From 60f2a059ec6f34f9d5c13dc82575f14b2d1f20fd Mon Sep 17 00:00:00 2001
From: Richard Hansen <rhansen@rhansen.org>
Date: Tue, 19 Oct 2021 04:36:13 -0400
Subject: [PATCH] Changeset: Deprecate `oldLen()` and `newLen()` functions

---
 src/node/handler/PadMessageHandler.js |  4 ++--
 src/static/js/Changeset.js            | 14 ++++++++++++--
 src/static/js/ace2_inner.js           |  7 +++----
 src/static/js/changesettracker.js     |  2 +-
 4 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/node/handler/PadMessageHandler.js b/src/node/handler/PadMessageHandler.js
index 8dcb6120c..03db4ad44 100644
--- a/src/node/handler/PadMessageHandler.js
+++ b/src/node/handler/PadMessageHandler.js
@@ -628,10 +628,10 @@ const handleUserChanges = async (socket, message) => {
 
     const prevText = pad.text();
 
-    if (Changeset.oldLen(rebasedChangeset) !== prevText.length) {
+    if (Changeset.unpack(rebasedChangeset).oldLen !== prevText.length) {
       throw new Error(
           `Can't apply changeset ${rebasedChangeset} with oldLen ` +
-          `${Changeset.oldLen(rebasedChangeset)} to document of length ${prevText.length}`);
+          `${Changeset.unpack(rebasedChangeset).oldLen} to document of length ${prevText.length}`);
     }
 
     const newRev = await pad.appendRevision(rebasedChangeset, thisSession.author);
diff --git a/src/static/js/Changeset.js b/src/static/js/Changeset.js
index 2393c8c35..aef04c1b4 100644
--- a/src/static/js/Changeset.js
+++ b/src/static/js/Changeset.js
@@ -286,18 +286,28 @@ class Changeset {
 /**
  * Returns the required length of the text before changeset can be applied.
  *
+ * @deprecated Use `Changeset.unpack(cs).oldLen` instead.
  * @param {string} cs - String representation of the Changeset
  * @returns {number} oldLen property
  */
-exports.oldLen = (cs) => Changeset.unpack(cs).oldLen;
+exports.oldLen = (cs) => {
+  padutils.warnDeprecated(
+      'Changeset.oldLen(cs) is deprecated; use Changeset.unpack(cs).oldLen instead');
+  return Changeset.unpack(cs).oldLen;
+};
 
 /**
  * Returns the length of the text after changeset is applied.
  *
+ * @deprecated Use `Changeset.unpack(cs).newLen` instead.
  * @param {string} cs - String representation of the Changeset
  * @returns {number} newLen property
  */
-exports.newLen = (cs) => Changeset.unpack(cs).newLen;
+exports.newLen = (cs) => {
+  padutils.warnDeprecated(
+      'Changeset.newLen(cs) is deprecated; use Changeset.unpack(cs).newLen instead');
+  return Changeset.unpack(cs).newLen;
+};
 
 /**
  * Parses a string of serialized changeset operations.
diff --git a/src/static/js/ace2_inner.js b/src/static/js/ace2_inner.js
index 6f16c7f5b..9549e5761 100644
--- a/src/static/js/ace2_inner.js
+++ b/src/static/js/ace2_inner.js
@@ -1447,11 +1447,10 @@ function Ace2Inner(editorInfo, cssManagers) {
   };
 
   const doRepApplyChangeset = (changes, insertsAfterSelection) => {
-    Changeset.unpack(changes).validate();
+    const cs = Changeset.unpack(changes).validate();
 
-    if (Changeset.oldLen(changes) !== rep.alltext.length) {
-      const errMsg = `${Changeset.oldLen(changes)}/${rep.alltext.length}`;
-      throw new Error(`doRepApplyChangeset length mismatch: ${errMsg}`);
+    if (cs.oldLen !== rep.alltext.length) {
+      throw new Error(`doRepApplyChangeset length mismatch: ${cs.oldLen}/${rep.alltext.length}`);
     }
 
     const editEvent = currentCallStack.editEvent;
diff --git a/src/static/js/changesettracker.js b/src/static/js/changesettracker.js
index 04abe7391..cfe82f4a3 100644
--- a/src/static/js/changesettracker.js
+++ b/src/static/js/changesettracker.js
@@ -167,7 +167,7 @@ const makeChangesetTracker = (scheduler, apool, aceCallbacksProvider) => {
       let cs = null;
       if (toSubmit) {
         submittedChangeset = toSubmit;
-        userChangeset = Changeset.identity(Changeset.newLen(toSubmit));
+        userChangeset = Changeset.identity(Changeset.unpack(toSubmit).newLen);
 
         cs = toSubmit;
       }