From 0c34216ed0b72ef060b3408fcb0bdd329bdaec81 Mon Sep 17 00:00:00 2001
From: Kevin Jahns <kevin.jahns@pm.me>
Date: Mon, 21 Jun 2021 12:04:40 +0200
Subject: [PATCH] merge pending structs in v1 format

---
 src/utils/encoding.js  | 21 ++++++++++---------
 src/utils/updates.js   | 30 +++++++++++++++++++++++++++
 tests/updates.tests.js | 46 +++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 87 insertions(+), 10 deletions(-)

diff --git a/src/utils/encoding.js b/src/utils/encoding.js
index 3506c05b..66536920 100644
--- a/src/utils/encoding.js
+++ b/src/utils/encoding.js
@@ -32,9 +32,11 @@ import {
   DSEncoderV2,
   DSDecoderV1,
   DSEncoderV1,
+  mergeUpdates,
   mergeUpdatesV2,
   Skip,
   diffUpdateV2,
+  convertUpdateFormatV2ToV1,
   DSDecoderV2, Doc, Transaction, GC, Item, StructStore // eslint-disable-line
 } from '../internals.js'
 
@@ -523,15 +525,16 @@ export const encodeStateAsUpdateV2 = (doc, encodedTargetStateVector = new Uint8A
   writeStateAsUpdate(encoder, doc, targetStateVector)
   const updates = [encoder.toUint8Array()]
   // also add the pending updates (if there are any)
-  // @todo support diffirent encoders
-  if (encoder.constructor === UpdateEncoderV2) {
-    if (doc.store.pendingDs) {
-      updates.push(doc.store.pendingDs)
-    }
-    if (doc.store.pendingStructs) {
-      updates.push(diffUpdateV2(doc.store.pendingStructs.update, encodedTargetStateVector))
-    }
-    if (updates.length > 1) {
+  if (doc.store.pendingDs) {
+    updates.push(doc.store.pendingDs)
+  }
+  if (doc.store.pendingStructs) {
+    updates.push(diffUpdateV2(doc.store.pendingStructs.update, encodedTargetStateVector))
+  }
+  if (updates.length > 1) {
+    if (encoder.constructor === UpdateEncoderV1) {
+      return mergeUpdates(updates.map((update, i) => i === 0 ? update : convertUpdateFormatV2ToV1(update)))
+    } else if (encoder.constructor === UpdateEncoderV2) {
       return mergeUpdatesV2(updates)
     }
   }
diff --git a/src/utils/updates.js b/src/utils/updates.js
index 6b54d83d..5e28aae8 100644
--- a/src/utils/updates.js
+++ b/src/utils/updates.js
@@ -514,3 +514,33 @@ const finishLazyStructWriting = (lazyWriter) => {
     encoding.writeUint8Array(restEncoder, partStructs.restEncoder)
   }
 }
+
+/**
+ * @param {Uint8Array} update
+ * @param {typeof UpdateDecoderV2 | typeof UpdateDecoderV1} YDecoder
+ * @param {typeof UpdateEncoderV2 | typeof UpdateEncoderV1 } YEncoder
+ */
+export const convertUpdateFormat = (update, YDecoder, YEncoder) => {
+  const updateDecoder = new YDecoder(decoding.createDecoder(update))
+  const lazyDecoder = new LazyStructReader(updateDecoder, false)
+  const updateEncoder = new YEncoder()
+  const lazyWriter = new LazyStructWriter(updateEncoder)
+
+  for (let curr = lazyDecoder.curr; curr !== null; curr = lazyDecoder.next()) {
+    writeStructToLazyStructWriter(lazyWriter, curr, 0)
+  }
+  finishLazyStructWriting(lazyWriter)
+  const ds = readDeleteSet(updateDecoder)
+  writeDeleteSet(updateEncoder, ds)
+  return updateEncoder.toUint8Array()
+}
+
+/**
+ * @param {Uint8Array} update
+ */
+export const convertUpdateFormatV1ToV2 = update => convertUpdateFormat(update, UpdateDecoderV1, UpdateEncoderV2)
+
+/**
+ * @param {Uint8Array} update
+ */
+export const convertUpdateFormatV2ToV1 = update => convertUpdateFormat(update, UpdateDecoderV2, UpdateEncoderV1)
diff --git a/tests/updates.tests.js b/tests/updates.tests.js
index 924dd220..9ae50440 100644
--- a/tests/updates.tests.js
+++ b/tests/updates.tests.js
@@ -240,5 +240,49 @@ export const testMergeUpdates2 = tc => {
 }
 
 /**
- * @todo be able to apply Skip structs to Yjs docs
+ * @param {t.TestCase} tc
  */
+export const testMergePendingUpdates = tc => {
+  const yDoc = new Y.Doc()
+  /**
+   * @type {Array<Uint8Array>}
+   */
+  const serverUpdates = []
+  yDoc.on('update', (update, origin, c) => {
+    serverUpdates.splice(serverUpdates.length, 0, update)
+  })
+  const yText = yDoc.getText('textBlock')
+  yText.applyDelta([{ insert: 'r' }])
+  yText.applyDelta([{ insert: 'o' }])
+  yText.applyDelta([{ insert: 'n' }])
+  yText.applyDelta([{ insert: 'e' }])
+  yText.applyDelta([{ insert: 'n' }])
+
+  const yDoc1 = new Y.Doc()
+  Y.applyUpdate(yDoc1, serverUpdates[0])
+  const update1 = Y.encodeStateAsUpdate(yDoc1)
+
+  const yDoc2 = new Y.Doc()
+  Y.applyUpdate(yDoc2, update1)
+  Y.applyUpdate(yDoc2, serverUpdates[1])
+  const update2 = Y.encodeStateAsUpdate(yDoc2)
+
+  const yDoc3 = new Y.Doc()
+  Y.applyUpdate(yDoc3, update2)
+  Y.applyUpdate(yDoc3, serverUpdates[3])
+  const update3 = Y.encodeStateAsUpdate(yDoc3)
+
+  const yDoc4 = new Y.Doc()
+  Y.applyUpdate(yDoc4, update3)
+  Y.applyUpdate(yDoc4, serverUpdates[2])
+  const update4 = Y.encodeStateAsUpdate(yDoc4)
+
+  const yDoc5 = new Y.Doc()
+  Y.applyUpdate(yDoc5, update4)
+  Y.applyUpdate(yDoc5, serverUpdates[4])
+  // @ts-ignore
+  const update5 = Y.encodeStateAsUpdate(yDoc5) // eslint-disable-line
+
+  const yText5 = yDoc5.getText('textBlock')
+  t.compareStrings(yText5.toString(), 'nenor')
+}