From 44929fb2c90363014689b7d13d83ce5f423d7367 Mon Sep 17 00:00:00 2001
From: Andre Staltz <andre@staltz.com>
Date: Wed, 18 Oct 2023 13:05:00 +0300
Subject: [PATCH] new API getMinRequiredDepth

---
 lib/index.js       | 33 +++++++++++++++++++++++++--------
 test/index.test.js |  5 +++--
 2 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/lib/index.js b/lib/index.js
index a84a389..c38da27 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -335,23 +335,40 @@ function initRecord(peer, config) {
 
   /**
    * @param {string} tangleID
+   * @returns {number}
    */
-  function getFieldRootsOfTangle(tangleID) {
+  function getMinRequiredDepth(tangleID) {
     assertDBExists(peer)
-    // prettier-ignore
-    if (!accountID) throw new Error('Cannot getFieldRootsByTangle() before loading')
 
     const rootMsg = peer.db.get(tangleID)
     if (!rootMsg) throw new Error(`Cannot find tangle root "${tangleID}"`)
-    // prettier-ignore
-    if (!MsgV3.isMoot(rootMsg, accountID)) throw new Error(`"${tangleID}" is not a moot`)
+    if (!MsgV3.isMoot(rootMsg)) throw new Error(`"${tangleID}" is not a moot`)
 
     const domain = rootMsg.metadata.domain
     // prettier-ignore
     if (!domain.startsWith(PREFIX)) throw new Error(`"${tangleID}" is not a record moot`)
-    const subdomain = toSubdomain(domain)
 
-    return getFieldRoots(subdomain)
+    // Discover field roots
+    const fieldRoots = new Set()
+    const tangle = peer.db.getTangle(tangleID)
+    const msgIDs = tangle.topoSort()
+    for (const msgID of msgIDs) {
+      const msg = peer.db.get(msgID)
+      if (!msg?.data) continue
+      for (const supersededMsgID of msg.data.supersedes) {
+        fieldRoots.delete(supersededMsgID)
+      }
+      fieldRoots.add(msgID)
+    }
+
+    // Get minimum depth of all field roots
+    let minDepth = Infinity
+    for (const msgID of fieldRoots) {
+      const depth = tangle.getDepth(msgID)
+      if (depth < minDepth) minDepth = depth
+    }
+
+    return minDepth
   }
 
   /**
@@ -437,7 +454,7 @@ function initRecord(peer, config) {
     update,
     read,
     getFieldRoots,
-    getFieldRootsOfTangle,
+    getMinRequiredDepth,
     squeeze,
 
     _squeezePotential,
diff --git a/test/index.test.js b/test/index.test.js
index d81ae31..ad53eaf 100644
--- a/test/index.test.js
+++ b/test/index.test.js
@@ -116,6 +116,8 @@ test('Record receives old branched update', async (t) => {
   const moot = MsgV3.createMoot(aliceID, 'record_v1__profile', aliceKeypair)
   const mootID = MsgV3.getMsgID(moot)
 
+  assert.equal(peer.record.getMinRequiredDepth(mootID), 7, 'getMinRequiredDepth')
+
   const tangle = new MsgV3.Tangle(mootID)
   tangle.add(mootID, moot)
   await p(peer.db.add)(moot, mootID)
@@ -143,8 +145,7 @@ test('Record receives old branched update', async (t) => {
     'fieldRoots'
   )
 
-  const altFieldRoots7 = peer.record.getFieldRootsOfTangle(mootID)
-  assert.deepEqual(altFieldRoots7, fieldRoots7, 'getFieldRootsOfTangle')
+  assert.equal(peer.record.getMinRequiredDepth(mootID), 1, 'getMinRequiredDepth')
 
   assert.equal(peer.record._squeezePotential('profile'), 6, 'squeezePotential=6')
 })