feat: load tweet conversations

src/features/posts/post-service.ts

@@ -1,10 +1,23 @@
-import type { SearchProduct, SearchResult, TweetData } from '@yuta/bird'
-import { buildSearchQuery, InputError, normalizeUserTarget } from './inputs'
+import type {
+  GetTweetResult,
+  SearchProduct,
+  SearchResult,
+  TweetData,
+} from '@yuta/bird'
+import {
+  buildSearchQuery,
+  InputError,
+  normalizeTweetId,
+  normalizeUserTarget,
+} from './inputs'
 import type {
   LoadError,
+  LoadFailure,
   LoadResult,
   Post,
   SearchPageInput,
+  ThreadLoadResult,
+  ThreadPageInput,
   UserPageInput,
 } from './types'
 
@@ -15,6 +28,15 @@ type UserLookupResult = {
 }
 
 export interface BirdReader {
+  getTweet(tweetId: string): Promise<GetTweetResult>
+  getThreadPaged(
+    tweetId: string,
+    options: {
+      cursor?: string
+      maxPages: number
+      pageDelayMs: number
+    },
+  ): Promise<SearchResult>
   getUserIdByUsername(username: string): Promise<UserLookupResult>
   getUserTweetsPaged(
     userId: string,
@@ -39,9 +61,12 @@ const failure = (
   code: LoadError['code'],
   message: string,
   retryable: boolean,
-): LoadResult => ({ ok: false, error: { code, message, retryable } })
+): LoadFailure => ({ ok: false, error: { code, message, retryable } })
 
-function upstreamFailure(diagnostic: unknown = ''): LoadResult {
+function upstreamFailure(
+  diagnostic: unknown = '',
+  subject: 'user' | 'post' = 'user',
+): LoadFailure {
   const message =
     diagnostic instanceof Error
       ? diagnostic.message
@@ -53,14 +78,18 @@ function upstreamFailure(diagnostic: unknown = ''): LoadResult {
     return failure('timeout', '取得がタイムアウトしました。', true)
   }
   if (lower.includes('not found')) {
-    return failure('user-not-found', 'ユーザーが見つかりませんでした。', false)
+    return subject === 'post'
+      ? failure('post-not-found', '投稿が見つかりませんでした。', false)
+      : failure('user-not-found', 'ユーザーが見つかりませんでした。', false)
   }
   if (lower.includes('suspended') || lower.includes('protected')) {
-    return failure(
-      'user-unavailable',
-      'このユーザーの投稿は取得できません。',
-      false,
-    )
+    return subject === 'post'
+      ? failure('post-unavailable', 'この投稿は取得できません。', false)
+      : failure(
+          'user-unavailable',
+          'このユーザーの投稿は取得できません。',
+          false,
+        )
   }
   console.error('Unexpected Bird failure:', diagnostic)
   return failure('upstream', 'X から投稿を取得できませんでした。', true)
@@ -87,6 +116,54 @@ function resultPage(result: SearchResult): LoadResult {
     : upstreamFailure(result.error)
 }
 
+export async function loadThreadPage(
+  reader: BirdReader,
+  input: ThreadPageInput,
+): Promise<ThreadLoadResult> {
+  try {
+    const tweetId = normalizeTweetId(input.tweetId)
+    let focalPost: Post | undefined
+    let conversationId: string
+
+    if (input.cursor && input.conversationId) {
+      conversationId = normalizeTweetId(input.conversationId)
+    } else {
+      const focal = await reader.getTweet(tweetId)
+      if (!focal.success || !focal.tweet) {
+        return upstreamFailure(focal.error ?? 'Tweet not found', 'post')
+      }
+      focalPost = publicPost(focal.tweet)
+      conversationId = normalizeTweetId(
+        focal.tweet.conversationId ?? focal.tweet.id,
+      )
+    }
+
+    const result = await reader.getThreadPaged(conversationId, {
+      ...(input.cursor ? { cursor: input.cursor } : {}),
+      maxPages: 1,
+      pageDelayMs: 0,
+    })
+    if (!result.success) {
+      return upstreamFailure(result.error, 'post')
+    }
+
+    return {
+      ok: true,
+      page: {
+        tweets: (result.tweets ?? []).map(publicPost),
+        focalPost,
+        conversationId,
+        nextCursor: result.nextCursor,
+      },
+    }
+  } catch (error) {
+    if (error instanceof InputError) {
+      return failure('invalid-input', error.message, false)
+    }
+    return upstreamFailure(error, 'post')
+  }
+}
+
 export async function loadUserPage(
   reader: BirdReader,
   input: UserPageInput,