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nostrweb/src/events.ts

63 lines
2.2 KiB
TypeScript

import {Event} from 'nostr-tools';
import {zeroLeadingBitsCount} from './utils/crypto';
export const isMention = ([tag, , , marker]: string[]) => tag === 'e' && marker === 'mention';
export const isPTag = ([tag]: string[]) => tag === 'p';
export const hasEventTag = (tag: string[]) => tag[0] === 'e';
/**
* validate proof-of-work of a nostr event per nip-13.
* the validation always requires difficulty commitment in the nonce tag.
*
* @param {EventObj} evt event to validate
* TODO: @param {number} targetDifficulty target proof-of-work difficulty
*/
export const validatePow = (evt: Event) => {
const tag = evt.tags.find(tag => tag[0] === 'nonce');
if (!tag) {
return false;
}
const difficultyCommitment = Number(tag[2]);
if (!difficultyCommitment || Number.isNaN(difficultyCommitment)) {
return false;
}
return zeroLeadingBitsCount(evt.id) >= difficultyCommitment;
}
export const sortByCreatedAt = (evt1: Event, evt2: Event) => {
if (evt1.created_at === evt2.created_at) {
// console.log('TODO: OMG exactly at the same time, figure out how to sort then', evt1, evt2);
}
return evt1.created_at > evt2.created_at ? -1 : 1;
};
export const sortEventCreatedAt = (created_at: number) => (
{created_at: a}: Event,
{created_at: b}: Event,
) => (
Math.abs(a - created_at) < Math.abs(b - created_at) ? -1 : 1
);
const isReply = ([tag, , , marker]: string[]) => tag === 'e' && marker !== 'mention';
/**
* find reply-to ID according to nip-10, find marked reply or root tag or
* fallback to positional (last) e tag or return null
* @param {event} evt
* @returns replyToID | null
*/
export const getReplyTo = (evt: Event): string | null => {
const eventTags = evt.tags.filter(isReply);
const withReplyMarker = eventTags.filter(([, , , marker]) => marker === 'reply');
if (withReplyMarker.length === 1) {
return withReplyMarker[0][1];
}
const withRootMarker = eventTags.filter(([, , , marker]) => marker === 'root');
if (withReplyMarker.length === 0 && withRootMarker.length === 1) {
return withRootMarker[0][1];
}
// fallback to deprecated positional 'e' tags (nip-10)
const lastTag = eventTags.at(-1);
return lastTag ? lastTag[1] : null;
};