Files
bitchat/bitchat/Views/LocationChannelsSheet.swift
T
d4f0c49787 Gateway mode: opt-in mesh↔Nostr uplink for geohash channels (#1384)
* Add capability bits to announce TLV

Announces now carry an optional capabilities TLV (0x05): a little-endian
bitfield with named bits for upcoming features (prekeys, wifiBulk,
gateway, groups, board, vouch, meshDiagnostics). Old clients skip the
unknown TLV; peers without it decode as nil so features can distinguish
"legacy peer" from "advertises nothing".

PeerCapabilities lives in BitFoundation with a minimal-length encoding
that preserves unknown bits for forward compatibility. Peer capabilities
are stored in the BLE peer registry on verified announce and exposed via
BLEService.peerCapabilities(_:). The local advertisement set is empty
until each feature ships its bit.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Gateway mode: opt-in mesh↔Nostr uplink for geohash channels

An opt-in "internet gateway" toggle lets one connected phone bridge the
local geohash channel for mesh-only peers: signed kind-20000 events ride
a new nostrCarrier (0x28) packet — directed to the gateway for uplink,
broadcast with TTL for downlink — with Schnorr verification at every
hop, CourierStore-style quotas, and explicit loop-prevention rules.

- BitFoundation: MessageType.nostrCarrier = 0x28
- NostrCarrierPacket: 2-byte-length TLV codec (direction, geohash,
  signed event JSON), 16 KiB cap, tolerant decoder
- GatewayService: closure-injected policy layer — verify gates (sig,
  kind, #g tag, age, size), uplink quotas (10/min/depositor rate limit,
  offline queue of 20 total / 5 per depositor, drop-oldest, flush on
  reconnect), downlink budget (30/min, bounded drop-oldest backlog),
  bounded loop-prevention ID sets
- BLEService: runtime capability bits (advertise .gateway only while
  the toggle is on, re-announce on change), signed directed uplink
  sends, carrier ingress with depositor signature verification
- Mesh-only senders uplink automatically from sendGeohash when no relay
  is connected and a reachable peer advertises .gateway; once-per-
  channel "sent via mesh gateway" notice
- UI: gateway toggle beside the Tor toggle, globe header indicator,
  VoiceOver labels, xcstrings entries

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Gateway: harden downlink freshness, uplink verify ordering, and drain

Fixes the confirmed downlink/uplink defects from the PR #1384 review +
Codex findings:

- Downlink age + #g gate (Codex P2 / review #1): rebroadcastRelayEvent
  now drops events outside the same freshness window receivers enforce
  and whose #g tag mismatches the carrier geohash, BEFORE spending any
  budget — so a 1h/200-event channel-resubscribe backfill no longer
  burns the 30/min BLE budget on events every receiver drops.
- Rate-limit + dedup before Schnorr (review #2): handleUplinkDeposit now
  runs cheap structural checks + carried-ID dedup + rate-token consume
  before isValidSignature(), so a replay flood is bounded by cheap work
  instead of unbounded main-actor verifies.
- Quota-dropped deposits not rendered (review #3): enqueueUplink reports
  acceptance and injectInbound only fires for events actually
  published/queued, ending the local-timeline divergence.
- Drain timer + mark-after-send (Codex P2 / review #4): a burst beyond
  budget now arms a timer to drain when the window frees; rebroadcast
  IDs are marked only after an event is actually sent, so overflow-
  dropped events stay retryable.
- Symmetric publish path (review #5): the gateway publish closure now
  refuses when no geo relay is known, matching the local send path
  instead of publishing dead traffic to default relays.
- Loop-rule doc (review #7): softened to reflect that rule 3 is a
  call-site convention with unit-tested backstops; added tests for the
  publishedEventIDs backstop, downlink freshness/mismatch, drain timer,
  and quota-drop non-injection.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Gateway: stop self-echo of uplinked events onto the mesh

Every event a gateway uplinks to the relays comes back through its own
geohash subscription. `rebroadcastRelayEvent` deduped against
`meshBroadcastEventIDs`, `rebroadcastEventIDs`, and `pendingDownlinks`,
but not `publishedEventIDs` — so an event this gateway just published
was downlink-rebroadcast onto the same mesh it originated from, doubling
BLE airtime per uplinked message and able to starve the 30/min downlink
budget on a busy channel (device-confirmed, filed on #1384).

Fix: also skip the downlink rebroadcast when the event id is in
`publishedEventIDs`. That set is already the bounded (drop-oldest,
capacity maxTrackedEventIDs) loop-rule-2 uplink cache, populated only by
`publish()`, so genuine inbound-from-internet events (never published
here) still rebroadcast normally. Reconciles cleanly with the existing
loop-prevention sets — no new state.

Adds a GatewayServiceTests case asserting an uplinked event that echoes
back via the subscription is not rebroadcast, while a genuine inbound
event still is.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: jack <jackjackbits@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
2026-07-07 14:55:17 +02:00

646 lines
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Swift
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import SwiftUI
import CoreLocation
#if os(iOS)
import UIKit
#else
import AppKit
#endif
struct LocationChannelsSheet: View {
@Binding var isPresented: Bool
@EnvironmentObject private var locationChannelsModel: LocationChannelsModel
@EnvironmentObject private var peerListModel: PeerListModel
@ThemedPalette private var palette
@State private var customGeohash: String = ""
@State private var customError: String? = nil
private var backgroundColor: Color { palette.background }
private enum Strings {
static let title: LocalizedStringKey = "location_channels.title"
static let description: LocalizedStringKey = "location_channels.description"
static let requestPermissions: LocalizedStringKey = "location_channels.action.request_permissions"
static let permissionDenied: LocalizedStringKey = "location_channels.permission_denied"
static let openSettings: LocalizedStringKey = "location_channels.action.open_settings"
static let loadingNearby: LocalizedStringKey = "location_channels.loading_nearby"
static let teleport: LocalizedStringKey = "location_channels.action.teleport"
static let bookmarked: LocalizedStringKey = "location_channels.bookmarked_section_title"
static let removeAccess: LocalizedStringKey = "location_channels.action.remove_access"
static let torTitle: LocalizedStringKey = "location_channels.tor.title"
static let torSubtitle: LocalizedStringKey = "location_channels.tor.subtitle"
static let gatewayTitle: LocalizedStringKey = "location_channels.gateway.title"
static let gatewaySubtitle: LocalizedStringKey = "location_channels.gateway.subtitle"
static let toggleOn: LocalizedStringKey = "common.toggle.on"
static let toggleOff: LocalizedStringKey = "common.toggle.off"
static let invalidGeohash = String(localized: "location_channels.error.invalid_geohash", comment: "Error shown when a custom geohash is invalid")
static let switchChannelHint = String(localized: "location_channels.accessibility.switch_hint", comment: "Accessibility hint on a channel row explaining activation switches to it")
static let addBookmark = String(localized: "location_channels.accessibility.add_bookmark", comment: "Accessibility action name for bookmarking a channel")
static let removeBookmark = String(localized: "location_channels.accessibility.remove_bookmark", comment: "Accessibility action name for removing a channel bookmark")
static func meshTitle(_ count: Int) -> String {
let label = String(localized: "location_channels.mesh_label", comment: "Label for the mesh channel row")
return rowTitle(label: label, count: count)
}
static func levelTitle(for level: GeohashChannelLevel, count: Int) -> String {
// High-precision uncertainty: if count is 0 for high-precision levels,
// show "?" because presence broadcasting is disabled for privacy.
let isHighPrecision = (level == .neighborhood || level == .block || level == .building)
if isHighPrecision && count == 0 {
return String(
format: String(localized: "location_channels.row_title_unknown", defaultValue: "%@ [? people]"),
locale: .current,
level.displayName
)
}
return rowTitle(label: level.displayName, count: count)
}
static func bookmarkTitle(geohash: String, count: Int) -> String {
// Check precision for bookmarks too
let len = geohash.count
// Neighborhood=6, Block=7, Building=8+
let isHighPrecision = (len >= 6)
if isHighPrecision && count == 0 {
return String(
format: String(localized: "location_channels.row_title_unknown", defaultValue: "%@ [? people]"),
locale: .current,
"#\(geohash)"
)
}
return rowTitle(label: "#\(geohash)", count: count)
}
static func subtitlePrefix(geohash: String, coverage: String) -> String {
String(
format: String(localized: "location_channels.subtitle_prefix", comment: "Subtitle prefix showing geohash and coverage"),
locale: .current,
geohash, coverage
)
}
static func subtitle(prefix: String, name: String?) -> String {
guard let name, !name.isEmpty else { return prefix }
return String(
format: String(localized: "location_channels.subtitle_with_name", comment: "Subtitle combining prefix and resolved location name"),
locale: .current,
prefix, name
)
}
private static func rowTitle(label: String, count: Int) -> String {
String(
format: String(localized: "location_channels.row_title", comment: "List row title with participant count"),
locale: .current,
label, count
)
}
}
var body: some View {
NavigationView {
VStack(alignment: .leading, spacing: 12) {
HStack(spacing: 12) {
Text(Strings.title)
.bitchatFont(size: 18)
Spacer()
closeButton
}
Text(Strings.description)
.bitchatFont(size: 12)
.foregroundColor(palette.secondary)
Group {
switch locationChannelsModel.permissionState {
case .notDetermined:
Button(action: { locationChannelsModel.enableLocationChannels() }) {
Text(Strings.requestPermissions)
.bitchatFont(size: 12)
.foregroundColor(standardGreen)
.frame(maxWidth: .infinity)
.padding(.vertical, 6)
.background(standardGreen.opacity(0.12))
.cornerRadius(6)
}
.buttonStyle(.plain)
case .denied, .restricted:
VStack(alignment: .leading, spacing: 8) {
Text(Strings.permissionDenied)
.bitchatFont(size: 12)
.foregroundColor(palette.secondary)
Button(Strings.openSettings, action: SystemSettings.location.open)
.buttonStyle(.plain)
}
case .authorized:
EmptyView()
}
}
channelList
Spacer()
}
.padding(.horizontal, 16)
.padding(.vertical, 12)
.themedSurface()
#if os(iOS)
.navigationBarTitleDisplayMode(.inline)
.navigationBarHidden(true)
#else
.navigationTitle("")
#endif
}
#if os(macOS)
.frame(minWidth: 420, minHeight: 520)
#endif
.themedSheetBackground()
.onAppear {
// Refresh channels when opening
if locationChannelsModel.permissionState == .authorized {
locationChannelsModel.refreshChannels()
}
// Begin periodic refresh while sheet is open
locationChannelsModel.beginLiveRefresh()
// Geohash sampling is now managed by ChatViewModel globally
}
.onDisappear {
locationChannelsModel.endLiveRefresh()
}
.onChange(of: locationChannelsModel.permissionState) { newValue in
if newValue == .authorized {
locationChannelsModel.refreshChannels()
}
}
.onChange(of: locationChannelsModel.availableChannels) { _ in }
}
private var closeButton: some View {
SheetCloseButton { isPresented = false }
}
private var channelList: some View {
ScrollView {
LazyVStack(spacing: 0) {
channelRow(title: Strings.meshTitle(peerListModel.reachableMeshPeerCount), subtitlePrefix: Strings.subtitlePrefix(geohash: "bluetooth", coverage: bluetoothRangeString()), isSelected: isMeshSelected, titleColor: standardBlue, titleBold: peerListModel.reachableMeshPeerCount > 0) {
locationChannelsModel.select(ChannelID.mesh)
isPresented = false
}
.padding(.vertical, 6)
let nearby = locationChannelsModel.availableChannels.filter { $0.level != .building }
if !nearby.isEmpty {
ForEach(nearby) { channel in
sectionDivider
let coverage = coverageString(forPrecision: channel.geohash.count)
let nameBase = locationName(for: channel.level)
let namePart = nameBase.map { formattedNamePrefix(for: channel.level) + $0 }
let participantCount = peerListModel.participantCount(for: channel.geohash)
let subtitlePrefix = Strings.subtitlePrefix(geohash: channel.geohash, coverage: coverage)
let highlight = participantCount > 0
channelRow(
title: Strings.levelTitle(for: channel.level, count: participantCount),
subtitlePrefix: subtitlePrefix,
subtitleName: namePart,
isSelected: isSelected(channel),
titleBold: highlight,
trailingAccessory: {
Button(action: { locationChannelsModel.toggleBookmark(channel.geohash) }) {
Image(systemName: locationChannelsModel.isBookmarked(channel.geohash) ? "bookmark.fill" : "bookmark")
.font(.bitchatSystem(size: 14))
}
.buttonStyle(.plain)
.padding(.leading, 8)
.accessibilityLabel(locationChannelsModel.isBookmarked(channel.geohash) ? Strings.removeBookmark : Strings.addBookmark)
},
accessoryActionTitle: locationChannelsModel.isBookmarked(channel.geohash) ? Strings.removeBookmark : Strings.addBookmark,
accessoryAction: { locationChannelsModel.toggleBookmark(channel.geohash) }
) {
locationChannelsModel.markTeleported(for: channel.geohash, false)
locationChannelsModel.select(ChannelID.location(channel))
isPresented = false
}
.padding(.vertical, 6)
}
} else {
sectionDivider
HStack(spacing: 8) {
ProgressView()
Text(Strings.loadingNearby)
.bitchatFont(size: 12)
}
.frame(maxWidth: .infinity, alignment: .leading)
.padding(.vertical, 10)
}
sectionDivider
customTeleportSection
.padding(.vertical, 8)
let bookmarkedList = locationChannelsModel.bookmarks
if !bookmarkedList.isEmpty {
sectionDivider
bookmarkedSection(bookmarkedList)
.padding(.vertical, 8)
}
if locationChannelsModel.permissionState == .authorized {
sectionDivider
torToggleSection
.padding(.top, 12)
gatewayToggleSection
.padding(.top, 8)
Button(action: SystemSettings.location.open) {
Text(Strings.removeAccess)
.bitchatFont(size: 12)
.foregroundColor(palette.alertRed)
.frame(maxWidth: .infinity)
.padding(.vertical, 6)
.background(Color.red.opacity(0.08))
.cornerRadius(6)
}
.buttonStyle(.plain)
.padding(.vertical, 8)
}
}
.frame(maxWidth: .infinity, alignment: .leading)
.padding(.vertical, 6)
.themedSurface()
}
.themedSurface()
}
private var sectionDivider: some View {
Rectangle()
.fill(dividerColor)
.frame(height: 1)
}
private var dividerColor: Color { palette.divider }
private var customTeleportSection: some View {
VStack(alignment: .leading, spacing: 6) {
HStack(spacing: 2) {
Text(verbatim: "#")
.bitchatFont(size: 14)
.foregroundColor(palette.secondary)
TextField("geohash", text: $customGeohash)
#if os(iOS)
.textInputAutocapitalization(.never)
.autocorrectionDisabled(true)
.keyboardType(.asciiCapable)
#endif
.bitchatFont(size: 14)
.onChange(of: customGeohash) { newValue in
let allowed = Set("0123456789bcdefghjkmnpqrstuvwxyz")
let filtered = newValue
.lowercased()
.replacingOccurrences(of: "#", with: "")
.filter { allowed.contains($0) }
if filtered.count > 12 {
customGeohash = String(filtered.prefix(12))
} else if filtered != newValue {
customGeohash = filtered
}
}
let normalized = customGeohash
.trimmed
.lowercased()
.replacingOccurrences(of: "#", with: "")
let isValid = validateGeohash(normalized)
Button(action: {
let gh = normalized
guard isValid else { customError = Strings.invalidGeohash; return }
locationChannelsModel.teleport(to: gh)
isPresented = false
}) {
HStack(spacing: 6) {
Text(Strings.teleport)
.bitchatFont(size: 14)
Image(systemName: "face.dashed")
.font(.bitchatSystem(size: 14))
}
}
.buttonStyle(.plain)
.bitchatFont(size: 14)
.padding(.vertical, 6)
.padding(.horizontal, 10)
.background(palette.secondary.opacity(0.12))
.cornerRadius(6)
.opacity(isValid ? 1.0 : 0.4)
.disabled(!isValid)
}
if let err = customError {
Text(err)
.bitchatFont(size: 12)
.foregroundColor(.red)
}
}
}
private func bookmarkedSection(_ entries: [String]) -> some View {
VStack(alignment: .leading, spacing: 8) {
Text(Strings.bookmarked)
.bitchatFont(size: 12)
.foregroundColor(palette.secondary)
LazyVStack(spacing: 0) {
ForEach(Array(entries.enumerated()), id: \.offset) { index, gh in
let level = levelForLength(gh.count)
let channel = GeohashChannel(level: level, geohash: gh)
let coverage = coverageString(forPrecision: gh.count)
let subtitle = Strings.subtitlePrefix(geohash: gh, coverage: coverage)
let name = locationChannelsModel.bookmarkNames[gh]
let participantCount = peerListModel.participantCount(for: gh)
channelRow(
title: Strings.bookmarkTitle(geohash: gh, count: participantCount),
subtitlePrefix: subtitle,
subtitleName: name.map { formattedNamePrefix(for: level) + $0 },
isSelected: locationChannelsModel.isSelected(channel),
trailingAccessory: {
Button(action: { locationChannelsModel.toggleBookmark(gh) }) {
Image(systemName: locationChannelsModel.isBookmarked(gh) ? "bookmark.fill" : "bookmark")
.font(.bitchatSystem(size: 14))
}
.buttonStyle(.plain)
.padding(.leading, 8)
.accessibilityLabel(locationChannelsModel.isBookmarked(gh) ? Strings.removeBookmark : Strings.addBookmark)
},
accessoryActionTitle: locationChannelsModel.isBookmarked(gh) ? Strings.removeBookmark : Strings.addBookmark,
accessoryAction: { locationChannelsModel.toggleBookmark(gh) }
) {
let inRegional = locationChannelsModel.availableChannels.contains { $0.geohash == gh }
if !inRegional && !locationChannelsModel.availableChannels.isEmpty {
locationChannelsModel.markTeleported(for: gh, true)
} else {
locationChannelsModel.markTeleported(for: gh, false)
}
locationChannelsModel.select(ChannelID.location(channel))
isPresented = false
}
.padding(.vertical, 6)
.onAppear { locationChannelsModel.resolveBookmarkNameIfNeeded(for: gh) }
if index < entries.count - 1 {
sectionDivider
}
}
}
}
}
private func isSelected(_ channel: GeohashChannel) -> Bool {
locationChannelsModel.isSelected(channel)
}
private var isMeshSelected: Bool {
if case .mesh = locationChannelsModel.selectedChannel { return true }
return false
}
@ViewBuilder
private func channelRow(
title: String,
subtitlePrefix: String,
subtitleName: String? = nil,
subtitleNameBold: Bool = false,
isSelected: Bool,
titleColor: Color? = nil,
titleBold: Bool = false,
@ViewBuilder trailingAccessory: () -> some View = { EmptyView() },
accessoryActionTitle: String? = nil,
accessoryAction: (() -> Void)? = nil,
action: @escaping () -> Void
) -> some View {
HStack(alignment: .center, spacing: 8) {
VStack(alignment: .leading) {
// Render title with smaller font for trailing count in parentheses
let parts = splitTitleAndCount(title)
HStack(spacing: 4) {
Text(parts.base)
.bitchatFont(size: 14)
.fontWeight(titleBold ? .bold : .regular)
.foregroundColor(titleColor ?? palette.primary)
if let count = parts.countSuffix, !count.isEmpty {
Text(count)
.bitchatFont(size: 11)
.foregroundColor(palette.secondary)
}
}
let subtitleFull = Strings.subtitle(prefix: subtitlePrefix, name: subtitleName)
Text(subtitleFull)
.bitchatFont(size: 12)
.foregroundColor(palette.secondary)
.lineLimit(1)
.truncationMode(.tail)
}
Spacer()
if isSelected {
Text(verbatim: "✔︎")
.bitchatFont(size: 16)
.foregroundColor(standardGreen)
}
trailingAccessory()
}
.frame(maxWidth: .infinity, alignment: .leading)
.contentShape(Rectangle())
.onTapGesture(perform: action)
// The row is a plain HStack with a tap gesture, which VoiceOver reads
// as disconnected static text. Expose it as one activatable button;
// the visible bookmark accessory is mirrored as a named action.
.accessibilityElement(children: .ignore)
.accessibilityLabel(Text(verbatim: "\(title), \(Strings.subtitle(prefix: subtitlePrefix, name: subtitleName))"))
.accessibilityAddTraits(isSelected ? [.isButton, .isSelected] : [.isButton])
.accessibilityHint(Strings.switchChannelHint)
.accessibilityAction(.default, action)
.accessibilityActions {
if let accessoryActionTitle, let accessoryAction {
Button(accessoryActionTitle, action: accessoryAction)
}
}
}
// Split a title like "#mesh [3 people]" into base and suffix "[3 people]"
private func splitTitleAndCount(_ s: String) -> (base: String, countSuffix: String?) {
guard let idx = s.lastIndex(of: "[") else { return (s, nil) }
let prefix = String(s[..<idx]).trimmed
let suffix = String(s[idx...])
return (prefix, suffix)
}
private func validateGeohash(_ s: String) -> Bool {
let allowed = Set("0123456789bcdefghjkmnpqrstuvwxyz")
guard !s.isEmpty, s.count <= 12 else { return false }
return s.allSatisfy { allowed.contains($0) }
}
private func levelForLength(_ len: Int) -> GeohashChannelLevel {
switch len {
case 0...2: return .region
case 3...4: return .province
case 5: return .city
case 6: return .neighborhood
case 7: return .block
case 8: return .building
default: return .block
}
}
}
// MARK: - TOR Toggle & Standardized Colors
extension LocationChannelsSheet {
private var torToggleBinding: Binding<Bool> {
Binding(
get: { locationChannelsModel.userTorEnabled },
set: { locationChannelsModel.setUserTorEnabled($0) }
)
}
private var torToggleSection: some View {
VStack(alignment: .leading, spacing: 8) {
Toggle(isOn: torToggleBinding) {
VStack(alignment: .leading, spacing: 2) {
Text(Strings.torTitle)
.bitchatFont(size: 12, weight: .semibold)
.foregroundColor(palette.primary)
Text(Strings.torSubtitle)
.bitchatFont(size: 11)
.foregroundColor(palette.secondary)
}
}
.toggleStyle(IRCToggleStyle(accent: palette.accent, onLabel: Strings.toggleOn, offLabel: Strings.toggleOff))
}
.padding(12)
.background(palette.secondary.opacity(0.12))
.cornerRadius(8)
}
private var gatewayToggleBinding: Binding<Bool> {
Binding(
get: { locationChannelsModel.gatewayEnabled },
set: { locationChannelsModel.setGatewayEnabled($0) }
)
}
private var gatewayToggleSection: some View {
VStack(alignment: .leading, spacing: 8) {
Toggle(isOn: gatewayToggleBinding) {
VStack(alignment: .leading, spacing: 2) {
Text(Strings.gatewayTitle)
.bitchatFont(size: 12, weight: .semibold)
.foregroundColor(palette.primary)
Text(Strings.gatewaySubtitle)
.bitchatFont(size: 11)
.foregroundColor(palette.secondary)
}
}
.toggleStyle(IRCToggleStyle(accent: palette.accent, onLabel: Strings.toggleOn, offLabel: Strings.toggleOff))
}
.padding(12)
.background(palette.secondary.opacity(0.12))
.cornerRadius(8)
}
private var standardGreen: Color { palette.primary }
private var standardBlue: Color { palette.accentBlue }
}
private struct IRCToggleStyle: ToggleStyle {
let accent: Color
let onLabel: LocalizedStringKey
let offLabel: LocalizedStringKey
func makeBody(configuration: Configuration) -> some View {
Button(action: { configuration.isOn.toggle() }) {
HStack(spacing: 12) {
configuration.label
Spacer()
Text(configuration.isOn ? onLabel : offLabel)
.textCase(.uppercase)
.bitchatFont(size: 12, weight: .semibold)
.foregroundColor(configuration.isOn ? accent : .secondary)
.padding(.vertical, 4)
.padding(.horizontal, 10)
.background(
RoundedRectangle(cornerRadius: 6)
.fill(accent.opacity(configuration.isOn ? 0.18 : 0.08))
)
.overlay(
RoundedRectangle(cornerRadius: 6)
.stroke(accent.opacity(configuration.isOn ? 0.35 : 0.15), lineWidth: 1)
)
}
}
.buttonStyle(.plain)
}
}
// MARK: - Coverage helpers
extension LocationChannelsSheet {
private func coverageString(forPrecision len: Int) -> String {
// Approximate max cell dimension at equator for a given geohash length.
// Values sourced from common geohash dimension tables.
let maxMeters: Double = {
switch len {
case 2: return 1_250_000
case 3: return 156_000
case 4: return 39_100
case 5: return 4_890
case 6: return 1_220
case 7: return 153
case 8: return 38.2
case 9: return 4.77
case 10: return 1.19
default:
if len <= 1 { return 5_000_000 }
// For >10, scale down conservatively by ~1/4 each char
let over = len - 10
return 1.19 * pow(0.25, Double(over))
}
}()
let usesMetric: Bool = {
if #available(iOS 16.0, macOS 13.0, *) {
return Locale.current.measurementSystem == .metric
} else {
return Locale.current.usesMetricSystem
}
}()
if usesMetric {
let km = maxMeters / 1000.0
return "~\(formatDistance(km)) km"
} else {
let miles = maxMeters / 1609.344
return "~\(formatDistance(miles)) mi"
}
}
private func formatDistance(_ value: Double) -> String {
if value >= 100 { return String(format: "%.0f", value.rounded()) }
if value >= 10 { return String(format: "%.1f", value) }
return String(format: "%.1f", value)
}
private func bluetoothRangeString() -> String {
let usesMetric: Bool = {
if #available(iOS 16.0, macOS 13.0, *) {
return Locale.current.measurementSystem == .metric
} else {
return Locale.current.usesMetricSystem
}
}()
// Approximate Bluetooth LE range for typical mobile devices; environment dependent
return usesMetric ? "~1050 m" : "~30160 ft"
}
private func locationName(for level: GeohashChannelLevel) -> String? {
locationChannelsModel.locationName(for: level)
}
private func formattedNamePrefix(for level: GeohashChannelLevel) -> String {
switch level {
case .region:
return ""
case .building, .block, .neighborhood, .city, .province:
return "~"
}
}
}