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import 'dart:async';
import 'dart:convert';
import 'package:web_socket_channel/web_socket_channel.dart';
import 'package:nostr_tools/nostr_tools.dart';
import 'package:http/http.dart' as http;
import '../../core/logger.dart';
import '../../core/exceptions/nostr_exception.dart';
import 'models/nostr_keypair.dart';
import 'models/nostr_event.dart';
import 'models/nostr_relay.dart';
import 'models/nostr_profile.dart';
/// Service for interacting with Nostr protocol.
///
/// This service provides:
/// - Keypair generation
/// - Event publishing to relays
/// - Metadata synchronization with multiple relays
///
/// The service is modular and UI-independent, designed for testing without real relays.
class NostrService {
/// List of configured relays.
final List<NostrRelay> _relays = [];
/// Active WebSocket connections to relays.
final Map<String, WebSocketChannel?> _connections = {};
/// Stream controllers for relay messages.
final Map<String, StreamController<Map<String, dynamic>>>
_messageControllers = {};
/// Creates a [NostrService] instance.
NostrService();
/// Generates a new Nostr keypair.
///
/// Returns a [NostrKeyPair] with random private and public keys.
NostrKeyPair generateKeyPair() {
return NostrKeyPair.generate();
}
/// Adds a relay to the service.
///
/// [relayUrl] - The WebSocket URL of the relay (e.g., 'wss://relay.example.com').
void addRelay(String relayUrl) {
final relay = NostrRelay.fromUrl(relayUrl);
if (!_relays.contains(relay)) {
_relays.add(relay);
}
}
/// Removes a relay from the service.
///
/// [relayUrl] - The URL of the relay to remove.
void removeRelay(String relayUrl) {
_relays.removeWhere((r) => r.url == relayUrl);
disconnectRelay(relayUrl);
}
/// Enables or disables a relay.
///
/// [relayUrl] - The URL of the relay to enable/disable.
/// [enabled] - Whether the relay should be enabled.
void setRelayEnabled(String relayUrl, bool enabled) {
final relay = _relays.firstWhere(
(r) => r.url == relayUrl,
orElse: () => throw NostrException('Relay not found: $relayUrl'),
);
relay.isEnabled = enabled;
// If disabling, also disconnect
if (!enabled && relay.isConnected) {
disconnectRelay(relayUrl);
}
}
/// Toggles all relays enabled/disabled.
///
/// [enabled] - Whether all relays should be enabled.
void setAllRelaysEnabled(bool enabled) {
for (final relay in _relays) {
relay.isEnabled = enabled;
if (!enabled && relay.isConnected) {
disconnectRelay(relay.url);
}
}
}
/// Gets the list of configured relays.
///
/// Automatically disables any relays that are enabled but not connected,
/// since enabled should always mean connected.
List<NostrRelay> getRelays() {
// Ensure enabled relays are actually connected
// If a relay is enabled but not connected, disable it
for (final relay in _relays) {
if (relay.isEnabled && !relay.isConnected) {
relay.isEnabled = false;
}
}
return List.unmodifiable(_relays);
}
/// Connects to a relay.
///
/// [relayUrl] - The URL of the relay to connect to.
///
/// Returns a [Stream] of messages from the relay.
///
/// Throws [NostrException] if connection fails.
Future<Stream<Map<String, dynamic>>> connectRelay(String relayUrl) async {
try {
// Check if relay is enabled
final relay = _relays.firstWhere(
(r) => r.url == relayUrl,
orElse: () => NostrRelay.fromUrl(relayUrl),
);
if (!relay.isEnabled) {
throw NostrException('Relay is disabled: $relayUrl');
}
if (_connections.containsKey(relayUrl) &&
_connections[relayUrl] != null) {
// Already connected
return _messageControllers[relayUrl]!.stream;
}
// WebSocketChannel.connect can throw synchronously (e.g., host lookup failure)
// But errors can also occur asynchronously in the stream
// Wrap in try-catch to ensure synchronous errors are caught
WebSocketChannel channel;
try {
Logger.info('Creating WebSocket connection to: $relayUrl');
channel = WebSocketChannel.connect(Uri.parse(relayUrl));
Logger.debug('WebSocketChannel created for: $relayUrl');
} catch (e) {
Logger.error('Failed to create WebSocketChannel for: $relayUrl', e);
throw NostrException('Failed to connect to relay: $e');
}
_connections[relayUrl] = channel;
final controller = StreamController<Map<String, dynamic>>.broadcast();
_messageControllers[relayUrl] = controller;
// Mark connection as established after a short delay if no errors occur
// WebSocket connection is established when channel is created successfully
// We'll wait a bit to catch any immediate connection errors
bool connectionConfirmed = false;
bool hasError = false;
// Set up error tracking before listening
Timer? connectionTimer;
connectionTimer = Timer(const Duration(milliseconds: 500), () {
if (!hasError && !connectionConfirmed) {
// No errors occurred, connection is established
connectionConfirmed = true;
relay.isConnected = true;
Logger.info('Connection confirmed for relay: $relayUrl (no errors after 500ms)');
}
});
// Listen for messages
channel.stream.listen(
(message) {
// First message received - connection is confirmed
if (!connectionConfirmed) {
connectionConfirmed = true;
relay.isConnected = true;
Logger.info('Connection confirmed for relay: $relayUrl (first message received)');
connectionTimer?.cancel();
}
try {
final data = jsonDecode(message as String);
if (data is List && data.isNotEmpty) {
final messageType = data[0] as String;
if (messageType == 'EVENT' && data.length >= 3) {
// EVENT format: ["EVENT", <subscription_id>, <event_json>]
// event_json can be either a JSON object or array format
final eventData = data[2];
controller.add({
'type': 'EVENT',
'subscription_id': data[1],
'data': eventData,
});
} else if (messageType == 'EOSE' && data.length >= 2) {
// EOSE format: ["EOSE", <subscription_id>]
controller.add({
'type': 'EOSE',
'subscription_id': data[1],
'data': null,
});
} else {
// Other message types
controller.add({
'type': messageType,
'data': data.length > 1 ? data[1] : null,
});
}
}
} catch (e) {
// Ignore invalid messages
}
},
onError: (error) {
hasError = true;
connectionTimer?.cancel();
Logger.error('WebSocket error for relay: $relayUrl', error);
relay.isConnected = false;
// Automatically disable relay when connection error occurs
relay.isEnabled = false;
Logger.warning('Relay $relayUrl disabled due to connection error');
controller.addError(NostrException('Relay error: $error'));
},
onDone: () {
hasError = true;
connectionTimer?.cancel();
Logger.warning('WebSocket stream closed for relay: $relayUrl');
relay.isConnected = false;
// Automatically disable relay when connection closes
relay.isEnabled = false;
Logger.warning('Relay $relayUrl disabled due to stream closure');
controller.close();
},
);
return controller.stream;
} catch (e) {
throw NostrException('Failed to connect to relay: $e');
}
}
/// Disconnects from a relay.
///
/// [relayUrl] - The URL of the relay to disconnect from.
void disconnectRelay(String relayUrl) {
final channel = _connections[relayUrl];
if (channel != null) {
channel.sink.close();
_connections.remove(relayUrl);
}
final controller = _messageControllers[relayUrl];
if (controller != null) {
controller.close();
_messageControllers.remove(relayUrl);
}
final relay = _relays.firstWhere((r) => r.url == relayUrl,
orElse: () => NostrRelay.fromUrl(relayUrl));
relay.isConnected = false;
}
/// Publishes an event to a relay.
///
/// [event] - The Nostr event to publish.
/// [relayUrl] - The URL of the relay to publish to.
///
/// Returns a [Future] that completes when the event is published.
///
/// Throws [NostrException] if publishing fails.
Future<void> publishEvent(NostrEvent event, String relayUrl) async {
try {
final channel = _connections[relayUrl];
if (channel == null) {
throw NostrException('Not connected to relay: $relayUrl');
}
// Convert to nostr_tools Event and then to JSON
final nostrToolsEvent = event.toNostrToolsEvent();
final eventJson = nostrToolsEvent.toJson();
// Send event in Nostr format: ["EVENT", <event_json>]
final message = jsonEncode(['EVENT', eventJson]);
channel.sink.add(message);
} catch (e) {
throw NostrException('Failed to publish event: $e');
}
}
/// Publishes an event to all enabled relays.
///
/// [event] - The Nostr event to publish.
///
/// Returns a map of relay URLs to success/failure status.
Future<Map<String, bool>> publishEventToAllRelays(NostrEvent event) async {
final results = <String, bool>{};
for (final relay in _relays) {
// Only publish to enabled relays
if (!relay.isEnabled) {
results[relay.url] = false;
continue;
}
// Try to connect if not already connected
if (!relay.isConnected) {
try {
final stream = await connectRelay(relay.url).timeout(
const Duration(seconds: 3),
onTimeout: () {
throw Exception('Connection timeout');
},
);
// Wait for connection to be established or fail
// Listen to the stream to catch connection errors
final completer = Completer<bool>();
late StreamSubscription subscription;
bool gotFirstMessage = false;
subscription = stream.listen(
(data) {
// Connection successful - we received data
gotFirstMessage = true;
if (!completer.isCompleted) {
completer.complete(true);
}
},
onError: (error) {
// Connection failed
if (!completer.isCompleted) {
completer.complete(false);
}
},
onDone: () {
// Stream closed before connection established
if (!completer.isCompleted) {
completer.complete(false);
}
},
);
// Wait for connection to establish (first message) or fail
// Give it a short timeout to see if connection succeeds
final connected = await completer.future.timeout(
const Duration(seconds: 2),
onTimeout: () {
subscription.cancel();
// If we got a first message, connection was established
return gotFirstMessage;
},
);
subscription.cancel();
// Check if relay is actually connected
if (!connected || !relay.isConnected) {
results[relay.url] = false;
continue;
}
} catch (e) {
results[relay.url] = false;
continue;
}
}
// Publish to the relay
try {
await publishEvent(event, relay.url);
results[relay.url] = true;
} catch (e) {
results[relay.url] = false;
}
}
return results;
}
/// Syncs metadata by publishing an event with metadata content.
///
/// [metadata] - The metadata to sync (as a Map).
/// [privateKey] - Private key for signing the event.
/// [kind] - Event kind (default: 0 for metadata).
///
/// Returns the created and published event.
///
/// Throws [NostrException] if sync fails.
Future<NostrEvent> syncMetadata({
required Map<String, dynamic> metadata,
required String privateKey,
int kind = 0,
}) async {
try {
// Create event with metadata as content
final content = jsonEncode(metadata);
final event = NostrEvent.create(
content: content,
kind: kind,
privateKey: privateKey,
);
// Publish to all connected relays
await publishEventToAllRelays(event);
return event;
} catch (e) {
throw NostrException('Failed to sync metadata: $e');
}
}
/// Fetches user profile (kind 0 metadata event) from relays.
///
/// [publicKey] - The public key (hex format) of the user.
/// [timeout] - Timeout for the request (default: 10 seconds).
///
/// Returns [NostrProfile] if found, null otherwise.
///
/// Throws [NostrException] if fetch fails.
Future<NostrProfile?> fetchProfile(String publicKey,
{Duration timeout = const Duration(seconds: 10)}) async {
if (_relays.isEmpty) {
throw NostrException('No relays configured');
}
// Try to fetch from connected relays first
for (final relay in _relays) {
if (relay.isConnected) {
try {
final profile =
await _fetchProfileFromRelay(publicKey, relay.url, timeout);
if (profile != null) {
return profile;
}
} catch (e) {
// Continue to next relay
continue;
}
}
}
// If no connected relays or all failed, try connecting to first relay
if (_relays.isNotEmpty) {
try {
final firstRelay = _relays.first;
if (!firstRelay.isConnected) {
await connectRelay(firstRelay.url).timeout(timeout);
}
return await _fetchProfileFromRelay(publicKey, firstRelay.url, timeout);
} catch (e) {
throw NostrException('Failed to fetch profile: $e');
}
}
return null;
}
/// Fetches profile from a specific relay.
Future<NostrProfile?> _fetchProfileFromRelay(
String publicKey, String relayUrl, Duration timeout) async {
final channel = _connections[relayUrl];
final messageController = _messageControllers[relayUrl];
if (channel == null || messageController == null) {
return null;
}
// Send REQ message to request kind 0 events for this public key
// Nostr REQ format: ["REQ", <subscription_id>, <filters>]
final reqId = 'profile_${DateTime.now().millisecondsSinceEpoch}';
final completer = Completer<NostrProfile?>();
final subscription = messageController.stream.listen(
(message) {
// Message format from connectRelay:
// {'type': 'EVENT', 'subscription_id': <id>, 'data': <event_json>}
// or {'type': 'EOSE', 'subscription_id': <id>, 'data': null}
if (message['type'] == 'EVENT' &&
message['subscription_id'] == reqId &&
message['data'] != null) {
try {
final eventData = message['data'];
Event nostrToolsEvent;
// Handle both JSON object and array formats
if (eventData is Map<String, dynamic>) {
// JSON object format
nostrToolsEvent = Event(
id: eventData['id'] as String? ?? '',
pubkey: eventData['pubkey'] as String? ?? '',
created_at: eventData['created_at'] as int? ?? 0,
kind: eventData['kind'] as int? ?? 0,
tags: (eventData['tags'] as List<dynamic>?)
?.map((tag) => (tag as List<dynamic>)
.map((e) => e.toString())
.toList())
.toList() ??
[],
content: eventData['content'] as String? ?? '',
sig: eventData['sig'] as String? ?? '',
verify: false, // Skip verification for profile fetching
);
} else if (eventData is List && eventData.length >= 7) {
// Array format: [id, pubkey, created_at, kind, tags, content, sig]
nostrToolsEvent = Event(
id: eventData[0] as String? ?? '',
pubkey: eventData[1] as String? ?? '',
created_at: eventData[2] as int? ?? 0,
kind: eventData[3] as int? ?? 0,
tags: (eventData[4] as List<dynamic>?)
?.map((tag) => (tag as List<dynamic>)
.map((e) => e.toString())
.toList())
.toList() ??
[],
content: eventData[5] as String? ?? '',
sig: eventData[6] as String? ?? '',
verify: false, // Skip verification for profile fetching
);
} else {
return; // Invalid format
}
// Convert to our NostrEvent model
final event = NostrEvent.fromNostrToolsEvent(nostrToolsEvent);
// Check if it's a kind 0 (metadata) event for this public key
if (event.kind == 0 &&
event.pubkey.toLowerCase() == publicKey.toLowerCase()) {
final profile = NostrProfile.fromEventContent(
publicKey: publicKey,
content: event.content,
updatedAt:
DateTime.fromMillisecondsSinceEpoch(event.createdAt * 1000),
);
if (!completer.isCompleted) {
completer.complete(profile);
}
}
} catch (e) {
// Ignore parsing errors
Logger.warning('Error parsing profile event: $e');
}
} else if (message['type'] == 'EOSE' &&
message['subscription_id'] == reqId) {
// End of stored events - no profile found
if (!completer.isCompleted) {
completer.complete(null);
}
}
},
onError: (error) {
if (!completer.isCompleted) {
completer.completeError(error);
}
},
);
// Send REQ message to request kind 0 events for this public key
final reqMessage = jsonEncode([
'REQ',
reqId,
{
'authors': [publicKey],
'kinds': [0],
'limit': 1,
}
]);
channel.sink.add(reqMessage);
try {
final profile = await completer.future.timeout(timeout);
subscription.cancel();
return profile;
} catch (e) {
subscription.cancel();
return null;
}
}
/// Queries events from a specific relay.
///
/// [publicKey] - The public key (hex format) to query events for.
/// [relayUrl] - The relay URL to query from.
/// [kinds] - List of event kinds to query (e.g., [30000] for recipes).
/// [timeout] - Timeout for the request (default: 30 seconds).
///
/// Returns a list of [NostrEvent] matching the query.
///
/// Throws [NostrException] if query fails.
Future<List<NostrEvent>> queryEvents(
String publicKey,
String relayUrl,
List<int> kinds, {
Duration timeout = const Duration(seconds: 30),
}) async {
final channel = _connections[relayUrl];
final messageController = _messageControllers[relayUrl];
if (channel == null || messageController == null) {
throw NostrException('Not connected to relay: $relayUrl');
}
final reqId = 'query_${DateTime.now().millisecondsSinceEpoch}';
final completer = Completer<List<NostrEvent>>();
final events = <NostrEvent>[];
final subscription = messageController.stream.listen(
(message) {
if (message['type'] == 'EVENT' &&
message['subscription_id'] == reqId &&
message['data'] != null) {
try {
final eventData = message['data'];
NostrEvent event;
// Parse event (handle both JSON object and array formats)
if (eventData is Map<String, dynamic>) {
event = NostrEvent.fromJson([
eventData['id'] ?? '',
eventData['pubkey'] ?? '',
eventData['created_at'] ?? 0,
eventData['kind'] ?? 0,
eventData['tags'] ?? [],
eventData['content'] ?? '',
eventData['sig'] ?? '',
]);
} else if (eventData is List && eventData.length >= 7) {
event = NostrEvent.fromJson(eventData);
} else {
return; // Skip invalid format
}
// Only process events matching the query
if (kinds.contains(event.kind) &&
event.pubkey.toLowerCase() == publicKey.toLowerCase()) {
events.add(event);
}
} catch (e) {
Logger.warning('Error parsing event: $e');
}
} else if (message['type'] == 'EOSE' &&
message['subscription_id'] == reqId) {
// End of stored events
if (!completer.isCompleted) {
completer.complete(events);
}
}
},
onError: (error) {
if (!completer.isCompleted) {
completer.completeError(error);
}
},
);
// Send REQ message
final reqMessage = jsonEncode([
'REQ',
reqId,
{
'authors': [publicKey],
'kinds': kinds,
'limit': 100,
}
]);
channel.sink.add(reqMessage);
try {
final result = await completer.future.timeout(timeout);
subscription.cancel();
return result;
} catch (e) {
subscription.cancel();
if (events.isNotEmpty) {
// Return what we got before timeout
return events;
}
throw NostrException('Failed to query events: $e');
}
}
/// Fetches preferred relays from a NIP-05 identifier.
///
/// NIP-05 verification endpoint format: https://<domain>/.well-known/nostr.json?name=<local-part>
/// The response can include relay hints in the format:
/// {
/// "names": { "<local-part>": "<hex-pubkey>" },
/// "relays": { "<hex-pubkey>": ["wss://relay1.com", "wss://relay2.com"] }
/// }
///
/// [nip05] - The NIP-05 identifier (e.g., 'user@domain.com').
/// [publicKey] - The public key (hex format) to match against relay hints.
///
/// Returns a list of preferred relay URLs, or empty list if none found.
///
/// Throws [NostrException] if fetch fails.
Future<List<String>> fetchPreferredRelaysFromNip05(
String nip05,
String publicKey,
) async {
try {
// Parse NIP-05 identifier (format: local-part@domain)
final parts = nip05.split('@');
if (parts.length != 2) {
throw NostrException('Invalid NIP-05 format: $nip05');
}
final localPart = parts[0];
final domain = parts[1];
// Construct the verification URL
final url =
Uri.https(domain, '/.well-known/nostr.json', {'name': localPart});
// Fetch the NIP-05 verification data
final response = await http.get(url).timeout(
const Duration(seconds: 10),
onTimeout: () {
throw NostrException('Timeout fetching NIP-05 data');
},
);
if (response.statusCode != 200) {
throw NostrException(
'Failed to fetch NIP-05 data: ${response.statusCode}');
}
// Parse the JSON response
final data = jsonDecode(response.body) as Map<String, dynamic>;
// Extract relay hints for the public key
final relays = data['relays'] as Map<String, dynamic>?;
if (relays == null) {
return [];
}
// Find relays for the matching public key (case-insensitive)
final publicKeyLower = publicKey.toLowerCase();
for (final entry in relays.entries) {
final keyLower = entry.key.toLowerCase();
if (keyLower == publicKeyLower) {
final relayList = entry.value;
if (relayList is List) {
return relayList
.map((r) => r.toString())
.where((r) => r.isNotEmpty)
.toList();
}
}
}
return [];
} catch (e) {
if (e is NostrException) {
rethrow;
}
throw NostrException('Failed to fetch preferred relays from NIP-05: $e');
}
}
/// Loads preferred relays from NIP-05 if available and adds them to the relay list.
///
/// [nip05] - The NIP-05 identifier (e.g., 'user@domain.com').
/// [publicKey] - The public key (hex format) to match against relay hints.
///
/// Returns the number of relays added.
///
/// Throws [NostrException] if fetch fails.
Future<int> loadPreferredRelaysFromNip05(
String nip05,
String publicKey,
) async {
try {
final preferredRelays =
await fetchPreferredRelaysFromNip05(nip05, publicKey);
int addedCount = 0;
for (final relayUrl in preferredRelays) {
try {
addRelay(relayUrl);
addedCount++;
} catch (e) {
// Skip invalid relay URLs
Logger.warning('Invalid relay URL from NIP-05: $relayUrl');
}
}
return addedCount;
} catch (e) {
if (e is NostrException) {
rethrow;
}
throw NostrException('Failed to load preferred relays from NIP-05: $e');
}
}
/// Replaces all existing relays with preferred relays from NIP-05.
///
/// This will:
/// 1. Disconnect and remove all current relays
/// 2. Fetch preferred relays from NIP-05
/// 3. Add the preferred relays
/// 4. Automatically enable and connect to the relays
///
/// [nip05] - The NIP-05 identifier (e.g., 'user@domain.com').
/// [publicKey] - The public key (hex format) to match against relay hints.
///
/// Returns the number of preferred relays added.
///
/// Throws [NostrException] if fetch fails.
Future<int> replaceRelaysWithPreferredFromNip05(
String nip05,
String publicKey,
) async {
try {
// Disconnect and remove all existing relays
final existingRelays = List<String>.from(_relays.map((r) => r.url));
for (final relayUrl in existingRelays) {
try {
disconnectRelay(relayUrl);
removeRelay(relayUrl);
} catch (e) {
// Continue even if disconnect fails
Logger.warning('Failed to disconnect relay $relayUrl: $e');
}
}
// Fetch preferred relays
final preferredRelays =
await fetchPreferredRelaysFromNip05(nip05, publicKey);
// Add preferred relays and enable them
int addedCount = 0;
final addedRelayUrls = <String>[];
for (final relayUrl in preferredRelays) {
try {
addRelay(relayUrl);
setRelayEnabled(relayUrl, true);
addedRelayUrls.add(relayUrl);
addedCount++;
} catch (e) {
// Skip invalid relay URLs
Logger.warning('Invalid relay URL from NIP-05: $relayUrl');
}
}
// Attempt to connect to all added relays in parallel
// Connections happen in the background - if they fail, relays will be auto-disabled
for (final relayUrl in addedRelayUrls) {
try {
// Connect in background - don't wait for it
connectRelay(relayUrl).then((stream) {
// Connection successful - stream will be handled by existing connection logic
Logger.info('Successfully connected to NIP-05 relay: $relayUrl');
}).catchError((error) {
// Connection failed - relay will be auto-disabled by getRelays() logic
Logger.warning('Failed to connect to NIP-05 relay: $relayUrl - $error');
try {
setRelayEnabled(relayUrl, false);
} catch (_) {
// Ignore errors
}
});
} catch (e) {
// Connection attempt failed - disable the relay
Logger.warning('Failed to connect to NIP-05 relay: $relayUrl - $e');
try {
setRelayEnabled(relayUrl, false);
} catch (_) {
// Ignore errors
}
}
}
Logger.info('Replaced ${existingRelays.length} relay(s) with $addedCount preferred relay(s) from NIP-05: $nip05 (all enabled and connecting)');
return addedCount;
} catch (e) {
if (e is NostrException) {
rethrow;
}
throw NostrException('Failed to replace relays with preferred from NIP-05: $e');
}
}
/// Closes all connections and cleans up resources.
void dispose() {
for (final relayUrl in _connections.keys.toList()) {
disconnectRelay(relayUrl);
}
_relays.clear();
}
}

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