Messenger receive file

• Add MessengerRegisterReceiveFileCallback function.
• Add MessengerStartFileTransfer function.
• Update MessengerSendFile function.
• Add MessengerReceiveFile function.

Sources/XXMessengerClient/Messenger/Functions/MessengerReceiveFile.swift

@@ -3,24 +3,79 @@ import XCTestDynamicOverlay
 import XXClient
 
 public struct MessengerReceiveFile {
+  public struct Params: Equatable {
+    public init(
+      transferId: Data,
+      callbackIntervalMS: Int = 250
+    ) {
+      self.transferId = transferId
+      self.callbackIntervalMS = callbackIntervalMS
+    }
+
+    public var transferId: Data
+    public var callbackIntervalMS: Int
+  }
+
+  public enum CallbackInfo: Equatable {
+    public enum Failure: Equatable {
+      case callbackError(NSError)
+      case progressError(String)
+      case receiveError(NSError)
+    }
+
+    case progress(transmitted: Int, total: Int)
+    case finished(Data)
+    case failed(Failure)
+  }
+
+  public typealias Callback = (CallbackInfo) -> Void
+
   public enum Error: Swift.Error, Equatable {
-    case notConnected
+    case fileTransferNotStarted
   }
 
-  public var run: () throws -> Void
+  public var run: (Params, @escaping Callback) throws -> Void
 
-  public func callAsFunction() throws -> Void {
-    try run()
+  public func callAsFunction(
+    _ params: Params,
+    callback: @escaping Callback
+  ) throws -> Void {
+    try run(params, callback)
   }
 }
 
 extension MessengerReceiveFile {
   public static func live(_ env: MessengerEnvironment) -> MessengerReceiveFile {
-    MessengerReceiveFile {
-      guard let e2e = env.e2e() else {
-        throw Error.notConnected
+    MessengerReceiveFile { params, callback in
+      guard let fileTransfer = env.fileTransfer() else {
+        throw Error.fileTransferNotStarted
       }
-      // TODO: implement receiving file
+      try fileTransfer.registerReceivedProgressCallback(
+        transferId: params.transferId,
+        period: params.callbackIntervalMS,
+        callback: FileTransferProgressCallback { result in
+          switch result {
+          case .success(let info):
+            if let error = info.progress.error {
+              callback(.failed(.progressError(error)))
+            } else if info.progress.completed {
+              do {
+                callback(.finished(try fileTransfer.receive(transferId: params.transferId)))
+              } catch {
+                callback(.failed(.receiveError(error as NSError)))
+              }
+            } else {
+              callback(.progress(
+                transmitted: info.progress.transmitted,
+                total: info.progress.total
+              ))
+            }
+
+          case .failure(let error):
+            callback(.failed(.callbackError(error)))
+          }
+        }
+      )
     }
   }
 }