Adopt Rust's new sessionPath that replaces the basePath (#2903)

ElementX/Sources/Services/UserSession/RestorationToken.swift

@@ -17,12 +17,27 @@
 import Foundation
 import MatrixRustSDK
 
-struct RestorationToken: Codable, Equatable {
+struct RestorationToken: Equatable {
     let session: MatrixRustSDK.Session
+    let sessionDirectory: URL
     let passphrase: String?
     let pusherNotificationClientIdentifier: String?
 }
 
+extension RestorationToken: Codable {
+    init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        
+        let session = try container.decode(MatrixRustSDK.Session.self, forKey: .session)
+        let sessionDirectory = try container.decodeIfPresent(URL.self, forKey: .sessionDirectory)
+        
+        self = try .init(session: session,
+                         sessionDirectory: sessionDirectory ?? .legacySessionDirectory(for: session.userId),
+                         passphrase: container.decodeIfPresent(String.self, forKey: .passphrase),
+                         pusherNotificationClientIdentifier: container.decodeIfPresent(String.self, forKey: .pusherNotificationClientIdentifier))
+    }
+}
+
 extension MatrixRustSDK.Session: Codable {
     public init(from decoder: Decoder) throws {
         let container = try decoder.container(keyedBy: CodingKeys.self)
@@ -50,3 +65,18 @@ extension MatrixRustSDK.Session: Codable {
         case accessToken, refreshToken, userId, deviceId, homeserverUrl, oidcData, slidingSyncProxy
     }
 }
+
+// MARK: Migrations
+
+private extension URL {
+    /// Gets the store directory of a legacy session that hasn't been migrated to the new token format.
+    ///
+    /// This should only be used to fill in the missing value when restoring a token as older versions of
+    /// the SDK set the session directory for us, based on the user's ID. Newer sessions now use a UUID,
+    /// which is generated app side during authentication.
+    static func legacySessionDirectory(for userID: String) -> URL {
+        // Rust sanitises the user ID replacing invalid characters with an _
+        let sanitisedUserID = userID.replacingOccurrences(of: ":", with: "_")
+        return .sessionsBaseDirectory.appendingPathComponent(sanitisedUserID)
+    }
+}