north-star / files / src / features / friends / sync.ts
sync.ts
| 1 | import { ref, onValue } from 'firebase/database'; |
| 2 | import type { Database } from 'firebase/database'; |
| 3 | import { decryptJson } from '../../core/crypto'; |
| 4 | |
| 5 | type FriendRecord = { |
| 6 | id?: string; |
| 7 | name?: string; |
| 8 | color?: string; |
| 9 | position?: { lat: number; lon: number }; |
| 10 | timestamp?: number; |
| 11 | lastSeen?: number; |
| 12 | encryptedState?: string; |
| 13 | encryptedPosition?: string; |
| 14 | [key: string]: unknown; |
| 15 | }; |
| 16 | |
| 17 | /** |
| 18 | * Subscribes to the friends node for a room, decrypting each record |
| 19 | * as needed. Calls onUpdate(friends) after every snapshot resolves. |
| 20 | * |
| 21 | * @param {object} opts |
| 22 | * @param {object} opts.db - Firebase Database instance |
| 23 | * @param {string} opts.roomId |
| 24 | * @param {CryptoKey|null} opts.roomKey - AES-GCM key, or null for unencrypted rooms |
| 25 | * @param {function} opts.onUpdate - (friends: object[]) => void |
| 26 | * @returns {{ friends: object[] }} Shared array reference, mutated in place on each update |
| 27 | */ |
| 28 | export function subscribeToFriends({ |
| 29 | db, |
| 30 | roomId, |
| 31 | roomKey, |
| 32 | onUpdate |
| 33 | }: { |
| 34 | db: Database; |
| 35 | roomId: string; |
| 36 | roomKey: CryptoKey | null; |
| 37 | onUpdate: (friends: FriendRecord[]) => void; |
| 38 | }) { |
| 39 | const friendsRef = ref(db, `rooms/${roomId}/friends`); |
| 40 | const friends: FriendRecord[] = []; |
| 41 | let snapshotVersion = 0; |
| 42 | |
| 43 | onValue(friendsRef, async (snapshot) => { |
| 44 | const version = ++snapshotVersion; |
| 45 | |
| 46 | const friendsData = snapshot.val(); |
| 47 | if (friendsData) { |
| 48 | const rawFriends = Object.values(friendsData as Record<string, FriendRecord>); |
| 49 | const decrypted = await Promise.all(rawFriends.map(async (p): Promise<FriendRecord | null> => { |
| 50 | if (p.encryptedState && roomKey) { |
| 51 | try { |
| 52 | const decryptedState = await decryptJson(roomKey, p.encryptedState) as Record<string, unknown>; |
| 53 | return { ...decryptedState, lastSeen: p.lastSeen }; |
| 54 | } catch (err) { |
| 55 | console.error('Failed to decrypt friend state', p.id, err); |
| 56 | return null; |
| 57 | } |
| 58 | } |
| 59 | if (p.encryptedPosition && roomKey) { |
| 60 | try { |
| 61 | const position = await decryptJson(roomKey, p.encryptedPosition) as { lat: number; lon: number }; |
| 62 | const { encryptedPosition: _stripped, ...rest } = p; |
| 63 | return { ...rest, position }; |
| 64 | } catch (err) { |
| 65 | console.error('Failed to decrypt legacy friend position', p.id, err); |
| 66 | return null; |
| 67 | } |
| 68 | } |
| 69 | return p; |
| 70 | })); |
| 71 | if (version !== snapshotVersion) return; |
| 72 | friends.length = 0; |
| 73 | friends.push(...decrypted.filter((item): item is FriendRecord => item !== null)); |
| 74 | } else { |
| 75 | if (version !== snapshotVersion) return; |
| 76 | friends.length = 0; |
| 77 | } |
| 78 | |
| 79 | onUpdate(friends); |
| 80 | }); |
| 81 | |
| 82 | return { friends }; |
| 83 | } |