From 48ec3716ca1b75148487420bac4185954ee8ef4d Mon Sep 17 00:00:00 2001
From: Ryan Di <ryan.weihao.di@gmail.com>
Date: Thu, 29 May 2025 16:19:20 +1000
Subject: [PATCH] feat: manage rooms locally

---
 excalidraw-app/collab/Collab.tsx   |  20 +++
 excalidraw-app/data/roomManager.ts | 193 +++++++++++++++++++++++++++++
 2 files changed, 213 insertions(+)
 create mode 100644 excalidraw-app/data/roomManager.ts

diff --git a/excalidraw-app/collab/Collab.tsx b/excalidraw-app/collab/Collab.tsx
index bed130e24a..595295611f 100644
--- a/excalidraw-app/collab/Collab.tsx
+++ b/excalidraw-app/collab/Collab.tsx
@@ -83,6 +83,7 @@ import {
   saveUsernameToLocalStorage,
 } from "../data/localStorage";
 import { resetBrowserStateVersions } from "../data/tabSync";
+import { roomManager } from "../data/roomManager";
 
 import { collabErrorIndicatorAtom } from "./CollabError";
 import Portal from "./Portal";
@@ -547,6 +548,25 @@ class Collab extends PureComponent<CollabProps, CollabState> {
       });
 
       this.saveCollabRoomToFirebase(getSyncableElements(elements));
+
+      // Save room data to local room manager for new rooms
+      try {
+        await roomManager.addRoom(
+          roomId,
+          roomKey,
+          getCollaborationLink({ roomId, roomKey }),
+          "", // User can edit this later
+        );
+      } catch (error) {
+        console.warn("Failed to save room to local storage:", error);
+      }
+    } else {
+      // Update access time for existing rooms
+      try {
+        await roomManager.updateRoomAccess(existingRoomLinkData.roomId);
+      } catch (error) {
+        console.warn("Failed to update room access time:", error);
+      }
     }
 
     // fallback in case you're not alone in the room but still don't receive
diff --git a/excalidraw-app/data/roomManager.ts b/excalidraw-app/data/roomManager.ts
new file mode 100644
index 0000000000..008cad901b
--- /dev/null
+++ b/excalidraw-app/data/roomManager.ts
@@ -0,0 +1,193 @@
+import {
+  generateEncryptionKey,
+  encryptData,
+  decryptData,
+} from "@excalidraw/excalidraw/data/encryption";
+
+export interface CollabRoom {
+  id: string;
+  roomId: string;
+  roomKey: string;
+  createdAt: number;
+  lastAccessed: number;
+  url: string;
+  name?: string;
+}
+
+interface EncryptedRoomData {
+  rooms: CollabRoom[];
+  version: number;
+}
+
+const ROOM_STORAGE_KEY = "excalidraw-user-rooms";
+const ROOM_STORAGE_VERSION = 1;
+
+class RoomManager {
+  private userKey: string | null = null;
+
+  private async getUserKey(): Promise<string> {
+    if (this.userKey) {
+      return this.userKey;
+    }
+
+    try {
+      const stored = localStorage.getItem(`${ROOM_STORAGE_KEY}-key`);
+      if (stored) {
+        this.userKey = stored;
+        return this.userKey;
+      }
+    } catch (error) {
+      console.warn("Failed to load user key from localStorage:", error);
+    }
+
+    this.userKey = await generateEncryptionKey();
+
+    try {
+      localStorage.setItem(`${ROOM_STORAGE_KEY}-key`, this.userKey);
+    } catch (error) {
+      console.warn("Failed to save user key to localStorage:", error);
+    }
+
+    return this.userKey;
+  }
+
+  private async encryptRoomData(
+    data: EncryptedRoomData,
+  ): Promise<{ data: ArrayBuffer; iv: Uint8Array }> {
+    const userKey = await this.getUserKey();
+    const jsonData = JSON.stringify(data);
+    const { encryptedBuffer, iv } = await encryptData(userKey, jsonData);
+    return { data: encryptedBuffer, iv };
+  }
+
+  private async decryptRoomData(
+    encryptedData: ArrayBuffer,
+    iv: Uint8Array,
+  ): Promise<EncryptedRoomData | null> {
+    try {
+      const userKey = await this.getUserKey();
+      const decryptedBuffer = await decryptData(iv, encryptedData, userKey);
+      const jsonString = new TextDecoder().decode(decryptedBuffer);
+      const data = JSON.parse(jsonString) as EncryptedRoomData;
+
+      if (data.version === ROOM_STORAGE_VERSION && Array.isArray(data.rooms)) {
+        return data;
+      }
+
+      return null;
+    } catch (error) {
+      console.warn("Failed to decrypt room data:", error);
+      return null;
+    }
+  }
+
+  private async loadRooms(): Promise<CollabRoom[]> {
+    try {
+      const storedData = localStorage.getItem(ROOM_STORAGE_KEY);
+      if (!storedData) {
+        return [];
+      }
+
+      const { data, iv } = JSON.parse(storedData);
+      const dataBuffer = new Uint8Array(data).buffer;
+      const ivArray = new Uint8Array(iv);
+
+      const decryptedData = await this.decryptRoomData(dataBuffer, ivArray);
+      return decryptedData?.rooms || [];
+    } catch (error) {
+      console.warn("Failed to load rooms:", error);
+      return [];
+    }
+  }
+
+  private async saveRooms(rooms: CollabRoom[]): Promise<void> {
+    try {
+      const data: EncryptedRoomData = {
+        rooms,
+        version: ROOM_STORAGE_VERSION,
+      };
+
+      const { data: encryptedData, iv } = await this.encryptRoomData(data);
+
+      const storageData = {
+        data: Array.from(new Uint8Array(encryptedData)),
+        iv: Array.from(iv),
+      };
+
+      localStorage.setItem(ROOM_STORAGE_KEY, JSON.stringify(storageData));
+    } catch (error) {
+      console.warn("Failed to save rooms:", error);
+    }
+  }
+
+  async addRoom(
+    roomId: string,
+    roomKey: string,
+    url: string,
+    name?: string,
+  ): Promise<void> {
+    const rooms = await this.loadRooms();
+
+    const filteredRooms = rooms.filter((room) => room.roomId !== roomId);
+
+    const newRoom: CollabRoom = {
+      id: crypto.randomUUID(),
+      roomId,
+      roomKey,
+      createdAt: Date.now(),
+      lastAccessed: Date.now(),
+      url,
+      name,
+    };
+
+    filteredRooms.unshift(newRoom);
+
+    // Limit to the most recent 20 rooms
+    const limitedRooms = filteredRooms.slice(0, 20);
+
+    await this.saveRooms(limitedRooms);
+  }
+
+  async getRooms(): Promise<CollabRoom[]> {
+    const rooms = await this.loadRooms();
+    return rooms.sort((a, b) => b.lastAccessed - a.lastAccessed);
+  }
+
+  async updateRoomAccess(roomId: string): Promise<void> {
+    const rooms = await this.loadRooms();
+    const room = rooms.find((r) => r.roomId === roomId);
+
+    if (room) {
+      room.lastAccessed = Date.now();
+      await this.saveRooms(rooms);
+    }
+  }
+
+  async deleteRoom(roomId: string): Promise<void> {
+    const rooms = await this.loadRooms();
+    const filteredRooms = rooms.filter((room) => room.roomId !== roomId);
+    await this.saveRooms(filteredRooms);
+  }
+
+  async updateRoomName(roomId: string, name: string): Promise<void> {
+    const rooms = await this.loadRooms();
+    const room = rooms.find((r) => r.roomId === roomId);
+
+    if (room) {
+      room.name = name;
+      await this.saveRooms(rooms);
+    }
+  }
+
+  async clearAllRooms(): Promise<void> {
+    try {
+      localStorage.removeItem(ROOM_STORAGE_KEY);
+      localStorage.removeItem(`${ROOM_STORAGE_KEY}-key`);
+      this.userKey = null;
+    } catch (error) {
+      console.warn("Failed to clear rooms:", error);
+    }
+  }
+}
+
+export const roomManager = new RoomManager();