From f523df3a0ef93f75941d6d317d17daffb4713800 Mon Sep 17 00:00:00 2001
From: Andre Staltz <andre@staltz.com>
Date: Thu, 14 Dec 2023 15:58:49 +0200
Subject: [PATCH] MsgV3.isFeedMsg() API

---
 lib/msg-v3/index.js        | 31 +++++++++++++++++++++++++++++++
 test/msg-v3/create.test.js |  3 +++
 2 files changed, 34 insertions(+)

diff --git a/lib/msg-v3/index.js b/lib/msg-v3/index.js
index 6363068..b48d3d1 100644
--- a/lib/msg-v3/index.js
+++ b/lib/msg-v3/index.js
@@ -49,6 +49,26 @@ const { isEmptyObject } = require('./util')
  * }} Msg
  */
 
+/**
+ * @template [T=any]
+ * @typedef {{
+ *   data: T;
+ *   metadata: {
+ *     dataHash: string;
+ *     dataSize: number;
+ *     account: string;
+ *     accountTips: Array<string>;
+ *     tangles: {
+ *       [tangleID in string]: TangleMetadata
+ *     };
+ *     domain: string;
+ *     v: 3;
+ *   };
+ *   pubkey: string;
+ *   sig: string;
+ * }} FeedMsg
+ */
+
 /**
  * @typedef {Iterator<Msg> & {values: () => Iterator<Msg>}} MsgIter
  *
@@ -280,6 +300,16 @@ function isRoot(msg) {
   return isEmptyObject(msg.metadata.tangles)
 }
 
+/**
+ * @template T
+ * @param {Msg<T>} msg
+ * @returns {msg is FeedMsg<T>}
+ */
+function isFeedMsg(msg) {
+  const {account, accountTips} = msg.metadata
+  return Array.isArray(accountTips) && account !== 'self' && account !== 'any'
+}
+
 /**
  * @param {any} x
  * @returns {x is Msg}
@@ -292,6 +322,7 @@ module.exports = {
   isMsg,
   isMoot,
   isRoot,
+  isFeedMsg,
   getMsgID,
   getMootID,
   create,
diff --git a/test/msg-v3/create.test.js b/test/msg-v3/create.test.js
index a5698b8..1055ce9 100644
--- a/test/msg-v3/create.test.js
+++ b/test/msg-v3/create.test.js
@@ -32,6 +32,7 @@ test('MsgV3.createAccount()', (t) => {
   assert.equal(accountMsg0.metadata.domain, 'person', 'domain')
   assert.equal(accountMsg0.metadata.v, 3, 'v')
   assert.equal(accountMsg0.pubkey, keypair.public, 'pubkey')
+  assert.equal(MsgV3.isFeedMsg(accountMsg0), false, 'not a feed msg')
 
   account = MsgV3.getMsgID(accountMsg0)
   assert.equal(account, 'UQN1Qmxr4rr9nCMQKs9u8P', 'account ID')
@@ -54,6 +55,7 @@ test('MsgV3.createMoot()', (t) => {
   assert.equal(moot.metadata.domain, 'post', 'domain')
   assert.equal(moot.metadata.v, 3, 'v')
   assert.equal(moot.pubkey, keypair.public, 'pubkey')
+  assert.equal(MsgV3.isFeedMsg(moot), false, 'not a feed msg')
 
   mootID = MsgV3.getMsgID(moot)
   assert.equal(mootID, 'AP2rJSfm9TwpNcMmbUsnRa', 'moot ID')
@@ -119,6 +121,7 @@ test('MsgV3.create()', (t) => {
     'rh8bc8QY7ju7yi4rt6y9njCyS3TVV1SBjn5dWGpKKRrC3XDMBc9KeNJgVCJLK8b8uiU5F49avAWt35P9kNaWZYH',
     'sig'
   )
+  assert.equal(MsgV3.isFeedMsg(msg1), true, 'is a feed msg')
 
   const msgID1 = 'MUvfNDk3gMPRy9CpTDEuvW'