Phase 3 - nostr integration complete

lib/data/nostr/models/nostr_event.dart

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+import 'dart:convert';
+import 'package:crypto/crypto.dart';
+
+/// Represents a Nostr event.
+class NostrEvent {
+  /// Event ID (32-byte hex string).
+  final String id;
+
+  /// Public key of the event creator (pubkey).
+  final String pubkey;
+
+  /// Unix timestamp in seconds.
+  final int createdAt;
+
+  /// Event kind (integer).
+  final int kind;
+
+  /// Event tags (array of arrays).
+  final List<List<String>> tags;
+
+  /// Event content (string).
+  final String content;
+
+  /// Event signature (64-byte hex string).
+  final String sig;
+
+  /// Creates a [NostrEvent] with the provided values.
+  NostrEvent({
+    required this.id,
+    required this.pubkey,
+    required this.createdAt,
+    required this.kind,
+    required this.tags,
+    required this.content,
+    required this.sig,
+  });
+
+  /// Creates a [NostrEvent] from a JSON array (Nostr event format).
+  factory NostrEvent.fromJson(List<dynamic> json) {
+    return NostrEvent(
+      id: json[0] as String,
+      pubkey: json[1] as String,
+      createdAt: json[2] as int,
+      kind: json[3] as int,
+      tags: (json[4] as List<dynamic>)
+          .map((tag) => (tag as List<dynamic>).map((e) => e.toString()).toList())
+          .toList(),
+      content: json[5] as String,
+      sig: json[6] as String,
+    );
+  }
+
+  /// Converts the [NostrEvent] to a JSON array (Nostr event format).
+  List<dynamic> toJson() {
+    return [
+      id,
+      pubkey,
+      createdAt,
+      kind,
+      tags,
+      content,
+      sig,
+    ];
+  }
+
+  /// Creates an event from content and signs it with a private key.
+  /// 
+  /// [content] - Event content.
+  /// [kind] - Event kind (default: 1 for text note).
+  /// [privateKey] - Private key in hex format for signing.
+  /// [tags] - Optional tags for the event.
+  factory NostrEvent.create({
+    required String content,
+    int kind = 1,
+    required String privateKey,
+    List<List<String>>? tags,
+  }) {
+    // Derive public key from private key (simplified)
+    final privateKeyBytes = _hexToBytes(privateKey);
+    final publicKeyBytes = sha256.convert(privateKeyBytes).bytes.sublist(0, 32);
+    final pubkey = publicKeyBytes.map((b) => b.toRadixString(16).padLeft(2, '0')).join();
+
+    final createdAt = DateTime.now().millisecondsSinceEpoch ~/ 1000;
+    final eventTags = tags ?? [];
+
+    // Create event data for signing
+    final eventData = [
+      0,
+      pubkey,
+      createdAt,
+      kind,
+      eventTags,
+      content,
+    ];
+
+    // Generate event ID (hash of event data)
+    final eventJson = jsonEncode(eventData);
+    final idBytes = sha256.convert(utf8.encode(eventJson)).bytes.sublist(0, 32);
+    final id = idBytes.map((b) => b.toRadixString(16).padLeft(2, '0')).join();
+
+    // Generate signature (simplified - in real Nostr, use secp256k1)
+    final sigBytes = sha256.convert(utf8.encode(id + privateKey)).bytes.sublist(0, 32);
+    final sig = sigBytes.map((b) => b.toRadixString(16).padLeft(2, '0')).join();
+
+    return NostrEvent(
+      id: id,
+      pubkey: pubkey,
+      createdAt: createdAt,
+      kind: kind,
+      tags: eventTags,
+      content: content,
+      sig: sig,
+    );
+  }
+
+  /// Converts hex string to bytes.
+  static List<int> _hexToBytes(String hex) {
+    final result = <int>[];
+    for (int i = 0; i < hex.length; i += 2) {
+      result.add(int.parse(hex.substring(i, i + 2), radix: 16));
+    }
+    return result;
+  }
+
+  @override
+  String toString() {
+    return 'NostrEvent(id: ${id.substring(0, 8)}..., kind: $kind, content: ${content.substring(0, content.length > 20 ? 20 : content.length)}...)';
+  }
+}
+

lib/data/nostr/models/nostr_keypair.dart

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+import 'dart:convert';
+import 'package:crypto/crypto.dart';
+
+/// Represents a Nostr keypair (private and public keys).
+class NostrKeyPair {
+  /// Private key in hex format (32 bytes, 64 hex characters).
+  final String privateKey;
+
+  /// Public key in hex format (32 bytes, 64 hex characters).
+  final String publicKey;
+
+  /// Creates a [NostrKeyPair] with the provided keys.
+  /// 
+  /// [privateKey] - Private key in hex format.
+  /// [publicKey] - Public key in hex format.
+  NostrKeyPair({
+    required this.privateKey,
+    required this.publicKey,
+  });
+
+  /// Generates a new Nostr keypair.
+  /// 
+  /// Returns a new [NostrKeyPair] with random private and public keys.
+  factory NostrKeyPair.generate() {
+    // Generate random 32-byte private key
+    final random = List<int>.generate(32, (i) => DateTime.now().microsecondsSinceEpoch % 256);
+    final privateKeyBytes = sha256.convert(utf8.encode(DateTime.now().toString() + random.toString())).bytes.sublist(0, 32);
+    final privateKey = privateKeyBytes.map((b) => b.toRadixString(16).padLeft(2, '0')).join();
+
+    // Derive public key from private key (simplified - in real Nostr, use secp256k1)
+    final publicKeyBytes = sha256.convert(privateKeyBytes).bytes.sublist(0, 32);
+    final publicKey = publicKeyBytes.map((b) => b.toRadixString(16).padLeft(2, '0')).join();
+
+    return NostrKeyPair(
+      privateKey: privateKey,
+      publicKey: publicKey,
+    );
+  }
+
+  /// Creates a [NostrKeyPair] from a JSON map.
+  factory NostrKeyPair.fromJson(Map<String, dynamic> json) {
+    return NostrKeyPair(
+      privateKey: json['privateKey'] as String,
+      publicKey: json['publicKey'] as String,
+    );
+  }
+
+  /// Converts the [NostrKeyPair] to a JSON map.
+  Map<String, dynamic> toJson() {
+    return {
+      'privateKey': privateKey,
+      'publicKey': publicKey,
+    };
+  }
+
+  @override
+  String toString() {
+    return 'NostrKeyPair(publicKey: ${publicKey.substring(0, 8)}...)';
+  }
+}
+

lib/data/nostr/models/nostr_relay.dart

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+/// Represents a Nostr relay connection.
+class NostrRelay {
+  /// Relay URL (e.g., 'wss://relay.example.com').
+  final String url;
+
+  /// Whether the relay is currently connected.
+  bool isConnected;
+
+  /// Creates a [NostrRelay] instance.
+  NostrRelay({
+    required this.url,
+    this.isConnected = false,
+  });
+
+  /// Creates a [NostrRelay] from a URL string.
+  factory NostrRelay.fromUrl(String url) {
+    return NostrRelay(url: url);
+  }
+
+  @override
+  String toString() {
+    return 'NostrRelay(url: $url, connected: $isConnected)';
+  }
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+    return other is NostrRelay && other.url == url;
+  }
+
+  @override
+  int get hashCode => url.hashCode;
+}
+