From b04e628e003585b5b0956c4b1acd859d3e8186dc Mon Sep 17 00:00:00 2001
From: codytseng <codytseng98@gmail.com>
Date: Sun, 9 Mar 2025 15:28:12 +0800
Subject: [PATCH] feat: cache post content

---
 .../PostEditor/NormalPostContent.tsx          | 24 ++++++++++++--
 src/components/PostEditor/index.tsx           |  4 +--
 .../TextareaWithMentions.tsx/index.tsx        | 11 +++++++
 src/services/post-content-cache.service.ts    | 32 +++++++++++++++++++
 4 files changed, 67 insertions(+), 4 deletions(-)
 create mode 100644 src/services/post-content-cache.service.ts

diff --git a/src/components/PostEditor/NormalPostContent.tsx b/src/components/PostEditor/NormalPostContent.tsx
index 0f2faae0..048c8462 100644
--- a/src/components/PostEditor/NormalPostContent.tsx
+++ b/src/components/PostEditor/NormalPostContent.tsx
@@ -4,9 +4,10 @@ import { createCommentDraftEvent, createShortTextNoteDraftEvent } from '@/lib/dr
 import { getRootEventTag } from '@/lib/event.ts'
 import { useNostr } from '@/providers/NostrProvider'
 import client from '@/services/client.service'
+import postContentCache from '@/services/post-content-cache.service'
 import { ChevronDown, ImageUp, LoaderCircle } from 'lucide-react'
 import { Event, kinds, nip19 } from 'nostr-tools'
-import { useState } from 'react'
+import { useEffect, useRef, useState } from 'react'
 import { useTranslation } from 'react-i18next'
 import TextareaWithMentions from '../TextareaWithMentions.tsx'
 import Mentions from './Mentions'
@@ -27,7 +28,7 @@ export default function NormalPostContent({
   const { t } = useTranslation()
   const { toast } = useToast()
   const { publish, checkLogin } = useNostr()
-  const [content, setContent] = useState(defaultContent)
+  const [content, setContent] = useState('')
   const [pictureInfos, setPictureInfos] = useState<{ url: string; tags: string[][] }[]>([])
   const [posting, setPosting] = useState(false)
   const [showMoreOptions, setShowMoreOptions] = useState(false)
@@ -35,8 +36,26 @@ export default function NormalPostContent({
   const [specifiedRelayUrls, setSpecifiedRelayUrls] = useState<string[] | undefined>(undefined)
   const [uploadingPicture, setUploadingPicture] = useState(false)
   const [mentions, setMentions] = useState<string[]>([])
+  const [cursorOffset, setCursorOffset] = useState(0)
+  const initializedRef = useRef(false)
   const canPost = !!content && !posting
 
+  useEffect(() => {
+    const cachedContent = postContentCache.get({ defaultContent, parentEvent })
+    if (cachedContent) {
+      setContent(cachedContent)
+    }
+    if (defaultContent) {
+      setCursorOffset(defaultContent.length)
+    }
+    initializedRef.current = true
+  }, [defaultContent, parentEvent])
+
+  useEffect(() => {
+    if (!initializedRef.current) return
+    postContentCache.set({ defaultContent, parentEvent }, content)
+  }, [content])
+
   const post = async (e: React.MouseEvent) => {
     e.stopPropagation()
     checkLogin(async () => {
@@ -130,6 +149,7 @@ export default function NormalPostContent({
         setTextValue={setContent}
         textValue={content}
         placeholder={t('Write something...')}
+        cursorOffset={cursorOffset}
       />
       {content && <Preview content={content} />}
       <SendOnlyToSwitch
diff --git a/src/components/PostEditor/index.tsx b/src/components/PostEditor/index.tsx
index 9b62ed42..15fe462c 100644
--- a/src/components/PostEditor/index.tsx
+++ b/src/components/PostEditor/index.tsx
@@ -10,11 +10,11 @@ import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs'
 import { useScreenSize } from '@/providers/ScreenSizeProvider'
 import { Event } from 'nostr-tools'
 import { Dispatch, useMemo } from 'react'
+import { useTranslation } from 'react-i18next'
 import { Sheet, SheetContent, SheetDescription, SheetHeader, SheetTitle } from '../ui/sheet'
 import NormalPostContent from './NormalPostContent'
 import PicturePostContent from './PicturePostContent'
 import Title from './Title'
-import { useTranslation } from 'react-i18next'
 
 export default function PostEditor({
   defaultContent = '',
@@ -55,7 +55,7 @@ export default function PostEditor({
         </TabsContent>
       </Tabs>
     )
-  }, [parentEvent])
+  }, [parentEvent, defaultContent])
 
   if (isSmallScreen) {
     return (
diff --git a/src/components/TextareaWithMentions.tsx/index.tsx b/src/components/TextareaWithMentions.tsx/index.tsx
index 75b5076f..da17bcdc 100644
--- a/src/components/TextareaWithMentions.tsx/index.tsx
+++ b/src/components/TextareaWithMentions.tsx/index.tsx
@@ -21,10 +21,12 @@ import { getCurrentWord, replaceWord } from './utils'
 export default function TextareaWithMentions({
   textValue,
   setTextValue,
+  cursorOffset = 0,
   ...props
 }: ComponentProps<'textarea'> & {
   textValue: string
   setTextValue: Dispatch<SetStateAction<string>>
+  cursorOffset?: number
 }) {
   const textareaRef = useRef<HTMLTextAreaElement>(null)
   const dropdownRef = useRef<HTMLDivElement>(null)
@@ -33,6 +35,15 @@ export default function TextareaWithMentions({
   const [debouncedCommandValue, setDebouncedCommandValue] = useState(commandValue)
   const [profiles, setProfiles] = useState<TProfile[]>([])
 
+  useEffect(() => {
+    if (textareaRef.current && cursorOffset !== 0) {
+      const textarea = textareaRef.current
+      const newPos = Math.max(0, textarea.selectionStart - cursorOffset)
+      textarea.setSelectionRange(newPos, newPos)
+      textarea.focus()
+    }
+  }, [cursorOffset])
+
   useEffect(() => {
     const handler = setTimeout(() => {
       setDebouncedCommandValue(commandValue)
diff --git a/src/services/post-content-cache.service.ts b/src/services/post-content-cache.service.ts
new file mode 100644
index 00000000..24f165fb
--- /dev/null
+++ b/src/services/post-content-cache.service.ts
@@ -0,0 +1,32 @@
+import { Event } from 'nostr-tools'
+
+class PostContentCacheService {
+  static instance: PostContentCacheService
+
+  private cache: Map<string, string> = new Map()
+
+  constructor() {
+    if (!PostContentCacheService.instance) {
+      PostContentCacheService.instance = this
+    }
+    return PostContentCacheService.instance
+  }
+
+  get({ defaultContent, parentEvent }: { defaultContent?: string; parentEvent?: Event } = {}) {
+    return this.cache.get(this.generateCacheKey(defaultContent, parentEvent)) ?? defaultContent
+  }
+
+  set(
+    { defaultContent, parentEvent }: { defaultContent?: string; parentEvent?: Event },
+    content: string
+  ) {
+    this.cache.set(this.generateCacheKey(defaultContent, parentEvent), content)
+  }
+
+  generateCacheKey(defaultContent: string = '', parentEvent?: Event): string {
+    return parentEvent ? parentEvent.id : defaultContent
+  }
+}
+
+const instance = new PostContentCacheService()
+export default instance