feat(auth): auto refresh token in background

Sources/Auth/AuthClient.swift

@@ -5,7 +5,11 @@ import Foundation
   import FoundationNetworking
 #endif
 
-public actor AuthClient {
+#if canImport(UIKit)
+  import UIKit
+#endif
+
+public final class AuthClient: Sendable {
   /// FetchHandler is a type alias for asynchronous network request handling.
   public typealias FetchHandler = @Sendable (
     _ request: URLRequest
@@ -22,6 +26,9 @@ public actor AuthClient {
     public let decoder: JSONDecoder
     public let fetch: FetchHandler
 
+    /// Whether the client should auto refresh token in background.
+    public let autoRefreshToken: Bool
+
     /// Initializes a AuthClient Configuration with optional parameters.
     ///
     /// - Parameters:
@@ -33,6 +40,8 @@ public actor AuthClient {
     ///   - encoder: The JSON encoder to use for encoding requests.
     ///   - decoder: The JSON decoder to use for decoding responses.
     ///   - fetch: The asynchronous fetch handler for network requests.
+    ///   - autoRefreshToken: Whether the client should auto refresh token in background, defaults
+    /// to true.
     public init(
       url: URL,
       headers: [String: String] = [:],
@@ -41,7 +50,8 @@ public actor AuthClient {
       logger: (any SupabaseLogger)? = nil,
       encoder: JSONEncoder = AuthClient.Configuration.jsonEncoder,
       decoder: JSONDecoder = AuthClient.Configuration.jsonDecoder,
-      fetch: @escaping FetchHandler = { try await URLSession.shared.data(for: $0) }
+      fetch: @escaping FetchHandler = { try await URLSession.shared.data(for: $0) },
+      autoRefreshToken: Bool = true
     ) {
       let headers = headers.merging(Configuration.defaultHeaders) { l, _ in l }
 
@@ -53,6 +63,7 @@ public actor AuthClient {
       self.encoder = encoder
       self.decoder = decoder
       self.fetch = fetch
+      self.autoRefreshToken = autoRefreshToken
     }
   }
 
@@ -94,6 +105,8 @@ public actor AuthClient {
   /// key in the client.
   public let admin: AuthAdmin
 
+  private var autoRefreshToken: AutoRefreshToken?
+
   /// Initializes a AuthClient with optional parameters.
   ///
   /// - Parameters:
@@ -105,15 +118,18 @@ public actor AuthClient {
   ///   - encoder: The JSON encoder to use for encoding requests.
   ///   - decoder: The JSON decoder to use for decoding responses.
   ///   - fetch: The asynchronous fetch handler for network requests.
-  public init(
+  ///   - autoRefreshToken: Whether the client should auto refresh token in background, defaults to
+  /// true.
+  public convenience init(
     url: URL,
     headers: [String: String] = [:],
     flowType: AuthFlowType = AuthClient.Configuration.defaultFlowType,
     localStorage: any AuthLocalStorage,
     logger: (any SupabaseLogger)? = nil,
     encoder: JSONEncoder = AuthClient.Configuration.jsonEncoder,
     decoder: JSONDecoder = AuthClient.Configuration.jsonDecoder,
-    fetch: @escaping FetchHandler = { try await URLSession.shared.data(for: $0) }
+    fetch: @escaping FetchHandler = { try await URLSession.shared.data(for: $0) },
+    autoRefreshToken: Bool = true
   ) {
     self.init(
       configuration: Configuration(
@@ -124,7 +140,8 @@ public actor AuthClient {
         logger: logger,
         encoder: encoder,
         decoder: decoder,
-        fetch: fetch
+        fetch: fetch,
+        autoRefreshToken: autoRefreshToken
       )
     )
   }
@@ -133,7 +150,7 @@ public actor AuthClient {
   ///
   /// - Parameters:
   ///   - configuration: The client configuration.
-  public init(configuration: Configuration) {
+  public convenience init(configuration: Configuration) {
     let api = APIClient.live(
       configuration: configuration,
       http: HTTPClient(
@@ -166,6 +183,10 @@ public actor AuthClient {
     mfa = AuthMFA()
     admin = AuthAdmin()
 
+    if configuration.autoRefreshToken {
+      autoRefreshToken = AutoRefreshToken()
+    }
+
     Current = Dependencies(
       configuration: configuration,
       sessionManager: sessionManager,
@@ -180,6 +201,33 @@ public actor AuthClient {
       codeVerifierStorage: codeVerifierStorage,
       logger: logger
     )
+
+    NotificationCenter.default.addObserver(
+      forName: UIApplication.willResignActiveNotification,
+      object: nil,
+      queue: nil
+    ) { [weak self] _ in
+      self?.appDidEnterBackground()
+    }
+    NotificationCenter.default.addObserver(
+      forName: UIApplication.didBecomeActiveNotification,
+      object: nil,
+      queue: nil
+    ) { [weak self] _ in
+      self?.appDidBecomeActive()
+    }
+  }
+
+  private func appDidEnterBackground() {
+    Task {
+      await autoRefreshToken?.stop()
+    }
+  }
+
+  private func appDidBecomeActive() {
+    Task {
+      await autoRefreshToken?.start()
+    }
   }
 
   /// Listen for auth state changes.
@@ -1023,7 +1071,6 @@ public actor AuthClient {
       .user.confirmedAt != nil
     {
       try await sessionManager.update(session)
-      eventEmitter.emit(.tokenRefreshed, session: session)
     }
 
     return session

Sources/Auth/Deprecated.swift

@@ -105,7 +105,7 @@ extension AuthClient {
     deprecated,
     message: "Replace usages of this initializer with new init(url:headers:flowType:localStorage:logger:encoder:decoder:fetch)"
   )
-  public init(
+  public convenience init(
     url: URL,
     headers: [String: String] = [:],
     flowType: AuthFlowType = Configuration.defaultFlowType,

Sources/Auth/Internal/AutoRefreshToken.swift

@@ -0,0 +1,73 @@
+//
+//  AutoRefreshToken.swift
+//
+//
+//  Created by Guilherme Souza on 06/04/24.
+//
+
+import Foundation
+
+actor AutoRefreshToken {
+  private var task: Task<Void, Never>?
+  private let autoRefreshTickDuration: TimeInterval = 30
+  private let autoRefreshTickThreshold = 3
+
+  @Dependency(\.sessionManager) var sessionManager
+  @Dependency(\.logger) var logger
+
+  func start() {
+    stop()
+
+    logger?.debug("start")
+
+    task = Task {
+      while !Task.isCancelled {
+        await autoRefreshTokenTick()
+        try? await Task.sleep(nanoseconds: UInt64(autoRefreshTickDuration) * NSEC_PER_SEC)
+      }
+    }
+  }
+
+  func stop() {
+    task?.cancel()
+    task = nil
+  }
+
+  private func autoRefreshTokenTick() async {
+    logger?.debug("begin")
+    defer {
+      logger?.debug("end")
+    }
+
+    let now = Date()
+
+    do {
+      let session = try await sessionManager.session()
+      if Task.isCancelled {
+        return
+      }
+
+      guard let expiresAt = session.expiresAt else {
+        return
+      }
+
+      // session will expire in this many ticks (or has already expired if <= 0)
+      let expiresInTicks = Int((expiresAt - now.timeIntervalSince1970) / autoRefreshTickDuration)
+
+      logger?
+        .debug(
+          "access token expires in \(expiresInTicks) ticks, a tick last \(autoRefreshTickDuration)s, refresh threshold is \(autoRefreshTickThreshold) ticks"
+        )
+
+      if expiresInTicks <= autoRefreshTickThreshold {
+        _ = try await sessionManager.refreshSession(session.refreshToken)
+      }
+
+    } catch AuthError.sessionNotFound {
+      logger?.debug("no session")
+      return
+    } catch {
+      logger?.error("Auto refresh tick failed with error: \(error)")
+    }
+  }
+}

Sources/Auth/Internal/SessionManager.swift

@@ -9,6 +9,7 @@ struct SessionManager: Sendable {
   var session: @Sendable (_ shouldValidateExpiration: Bool) async throws -> Session
   var update: @Sendable (_ session: Session) async throws -> Void
   var remove: @Sendable () async -> Void
+  var refreshSession: @Sendable (_ refreshToken: String) async throws -> Session
 }
 
 extension SessionManager {
@@ -24,7 +25,8 @@ extension SessionManager {
     return SessionManager(
       session: { try await manager.session(shouldValidateExpiration: $0) },
       update: { try await manager.update($0) },
-      remove: { await manager.remove() }
+      remove: { await manager.remove() },
+      refreshSession: { try await manager.refreshSession($0) }
     )
   }()
 }
@@ -38,6 +40,9 @@ private actor _DefaultSessionManager {
   @Dependency(\.sessionRefresher)
   private var sessionRefresher: SessionRefresher
 
+  @Dependency(\.eventEmitter)
+  private var eventEmitter: EventEmitter
+
   func session(shouldValidateExpiration: Bool) async throws -> Session {
     if let task {
       return try await task.value
@@ -54,19 +59,25 @@ private actor _DefaultSessionManager {
     task = Task {
       defer { task = nil }
 
-      let session = try await sessionRefresher.refreshSession(currentSession.session.refreshToken)
-      try update(session)
-      return session
+      return try await refreshSession(currentSession.session.refreshToken)
     }
 
     return try await task!.value
   }
 
   func update(_ session: Session) throws {
     try storage.storeSession(StoredSession(session: session))
+    eventEmitter.emit(.tokenRefreshed, session: session)
   }
 
   func remove() {
     try? storage.deleteSession()
   }
+
+  @discardableResult
+  func refreshSession(_ refreshToken: String) async throws -> Session {
+    let session = try await sessionRefresher.refreshSession(refreshToken)
+    try update(session)
+    return session
+  }
 }