From 0a165cb2adbc0bde12b90bad6dc57b3f99545bcb Mon Sep 17 00:00:00 2001
From: Nolan Lawson <nolan@nolanlawson.com>
Date: Sat, 10 Feb 2018 14:19:10 -0800
Subject: [PATCH] dont scroll to first item, it obscures back button

---
 .../PseudoVirtualListLazyItem.html               |  1 -
 routes/_components/timeline/Timeline.html        | 16 ++++++++++++----
 routes/_store/timelineComputations.js            |  1 +
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/routes/_components/pseudoVirtualList/PseudoVirtualListLazyItem.html b/routes/_components/pseudoVirtualList/PseudoVirtualListLazyItem.html
index 2aa7d7a..0e3046f 100644
--- a/routes/_components/pseudoVirtualList/PseudoVirtualListLazyItem.html
+++ b/routes/_components/pseudoVirtualList/PseudoVirtualListLazyItem.html
@@ -4,7 +4,6 @@
                          :key
                          :index
                          :length
-                         :scrollToThisItem
                          :intersectionObserver
                          :isIntersecting
                          :isCached
diff --git a/routes/_components/timeline/Timeline.html b/routes/_components/timeline/Timeline.html
index 1afb517..42c83ac 100644
--- a/routes/_components/timeline/Timeline.html
+++ b/routes/_components/timeline/Timeline.html
@@ -37,7 +37,7 @@
                        items="{{$timelineItemIds}}"
                        shown="{{$initialized}}"
                        on:initializedVisibleItems="initialize()"
-                       scrollToItem="{{timelineValue}}"
+                       scrollToItem="{{scrollToItem}}"
                        realm="{{$currentInstance + '/' + timeline}}"
     />
   {{/if}}
@@ -115,9 +115,17 @@
       timelineValue: (timeline) => {
         return timeline.split('/').slice(-1)[0]
       },
-      // for threads, it's simpler to just render all items due to need to scroll to the right item
-      // TODO: this can be optimized to use a virtual list
-      virtual: (timelineType) => timelineType !=='status'
+      // for threads, it's simpler to just render all items as a pseudo-virtual list
+      // due to need to scroll to the right item and thus calculate all item heights up-front
+      virtual: (timelineType) => timelineType !=='status',
+      scrollToItem: (timelineType, timelineValue, $firstTimelineItemId) => {
+        // Scroll to the first item if this is a "status in own thread" timeline.
+        // Don't scroll to the first item because it obscures the "back" button.
+        return timelineType === 'status'
+          && $firstTimelineItemId
+          && timelineValue !== $firstTimelineItemId
+          && timelineValue
+      }
     },
     store: () => store,
     components: {
diff --git a/routes/_store/timelineComputations.js b/routes/_store/timelineComputations.js
index dd332fb..a4c9e64 100644
--- a/routes/_store/timelineComputations.js
+++ b/routes/_store/timelineComputations.js
@@ -16,5 +16,6 @@ export function timelineComputations (store) {
   computeForTimeline(store, 'lastFocusedElementSelector')
   computeForTimeline(store, 'ignoreBlurEvents')
 
+  store.compute('firstTimelineItemId', ['timelineItemIds'], (timelineItemIds) => timelineItemIds && timelineItemIds.length && timelineItemIds[0])
   store.compute('lastTimelineItemId', ['timelineItemIds'], (timelineItemIds) => timelineItemIds && timelineItemIds.length && timelineItemIds[timelineItemIds.length - 1])
 }