nip10: improve, support quotes, author hints, change the way legacy refs are discovered.

nip10.ts

@@ -1,7 +1,7 @@
 import type { Event } from './core.ts'
 import type { EventPointer, ProfilePointer } from './nip19.ts'
 
-export type NIP10Result = {
+export function parse(event: Pick<Event, 'tags'>): {
   /**
    * Pointer to the root of the thread.
    */
@@ -13,29 +13,80 @@ export type NIP10Result = {
   reply: EventPointer | undefined
 
   /**
-   * Pointers to events which may or may not be in the reply chain.
+   * Pointers to events that may or may not be in the reply chain.
    */
   mentions: EventPointer[]
 
+  /**
+   * Pointers to events that were directly quoted.
+   */
+  quotes: EventPointer[]
+
   /**
    * List of pubkeys that are involved in the thread in no particular order.
    */
   profiles: ProfilePointer[]
-}
-
-export function parse(event: Pick<Event, 'tags'>): NIP10Result {
-  const result: NIP10Result = {
+} {
+  const result: ReturnType<typeof parse> = {
     reply: undefined,
     root: undefined,
     mentions: [],
     profiles: [],
+    quotes: [],
   }
 
-  const eTags: string[][] = []
+  let maybeParent: EventPointer | undefined
+  let maybeRoot: EventPointer | undefined
+
+  for (let i = event.tags.length - 1; i >= 0; i--) {
+    const tag = event.tags[i]
 
-  for (const tag of event.tags) {
     if (tag[0] === 'e' && tag[1]) {
-      eTags.push(tag)
+      const [_, eTagEventId, eTagRelayUrl, eTagMarker, eTagAuthor] = tag as [
+        string,
+        string,
+        undefined | string,
+        undefined | string,
+        undefined | string,
+      ]
+
+      const eventPointer: EventPointer = {
+        id: eTagEventId,
+        relays: eTagRelayUrl ? [eTagRelayUrl] : [],
+        author: eTagAuthor,
+      }
+
+      if (eTagMarker === 'root') {
+        result.root = eventPointer
+        continue
+      }
+
+      if (eTagMarker === 'reply') {
+        result.reply = eventPointer
+        continue
+      }
+
+      if (eTagMarker === 'mention') {
+        result.mentions.push(eventPointer)
+        continue
+      }
+
+      if (!maybeParent) {
+        maybeParent = eventPointer
+      } else {
+        maybeRoot = eventPointer
+      }
+
+      result.mentions.push(eventPointer)
+      continue
+    }
+
+    if (tag[0] === 'q' && tag[1]) {
+      const [_, eTagEventId, eTagRelayUrl] = tag as [string, string, undefined | string]
+      result.quotes.push({
+        id: eTagEventId,
+        relays: eTagRelayUrl ? [eTagRelayUrl] : [],
+      })
     }
 
     if (tag[0] === 'p' && tag[1]) {
@@ -43,49 +94,51 @@ export function parse(event: Pick<Event, 'tags'>): NIP10Result {
         pubkey: tag[1],
         relays: tag[2] ? [tag[2]] : [],
       })
+      continue
     }
   }
 
-  for (let eTagIndex = 0; eTagIndex < eTags.length; eTagIndex++) {
-    const eTag = eTags[eTagIndex]
-
-    const [_, eTagEventId, eTagRelayUrl, eTagMarker] = eTag as [string, string, undefined | string, undefined | string]
-
-    const eventPointer: EventPointer = {
-      id: eTagEventId,
-      relays: eTagRelayUrl ? [eTagRelayUrl] : [],
-    }
-
-    const isFirstETag = eTagIndex === 0
-    const isLastETag = eTagIndex === eTags.length - 1
-
-    if (eTagMarker === 'root') {
-      result.root = eventPointer
-      continue
-    }
-
-    if (eTagMarker === 'reply') {
-      result.reply = eventPointer
-      continue
-    }
-
-    if (eTagMarker === 'mention') {
-      result.mentions.push(eventPointer)
-      continue
-    }
-
-    if (isFirstETag) {
-      result.root = eventPointer
-      continue
-    }
-
-    if (isLastETag) {
-      result.reply = eventPointer
-      continue
-    }
-
-    result.mentions.push(eventPointer)
+  // get legacy (positional) markers, set reply to root and vice-versa if one of them is missing
+  if (!result.root) {
+    result.root = maybeRoot || maybeParent || result.reply
   }
+  if (!result.reply) {
+    result.reply = maybeParent || result.root
+  }
+
+  // remove root and reply from mentions, inherit relay hints from authors if any
+  ;[result.reply, result.root].forEach(ref => {
+    let idx = result.mentions.indexOf(ref!)
+    if (idx !== -1) {
+      result.mentions.splice(idx, 1)
+    }
+    if (ref!.author) {
+      let author = result.profiles.find(p => p.pubkey === ref!.author)
+      if (author && author.relays) {
+        if (!ref!.relays) {
+          ref!.relays = []
+        }
+        author.relays.forEach(url => {
+          if (ref?.relays!?.indexOf(url) === -1) ref!.relays!.push(url)
+        })
+        author.relays = ref!.relays
+      }
+    }
+  })
+  result.mentions.forEach(ref => {
+    if (ref!.author) {
+      let author = result.profiles.find(p => p.pubkey === ref.author)
+      if (author && author.relays) {
+        if (!ref.relays) {
+          ref.relays = []
+        }
+        author.relays.forEach(url => {
+          if (ref.relays!.indexOf(url) === -1) ref.relays!.push(url)
+        })
+        author.relays = ref.relays
+      }
+    }
+  })
 
   return result
 }