feat: refactor thought threads handling to improve structure and efficiency

thoughts-frontend/lib/utils.ts

@@ -1,35 +1,39 @@
 import { clsx, type ClassValue } from "clsx"
 import { twMerge } from "tailwind-merge"
-import { Thought } from "./api";
+import { Thought, ThoughtThread as ThoughtThreadType } from "./api";
 
 export function cn(...inputs: ClassValue[]) {
   return twMerge(clsx(inputs))
 }
 
-export function buildThoughtThreads(allThoughts: Thought[]) {
-  const repliesByParentId = new Map<string, Thought[]>();
-  const topLevelThoughts: Thought[] = [];
+export function buildThoughtThreads(thoughts: Thought[]): ThoughtThreadType[] {
+  const thoughtMap = new Map<string, Thought>();
+  thoughts.forEach((t) => thoughtMap.set(t.id, t));
 
-  // 1. Group all thoughts into top-level posts or replies
-  for (const thought of allThoughts) {
+  const threads: ThoughtThreadType[] = [];
+  const repliesMap: Record<string, Thought[]> = {};
+
+  thoughts.forEach((thought) => {
     if (thought.replyToId) {
-      // It's a reply, group it with its parent
-      const replies = repliesByParentId.get(thought.replyToId) || [];
-      replies.push(thought);
-      repliesByParentId.set(thought.replyToId, replies);
-    } else {
-      // It's a top-level thought
-      topLevelThoughts.push(thought);
+      if (!repliesMap[thought.replyToId]) {
+        repliesMap[thought.replyToId] = [];
+      }
+      repliesMap[thought.replyToId].push(thought);
     }
+  });
+
+  function buildThread(thought: Thought): ThoughtThreadType {
+    return {
+      ...thought,
+      replies: (repliesMap[thought.id] || []).map(buildThread),
+    };
   }
 
-  // 2. Sort top-level thoughts by date, newest first
-  topLevelThoughts.sort((a, b) => new Date(b.createdAt).getTime() - new Date(a.createdAt).getTime());
+  thoughts.forEach((thought) => {
+    if (!thought.replyToId) {
+      threads.push(buildThread(thought));
+    }
+  });
 
-  // 3. Sort replies within each thread by date, oldest first for conversational flow
-  for (const replies of repliesByParentId.values()) {
-    replies.sort((a, b) => new Date(a.createdAt).getTime() - new Date(b.createdAt).getTime());
-  }
-
-  return { topLevelThoughts, repliesByParentId };
+  return threads;
 }