {
		// No pointer, or one this binary cannot read: GeoIP is off on this
		// box (spec §3), never "keep what is loaded" (plan review R1-7).
		m.genMu.Lock()
		if m.loadedSHA != "" {
			if errors.Is(err, geoip.ErrUnknownVersion) {
				log.Printf("edge: geoip turned off; the published pointer has a version this binary cannot read")
			} else {
				log.Printf("edge: geoip turned off; no database published")
			}
		}
		m.pointerSHA, m.skipSHA = "", map[string]string{}
		m.pointerPresent, m.pointerType, m.pointerBuild, m.pointerMarked, m.wantSince = false, "", time.Time{}, false, time.Time{}
		m.pointerKnown = true
		m.clearLocked()
		m.lastErr = ""
		m.genMu.Unlock()
		return nil
	}
	if raw == nil && err != nil {
		return m.fail("pointer unreadable", err)
	}
	if err != nil {
		return m.fail("pointer invalid", err)
	}
	m.genMu.Lock()
	m.pointerPresent, m.pointerType, m.pointerBuild, m.pointerMarked = true, p.DatabaseType, p.Build(), p.Expired
	m.pointerKnown = true
	switch {
	case p.Expired || geoip.Expired(p.DatabaseType, p.Build(), m.now()):
		m.wantSince = time.Time{}
	case p.SHA256 == m.loadedSHA:
		m.wantSince = time.Time{}
	case m.wantSince.IsZero():
		m.wantSince = m.now()
	}
	if p.SHA256 != m.pointerSHA {
		// The pointer moved (to anything, including back to an sha seen
		// before): every earlier rejection is void (plan review R1-8).
		m.pointerSHA, m.skipSHA = p.SHA256, map[string]string{}
	}
	if p.Expired || geoip.Expired(p.DatabaseType, p.Build(), m.now()) {
		if m.skipSHA[p.SHA256] != "expired" {
			log.Printf("edge: geoip database %s expired (GeoLite2, 30 days after build) and was removed", short(p.SHA256))
		}
		m.skipSHA[p.SHA256] = "expired"
		m.clearLocked()
		m.lastErr = ""
		m.genMu.Unlock()
		return nil
	}
	if p.SHA256 == m.loadedSHA {
		m.lastErr = ""
		if m.syncPending {
			// The selection was never made durable: retry the sync, and once
			// it lands the retained recovery copies can go (code review
			// R10-2).
			if err := syncDirFn(m.dir); err == nil {
				m.syncPending, m.unsynced = false, nil
				m.cleanLocked(m.loadedSHA, false)
			}
		}
		m.genMu.Unlock()
		return nil
	}
	if _, skip := m.skipSHA[p.SHA256]; skip {
		m.genMu.Unlock()
		return nil
	}
	m.genMu.Unlock()

	if err := os.MkdirAll(m.dir, 0o755); err != nil {
		return m.fail("local directory unusable", err)
	}
	tmp, err := m.download(ctx, p)
	if err == nil && !m.pointerStillNames(ctx, p.SHA256) {
		os.Remove(tmp)
		if recheck {
			return m.poll(ctx, false)
		}
		return nil
	}
	if err != nil {
		if errors.Is(err, errGeoDigest) || errors.Is(err, errGeoSize) {
			m.genMu.Lock()
			m.skipSHA[p.SHA256] = "rejected"
			m.genMu.Unlock()
			log.Printf("edge: geoip blob %s rejected: %v", short(p.SHA256), err)
		}
		return m.fail("blob unavailable", err)
	}
	return m.install(tmp, p)
}

// downloadHook is a test seam: called after .incoming is created, before
// the body is copied, so a test can run an expiry tick mid-download.
var downloadHook func()

// pointerStillNames re-reads the pointer after a download: only a
// candidate the pointer still selects (unexpired) may be installed. A read
// failure answers false, which defers the install to the next pass rather
// than installing something nobody has confirmed is still wanted.
func (m *geoMirror) pointerStillNames(ctx context.Context, sha string) bool {
	raw, err := m.readPointer(ctx)
	if err != nil {
		return false
	}
	p, err := geoip.ParsePointer(raw)
	return err == nil && p.SHA256 == sha && !p.Expired && !geoip.Expired(p.DatabaseType, p.Build(), m.now())
}

var (
	errGeoDigest = errors.New("digest mismatch")
	errGeoSize   = errors.New("size mismatch")
)

// download streams the blob to .incoming-<sha>, checks size and digest,
// fsyncs, and returns its path. Outside genMu.
func (m *geoMirror) download(ctx context.Context, p geoip.Pointer) (string, error) {
	rc, _, err := release.OpenObject(ctx, m.store, p.Key)
	if err != nil {
		return "", err
	}
	defer rc.Close()
	tmp := filepath.Join(m.dir, ".incoming-"+p.SHA256)
	f, err := os.OpenFile(tmp, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0o644)
	if err != nil {
		return "", err
	}
	limit := p.Size
	if m.maxBytes < limit {
		limit = m.maxBytes
	}
	if downloadHook != nil {
		downloadHook()
	}
	h := sha256.New()
	n, err := io.Copy(io.MultiWriter(f, h), io.LimitReader(rc, limit+1))
	if err == nil {
		err = f.Sync()
	}
	if cerr := f.Close(); err == nil {
		err = cerr
	}
	switch {
	case err != nil:
		os.Remove(tmp)
		return "", err
	case n > limit || n != p.Size:
		// n > limit: the blob ran past the cap (the box's maxBytes may be
		// below what the pointer claims), however the counts compare.
		os.Remove(tmp)
		return "", errGeoSize
	case hex.EncodeToString(h.Sum(nil)) != p.SHA256:
		os.Remove(tmp)
		return "", errGeoDigest
	}
	return tmp, nil
}

// install commits a verified download under genMu (spec §5.3 steps 3-5),
// re-checking expiry against the file's own metadata first.
func (m *geoMirror) install(tmp string, p geoip.Pointer) error {
	m.genMu.Lock()
	defer m.genMu.Unlock()
	final := m.path(p.SHA256)
	if err := os.Rename(tmp, final); err != nil {
		os.Remove(tmp)
		return m.failLocked("install failed", err)
	}
	syncDir(m.dir)
	db, err := geo.OpenMMDBTrusted(final)
	if err != nil {
		m.removeGenerationLocked(p.SHA256)
		m.skipSHA[p.SHA256] = "rejected"
		log.Printf("edge: geoip blob %s rejected: unopenable", short(p.SHA256))
		return m.failLocked("blob unopenable", err)
	}
	if geoip.Expired(db.Source(), db.BuildEpoch(), m.now()) {
		db.Close()
		m.removeGenerationLocked(p.SHA256)
		m.skipSHA[p.SHA256] = "expired"
		log.Printf("edge: geoip database %s expired (GeoLite2, 30 days after build) and was removed", short(p.SHA256))
		return nil
	}
	if err := m.writeCurrentLocked(geoCurrent{SHA256: p.SHA256, DatabaseType: db.Source(), BuildEpoch: db.BuildEpoch().Unix()}); err != nil {
		db.Close()
		m.removeGenerationLocked(p.SHA256)
		return m.failLocked("install failed", err)
	}
	prev := geoCurrent{SHA256: m.loadedSHA, DatabaseType: m.loadedType, BuildEpoch: m.loadedBuild.Unix()}
	m.sw.Swap(db)
	m.loadedSHA, m.loadedType, m.loadedBuild = p.SHA256, db.Source(), db.BuildEpoch()
	if m.syncPending {
		// Until a sync succeeds, any `current` since the last durable one
		// could come back after a crash: keep every one of them (code
		// review R2 on R1-4).
		if m.unsynced == nil {
			m.unsynced = map[string]geoCurrent{}
		}
		if prev.SHA256 != "" {
			m.unsynced[prev.SHA256] = prev
		}
		keep := []string{p.SHA256}
		for sha := range m.unsynced {
			keep = append(keep, sha)
		}
		m.cleanLockedKeeping(false, keep...)
	} else {
		m.cleanLocked(p.SHA256, false)
	}
	m.lastErr, m.failingAt, m.wantSince = "", time.Time{}, time.Time{}
	log.Printf("edge: geoip database %s (%s, built %s) loaded", short(p.SHA256), db.Source(), db.BuildEpoch().Format("2006-01-02"))
	return nil
}

// removeGenerationLocked deletes a failed install's file unless the same
// generation is one a crash could bring back (loaded, or kept while syncs
// fail): republishing a retained A must never delete A on an error path
// (code review R3 on R1-4).
func (m *geoMirror) removeGenerationLocked(sha string) {
	if _, retained := m.unsynced[sha]; sha == m.loadedSHA || retained {
		return
	}
	os.Remove(m.path(sha))
}

// ExpireTick is D1 on the loaded generation, under genMu, so it can only
// ever remove the generation that is current at that moment (codex R3-1).
func (m *geoMirror) ExpireTick() {
	m.genMu.Lock()
	defer m.genMu.Unlock()
	// Retained recovery copies obey D1 too (code review R10-2): an expired
	// GeoLite2 kept only in case a crash brings it back is destroyed.
	for sha, g := range m.unsynced {
		if geoip.Expired(g.DatabaseType, time.Unix(g.BuildEpoch, 0), m.now()) {
			os.Remove(m.path(sha))
			delete(m.unsynced, sha)
		}
	}
	if m.loadedSHA == "" || !geoip.Expired(m.loadedType, m.loadedBuild, m.now()) {
		return
	}
	log.Printf("edge: geoip database %s expired (GeoLite2, 30 days after build) and was removed", short(m.loadedSHA))
	m.skipSHA[m.loadedSHA] = "expired"
	m.clearLocked()
}

func (m *geoMirror) fail(category string, err error) error {
	m.genMu.Lock()
	defer m.genMu.Unlock()
	return m.failLocked(category, err)
}

// failLocked records the category for the heartbeat and logs at most hourly
// while failing. The error text is never logged: it may carry a key or
// bytes; the category is the message (spec §12).
func (m *geoMirror) failLocked(category string, err error) error {
	now := m.now()
	if m.lastErr == "" {
		m.failingAt = now
	}
	m.lastErr = category
	if now.Sub(m.lastFailLog) >= time.Hour {
		m.lastFailLog = now
		log.Printf("edge: geoip %s; keeping the loaded database", category)
	}
	return fmt.Errorf("%s: %w", category, err)
}

// readFeedStatus refreshes the feed reason's inputs, best effort: a
// missing or unreadable feed.json means no feed reason.
func (m *geoMirror) readFeedStatus(ctx context.Context) {
	ctx, cancel := context.WithTimeout(ctx, geoPointerReadTimeout)
	defer cancel()
	raw, err := readCapped(ctx, m.store, geoip.FeedKey, geoip.MaxPointerBytes)
	if errors.Is(err, os.ErrNotExist) {
		m.genMu.Lock()
		m.feedFailing, m.feedBox, m.feedKnown = false, "", true // no feed: confirmed
		m.genMu.Unlock()
		return
	}
	if err != nil {
		return // keep the last known state: a blip must not clear a firing alert (code review R2-3)
	}
	st, err := geoip.ParseFeedStatus(raw)
	if err != nil {
		return
	}
	m.genMu.Lock()
	m.feedFailing, m.feedBox, m.feedKnown = st.Failing(), st.Box, true
	m.genMu.Unlock()
}

// Alert reason codes (geoip spec §10.4), the geoip rule's reading.
const (
	GeoAlertNone      = 0
	GeoAlertStale     = 1 // the loaded database is over 45 days old
	GeoAlertExpiring  = 2 // a GeoLite2 database within 9 days of D1
	GeoAlertExpired   = 3 // the pointer is expired, marked or by the clock
	GeoAlertNotLoaded = 4 // a live pointer not loaded here for over an hour
	GeoAlertFeed      = 5 // the feed has failed 7 times in a row (the console's box only)
)

// AlertCode is the geoip rule's reading for this box: the most severe
// reason that holds (3, 4, 2, 1, then 5), or 0. known=false until both the
// pointer and the feed status have been read (or confirmed absent) once.
func (m *geoMirror) AlertCode(now time.Time, box string) (code float64, known bool) {
	m.genMu.Lock()
	defer m.genMu.Unlock()
	// A reason established from what IS known is reported even when the
	// other input is not (code review R5-1): an unreadable feed.json must
	// not hide a confirmed expiry. Only "healthy" needs everything known.
	if c := m.alertCodeLocked(now, box); c != GeoAlertNone {
		return c, true
	}
	if !m.pointerKnown || !m.feedKnown {
		return GeoAlertNone, false
	}
	return GeoAlertNone, true
}

func (m *geoMirror) alertCodeLocked(now time.Time, box string) float64 {
	// pointerPresent is only ever true after a successful read, and
	// feedFailing only after a parsed feed.json, so each reason below rests
	// on state that was actually read.
	expired := m.pointerPresent && (m.pointerMarked || geoip.Expired(m.pointerType, m.pointerBuild, now))
	switch {
	case expired:
		return GeoAlertExpired
	case m.pointerPresent && !m.wantSince.IsZero() && now.Sub(m.wantSince) > time.Hour:
		return GeoAlertNotLoaded
	case m.loadedSHA != "" && strings.HasPrefix(m.loadedType, "GeoLite2-") && now.Sub(m.loadedBuild) >= geoip.GeoLiteWarn:
		return GeoAlertExpiring
	case m.loadedSHA != "" && now.Sub(m.loadedBuild) > geoip.StaleAfter:
		return GeoAlertStale
	case m.feedFailing && box != "" && m.feedBox == box:
		return GeoAlertFeed
	}
	return GeoAlertNone
}

// readPointer is one bounded pointer read.
func (m *geoMirror) readPointer(ctx context.Context) ([]byte, error) {
	ctx, cancel := context.WithTimeout(ctx, geoPointerReadTimeout)
	defer cancel()
	return readCapped(ctx, m.store, geoip.PointerKey, geoip.MaxPointerBytes)
}

// readCapped reads key through OpenObject, refusing more than max bytes.
func readCapped(ctx context.Context, s release.Store, key string, max int) ([]byte, error) {
	rc, _, err := release.OpenObject(ctx, s, key)
	if err != nil {
		return nil, err
	}
	defer rc.Close()
	b, err := io.ReadAll(io.LimitReader(rc, int64(max)+1))
	if err != nil {
		return nil, err
	}
	if len(b) > max {
		return nil, fmt.Errorf("%s larger than %d bytes", key, max)
	}
	return b, nil
}

// run is the process-lifetime loop: a poll every interval+jitter, each
// bounded by geoMirrorDeadline, and an independent expiry ticker that never
// touches the network.
func (m *geoMirror) run(stop <-chan struct{}) {
	go func() {
		t := time.NewTicker(geoExpiryInterval)
		defer t.Stop()
		for {
			select {
			case <-stop:
				return
			case <-t.C:
				m.ExpireTick()
			}
		}
	}()
	for {
		// The next pass is due interval+jitter after this one STARTED, not
		// after it finished: a pass is bounded by geoMirrorDeadline (10 min),
		// so a change to the pointer is seen within interval+jitter (11 min)
		// even when a long download was in flight (codex R8-2).
		next := time.Now().Add(geoMirrorInterval + rand.N(geoMirrorJitter))
		ctx, cancel := context.WithTimeout(context.Background(), geoMirrorDeadline)
		m.Poll(ctx)
		cancel()
		select {
		case <-stop:
			return
		case <-time.After(time.Until(next)):
		}
	}
}

// WithGeoTunnelClient marks this edge as a tunnel client's: it never mirrors
// the GeoIP database and takes the hub's answer instead (spec §5.1).
func WithGeoTunnelClient() RunOption { return func(e *Edge) { e.geoTunnelClient = true } }

// GeoIPState is the heartbeat block (spec §5.5).
func (e *Edge) GeoIPState() GeoIPState {
	if e.geoMirror != nil {
		return e.geoMirror.State()
	}
	if e.geoMode == "" {
		return GeoIPState{Mode: "none"}
	}
	return GeoIPState{Mode: e.geoMode}
}

// GeoIPAlertCode is the geoip rule's reading for this box (spec §10.4);
// 0 on an edge with no mirror. known=false means "no reading yet".
func (e *Edge) GeoIPAlertCode(now time.Time) (float64, bool) {
	if e.geoMirror == nil {
		return GeoAlertNone, true
	}
	return e.geoMirror.AlertCode(now, e.box)
}