WizardConnect/packages/core/src/relay-client.ts

// Copyright (C) 2026 Whiterun LLC,
// This software is licensed under the GNU Lesser General Public License (LGPL), version 3.0 or later.
// A copy of the license can be found in the LICENSE file or at https://www.gnu.org/licenses/lgpl-3.0.html

import { throwUnless, unwrap } from "./primitives.js";
import {
  SimplePool,
  useWebSocketImplementation,
  type SubCloser,
} from "nostr-tools/pool";
import { wrapEvent, unwrapEvent } from "nostr-tools/nip59";
import type { NostrEvent } from "nostr-tools/core";
import WebSocket from "isomorphic-ws";
import { binToHex, hash256, secp256k1 } from "@bitauth/libauth";
import { EventEmitter } from "eventemitter3";
import {
  isProtocolMessage,
  ProtocolMessage,
  RelayMsgAction,
} from "./protocols/hdwalletv1.js";
import { deriveNostrPublicKey } from "./utilnostr.js";
import { MessageQueue } from "./message-queue.js";
import { debug, error as logError, Scope } from "./log.js";

useWebSocketImplementation(WebSocket);

const KIND_GIFT_WRAP = 1059;
const KIND_PRIVATE_DIRECT_MESSAGE = 14;

export interface RelayClientConfig {
  explicitRelayUrls: string[];
  signerPrivateKey: Uint8Array;
  pairedPublicKey?: Uint8Array;
  logNetworkActivity?: boolean;
}

export class RelayClient extends EventEmitter {
  private pool: SimplePool;
  private sharedPool: boolean;
  private pairedPubkeyHex: string;
  private config: RelayClientConfig;
  private subscription: SubCloser | null = null;
  private myPubkey: Uint8Array;
  private myPubkeyHex: string;
  private lastProcessedTimestamp: number = 0;
  private messageQueue: MessageQueue;
  private readyTimeoutId: ReturnType<typeof setTimeout> | null = null;

  private sequence: number = Math.floor(
    Math.random() * (Number.MAX_SAFE_INTEGER - 500_000),
  );

  private pendingCalls = new Map<
    number,
    {
      resolve: (_value: any) => void;
      reject: (_error: Error) => void;
    }
  >();

  private pendingDeliveries = new Map<
    number,
    {
      resolve: (_value: any) => void;
      reject: (_error: Error) => void;
    }
  >();

  constructor(config: RelayClientConfig, pool?: SimplePool) {
    super();
    this.config = {
      logNetworkActivity: true,
      ...config,
    };
    this.pool = pool ?? new SimplePool();
    this.sharedPool = pool !== undefined;

    this.messageQueue = new MessageQueue({
      logActivity: this.config.logNetworkActivity,
    });

    this.myPubkey = unwrap(
      secp256k1.derivePublicKeyCompressed(this.config.signerPrivateKey),
    );
    this.myPubkeyHex = deriveNostrPublicKey(this.config.signerPrivateKey);

    if (this.config.pairedPublicKey) {
      const pairedNostrPubkey =
        this.config.pairedPublicKey.length === 33
          ? this.config.pairedPublicKey.slice(1)
          : this.config.pairedPublicKey;
      this.pairedPubkeyHex = binToHex(pairedNostrPubkey);
    } else {
      this.pairedPubkeyHex = "";
    }
  }

  setPairedPublicKey(pairedPublicKey: Uint8Array): void {
    this.config.pairedPublicKey = pairedPublicKey;
    const pairedNostrPubkey =
      pairedPublicKey.length === 33
        ? pairedPublicKey.slice(1)
        : pairedPublicKey;
    this.pairedPubkeyHex = binToHex(pairedNostrPubkey);
    this.emit("paired");
  }

  getPublicKey(): Uint8Array {
    return this.myPubkey;
  }

  getPublicKeyHex(): string {
    return this.myPubkeyHex;
  }

  isKeyExchangeComplete(): boolean {
    if (!this.config.pairedPublicKey) {
      return false;
    }
    return !this.config.pairedPublicKey.every((byte) => byte === 0);
  }

  async connect(): Promise<void> {
    if (this.config.logNetworkActivity) {
      debug(Scope.Relay, `Connecting to relay...`);
    }

    if (this.lastProcessedTimestamp === 0) {
      this.lastProcessedTimestamp = Math.floor(Date.now() / 1000) - 2;
    }

    try {
      this.subscription = this.pool.subscribeMany(
        this.config.explicitRelayUrls,
        { kinds: [KIND_GIFT_WRAP], "#p": [this.myPubkeyHex] },
        {
          onevent: (event: NostrEvent) => this.handleWrappedEvent(event),
          oneose: () => {
            if (this.readyTimeoutId) {
              clearTimeout(this.readyTimeoutId);
              this.readyTimeoutId = null;
            }
            if (this.config.logNetworkActivity) {
              debug(Scope.Relay, `EOSE received, relay connected`);
            }
            this.messageQueue.setReady((msg) => this.publishMessage(msg));
            this.emit("connection");
          },
          onclose: (reasons: string[]) => {
            if (this.config.logNetworkActivity) {
              debug(Scope.Relay, `Subscription closed: ${reasons.join(", ")}`);
            }
            this.emit("disconnect", new Error("Subscription closed"));
          },
        },
      );

      // Fallback: if EOSE doesn't arrive within 5 seconds, assume ready
      this.readyTimeoutId = setTimeout(() => {
        if (!this.messageQueue.getReady()) {
          if (this.config.logNetworkActivity) {
            debug(Scope.Relay, `EOSE timeout, assuming ready`);
          }
          this.messageQueue.setReady((msg) => this.publishMessage(msg));
          this.emit("connection");
        }
        this.readyTimeoutId = null;
      }, 5000);

      if (this.config.logNetworkActivity) {
        debug(
          Scope.Relay,
          `Subscription created, waiting for relay connection`,
        );
      }
    } catch (error) {
      if (this.config.logNetworkActivity) {
        logError(Scope.Relay, `Connection failed:`, error);
      }
      throw error;
    }
  }

  async disconnect(): Promise<void> {
    this.lastProcessedTimestamp = Math.floor(Date.now() / 1000);
    this.messageQueue.setNotReady();

    if (this.readyTimeoutId) {
      clearTimeout(this.readyTimeoutId);
      this.readyTimeoutId = null;
    }

    if (this.subscription) {
      this.subscription.close();
      this.subscription = null;
    }

    if (!this.sharedPool) {
      this.pool.close(this.config.explicitRelayUrls);
    }
  }

  getLastProcessedTimestamp(): number {
    return this.lastProcessedTimestamp;
  }

  setLastProcessedTimestamp(timestamp: number): void {
    this.lastProcessedTimestamp = timestamp;
  }

  async relay(message: ProtocolMessage): Promise<void> {
    if (!this.config.pairedPublicKey) {
      throw new Error(
        "Cannot relay message: paired public key not set. Call setPairedPublicKey() first.",
      );
    }

    if (!this.messageQueue.getReady()) {
      return this.messageQueue.enqueue(message);
    }

    return this.publishMessage(message);
  }

  private async publishMessage(message: ProtocolMessage): Promise<void> {
    this.netlog("send", message.action);

    const wrapped = wrapEvent(
      {
        kind: KIND_PRIVATE_DIRECT_MESSAGE,
        content: JSON.stringify(message),
        created_at: Math.floor(Date.now() / 1000),
        tags: [["p", this.pairedPubkeyHex]],
      },
      this.config.signerPrivateKey,
      this.pairedPubkeyHex,
    );

    try {
      await Promise.any(
        this.pool.publish(this.config.explicitRelayUrls, wrapped),
      );
      if (this.config.logNetworkActivity) {
        debug(Scope.Relay, `Published message ${message.action} to relay`);
      }
    } catch (error) {
      if (this.config.logNetworkActivity) {
        logError(
          Scope.Relay,
          `Failed to publish message ${message.action}:`,
          error,
        );
      }
      throw error;
    }
  }

  private handleWrappedEvent(wrappedEvent: NostrEvent): void {
    try {
      const rumor = unwrapEvent(wrappedEvent, this.config.signerPrivateKey);

      if (rumor.kind === KIND_PRIVATE_DIRECT_MESSAGE) {
        let payload: ProtocolMessage;
        try {
          payload = JSON.parse(rumor.content);
        } catch (e) {
          if (this.config.logNetworkActivity) {
            logError(
              Scope.Relay,
              "Failed to parse message content as JSON:",
              e,
            );
          }
          return;
        }

        if (
          !payload.time ||
          (this.lastProcessedTimestamp > 0 &&
            payload.time < this.lastProcessedTimestamp)
        ) {
          if (this.config.logNetworkActivity) {
            debug(
              Scope.Relay,
              `Ignoring already-processed message (time: ${payload.time}, action: ${payload.action}, last processed: ${this.lastProcessedTimestamp})`,
            );
          }
          return;
        }

        // wallet_ready carries the key exchange data (public_key + secret) so it
        // must bypass the peer filter — the dapp doesn't know the wallet's pubkey yet.
        const isKeyExchangeMessage =
          payload.action === RelayMsgAction.WalletReady;

        if (!isKeyExchangeMessage && this.config.pairedPublicKey) {
          const pairedNostrPubkey =
            this.config.pairedPublicKey.length === 33
              ? binToHex(this.config.pairedPublicKey.slice(1))
              : binToHex(this.config.pairedPublicKey);
          if (rumor.pubkey !== pairedNostrPubkey) {
            if (this.config.logNetworkActivity) {
              debug(
                Scope.Relay,
                `Ignoring '${payload.action}' message from unknown peer: ${rumor.pubkey} (expected: ${pairedNostrPubkey})`,
              );
            }
            return;
          }
        }

        if (this.config.logNetworkActivity) {
          debug(Scope.Relay, `Received message ${payload.action} from relay`);
        }
        this.handleRelayMessage(payload);
      } else {
        if (this.config.logNetworkActivity) {
          debug(
            Scope.Relay,
            `Ignoring non-PrivateDirectMessage, kind: ${rumor.kind}`,
          );
        }
      }
    } catch (error) {
      if (this.config.logNetworkActivity) {
        logError(Scope.Relay, "Error handling incoming message:", error);
      }
      this.emitError(error as Error);
    }
  }

  isConnected(): boolean {
    return true;
  }

  private netlog(
    direction: "recv" | "send",
    what: string,
    sequence?: number,
  ): void {
    if (!this.config.logNetworkActivity) {
      return;
    }
    const us = binToHex(hash256(this.config.signerPrivateKey)).slice(-6);
    const them = this.config.pairedPublicKey
      ? binToHex(this.config.pairedPublicKey).slice(-6)
      : "??????";
    const pending = `c${this.pendingCalls.size} d${this.pendingDeliveries.size}`;
    if (direction === "send") {
      debug(
        Scope.Relay,
        `net [${sequence ?? "?"} ${pending}] ${us} -> ${them}: ${what}`,
      );
    } else {
      debug(
        Scope.Relay,
        `net [${sequence ?? "?"} ${pending}] ${us} <- ${them}: ${what}`,
      );
    }
  }

  private async handleRelayMessage(message: ProtocolMessage): Promise<void> {
    throwUnless(
      isProtocolMessage(message),
      `Invalid protocol message: ${message}`,
    );
    this.emit("message", message);
  }

  public nextSequence(): number {
    const current = this.sequence;
    this.sequence += 2;
    return current;
  }

  private emitError(error: Error): void {
    this.emit("error", error);
  }
}