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 NDK, {
  NDKPrivateKeySigner,
  NDKUser,
  NDKEvent,
  NDKKind,
  giftWrap,
  giftUnwrap,
  NDKSubscription,
} from "@nostr-dev-kit/ndk";
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";

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

export class RelayClient extends EventEmitter {
  private ndk: NDK;
  private paired: NDKUser;
  private config: RelayClientConfig;
  private messageSubscription: NDKSubscription | null = null;
  private myPubkey: Uint8Array;
  private myPubkeyHex: string;
  private lastProcessedTimestamp: number = 0;
  private messageQueue: MessageQueue;

  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) {
    super();
    this.config = {
      logNetworkActivity: true,
      ...config,
    };
    this.ndk = new NDK({
      explicitRelayUrls: this.config.explicitRelayUrls,
      signer: new NDKPrivateKeySigner(this.config.signerPrivateKey),
      enableOutboxModel: false,
      autoConnectUserRelays: false,
    });

    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.paired = new NDKUser({ pubkey: binToHex(pairedNostrPubkey) });
    } else {
      this.paired = new NDKUser({ pubkey: "" });
    }
  }

  setPairedPublicKey(pairedPublicKey: Uint8Array): void {
    this.config.pairedPublicKey = pairedPublicKey;
    const pairedNostrPubkey =
      pairedPublicKey.length === 33
        ? pairedPublicKey.slice(1)
        : pairedPublicKey;
    this.paired = new NDKUser({ pubkey: 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 {
      await this.ndk.connect();

      if (this.config.logNetworkActivity) {
        debug(Scope.Relay, `NDK connect() resolved`);
      }

      this.messageSubscription = this.ndk.subscribe(
        {
          kinds: [NDKKind.GiftWrap],
          "#p": [this.myPubkeyHex],
        },
        { closeOnEose: false },
      );

      this.messageSubscription.on("event", async (wrappedEvent: NDKEvent) => {
        try {
          const signer = this.ndk.signer;
          if (!signer) {
            throw new Error("No signer available");
          }

          const rumor = await giftUnwrap(wrappedEvent, undefined, signer);

          if (rumor.kind === NDKKind.PrivateDirectMessage) {
            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);
        }
      });

      this.messageSubscription.on("close", () => {
        if (this.config.logNetworkActivity) {
          debug(Scope.Relay, "Subscription closed, connection may be stale");
        }
        this.emit("disconnect", new Error("Subscription closed"));
      });

      this.waitForRelaysReady();

      if (this.config.logNetworkActivity) {
        debug(
          Scope.Relay,
          `Subscription created and handler set up, emitting connection event`,
        );
      }

      this.emit("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.messageSubscription) {
      this.messageSubscription.stop();
      this.messageSubscription = null;
    }
  }

  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 signer = this.ndk.signer;
    if (!signer) {
      throw new Error("No signer available");
    }

    const rumor = new NDKEvent(this.ndk);
    rumor.kind = NDKKind.PrivateDirectMessage;
    rumor.content = JSON.stringify(message);
    rumor.created_at = Math.floor(Date.now() / 1000);
    rumor.tags = [["p", this.paired.pubkey]];

    const wrappedEvent = await giftWrap(rumor, this.paired, signer);

    try {
      await wrappedEvent.publish();
      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 async waitForRelaysReady(): Promise<void> {
    const maxWaitTime = 5000;
    const checkInterval = 100;
    const startTime = Date.now();

    const checkRelays = async (): Promise<void> => {
      const pool = (this.ndk as any).pool;
      if (pool) {
        const relays = pool.relays || [];
        // NDKRelayStatus: DISCONNECTED=1, CONNECTED=5, AUTHENTICATED=8
        const connectedRelays = Array.from(relays.values()).filter(
          (relay: any) => relay.status >= 5,
        );

        if (connectedRelays.length > 0) {
          if (this.config.logNetworkActivity) {
            debug(
              Scope.Relay,
              `Relays ready (${connectedRelays.length} connected), processing queued messages`,
            );
          }
          await this.messageQueue.setReady((msg) => this.publishMessage(msg));
          return;
        }
      }

      if (Date.now() - startTime < maxWaitTime) {
        setTimeout(checkRelays, checkInterval);
      } else {
        if (this.config.logNetworkActivity) {
          debug(
            Scope.Relay,
            "Relay ready check timeout, assuming ready and processing queued messages",
          );
        }
        await this.messageQueue.setReady((msg) => this.publishMessage(msg));
      }
    };

    setTimeout(checkRelays, 200);
  }

  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);
  }
}