Add transform operation

4 files changed, 169 insertions, 0 deletions

diff --git a/ios/MullvadVPN.xcodeproj/project.pbxproj b/ios/MullvadVPN.xcodeproj/project.pbxproj
index be16e9c4c6..6933de9e76 100644
--- a/ios/MullvadVPN.xcodeproj/project.pbxproj
+++ b/ios/MullvadVPN.xcodeproj/project.pbxproj
@@ -8,6 +8,9 @@
 
 /* Begin PBXBuildFile section */
 		5801C9A527A14B2A0031566A /* TunnelManagerState.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5801C9A427A14B2A0031566A /* TunnelManagerState.swift */; };
+		58059DDC28465E8F002B1049 /* TransformOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58059DDB28465E8F002B1049 /* TransformOperation.swift */; };
+		58059DDE28468158002B1049 /* OutputOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58059DDD28468158002B1049 /* OutputOperation.swift */; };
+		58059DE02846823E002B1049 /* ResultOperation+Output.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58059DDF2846823E002B1049 /* ResultOperation+Output.swift */; };
 		58059DE228468255002B1049 /* ResultOperation+Fallible.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58059DE128468255002B1049 /* ResultOperation+Fallible.swift */; };
 		5806767C27048E9B00C858CB /* PacketTunnelProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58CE5E7B224146470008646E /* PacketTunnelProvider.swift */; };
 		5807483B27DB8A980020ECBF /* WireGuardKitTypes in Frameworks */ = {isa = PBXBuildFile; productRef = 5807483A27DB8A980020ECBF /* WireGuardKitTypes */; };
@@ -343,6 +346,9 @@
 
 /* Begin PBXFileReference section */
 		5801C9A427A14B2A0031566A /* TunnelManagerState.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TunnelManagerState.swift; sourceTree = "<group>"; };
+		58059DDB28465E8F002B1049 /* TransformOperation.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TransformOperation.swift; sourceTree = "<group>"; };
+		58059DDD28468158002B1049 /* OutputOperation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OutputOperation.swift; sourceTree = "<group>"; };
+		58059DDF2846823E002B1049 /* ResultOperation+Output.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "ResultOperation+Output.swift"; sourceTree = "<group>"; };
 		58059DE128468255002B1049 /* ResultOperation+Fallible.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "ResultOperation+Fallible.swift"; sourceTree = "<group>"; };
 		5807E2BF2432038B00F5FF30 /* String+Split.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "String+Split.swift"; sourceTree = "<group>"; };
 		5807E2C1243203D000F5FF30 /* StringTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = StringTests.swift; sourceTree = "<group>"; };
@@ -637,11 +643,14 @@
 				5840BE34279EDB16002836BA /* OperationCompletion.swift */,
 				589D28772846250500F9A7B3 /* OperationCondition.swift */,
 				589D28792846250500F9A7B3 /* OperationObserver.swift */,
+				58059DDD28468158002B1049 /* OutputOperation.swift */,
 				5820675D26E6839900655B05 /* PresentAlertOperation.swift */,
 				5846226426E0D9630035F7C2 /* ProductsRequestOperation.swift */,
 				58F7D26427EB50A300E4D821 /* ResultOperation.swift */,
 				5842102D282D3FC200F24E46 /* ResultBlockOperation.swift */,
 				58059DE128468255002B1049 /* ResultOperation+Fallible.swift */,
+				58059DDF2846823E002B1049 /* ResultOperation+Output.swift */,
+				58059DDB28465E8F002B1049 /* TransformOperation.swift */,
 			);
 			path = Operations;
 			sourceTree = "<group>";
@@ -1298,6 +1307,7 @@
 				5875960726F36B3A00BF6711 /* TunnelIPCError.swift in Sources */,
 				58F8AC0E25D3F8CE002BE0ED /* ProblemReportReviewViewController.swift in Sources */,
 				58CCA010224249A1004F3011 /* ConnectViewController.swift in Sources */,
+				58059DE02846823E002B1049 /* ResultOperation+Output.swift in Sources */,
 				588BCF282816D664009ADCEC /* RESTResponseHandler.swift in Sources */,
 				58554F77280AFD5C00013055 /* RESTTaskIdentifier.swift in Sources */,
 				58BFA5C622A7C97F00A6173D /* RelayCacheTracker.swift in Sources */,
@@ -1423,6 +1433,7 @@
 				584592612639B4A200EF967F /* ConsentContentView.swift in Sources */,
 				58B5A895280AACC4009FDE99 /* RESTRequestFactory.swift in Sources */,
 				584EBDBD2747C98F00A0C9FD /* NSAttributedString+Markdown.swift in Sources */,
+				58059DDC28465E8F002B1049 /* TransformOperation.swift in Sources */,
 				5875960A26F371FC00BF6711 /* TunnelIPCSession.swift in Sources */,
 				58FB865E26EA284E00F188BC /* LogFormatting.swift in Sources */,
 				585DA88726B0277200B8C587 /* RESTError.swift in Sources */,
@@ -1444,6 +1455,7 @@
 				58FD5BF22424F7D700112C88 /* UserInterfaceInteractionRestriction.swift in Sources */,
 				5811DE50239014550011EB53 /* NEVPNStatus+Debug.swift in Sources */,
 				58C3A4B222456F1B00340BDB /* AccountInputGroupView.swift in Sources */,
+				58059DDE28468158002B1049 /* OutputOperation.swift in Sources */,
 				589D287B2846250500F9A7B3 /* AsyncOperationQueue.swift in Sources */,
 				58F840B22464491D0044E708 /* ChainedError.swift in Sources */,
 				588BCF24280FE43D009ADCEC /* RESTDevicesProxy.swift in Sources */,
diff --git a/ios/MullvadVPN/Operations/OutputOperation.swift b/ios/MullvadVPN/Operations/OutputOperation.swift
new file mode 100644
index 0000000000..0a7f50df5b
--- /dev/null
+++ b/ios/MullvadVPN/Operations/OutputOperation.swift
@@ -0,0 +1,15 @@
+//
+//  OutputOperation.swift
+//  MullvadVPN
+//
+//  Created by pronebird on 31/05/2022.
+//  Copyright © 2022 Mullvad VPN AB. All rights reserved.
+//
+
+import Foundation
+
+protocol OutputOperation: Operation {
+    associatedtype Output
+
+    var output: Output? { get }
+}
diff --git a/ios/MullvadVPN/Operations/ResultOperation+Output.swift b/ios/MullvadVPN/Operations/ResultOperation+Output.swift
new file mode 100644
index 0000000000..db5cd2a6e7
--- /dev/null
+++ b/ios/MullvadVPN/Operations/ResultOperation+Output.swift
@@ -0,0 +1,15 @@
+//
+//  ResultOperation+Output.swift
+//  MullvadVPN
+//
+//  Created by pronebird on 31/05/2022.
+//  Copyright © 2022 Mullvad VPN AB. All rights reserved.
+//
+
+import Foundation
+
+extension ResultOperation: OutputOperation {
+    var output: Success? {
+        return completion?.value
+    }
+}
diff --git a/ios/MullvadVPN/Operations/TransformOperation.swift b/ios/MullvadVPN/Operations/TransformOperation.swift
new file mode 100644
index 0000000000..b09b5780c1
--- /dev/null
+++ b/ios/MullvadVPN/Operations/TransformOperation.swift
@@ -0,0 +1,127 @@
+//
+//  TransformOperation.swift
+//  AsyncOperationQueueTest
+//
+//  Created by pronebird on 31/05/2022.
+//
+
+import Foundation
+
+final class TransformOperation<Input, Output, Failure: Error>: ResultOperation<Output, Failure> {
+    typealias ExecutionBlock = ((Input, TransformOperation<Input, Output, Failure>) -> Void)
+    typealias ThrowingExecutionBlock = ((Input) throws -> Output)
+
+    private var input: Input?
+    private var executionBlock: ExecutionBlock?
+    private var configurationBlocks: [() -> Void] = []
+    private var cancellationBlocks: [() -> Void] = []
+
+    init(
+        dispatchQueue: DispatchQueue? = nil,
+        input: Input? = nil,
+        block: ExecutionBlock? = nil
+    )
+    {
+        self.input = input
+        self.executionBlock = block
+
+        super.init(dispatchQueue: dispatchQueue)
+    }
+
+    convenience init(
+        dispatchQueue: DispatchQueue?,
+        input: Input? = nil,
+        block: @escaping ThrowingExecutionBlock
+    )
+    {
+        self.init(
+            dispatchQueue: dispatchQueue,
+            input: input,
+            block: Self.wrapThrowingBlock(block)
+        )
+    }
+
+    override func main() {
+        for configurationBlock in configurationBlocks {
+            configurationBlock()
+        }
+
+        configurationBlocks.removeAll()
+
+        guard let input = input, let executionBlock = executionBlock else {
+            finish(completion: .cancelled)
+            return
+        }
+
+        executionBlock(input, self)
+    }
+
+    override func operationDidCancel() {
+        let blocks = cancellationBlocks
+        cancellationBlocks.removeAll()
+
+        for block in blocks {
+            block()
+        }
+    }
+
+    override func operationDidFinish() {
+        cancellationBlocks.removeAll()
+        executionBlock = nil
+    }
+
+    func setExecutionBlock(_ block: @escaping ExecutionBlock) {
+        dispatchQueue.async {
+            assert(!self.isExecuting && !self.isFinished)
+            self.executionBlock = block
+        }
+    }
+
+    func setExecutionBlock(_ block: @escaping ThrowingExecutionBlock) {
+        setExecutionBlock(Self.wrapThrowingBlock(block))
+    }
+
+    func addCancellationBlock(_ block: @escaping () -> Void) {
+        dispatchQueue.async {
+            if self.isCancelled {
+                block()
+            } else {
+                self.cancellationBlocks.append(block)
+            }
+        }
+    }
+
+    func inject<T>(from dependency: T) where T: OutputOperation, T.Output == Input {
+        inject(from: dependency, via: { $0 })
+    }
+
+    func inject<T>(from dependency: T, via block: @escaping (T.Output) -> Input) where T: OutputOperation {
+        dispatchQueue.async {
+            self.configurationBlocks.append { [weak self] in
+                guard let self = self else { return }
+
+                if let output = dependency.output {
+                    self.input = block(output)
+                }
+            }
+
+        }
+        addDependency(dependency)
+    }
+
+    private class func wrapThrowingBlock(_ executionBlock: @escaping ThrowingExecutionBlock) -> ExecutionBlock {
+        return { input, operation in
+            do {
+                let value = try executionBlock(input)
+
+                operation.finish(completion: .success(value))
+            } catch {
+                let castedError = error as! Failure
+
+                operation.finish(completion: .failure(castedError))
+            }
+        }
+    }
+
+}
+