feat: Add graceful degradation for relays; Closes #95 and #96

Author: Myzel394

lib/api/nostr-relays.dart

@@ -1,13 +1,112 @@
 import 'dart:convert';
 
+import 'package:flutter_logs/flutter_logs.dart';
 import "package:http/http.dart" as http;
 import 'package:locus/constants/apis.dart';
 import 'package:locus/constants/values.dart';
 
-Future<Map<String, dynamic>> getNostrRelays() async {
-  final response = await http.get(Uri.parse(NOSTR_LIST_URI)).timeout(HTTP_TIMEOUT);
+final RELAY_FETCHER_FUNCTIONS = [
+  NostrWatchAPI.getPublicNostrRelays,
+  NostrBandAPI.getTrendingProfiles,
+  NostrWatchAPI.getAllNostrRelays,
+      () => Future.value(FALLBACK_RELAYS),
+];
+
+// Tries each of the fallback relays until one works
+Future<Map<String, List<String>>> getNostrRelays() async {
+  FlutterLogs.logInfo(LOG_TAG, "Get Nostr Relays", "Fetching Nostr Relays");
+
+  for (final fetch in RELAY_FETCHER_FUNCTIONS) {
+    FlutterLogs.logInfo(LOG_TAG, "Get Nostr Relays", "Trying method $fetch");
+
+    try {
+      final relays = await fetch();
+
+      return {
+        "relays": relays,
+      };
+    } catch (error) {
+      FlutterLogs.logError(
+        LOG_TAG,
+        "Get Nostr Relays",
+        "Failed to fetch relays: $error",
+      );
+    }
+  }
+
+  FlutterLogs.logWarn(
+    LOG_TAG,
+    "Get Nostr Relays",
+    "Failed to fetch relays. Falling back to default relays",
+  );
 
   return {
-    "relays": List<String>.from(jsonDecode(response.body)),
+    "relays": FALLBACK_RELAYS,
   };
 }
+
+class NostrWatchAPI {
+  static Future<List<String>> getPublicNostrRelays() async {
+    final response = await http
+        .get(Uri.parse(NOSTR_PUBLIC_RELAYS_LIST_URI))
+        .timeout(HTTP_TIMEOUT);
+
+    return List<String>.from(jsonDecode(response.body));
+  }
+
+  static Future<List<String>> getAllNostrRelays() async {
+    final response = await http
+        .get(Uri.parse(NOSTR_ONLINE_RELAYS_LIST_URI))
+        .timeout(HTTP_TIMEOUT);
+
+    return List<String>.from(jsonDecode(response.body));
+  }
+}
+
+class NostrBandAPI {
+  static Future<List<String>> getTrendingProfiles() async {
+    final response = await http
+        .get(Uri.parse(NOSTR_TRENDING_PROFILES_URI))
+        .timeout(HTTP_TIMEOUT);
+
+    return List<String>.from(
+        List<dynamic>.from(jsonDecode(response.body)["profiles"])
+            .map((e) => e["relays"])
+            .expand((element) => element)
+            .toSet());
+  }
+}
+
+// Top 30 most used free relays
+const FALLBACK_RELAYS = [
+  "relay.damus.io",
+  "eden.nostr.land",
+  "nos.lol",
+  "relay.snort.social",
+  "relay.current.fyi",
+  "brb.io",
+  "nostr.orangepill.dev",
+  "nostr-pub.wellorder.net",
+  "nostr.bitcoiner.social",
+  "nostr.wine",
+  "nostr.oxtr.dev",
+  "relay.nostr.bg",
+  "nostr.mom",
+  "nostr.fmt.wiz.biz",
+  "relay.nostr.band",
+  "nostr-pub.semisol.dev",
+  "nostr.milou.lol",
+  "nostr.onsats.org",
+  "relay.nostr.info",
+  "puravida.nostr.land",
+  "offchain.pub",
+  "relay.orangepill.dev",
+  "no.str.cr",
+  "nostr.zebedee.cloud",
+  "atlas.nostr.land",
+  "nostr-relay.wlvs.space",
+  "relay.nostrati.com",
+  "relay.nostr.com.au",
+  "relay.inosta.cc",
+  "nostr.rocks",
+];

lib/constants/apis.dart

@@ -1 +1,4 @@
-const NOSTR_LIST_URI = "https://api.nostr.watch/v1/public";
+const NOSTR_PUBLIC_RELAYS_LIST_URI = "https://api.nostr.watch/v1/public";
+const NOSTR_ONLINE_RELAYS_LIST_URI = "https://api.nostr.watch/v1/online";
+const NOSTR_TRENDING_PROFILES_URI =
+    "https://api.nostr.band/v0/trending/profiles";

lib/widgets/RelaySelectSheet.dart

@@ -15,9 +15,11 @@ import 'package:locus/widgets/ModalSheet.dart';
 import '../api/nostr-relays.dart';
 import '../utils/cache.dart';
 
-String removeProtocol(final String url) => url.toLowerCase().replaceAll(RegExp(r'^wss://'), '');
+String removeProtocol(final String url) =>
+    url.toLowerCase().replaceAll(RegExp(r'^wss://'), '');
 
-String addProtocol(final String url) => url.toLowerCase().startsWith('wss://') ? url : 'wss://$url';
+String addProtocol(final String url) =>
+    url.toLowerCase().startsWith('wss://') ? url : 'wss://$url';
 
 class RelayController extends ChangeNotifier {
   late final List<String> _relays;
@@ -103,7 +105,8 @@ class _RelaySelectSheetState extends State<RelaySelectSheet> {
         return;
       }
 
-      final normalizedSelectedRelays = widget.controller.relays.map(removeProtocol);
+      final normalizedSelectedRelays =
+          widget.controller.relays.map(removeProtocol);
 
       if (normalizedSelectedRelays.contains(value)) {
         setState(() {
@@ -201,8 +204,11 @@ class _RelaySelectSheetState extends State<RelaySelectSheet> {
       },
       extractValue: (dynamic element) => element as String,
       builder: (_, List<dynamic> foundRelays) {
-        final uncheckedFoundRelays = foundRelays.where((element) => !checkedRelaysSet.contains(element)).toList();
-        final allRelays = List<String>.from([...widget.controller.relays, ...uncheckedFoundRelays]);
+        final uncheckedFoundRelays = foundRelays
+            .where((element) => !checkedRelaysSet.contains(element))
+            .toList();
+        final allRelays = List<String>.from(
+            [...widget.controller.relays, ...uncheckedFoundRelays]);
 
         final length = allRelays.length + (isValueNew ? 1 : 0);