From 2c80c1f288befed569f2927fddfbd1f04284a221 Mon Sep 17 00:00:00 2001
From: Eric Bailey <git@esb.lol>
Date: Wed, 28 May 2025 15:56:02 -0500
Subject: [PATCH] Checkpoint new traversal

---
 .../PostThread/components/ThreadReply.tsx     | 11 +--
 src/state/queries/usePostThread/index.ts      |  2 +-
 src/state/queries/usePostThread/traversal.ts  | 70 ++++++++++++++++++-
 src/state/queries/usePostThread/types.ts      | 17 +++++
 src/state/queries/usePostThread/utils.ts      | 65 +++++++++++++++++
 src/state/queries/usePostThread/views.ts      |  3 +-
 6 files changed, 154 insertions(+), 14 deletions(-)

diff --git a/src/screens/PostThread/components/ThreadReply.tsx b/src/screens/PostThread/components/ThreadReply.tsx
index 22abc7d365..4b7409c299 100644
--- a/src/screens/PostThread/components/ThreadReply.tsx
+++ b/src/screens/PostThread/components/ThreadReply.tsx
@@ -193,19 +193,14 @@ let PostThreadItemLoaded = ({
           ],
       ]}>
       {Array.from(Array(indents)).map((_, n: number) => {
-        const isLastIteration = n === indents - 1
+        const isSkipped = item.ui.skippedIndents.has(n)
         return (
           <View
             key={`${post.uri}-padding-${n}`}
             style={[
               t.atoms.border_contrast_low,
               {
-                borderRightWidth:
-                  isLastIteration &&
-                  item.ui.isDeadEnd &&
-                  !item.ui.precedesParentReadMore
-                    ? 0
-                    : REPLY_LINE_WIDTH,
+                borderRightWidth: isSkipped ? 0 : REPLY_LINE_WIDTH,
                 width: TREE_INDENT + TREE_AVI_WIDTH / 2,
                 left: 1,
               },
@@ -229,7 +224,7 @@ let PostThreadItemLoaded = ({
                 !item.ui.precedesParentReadMore &&
                 !item.ui.precedesChildReadMore && [a.pb_sm],
             ]}>
-            {item.ui.indent > 1 && item.ui.parentHasBranchingReplies && (
+            {item.ui.indent > 1 && (
               <View
                 style={[
                   a.absolute,
diff --git a/src/state/queries/usePostThread/index.ts b/src/state/queries/usePostThread/index.ts
index 8c4b509359..b553399dc5 100644
--- a/src/state/queries/usePostThread/index.ts
+++ b/src/state/queries/usePostThread/index.ts
@@ -41,7 +41,7 @@ export function usePostThread({
       const {data} = await agent.app.bsky.unspecced.getPostThreadV2({
         anchor: params.anchor!,
         branchingFactor: params.view === 'linear' ? 1 : 3, // 100 TODO
-        below: 3,
+        below: 6,
         sort: params.sort,
         prioritizeFollowedUsers: params.prioritizeFollowedUsers,
       })
diff --git a/src/state/queries/usePostThread/traversal.ts b/src/state/queries/usePostThread/traversal.ts
index 31c6f29f0a..6d95db7aa1 100644
--- a/src/state/queries/usePostThread/traversal.ts
+++ b/src/state/queries/usePostThread/traversal.ts
@@ -6,6 +6,7 @@ import {
 
 import {
   HiddenReplyKind,
+  type NTraversalMetadata,
   type PostThreadParams,
   type Slice,
   type TraversalMetadata,
@@ -13,6 +14,8 @@ import {
 import {
   getPostRecord,
   getPostTraversalMetadata,
+  getThreadPostUI,
+  getTraversalMetadata,
 } from '#/state/queries/usePostThread/utils'
 import * as views from '#/state/queries/usePostThread/views'
 
@@ -147,7 +150,6 @@ export function flatten(
       }
     }
   }
-  console.log(flattened)
 
   /*
    * Insert hidden items and buttons to show them
@@ -205,6 +207,11 @@ export function sort(
   const muted: Slice[] = []
   const postDataMap = new Map<string, TraversalMetadata | undefined>()
 
+  const metadatas = new Map<string, NTraversalMetadata>()
+
+  // @ts-ignore
+  window.__data = metadatas // for debugging
+
   traversal: for (let i = 0; i < thread.length; i++) {
     const item = thread[i]
 
@@ -297,8 +304,25 @@ export function sort(
         i = branch.end
         continue traversal
       } else if (AppBskyUnspeccedGetPostThreadV2.isThreadItemPost(item.value)) {
+        const parentMetadata = metadatas.get(
+          getPostRecord(item.value.post).reply?.parent?.uri || '',
+        )
         const oneUp = thread.at(i - 1)
         const oneDown = thread.at(i + 1)
+        const metadata = getTraversalMetadata({
+          item,
+          parentMetadata,
+          prevItem: oneUp,
+          nextItem: oneDown,
+        })
+        if (parentMetadata) {
+          parentMetadata.seenReplies += 1
+          metadata.isLastSibling =
+            parentMetadata.replies === parentMetadata.seenReplies
+        }
+        metadatas.set(item.uri, metadata)
+        metadatas.set(metadata.text, metadata) // TODO debugging
+
         const post = views.threadPost({
           uri: item.uri,
           depth: item.depth,
@@ -345,6 +369,26 @@ export function sort(
               if (
                 AppBskyUnspeccedGetPostThreadV2.isThreadItemPost(child.value)
               ) {
+                const childParentMetadata = metadatas.get(
+                  getPostRecord(child.value.post).reply?.parent?.uri || '',
+                )
+                const prevItem = thread[ci - 1]
+                const nextItem = thread[ci + 1]
+                const childMetadata = getTraversalMetadata({
+                  item: child,
+                  prevItem,
+                  nextItem,
+                  parentMetadata: childParentMetadata,
+                })
+                if (childParentMetadata) {
+                  childParentMetadata.seenReplies += 1
+                  childMetadata.isLastSibling =
+                    childParentMetadata.replies ===
+                    childParentMetadata.seenReplies
+                }
+                metadatas.set(item.uri, childMetadata)
+                metadatas.set(childMetadata.text, childMetadata) // TODO debugging
+
                 const childPost = views.threadPost({
                   uri: child.uri,
                   depth: child.depth,
@@ -352,8 +396,8 @@ export function sort(
                   traversalMetadata: postDataMap.get(
                     getPostRecord(child.value.post)?.reply?.parent?.uri || '',
                   ),
-                  oneUp: thread[ci - 1],
-                  oneDown: thread[ci + 1],
+                  oneUp: prevItem,
+                  oneDown: nextItem,
                   moderationOpts,
                 })
                 postDataMap.set(child.uri, getPostTraversalMetadata(childPost))
@@ -394,6 +438,26 @@ export function sort(
     }
   }
 
+  for (const item of items) {
+    if (item.type === 'threadPost') {
+      const metadata = metadatas.get(item.uri)
+      if (metadata) {
+        if (metadata.parentMetadata) {
+          metadata.skippedIndents = new Set([
+            ...metadata.parentMetadata.skippedIndents,
+          ])
+        }
+        if (metadata.isLastSibling) {
+          metadata.skippedIndents.add(item.depth - 2)
+        }
+
+        item.ui = getThreadPostUI(metadata)
+      }
+    }
+  }
+
+  // console.log(metadatas)
+
   return {
     items,
     hidden,
diff --git a/src/state/queries/usePostThread/types.ts b/src/state/queries/usePostThread/types.ts
index a0ccc24a3b..3e64d78eef 100644
--- a/src/state/queries/usePostThread/types.ts
+++ b/src/state/queries/usePostThread/types.ts
@@ -64,6 +64,8 @@ export type Slice =
          * this item.
          */
         precedesChildReadMore?: boolean
+        skippedIndents: Set<number>
+        [key: string]: any
       }
     }
   | {
@@ -109,3 +111,18 @@ export type TraversalMetadata = {
   indent: number
   hasBranchingReplies: boolean
 }
+
+export type NTraversalMetadata = {
+  depth: number
+  indent: number
+  replies: number
+  unhydratedReplies: number
+  seenReplies: number
+  hasBranchingReplies: boolean
+  isLastSibling: boolean
+  parentMetadata?: NTraversalMetadata
+  prevItemDepth?: number
+  nextItemDepth?: number
+  skippedIndents: Set<number>
+  [key: string]: any
+}
diff --git a/src/state/queries/usePostThread/utils.ts b/src/state/queries/usePostThread/utils.ts
index 9a09fc68f8..592472bac4 100644
--- a/src/state/queries/usePostThread/utils.ts
+++ b/src/state/queries/usePostThread/utils.ts
@@ -7,6 +7,7 @@ import {
 } from '@atproto/api'
 
 import {
+  type NTraversalMetadata,
   type Slice,
   type TraversalMetadata,
 } from '#/state/queries/usePostThread/types'
@@ -57,3 +58,67 @@ export function getPostTraversalMetadata(
     hasBranchingReplies: replyCount > 1 && replyCount - unhydratedReplies > 1,
   }
 }
+
+export function getTraversalMetadata({
+  item,
+  prevItem,
+  nextItem,
+  parentMetadata,
+}: {
+  item: AppBskyUnspeccedGetPostThreadV2.ThreadItem
+  prevItem?: AppBskyUnspeccedGetPostThreadV2.ThreadItem
+  nextItem?: AppBskyUnspeccedGetPostThreadV2.ThreadItem
+  parentMetadata?: NTraversalMetadata
+}): NTraversalMetadata {
+  if (!AppBskyUnspeccedGetPostThreadV2.isThreadItemPost(item.value)) {
+    throw new Error(`Expected thread item to be a post`)
+  }
+  const replies = item.value.post.replyCount || 0
+  const unhydratedReplies = item.value.moreReplies || 0
+  const hasBranchingReplies = replies > 1 && replies - unhydratedReplies > 1
+
+  return {
+    depth: item.depth,
+    // TODO maybe not used
+    indent: parentMetadata?.hasBranchingReplies
+      ? item.depth
+      : parentMetadata?.indent || item.depth,
+    replies,
+    unhydratedReplies,
+    seenReplies: 0,
+    hasBranchingReplies,
+    parentMetadata,
+    isLastSibling: false,
+    skippedIndents: new Set(),
+    prevItemDepth: prevItem?.depth,
+    nextItemDepth: nextItem?.depth,
+
+    // TODO non-spec
+    text: getPostRecord(item.value.post).text,
+  }
+}
+
+export function getThreadPostUI({
+  depth,
+  indent,
+  replies,
+  parentMetadata,
+  prevItemDepth,
+  nextItemDepth,
+  skippedIndents,
+}: NTraversalMetadata) {
+  return {
+    isAnchor: depth === 0,
+    showParentReplyLine:
+      !!prevItemDepth && prevItemDepth !== 0 && prevItemDepth < depth,
+    showChildReplyLine: replies > 0,
+    indent: depth,
+    parentHasBranchingReplies: !!parentMetadata?.hasBranchingReplies,
+    /*
+     * If there are no slices below this one, or the next slice is less
+     * indented than the computed indent for this post.
+     */
+    isDeadEnd: nextItemDepth === undefined || nextItemDepth < indent,
+    skippedIndents,
+  }
+}
diff --git a/src/state/queries/usePostThread/views.ts b/src/state/queries/usePostThread/views.ts
index 189c52942a..e763fe38f4 100644
--- a/src/state/queries/usePostThread/views.ts
+++ b/src/state/queries/usePostThread/views.ts
@@ -117,6 +117,7 @@ export function threadPost({
        * indented than the computed indent for this post.
        */
       isDeadEnd: !oneDown || oneDown?.depth < indent,
+      skippedIndents: new Set(),
     },
   }
 }
@@ -152,11 +153,9 @@ export function postViewToThreadPlaceholder(
     value: {
       $type: 'app.bsky.unspecced.getPostThreadV2#threadItemPost',
       post,
-      hiddenByThreadgate: false,
       opThread: false,
       moreParents: false,
       moreReplies: 0,
-      mutedByViewer: false,
     },
   }
 }