@nostr-dev-kit/ndk/src/outbox/relay-ranking.ts

NDK - Nostr Development Kit. Includes AI Guardrails to catch common mistakes during development.

import type { NDK } from "../ndk";
import type { Hexpubkey } from "../user";
import { getRelaysForSync } from "./write";

export function getTopRelaysForAuthors(ndk: NDK, authors: Hexpubkey[]): WebSocket["url"][] {
    const relaysWithCount = new Map<WebSocket["url"], number>();

    authors.forEach((author) => {
        const writeRelays = getRelaysForSync(ndk, author);
        if (writeRelays) {
            writeRelays.forEach((relay) => {
                const count = relaysWithCount.get(relay) || 0;
                relaysWithCount.set(relay, count + 1);
            });
        }
    });

    /**
     * TODO: Here we are sorting the relays just by number of authors that write to them.
     * Here is the place where the relay scoring can be used to modify the weights of the relays.
     */

    // Sort the relays by the number of authors that write to them
    const sortedRelays = Array.from(relaysWithCount.entries()).sort((a, b) => b[1] - a[1]);

    return sortedRelays.map((entry) => entry[0]);
}