import { bytesToHex } from '@noble/hashes/utils' import { type UnsignedEvent, type Event } from './pure.ts' import { sha256 } from '@noble/hashes/sha256' import { utf8Encoder } from './utils.ts' /** Get POW difficulty from a Nostr hex ID. */ export function getPow(hex: string): number { let count = 0 for (let i = 0; i < 64; i += 8) { const nibble = parseInt(hex.substring(i, i + 8), 16) if (nibble === 0) { count += 32 } else { count += Math.clz32(nibble) 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. */ export function minePow(unsigned: UnsignedEvent, difficulty: number): Omit { let count = 0 const event = unsigned as Omit 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 = fastEventHash(event) if (getPow(event.id) >= difficulty) { break } } return event } export function fastEventHash(evt: UnsignedEvent): string { return bytesToHex( sha256(utf8Encoder.encode(JSON.stringify([0, evt.pubkey, evt.created_at, evt.kind, evt.tags, evt.content]))), ) }