Add NIP-21 and NIP-27 modules for parsing nostr URIs

nip21.ts

@@ -0,0 +1,37 @@
+import * as nip19 from './nip19'
+import * as nip21 from './nip21'
+
+/**
+ * Bech32 regex.
+ * @see https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki#bech32
+ */
+export const BECH32_REGEX = /[\x21-\x7E]{1,83}1[023456789acdefghjklmnpqrstuvwxyz]{6,}/
+
+/** Nostr URI regex, eg `nostr:npub1...` */
+export const NOSTR_URI_REGEX = new RegExp(`nostr:(${BECH32_REGEX.source})`)
+
+/** Test whether the value is a Nostr URI. */
+export function test(value: unknown): value is `nostr:${string}` {
+  return typeof value === 'string' && new RegExp(`^${NOSTR_URI_REGEX.source}$`).test(value)
+}
+
+/** Parsed Nostr URI data. */
+export interface NostrURI {
+  /** Full URI including the `nostr:` protocol. */
+  uri: `nostr:${string}`
+  /** The bech32-encoded data (eg `npub1...`). */
+  value: string
+  /** Decoded bech32 string, according to NIP-19. */
+  decoded: nip19.DecodeResult
+}
+
+/** Parse and decode a Nostr URI. */
+export function parse(uri: string): NostrURI {
+  const match = uri.match(new RegExp(`^${nip21.NOSTR_URI_REGEX.source}$`))
+  if (!match) throw new Error(`Invalid Nostr URI: ${uri}`)
+  return {
+    uri: match[0] as `nostr:${string}`,
+    value: match[1],
+    decoded: nip19.decode(match[1]),
+  }
+}