TAO/client/src/powWorker.ts

import { type UnsignedEvent, type Event, getEventHash } from 'nostr-tools'

// eslint-disable-next-line no-restricted-globals
const ctx: Worker = self as any;

// Respond to message from parent thread
ctx.addEventListener('message', (event) => {
    console.log("Received message in worker:", event.data);
    
    const { unsigned, difficulty } = event.data;
    
    const result = minePow(unsigned, difficulty);
    console.log("Mining result:", result);
    
    // Post the mined event back to the main thread
    ctx.postMessage(result);
});

ctx.onerror = function(e) {
    console.error("Worker error:", e);
};

/** Get POW difficulty from a Nostr hex ID. */
export function getPow(hex: string): number {
    let count = 0

    for (let i = 0; i < hex.length; i++) {
        const nibble = parseInt(hex[i], 16)
        if (nibble === 0) {
            count += 4
        } else {
            count += Math.clz32(nibble) - 28
            break
        }
    }

    return count
}

/**
 * Mine an event with the desired POW. This function mutates the event.
 * Note that this operation is synchronous and should be run in a worker context to avoid blocking the main thread.
 *
 * Adapted from Snort: https://git.v0l.io/Kieran/snort/src/commit/4df6c19248184218c4c03728d61e94dae5f2d90c/packages/system/src/pow-util.ts#L14-L36
 */
export function minePow<K extends number>(unsigned: UnsignedEvent<K>, difficulty: number): Omit<Event<K>, 'sig'> {
    let count = 0

    const event = unsigned as Omit<Event<K>, 'sig'>
    const tag = ['nonce', count.toString(), difficulty.toString()]

    event.tags.push(tag)

    while (true) {
        const now = Math.floor(new Date().getTime() / 1000)

        if (now !== event.created_at) {
            count = 0
            event.created_at = now
        }

        tag[1] = (++count).toString()

        event.id = getEventHash(event)

        if (getPow(event.id) >= difficulty) {
            break
        }
    }

    return event
}

export default ctx;