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

nip27.ts

@@ -0,0 +1,59 @@
+import * as nip19 from './nip19'
+import * as nip21 from './nip21'
+
+/** Regex to find NIP-21 URIs inside event content. */
+export const regex = () => new RegExp(`\\b${nip21.NOSTR_URI_REGEX.source}\\b`, 'g')
+
+/** Match result for a Nostr URI in event content. */
+export interface NostrURIMatch extends nip21.NostrURI {
+  /** Index where the URI begins in the event content. */
+  start: number
+  /** Index where the URI ends in the event content. */
+  end: number
+}
+
+/** Find and decode all NIP-21 URIs. */
+export function find(content: string): NostrURIMatch[] {
+  const matches = content.matchAll(regex())
+
+  return [...matches].map((match) => {
+    const [uri, value] = match
+
+    return {
+      uri: uri as `nostr:${string}`,
+      value,
+      decoded: nip19.decode(value),
+      start: match.index!,
+      end: match.index! + uri.length,
+    }
+  })
+}
+
+/**
+ * Replace all occurrences of Nostr URIs in the text.
+ *
+ * WARNING: using this on an HTML string is potentially unsafe!
+ *
+ * @example
+ * ```ts
+ * nip27.replaceAll(event.content, ({ decoded, value }) => {
+ *   switch(decoded.type) {
+ *     case 'npub':
+ *       return renderMention(decoded)
+ *     case 'note':
+ *       return renderNote(decoded)
+ *     default:
+ *       return value
+ *   }
+ * })
+ * ```
+ */
+export function replaceAll(content: string, replacer: (match: nip21.NostrURI) => string): string {
+  return content.replaceAll(regex(), (uri, value) => {
+    return replacer({
+      uri: uri as `nostr:${string}`,
+      value,
+      decoded: nip19.decode(value),
+    })
+  })
+}