snort/packages/system/src/zaps.ts

import { FeedCache } from "@snort/shared";
import { sha256, decodeInvoice, InvoiceDetails } from "@snort/shared";
import { HexKey, NostrEvent } from "./nostr";
import { findTag } from "./utils";
import { MetadataCache } from "./cache";

function getInvoice(zap: NostrEvent): InvoiceDetails | undefined {
  const bolt11 = findTag(zap, "bolt11");
  if (!bolt11) {
    throw new Error("Invalid zap, missing bolt11 tag");
  }
  return decodeInvoice(bolt11);
}

export function parseZap(zapReceipt: NostrEvent, userCache: FeedCache<MetadataCache>, refNote?: NostrEvent): ParsedZap {
  let innerZapJson = findTag(zapReceipt, "description");
  if (innerZapJson) {
    try {
      const invoice = getInvoice(zapReceipt);
      if (innerZapJson.startsWith("%")) {
        innerZapJson = decodeURIComponent(innerZapJson);
      }
      const zapRequest: NostrEvent = JSON.parse(innerZapJson);
      if (Array.isArray(zapRequest)) {
        // old format, ignored
        throw new Error("deprecated zap format");
      }
      const isForwardedZap = refNote?.tags.some(a => a[0] === "zap") ?? false;
      const anonZap = zapRequest.tags.find(a => a[0] === "anon");
      const metaHash = sha256(innerZapJson);
      const pollOpt = zapRequest.tags.find(a => a[0] === "poll_option")?.[1];
      const ret: ParsedZap = {
        id: zapReceipt.id,
        zapService: zapReceipt.pubkey,
        amount: (invoice?.amount ?? 0) / 1000,
        event: findTag(zapRequest, "e"),
        sender: zapRequest.pubkey,
        receiver: findTag(zapRequest, "p"),
        valid: true,
        anonZap: anonZap !== undefined,
        content: zapRequest.content,
        errors: [],
        pollOption: pollOpt ? Number(pollOpt) : undefined,
      };
      if (invoice?.descriptionHash !== metaHash) {
        ret.valid = false;
        ret.errors.push("description_hash does not match zap request");
      }
      if (findTag(zapRequest, "p") !== findTag(zapReceipt, "p")) {
        ret.valid = false;
        ret.errors.push("p tags dont match");
      }
      if (ret.event && ret.event !== findTag(zapReceipt, "e")) {
        ret.valid = false;
        ret.errors.push("e tags dont match");
      }
      if (findTag(zapRequest, "amount") === invoice?.amount) {
        ret.valid = false;
        ret.errors.push("amount tag does not match invoice amount");
      }
      if (userCache.getFromCache(ret.receiver)?.zapService !== ret.zapService && !isForwardedZap) {
        ret.valid = false;
        ret.errors.push("zap service pubkey doesn't match");
      }
      return ret;
    } catch (e) {
      // ignored: console.debug("Invalid zap", zapReceipt, e);
    }
  }
  return {
    id: zapReceipt.id,
    zapService: zapReceipt.pubkey,
    amount: 0,
    valid: false,
    anonZap: false,
    errors: ["invalid zap, parsing failed"],
  };
}

export interface ParsedZap {
  id: HexKey;
  event?: HexKey;
  receiver?: HexKey;
  amount: number;
  content?: string;
  sender?: HexKey;
  valid: boolean;
  zapService: HexKey;
  anonZap: boolean;
  errors: Array<string>;
  pollOption?: number;
}