Sources/SophaxChatCore/DHT/DHTStorage.swift

1// DHTStorage.swift
2// SophaxChatCore
3//
4// Persists the KBucketTable snapshot to an AES-256-GCM encrypted blob
5// via MessageStore.saveEncryptedBlob — same directory and key as message storage.
6// Survives app restarts so we don't cold-bootstrap every time.
7
8import Foundation
9
10public final class DHTStorage: @unchecked Sendable {
11
12    private let messageStore: MessageStore
13    private static let fileName = "dht_kbuckets"
14
15    public init(messageStore: MessageStore) {
16        self.messageStore = messageStore
17    }
18
19    // MARK: - Persist
20
21    /// Saves the k-bucket snapshot (flat array of DHTContact arrays) to encrypted storage.
22    public func save(snapshot: [[DHTContact]]) {
23        guard let data = try? JSONEncoder().encode(snapshot) else { return }
24        try? messageStore.saveEncryptedBlob(data, fileName: Self.fileName)
25    }
26
27    /// Loads and decodes the previously saved k-bucket snapshot.
28    /// Returns an empty array if no snapshot exists or decoding fails.
29    public func load() -> [DHTContact] {
30        guard let data = messageStore.loadEncryptedBlob(fileName: Self.fileName),
31              let snapshot = try? JSONDecoder().decode([[DHTContact]].self, from: data)
32        else { return [] }
33        return snapshot.flatMap { $0 }
34    }
35}