add parseReferences() for NIP-10 and NIP-27.

references.ts

@@ -0,0 +1,104 @@
+import {Event} from './event'
+import {decode, AddressPointer, ProfilePointer, EventPointer} from './nip19'
+
+type Reference = {
+  text: string
+  profile?: ProfilePointer
+  event?: EventPointer
+  address?: AddressPointer
+}
+
+const mentionRegex =
+  /\bnostr:((note|npub|naddr|nevent|nprofile)1\w+)\b|#\[(\d+)\]/g
+
+export function parseReferences(evt: Event): Reference[] {
+  let references: Reference[] = []
+  for (let ref of evt.content.matchAll(mentionRegex)) {
+    if (ref[2]) {
+      // it's a NIP-27 mention
+      try {
+        let {type, data} = decode(ref[1])
+        switch (type) {
+          case 'npub': {
+            references.push({
+              text: ref[0],
+              profile: {pubkey: data as string, relays: []}
+            })
+            break
+          }
+          case 'nprofile': {
+            references.push({
+              text: ref[0],
+              profile: data as ProfilePointer
+            })
+            break
+          }
+          case 'note': {
+            references.push({
+              text: ref[0],
+              event: {id: data as string, relays: []}
+            })
+            break
+          }
+          case 'nevent': {
+            references.push({
+              text: ref[0],
+              event: data as EventPointer
+            })
+            break
+          }
+          case 'naddr': {
+            references.push({
+              text: ref[0],
+              address: data as AddressPointer
+            })
+            break
+          }
+        }
+      } catch (err) {
+        /***/
+      }
+    } else if (ref[3]) {
+      // it's a NIP-10 mention
+      let idx = parseInt(ref[3], 10)
+      let tag = evt.tags[idx]
+      if (!tag) continue
+
+      switch (tag[0]) {
+        case 'p': {
+          references.push({
+            text: ref[0],
+            profile: {pubkey: tag[1], relays: tag[2] ? [tag[2]] : []}
+          })
+          break
+        }
+        case 'e': {
+          references.push({
+            text: ref[0],
+            event: {id: tag[1], relays: tag[2] ? [tag[2]] : []}
+          })
+          break
+        }
+        case 'a': {
+          try {
+            let [kind, pubkey, identifier] = ref[1].split(':')
+            references.push({
+              text: ref[0],
+              address: {
+                identifier,
+                pubkey,
+                kind: parseInt(kind, 10),
+                relays: tag[2] ? [tag[2]] : []
+              }
+            })
+          } catch (err) {
+            /***/
+          }
+          break
+        }
+      }
+    }
+  }
+
+  return references
+}