From 78a1e0b805c6c85a69d95332b46aeb095f6663db Mon Sep 17 00:00:00 2001
From: Eric Eastwood <contact@ericeastwood.com>
Date: Thu, 3 Nov 2022 04:16:56 -0500
Subject: [PATCH] Add permalink highlighting

Fix https://github.com/matrix-org/matrix-public-archive/issues/4
---
 shared/hydrogen-vm-render-script.js           |  4 ++--
 shared/lib/url-creator.js                     | 19 ++++---------------
 shared/viewmodels/ArchiveRoomViewModel.js     | 17 ++++++++++-------
 .../JumpToNextActivitySummaryTileViewModel.js |  1 -
 shared/views/ArchiveRoomView.js               |  7 +------
 5 files changed, 17 insertions(+), 31 deletions(-)

diff --git a/shared/hydrogen-vm-render-script.js b/shared/hydrogen-vm-render-script.js
index 91be577e..aa9a6879 100644
--- a/shared/hydrogen-vm-render-script.js
+++ b/shared/hydrogen-vm-render-script.js
@@ -56,7 +56,7 @@ async function mountHydrogen() {
   const appElement = document.querySelector('#app');
 
   const qs = new URLSearchParams(window?.location?.search);
-  const scrollStartPosition = qs.get('continue');
+  const scrollStartEventId = qs.get('at');
 
   const platformConfig = {};
   const assetPaths = {};
@@ -126,7 +126,7 @@ async function mountHydrogen() {
     // The timestamp from the URL that was originally visited
     dayTimestampFrom: fromTimestamp,
     dayTimestampTo: toTimestamp,
-    scrollStartPosition,
+    scrollStartEventId,
     events,
     stateEventMap,
     shouldIndex,
diff --git a/shared/lib/url-creator.js b/shared/lib/url-creator.js
index c34b94e8..6adefa0e 100644
--- a/shared/lib/url-creator.js
+++ b/shared/lib/url-creator.js
@@ -65,7 +65,7 @@ class URLCreator {
     return `${urlJoin(this._basePath, `${urlPath}`)}${qsToUrlPiece(qs)}`;
   }
 
-  archiveUrlForDate(roomIdOrAlias, date, { viaServers = [], scrollStartPosition } = {}) {
+  archiveUrlForDate(roomIdOrAlias, date, { viaServers = [], scrollStartEventId } = {}) {
     assert(roomIdOrAlias);
     assert(date);
 
@@ -73,8 +73,8 @@ class URLCreator {
     [].concat(viaServers).forEach((viaServer) => {
       qs.append('via', viaServer);
     });
-    if (scrollStartPosition) {
-      qs.append('continue', scrollStartPosition);
+    if (scrollStartEventId) {
+      qs.append('at', scrollStartEventId);
     }
 
     const urlPath = this._getArchiveUrlPathForRoomIdOrAlias(roomIdOrAlias);
@@ -86,15 +86,7 @@ class URLCreator {
     return `${urlJoin(this._basePath, `${urlPath}/date/${urlDate}`)}${qsToUrlPiece(qs)}`;
   }
 
-  archiveJumpUrlForRoom(
-    roomIdOrAlias,
-    {
-      ts,
-      dir,
-      // where the scroll position should continue from ['top'|'bottom']
-      scrollStartPosition,
-    }
-  ) {
+  archiveJumpUrlForRoom(roomIdOrAlias, { ts, dir }) {
     assert(roomIdOrAlias);
     assert(ts);
     assert(dir);
@@ -102,9 +94,6 @@ class URLCreator {
     let qs = new URLSearchParams();
     qs.append('ts', ts);
     qs.append('dir', dir);
-    if (scrollStartPosition) {
-      qs.append('continue', scrollStartPosition);
-    }
 
     const urlPath = this._getArchiveUrlPathForRoomIdOrAlias(roomIdOrAlias);
 
diff --git a/shared/viewmodels/ArchiveRoomViewModel.js b/shared/viewmodels/ArchiveRoomViewModel.js
index ff56d0dc..a6ef028c 100644
--- a/shared/viewmodels/ArchiveRoomViewModel.js
+++ b/shared/viewmodels/ArchiveRoomViewModel.js
@@ -64,7 +64,7 @@ class ArchiveRoomViewModel extends ViewModel {
       room,
       dayTimestampFrom,
       dayTimestampTo,
-      scrollStartPosition,
+      scrollStartEventId,
       events,
       stateEventMap,
       shouldIndex,
@@ -82,7 +82,6 @@ class ArchiveRoomViewModel extends ViewModel {
     this._room = room;
     this._dayTimestampFrom = dayTimestampFrom;
     this._dayTimestampTo = dayTimestampTo;
-    this._scrollStartPosition = scrollStartPosition === 'top' ? 'top' : 'bottom';
     this._currentTopPositionEventEntry = null;
     this._matrixPublicArchiveURLCreator = new MatrixPublicArchiveURLCreator(basePath);
     this._basePath = basePath;
@@ -142,9 +141,17 @@ class ArchiveRoomViewModel extends ViewModel {
 
     this._timelineViewModel = {
       showJumpDown: false,
-      setVisibleTileRange: () => {},
+      setVisibleTileRange() {},
       tiles,
+      // This will cause the event ID to be scrolled into view
+      get eventIdHighlighted() {
+        return scrollStartEventId;
+      },
     };
+    // Set the event highlight
+    if (scrollStartEventId) {
+      eventEntriesByEventId[scrollStartEventId].setIsHighlighted(true);
+    }
 
     // FIXME: Do we have to fake this?
     this.rightPanelModel = {
@@ -250,10 +257,6 @@ class ArchiveRoomViewModel extends ViewModel {
     return this._currentTopPositionEventEntry;
   }
 
-  get scrollStartPosition() {
-    return this._scrollStartPosition;
-  }
-
   get shouldShowRightPanel() {
     return this._shouldShowRightPanel;
   }
diff --git a/shared/viewmodels/JumpToNextActivitySummaryTileViewModel.js b/shared/viewmodels/JumpToNextActivitySummaryTileViewModel.js
index 3cf7f4e5..5b2c9034 100644
--- a/shared/viewmodels/JumpToNextActivitySummaryTileViewModel.js
+++ b/shared/viewmodels/JumpToNextActivitySummaryTileViewModel.js
@@ -38,7 +38,6 @@ class JumpToNextActivitySummaryTileViewModel extends SimpleTile {
       {
         ts: this.rangeEndTimestamp,
         dir: 'f',
-        scrollStartPosition: 'top',
       }
     );
   }
diff --git a/shared/views/ArchiveRoomView.js b/shared/views/ArchiveRoomView.js
index 85c27ea0..3a4c0cb3 100644
--- a/shared/views/ArchiveRoomView.js
+++ b/shared/views/ArchiveRoomView.js
@@ -146,12 +146,7 @@ class ArchiveRoomView extends TemplateView {
         t.main({ className: 'ArchiveRoomView_mainArea' }, [
           t.view(new RoomHeaderView(vm)),
           t.main({ className: 'ArchiveRoomView_mainBody' }, [
-            t.view(
-              new TimelineView(vm.timelineViewModel, {
-                viewClassForTile: customViewClassForTile,
-                stickToBottom: vm.scrollStartPosition === 'bottom',
-              })
-            ),
+            t.view(new TimelineView(vm.timelineViewModel, customViewClassForTile)),
             t.view(new DisabledComposerView(vm)),
           ]),
         ]),