From f09de006f413ce4d230fb05ba46afa2740ed0b05 Mon Sep 17 00:00:00 2001
From: Denis Obukhov <denis.obukhov@exyte.com>
Date: Mon, 25 Oct 2021 16:27:35 +0700
Subject: [PATCH] Add the ability to retry a request

---
 .../Calls/NetworkingClient+Requests.swift     | 24 ++++++++++++----
 Sources/Networking/NetworkingClient.swift     |  4 +--
 Sources/Networking/NetworkingRequest.swift    | 28 ++++++++++++++++---
 3 files changed, 44 insertions(+), 12 deletions(-)

diff --git a/Sources/Networking/Calls/NetworkingClient+Requests.swift b/Sources/Networking/Calls/NetworkingClient+Requests.swift
index 7486221..6d0428f 100644
--- a/Sources/Networking/Calls/NetworkingClient+Requests.swift
+++ b/Sources/Networking/Calls/NetworkingClient+Requests.swift
@@ -32,15 +32,27 @@ public extension NetworkingClient {
 
     internal func request(_ httpVerb: HTTPVerb, _ route: String, params: Params = Params()) -> NetworkingRequest {
         let req = NetworkingRequest()
-        req.baseURL              = baseURL
-        req.logLevels            = logLevels
-        req.headers              = headers
         req.httpVerb             = httpVerb
         req.route                = route
         req.params               = params
-        req.parameterEncoding    = parameterEncoding
-        req.sessionConfiguration = sessionConfiguration
-        req.timeout              = timeout
+
+        let updateRequest = { [weak req, weak self] in
+            guard let self = self else { return }
+            req?.baseURL              = self.baseURL
+            req?.logLevels            = self.logLevels
+            req?.headers              = self.headers
+            req?.parameterEncoding    = self.parameterEncoding
+            req?.sessionConfiguration = self.sessionConfiguration
+            req?.timeout              = self.timeout
+        }
+        updateRequest()
+        req.requestRetrier = { [weak self] in
+            self?.requestRetrier?($0, $1)?
+                .handleEvents(receiveOutput: { _ in
+                    updateRequest()
+                })
+                .eraseToAnyPublisher()
+        }
         return req
     }
 }
diff --git a/Sources/Networking/NetworkingClient.swift b/Sources/Networking/NetworkingClient.swift
index 010182d..3050459 100644
--- a/Sources/Networking/NetworkingClient.swift
+++ b/Sources/Networking/NetworkingClient.swift
@@ -1,8 +1,7 @@
 import Foundation
 import Combine
 
-public struct NetworkingClient {
-
+public class NetworkingClient {
     /**
         Instead of using the same keypath for every call eg: "collection",
         this enables to use a default keypath for parsing collections.
@@ -15,6 +14,7 @@ public struct NetworkingClient {
     public var parameterEncoding = ParameterEncoding.urlEncoded
     public var timeout: TimeInterval?
     public var sessionConfiguration = URLSessionConfiguration.default
+    public var requestRetrier: NetworkRequestRetrier?
 
     /**
         Prints network calls to the console.
diff --git a/Sources/Networking/NetworkingRequest.swift b/Sources/Networking/NetworkingRequest.swift
index 8fce024..2a9c06f 100644
--- a/Sources/Networking/NetworkingRequest.swift
+++ b/Sources/Networking/NetworkingRequest.swift
@@ -8,6 +8,8 @@
 import Foundation
 import Combine
 
+public typealias NetworkRequestRetrier = (_ request: URLRequest, _ error: Error) -> AnyPublisher<Void, Error>?
+
 public class NetworkingRequest: NSObject {
     
     var parameterEncoding = ParameterEncoding.urlEncoded
@@ -25,7 +27,9 @@ public class NetworkingRequest: NSObject {
     var timeout: TimeInterval?
     let progressPublisher = PassthroughSubject<Progress, Error>()
     var sessionConfiguration: URLSessionConfiguration?
-    
+    var requestRetrier: NetworkRequestRetrier?
+    private let maxRetryCount = 3
+
     public func uploadPublisher() -> AnyPublisher<(Data?, Progress), Error> {
         
         guard let urlRequest = buildURLRequest() else {
@@ -63,9 +67,12 @@ public class NetworkingRequest: NSObject {
         return Publishers.Merge(callPublisher, progressPublisher2)
             .receive(on: DispatchQueue.main).eraseToAnyPublisher()
     }
-    
+
     public func publisher() -> AnyPublisher<Data, Error> {
-        
+        publisher(retryCount: maxRetryCount)
+    }
+
+    private func publisher(retryCount: Int) -> AnyPublisher<Data, Error> {
         guard let urlRequest = buildURLRequest() else {
             return Fail(error: NetworkingError.unableToParseRequest as Error)
                 .eraseToAnyPublisher()
@@ -87,7 +94,20 @@ public class NetworkingRequest: NSObject {
                     }
                 }
                 return data
-            }.mapError { error -> NetworkingError in
+            }.tryCatch({ [weak self, urlRequest] error -> AnyPublisher<Data, Error> in
+                guard
+                    let self = self,
+                    retryCount > 1,
+                    let retryPublisher = self.requestRetrier?(urlRequest, error)
+                else {
+                    throw error
+                }
+                return retryPublisher
+                    .flatMap { _ -> AnyPublisher<Data, Error> in
+                        self.publisher(retryCount: retryCount - 1)
+                    }
+                    .eraseToAnyPublisher()
+            }).mapError { error -> NetworkingError in
                 return NetworkingError(error: error)
             }.receive(on: DispatchQueue.main).eraseToAnyPublisher()
     }