From 86d2a36731e8ecc3dead4d46cdfb92c1b73f2f00 Mon Sep 17 00:00:00 2001
From: undefined <i@undefined.moe>
Date: Tue, 25 Aug 2026 05:39:05 +0000
Subject: [PATCH] ui: migrate scratchpad drafts to IndexedDB

---
 .../components/scratchpad/reducers/editor.ts  | 25 ++++------------
 .../ui-default/pages/problem_detail.page.tsx  | 29 +++++++++++++++++++
 packages/ui-default/utils/db.ts               | 24 ++++++++++++++-
 3 files changed, 57 insertions(+), 21 deletions(-)

diff --git a/packages/ui-default/components/scratchpad/reducers/editor.ts b/packages/ui-default/components/scratchpad/reducers/editor.ts
index bc033bb74..bee53cd62 100644
--- a/packages/ui-default/components/scratchpad/reducers/editor.ts
+++ b/packages/ui-default/components/scratchpad/reducers/editor.ts
@@ -1,24 +1,9 @@
-let cacheKey = `${UserContext._id}/${UiContext.pdoc.domainId}/${UiContext.pdoc.docId}`;
-if (UiContext.tdoc?._id) cacheKey += `@${UiContext.tdoc._id}`;
-
-// TODO switch to indexeddb
 export default function reducer(state = {
-  lang: localStorage.getItem(`${cacheKey}#lang`) || UiContext.codeLang,
-  code: localStorage.getItem(cacheKey) || UiContext.codeTemplate,
+  lang: UiContext.codeLang,
+  code: UiContext.codeTemplate,
 }, action: any = {}) {
-  if (action.type === 'SCRATCHPAD_EDITOR_UPDATE_CODE') {
-    localStorage.setItem(cacheKey, action.payload);
-    return {
-      ...state,
-      code: action.payload,
-    };
-  }
-  if (action.type === 'SCRATCHPAD_EDITOR_SET_LANG') {
-    localStorage.setItem(`${cacheKey}#lang`, action.payload);
-    return {
-      ...state,
-      lang: action.payload,
-    };
-  }
+  if (action.type === 'SCRATCHPAD_EDITOR_HYDRATE') return action.payload;
+  if (action.type === 'SCRATCHPAD_EDITOR_UPDATE_CODE') return { ...state, code: action.payload };
+  if (action.type === 'SCRATCHPAD_EDITOR_SET_LANG') return { ...state, lang: action.payload };
   return state;
 }
diff --git a/packages/ui-default/pages/problem_detail.page.tsx b/packages/ui-default/pages/problem_detail.page.tsx
index 00507ec11..35d4ecf9b 100644
--- a/packages/ui-default/pages/problem_detail.page.tsx
+++ b/packages/ui-default/pages/problem_detail.page.tsx
@@ -1,5 +1,6 @@
 import $ from 'jquery';
 import * as yaml from 'js-yaml';
+import _ from 'lodash';
 import React from 'react';
 import { createRoot } from 'react-dom/client';
 import { confirm } from 'vj/components/dialog';
@@ -144,6 +145,34 @@ const page = new NamedPage(['problem_detail', 'contest_detail_problem', 'homewor
     const { default: ScratchpadApp } = await import('../components/scratchpad');
     const { default: ScratchpadReducer } = await import('../components/scratchpad/reducers');
     const { Provider, store } = await loadReactRedux(ScratchpadReducer);
+    let cacheKey = `${UserContext._id}/${UiContext.pdoc.domainId}/${UiContext.pdoc.docId}`;
+    if (UiContext.tdoc?._id) cacheKey += `@${UiContext.tdoc._id}`;
+    try {
+      const draft = await (await openDB).get('scratchpad-drafts', cacheKey);
+      if (draft) {
+        store.dispatch({
+          type: 'SCRATCHPAD_EDITOR_HYDRATE',
+          payload: {
+            code: draft.code ?? UiContext.codeTemplate,
+            lang: draft.lang ?? UiContext.codeLang,
+          },
+        });
+      }
+    } catch { }
+
+    let previousEditorState = store.getState().editor;
+    let write = Promise.resolve();
+    const saveDraft = _.debounce((code: string, lang: string) => {
+      write = write
+        .then(() => openDB.then((db) => db.put('scratchpad-drafts', { id: cacheKey, code, lang })))
+        .catch(() => { });
+    }, 400);
+    store.subscribe(() => {
+      const editor = store.getState().editor;
+      if (editor === previousEditorState) return;
+      previousEditorState = editor;
+      saveDraft(editor.code, editor.lang);
+    });
 
     // @ts-ignore
     window.store = store;
diff --git a/packages/ui-default/utils/db.ts b/packages/ui-default/utils/db.ts
index 0f2e853bd..bee69f419 100644
--- a/packages/ui-default/utils/db.ts
+++ b/packages/ui-default/utils/db.ts
@@ -1,7 +1,9 @@
 import { openDB as _open } from 'idb';
 import { alert } from 'vj/components/dialog';
 
-export const openDB = _open('hydro', 2, {
+const scratchpadCleanup: string[] = [];
+
+export const openDB = _open('hydro', 3, {
   upgrade(db, oldVersion) {
     if (oldVersion < 1) {
       const solutionStore = db.createObjectStore('solutions', { keyPath: 'id' });
@@ -18,6 +20,23 @@ export const openDB = _open('hydro', 2, {
       }
     }
     if (oldVersion < 2) db.createObjectStore('domain-info', { keyPath: 'id' });
+    if (oldVersion < 3) {
+      const scratchpadStore = db.createObjectStore('scratchpad-drafts', { keyPath: 'id' });
+      const drafts = new Map<string, { id: string, code?: string, lang?: string }>();
+      const scratchpadKey = /^(\d+\/[A-Za-z]\w{3,31}\/\d+(?:@[\dA-Fa-f]{24})?)(#lang)?$/;
+      for (const key of Object.keys(localStorage)) {
+        const match = key.match(scratchpadKey);
+        if (!match) continue;
+        const value = localStorage.getItem(key);
+        if (value === null) continue;
+        const draft = drafts.get(match[1]) || { id: match[1] };
+        if (match[2]) draft.lang = value;
+        else draft.code = value;
+        drafts.set(draft.id, draft);
+        scratchpadCleanup.push(key);
+      }
+      for (const draft of drafts.values()) scratchpadStore.put(draft);
+    }
   },
   blocked(currentVersion, blockedVersion) {
     console.error('IDB Blocked by version', blockedVersion, 'want', currentVersion);
@@ -30,4 +49,7 @@ export const openDB = _open('hydro', 2, {
   terminated() {
     console.error('IDB Terminated');
   },
+}).then((db) => {
+  for (const key of scratchpadCleanup) localStorage.removeItem(key);
+  return db;
 });