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

README.md

@@ -170,6 +170,26 @@ let relaysForEvent = pool.seenOn(
 // relaysForEvent will be an array of URLs from relays a given event was seen on
 ```
 
+### Parsing references (mentions) from a content using NIP-10 and NIP-27
+
+```js
+import {parseReferences} from 'nostr-tools'
+
+let references = parseReferences(event)
+let simpleAugmentedContent = event.content
+for (let i = 0; i < references.length; i++) {
+  let {text, profile, event, address} = references[i]
+  let augmentedReference = profile
+    ? `<strong>@${profilesCache[profile.pubkey].name}</strong>`
+    : event
+    ? `<em>${eventsCache[event.id].content.slice(0, 5)}</em>`
+    : address
+    ? `<a href="${text}">[link]</a>`
+    : text
+  simpleAugmentedContent.replaceAll(text, augmentedReference)
+}
+```
+
 ### Querying profile data from a NIP-05 address
 
 ```js

index.ts

@@ -3,6 +3,7 @@ export * from './relay'
 export * from './event'
 export * from './filter'
 export * from './pool'
+export * from './references'
 
 export * as nip04 from './nip04'
 export * as nip05 from './nip05'

references.test.js

@@ -0,0 +1,62 @@
+/* eslint-env jest */
+
+const {parseReferences} = require('./lib/nostr.cjs')
+
+test('parse mentions', () => {
+  let evt = {
+    tags: [
+      [
+        'p',
+        'c9d556c6d3978d112d30616d0d20aaa81410e3653911dd67787b5aaf9b36ade8',
+        'wss://nostr.com'
+      ],
+      [
+        'e',
+        'a84c5de86efc2ec2cff7bad077c4171e09146b633b7ad117fffe088d9579ac33',
+        'wss://other.com',
+        'reply'
+      ],
+      [
+        'e',
+        '31d7c2875b5fc8e6f9c8f9dc1f84de1b6b91d1947ea4c59225e55c325d330fa8',
+        ''
+      ]
+    ],
+    content:
+      'hello #[0], have you seen #[2]? it was made by nostr:nprofile1qqsvc6ulagpn7kwrcwdqgp797xl7usumqa6s3kgcelwq6m75x8fe8yc5usxdg on nostr:nevent1qqsvc6ulagpn7kwrcwdqgp797xl7usumqa6s3kgcelwq6m75x8fe8ychxp5v4! broken #[3]'
+  }
+
+  expect(parseReferences(evt)).toEqual([
+    {
+      text: '#[0]',
+      profile: {
+        pubkey:
+          'c9d556c6d3978d112d30616d0d20aaa81410e3653911dd67787b5aaf9b36ade8',
+        relays: ['wss://nostr.com']
+      }
+    },
+    {
+      text: '#[2]',
+      event: {
+        id: '31d7c2875b5fc8e6f9c8f9dc1f84de1b6b91d1947ea4c59225e55c325d330fa8',
+        relays: []
+      }
+    },
+    {
+      text: 'nostr:nprofile1qqsvc6ulagpn7kwrcwdqgp797xl7usumqa6s3kgcelwq6m75x8fe8yc5usxdg',
+      profile: {
+        pubkey:
+          'cc6b9fea033f59c3c39a0407c5f1bfee439b077508d918cfdc0d6fd431d39393',
+        relays: []
+      }
+    },
+    {
+      text: 'nostr:nevent1qqsvc6ulagpn7kwrcwdqgp797xl7usumqa6s3kgcelwq6m75x8fe8ychxp5v4',
+      event: {
+        id: 'cc6b9fea033f59c3c39a0407c5f1bfee439b077508d918cfdc0d6fd431d39393',
+        relays: [],
+        author: undefined
+      }
+    }
+  ])
+})

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
+}