1 files changed, 313 insertions, 0 deletions
diff --git a/excalidraw-app/data/firebase.ts b/excalidraw-app/data/firebase.ts
new file mode 100644
index 0000000..a871b48
--- /dev/null
+++ b/excalidraw-app/data/firebase.ts
@@ -0,0 +1,313 @@
+import { reconcileElements } from "@excalidraw/excalidraw";
+import type {
+  ExcalidrawElement,
+  FileId,
+  OrderedExcalidrawElement,
+} from "@excalidraw/excalidraw/element/types";
+import { getSceneVersion } from "@excalidraw/excalidraw/element";
+import type Portal from "../collab/Portal";
+import { restoreElements } from "@excalidraw/excalidraw/data/restore";
+import type {
+  AppState,
+  BinaryFileData,
+  BinaryFileMetadata,
+  DataURL,
+} from "@excalidraw/excalidraw/types";
+import { FILE_CACHE_MAX_AGE_SEC } from "../app_constants";
+import { decompressData } from "@excalidraw/excalidraw/data/encode";
+import {
+  encryptData,
+  decryptData,
+} from "@excalidraw/excalidraw/data/encryption";
+import { MIME_TYPES } from "@excalidraw/excalidraw/constants";
+import type { SyncableExcalidrawElement } from ".";
+import { getSyncableElements } from ".";
+import { initializeApp } from "firebase/app";
+import {
+  getFirestore,
+  doc,
+  getDoc,
+  runTransaction,
+  Bytes,
+} from "firebase/firestore";
+import { getStorage, ref, uploadBytes } from "firebase/storage";
+import type { Socket } from "socket.io-client";
+import type { RemoteExcalidrawElement } from "@excalidraw/excalidraw/data/reconcile";
+
+// private
+// -----------------------------------------------------------------------------
+
+let FIREBASE_CONFIG: Record<string, any>;
+try {
+  FIREBASE_CONFIG = JSON.parse(import.meta.env.VITE_APP_FIREBASE_CONFIG);
+} catch (error: any) {
+  console.warn(
+    `Error JSON parsing firebase config. Supplied value: ${
+      import.meta.env.VITE_APP_FIREBASE_CONFIG
+    }`,
+  );
+  FIREBASE_CONFIG = {};
+}
+
+let firebaseApp: ReturnType<typeof initializeApp> | null = null;
+let firestore: ReturnType<typeof getFirestore> | null = null;
+let firebaseStorage: ReturnType<typeof getStorage> | null = null;
+
+const _initializeFirebase = () => {
+  if (!firebaseApp) {
+    firebaseApp = initializeApp(FIREBASE_CONFIG);
+  }
+  return firebaseApp;
+};
+
+const _getFirestore = () => {
+  if (!firestore) {
+    firestore = getFirestore(_initializeFirebase());
+  }
+  return firestore;
+};
+
+const _getStorage = () => {
+  if (!firebaseStorage) {
+    firebaseStorage = getStorage(_initializeFirebase());
+  }
+  return firebaseStorage;
+};
+
+// -----------------------------------------------------------------------------
+
+export const loadFirebaseStorage = async () => {
+  return _getStorage();
+};
+
+type FirebaseStoredScene = {
+  sceneVersion: number;
+  iv: Bytes;
+  ciphertext: Bytes;
+};
+
+const encryptElements = async (
+  key: string,
+  elements: readonly ExcalidrawElement[],
+): Promise<{ ciphertext: ArrayBuffer; iv: Uint8Array }> => {
+  const json = JSON.stringify(elements);
+  const encoded = new TextEncoder().encode(json);
+  const { encryptedBuffer, iv } = await encryptData(key, encoded);
+
+  return { ciphertext: encryptedBuffer, iv };
+};
+
+const decryptElements = async (
+  data: FirebaseStoredScene,
+  roomKey: string,
+): Promise<readonly ExcalidrawElement[]> => {
+  const ciphertext = data.ciphertext.toUint8Array();
+  const iv = data.iv.toUint8Array();
+
+  const decrypted = await decryptData(iv, ciphertext, roomKey);
+  const decodedData = new TextDecoder("utf-8").decode(
+    new Uint8Array(decrypted),
+  );
+  return JSON.parse(decodedData);
+};
+
+class FirebaseSceneVersionCache {
+  private static cache = new WeakMap<Socket, number>();
+  static get = (socket: Socket) => {
+    return FirebaseSceneVersionCache.cache.get(socket);
+  };
+  static set = (
+    socket: Socket,
+    elements: readonly SyncableExcalidrawElement[],
+  ) => {
+    FirebaseSceneVersionCache.cache.set(socket, getSceneVersion(elements));
+  };
+}
+
+export const isSavedToFirebase = (
+  portal: Portal,
+  elements: readonly ExcalidrawElement[],
+): boolean => {
+  if (portal.socket && portal.roomId && portal.roomKey) {
+    const sceneVersion = getSceneVersion(elements);
+
+    return FirebaseSceneVersionCache.get(portal.socket) === sceneVersion;
+  }
+  // if no room exists, consider the room saved so that we don't unnecessarily
+  // prevent unload (there's nothing we could do at that point anyway)
+  return true;
+};
+
+export const saveFilesToFirebase = async ({
+  prefix,
+  files,
+}: {
+  prefix: string;
+  files: { id: FileId; buffer: Uint8Array }[];
+}) => {
+  const storage = await loadFirebaseStorage();
+
+  const erroredFiles: FileId[] = [];
+  const savedFiles: FileId[] = [];
+
+  await Promise.all(
+    files.map(async ({ id, buffer }) => {
+      try {
+        const storageRef = ref(storage, `${prefix}/${id}`);
+        await uploadBytes(storageRef, buffer, {
+          cacheControl: `public, max-age=${FILE_CACHE_MAX_AGE_SEC}`,
+        });
+        savedFiles.push(id);
+      } catch (error: any) {
+        erroredFiles.push(id);
+      }
+    }),
+  );
+
+  return { savedFiles, erroredFiles };
+};
+
+const createFirebaseSceneDocument = async (
+  elements: readonly SyncableExcalidrawElement[],
+  roomKey: string,
+) => {
+  const sceneVersion = getSceneVersion(elements);
+  const { ciphertext, iv } = await encryptElements(roomKey, elements);
+  return {
+    sceneVersion,
+    ciphertext: Bytes.fromUint8Array(new Uint8Array(ciphertext)),
+    iv: Bytes.fromUint8Array(iv),
+  } as FirebaseStoredScene;
+};
+
+export const saveToFirebase = async (
+  portal: Portal,
+  elements: readonly SyncableExcalidrawElement[],
+  appState: AppState,
+) => {
+  const { roomId, roomKey, socket } = portal;
+  if (
+    // bail if no room exists as there's nothing we can do at this point
+    !roomId ||
+    !roomKey ||
+    !socket ||
+    isSavedToFirebase(portal, elements)
+  ) {
+    return null;
+  }
+
+  const firestore = _getFirestore();
+  const docRef = doc(firestore, "scenes", roomId);
+
+  const storedScene = await runTransaction(firestore, async (transaction) => {
+    const snapshot = await transaction.get(docRef);
+
+    if (!snapshot.exists()) {
+      const storedScene = await createFirebaseSceneDocument(elements, roomKey);
+
+      transaction.set(docRef, storedScene);
+
+      return storedScene;
+    }
+
+    const prevStoredScene = snapshot.data() as FirebaseStoredScene;
+    const prevStoredElements = getSyncableElements(
+      restoreElements(await decryptElements(prevStoredScene, roomKey), null),
+    );
+    const reconciledElements = getSyncableElements(
+      reconcileElements(
+        elements,
+        prevStoredElements as OrderedExcalidrawElement[] as RemoteExcalidrawElement[],
+        appState,
+      ),
+    );
+
+    const storedScene = await createFirebaseSceneDocument(
+      reconciledElements,
+      roomKey,
+    );
+
+    transaction.update(docRef, storedScene);
+
+    // Return the stored elements as the in memory `reconciledElements` could have mutated in the meantime
+    return storedScene;
+  });
+
+  const storedElements = getSyncableElements(
+    restoreElements(await decryptElements(storedScene, roomKey), null),
+  );
+
+  FirebaseSceneVersionCache.set(socket, storedElements);
+
+  return storedElements;
+};
+
+export const loadFromFirebase = async (
+  roomId: string,
+  roomKey: string,
+  socket: Socket | null,
+): Promise<readonly SyncableExcalidrawElement[] | null> => {
+  const firestore = _getFirestore();
+  const docRef = doc(firestore, "scenes", roomId);
+  const docSnap = await getDoc(docRef);
+  if (!docSnap.exists()) {
+    return null;
+  }
+  const storedScene = docSnap.data() as FirebaseStoredScene;
+  const elements = getSyncableElements(
+    restoreElements(await decryptElements(storedScene, roomKey), null),
+  );
+
+  if (socket) {
+    FirebaseSceneVersionCache.set(socket, elements);
+  }
+
+  return elements;
+};
+
+export const loadFilesFromFirebase = async (
+  prefix: string,
+  decryptionKey: string,
+  filesIds: readonly FileId[],
+) => {
+  const loadedFiles: BinaryFileData[] = [];
+  const erroredFiles = new Map<FileId, true>();
+
+  await Promise.all(
+    [...new Set(filesIds)].map(async (id) => {
+      try {
+        const url = `https://firebasestorage.googleapis.com/v0/b/${
+          FIREBASE_CONFIG.storageBucket
+        }/o/${encodeURIComponent(prefix.replace(/^\//, ""))}%2F${id}`;
+        const response = await fetch(`${url}?alt=media`);
+        if (response.status < 400) {
+          const arrayBuffer = await response.arrayBuffer();
+
+          const { data, metadata } = await decompressData<BinaryFileMetadata>(
+            new Uint8Array(arrayBuffer),
+            {
+              decryptionKey,
+            },
+          );
+
+          const dataURL = new TextDecoder().decode(data) as DataURL;
+
+          loadedFiles.push({
+            mimeType: metadata.mimeType || MIME_TYPES.binary,
+            id,
+            dataURL,
+            created: metadata?.created || Date.now(),
+            lastRetrieved: metadata?.created || Date.now(),
+          });
+        } else {
+          erroredFiles.set(id, true);
+        }
+      } catch (error: any) {
+        erroredFiles.set(id, true);
+        console.error(error);
+      }
+    }),
+  );
+
+  return { loadedFiles, erroredFiles };
+};