Initial commit

src/cashu.ts

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+import {getDecodedToken} from "@cashu/cashu-ts";
+import type {Proof, TokenEntry} from "@cashu/cashu-ts";
+import {getMailSubscriptionDurationForSats} from "./general.ts";
+
+class InvalidTokenException extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = 'InvalidTokenException';
+  }
+}
+
+export class TokenInfo {
+  private static readonly ALLOWED_MINTS: readonly string[] = [
+    'https://mint.minibits.cash/Bitcoin',
+    'https://stablenut.umint.cash',
+    'https://mint.lnvoltz.com',
+    'https://mint.coinos.io',
+    'https://mint.lnwallet.app',
+    'https://mint.0xchat.com'
+  ] as const;
+  private static readonly MIN_AMOUNT = 21 as const;
+
+  public readonly token: TokenEntry;
+  public readonly amount: number;
+  public readonly mint: string;
+  public readonly proofs: Proof[];
+
+  constructor(protected readonly tokenString: string) {
+    const decodedTokenData = getDecodedToken(tokenString);
+    if (decodedTokenData.unit !== 'sat' || decodedTokenData.token.length !== 1)
+      throw new InvalidTokenException('Invalid token format. We only accept a single token denominated in sats');
+    this.token = decodedTokenData.token[0];
+    this.amount = this.token.proofs.reduce((c, x) => c + x.amount, 0);
+    if (this.amount < TokenInfo.MIN_AMOUNT)
+      throw new InvalidTokenException(`Invalid amount. Minimum required: ${TokenInfo.MIN_AMOUNT} sats`);
+    if (!TokenInfo.ALLOWED_MINTS.includes(this.token.mint))
+      throw new InvalidTokenException('Unsupported mint');
+    this.mint = this.token.mint;
+    this.proofs = this.token.proofs;
+  }
+}
+
+export class TokenInfoWithMailSubscriptionDuration extends TokenInfo {
+  public readonly duration: number;
+
+  constructor(tokenString: string) {
+    super(tokenString);
+    this.duration = getMailSubscriptionDurationForSats(this.amount);
+  }
+}

src/email.ts

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+/**
+ * Parses a raw email string into its constituent parts, including subject, headers, and body.
+ *
+ * @param emailText The raw email text to parse.
+ * @returns An object containing the extracted email components.
+ */
+export function parseEmail(emailText: string) {
+  const lines = emailText.split('\n');
+  const headers: { [key: string]: string } = {};
+  let bodyLines = [];
+  let isBody = false;
+
+  for (let line of lines) {
+    if (!isBody) {
+      if (line.trim() === '') {
+        isBody = true;
+        continue;
+      }
+
+      const colonIndex = line.indexOf(':');
+      if (colonIndex !== -1) {
+        const key = line.slice(0, colonIndex);
+        headers[key] = line.slice(colonIndex + 1).trim();
+      }
+    } else
+      bodyLines.push(line);
+  }
+
+  return {
+    subject: headers['Subject'] || 'No subject',
+    headers,
+    body: bodyLines.join('\n').trim()
+  };
+}

src/general.ts

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+export function randomTimeUpTo2DaysInThePast() {
+  const now = Date.now();
+  const twoDaysAgo = now - 2 * 24 * 60 * 60 * 1000 - 3600 * 1000; // 1 hour buffer in case of clock skew
+  return Math.floor((Math.floor(Math.random() * (now - twoDaysAgo)) + twoDaysAgo) / 1000);
+}
+
+export function getMailSubscriptionDurationForSats(n: number) {
+  const twentyOneSatsToSeconds = 8640 / 21;
+  return Math.floor(n * twentyOneSatsToSeconds);
+}

src/index.ts

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+export * from "./cashu";
+export * from "./general";
+export * from "./nostr.ts";
+export * from "./email.ts";

src/nostr.ts

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+import NDK, {NDKEvent, NDKPrivateKeySigner, NDKUser} from "@nostr-dev-kit/ndk";
+import {generateSecretKey} from "nostr-tools";
+import {randomTimeUpTo2DaysInThePast} from "./general.ts";
+
+export async function encryptEventForRecipient(
+  ndk: NDK,
+  event: NDKEvent,
+  recipient: NDKUser
+): Promise<NDKEvent> {
+  await ndk.connect();
+  let randomKey = generateSecretKey();
+  const randomKeySinger = new NDKPrivateKeySigner(randomKey);
+  const seal = new NDKEvent();
+  seal.pubkey = recipient.pubkey;
+  seal.kind = 13;
+  seal.content = await ndk.signer!.nip44Encrypt(recipient, JSON.stringify(event));
+  seal.created_at = randomTimeUpTo2DaysInThePast();
+  await seal.sign(ndk.signer);
+  const giftWrap = new NDKEvent();
+  giftWrap.kind = 1059;
+  giftWrap.created_at = randomTimeUpTo2DaysInThePast();
+  giftWrap.content = await randomKeySinger.nip44Encrypt(recipient, JSON.stringify(seal));
+  giftWrap.tags.push(['p', recipient.pubkey]);
+  await giftWrap.sign(randomKeySinger);
+  giftWrap.ndk = ndk;
+  return giftWrap;
+}