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Create custom
Publisher type ahead of support for more advanced beh…
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| // Ombi | ||
| // RequestPublisher.swift | ||
| // | ||
| // MIT License | ||
| // | ||
| // Copyright (c) 2021 Varun Santhanam | ||
| // Permission is hereby granted, free of charge, to any person obtaining a copy | ||
| // of this software and associated documentation files (the Software), to deal | ||
| // | ||
| // in the Software without restriction, including without limitation the rights | ||
| // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | ||
| // copies of the Software, and to permit persons to whom the Software is | ||
| // furnished to do so, subject to the following conditions: | ||
| // | ||
| // The above copyright notice and this permission notice shall be included in all | ||
| // copies or substantial portions of the Software. | ||
| // | ||
| // THE SOFTWARE IS PROVIDED AS IS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | ||
| // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | ||
| // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | ||
| // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | ||
| // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | ||
| // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | ||
| // SOFTWARE. | ||
|
|
||
| import Combine | ||
| import Foundation | ||
| import os.log | ||
|
|
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| final class RequestPublisher<RequestBody, ResponseBody, ResponseError>: Publisher where ResponseError: Error { | ||
|
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| // MARK: - Initializers | ||
|
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| init<T>(session: URLSession, | ||
| request: T, | ||
| host: String, | ||
| injectedHeaders: RequestHeaders, | ||
| backupAuthentication: RequestAuthentication?, | ||
| log: OSLog?) where T: Requestable, T.RequestBody == RequestBody, T.ResponseBody == ResponseBody, T.ResponseError == ResponseError { | ||
| self.session = session | ||
| self.request = .init(request) | ||
| self.host = host | ||
| self.injectedHeaders = injectedHeaders | ||
| self.backupAuthentication = backupAuthentication | ||
| self.log = log | ||
| } | ||
|
|
||
| // MARK: - Publisher | ||
|
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| func receive<S>(subscriber: S) where S: Subscriber, RequestError<ResponseError> == S.Failure, RequestResponse<ResponseBody> == S.Input { | ||
| subscriber.receive(subscription: RequestSubscription<S, RequestBody, ResponseBody, ResponseError>(requestPublisher: self, downstream: subscriber)) | ||
| } | ||
|
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| typealias Output = RequestResponse<ResponseBody> | ||
|
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| typealias Failure = RequestError<ResponseError> | ||
|
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| // MARK: - Private | ||
|
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| fileprivate let session: URLSession | ||
| fileprivate let request: AnyRequestable<RequestBody, ResponseBody, ResponseError> | ||
| fileprivate let host: String | ||
| fileprivate let injectedHeaders: RequestHeaders | ||
| fileprivate let backupAuthentication: RequestAuthentication? | ||
| fileprivate let log: OSLog? | ||
|
|
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| } | ||
|
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| private class RequestSubscription<Downstream, RequestBody, ResponseBody, ResponseError>: Subscription where Downstream: Subscriber, Downstream.Input == RequestPublisher<RequestBody, ResponseBody, ResponseError>.Output, Downstream.Failure == RequestPublisher<RequestBody, ResponseBody, ResponseError>.Failure, ResponseError: Error { | ||
|
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| // MARK: - Initializers | ||
|
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| init(requestPublisher: RequestPublisher<RequestBody, ResponseBody, ResponseError>, downstream: Downstream) { | ||
| lock = .init() | ||
| self.requestPublisher = requestPublisher | ||
| self.downstream = downstream | ||
| demand = .max(0) | ||
| } | ||
|
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| // MARK: - Subscription | ||
|
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| func request(_ demand: Subscribers.Demand) { | ||
| lock.lock() | ||
| guard let requestPublisher = requestPublisher else { | ||
| lock.unlock() | ||
| return | ||
| } | ||
|
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| guard var urlComponents = URLComponents(string: requestPublisher.host) else { | ||
| self.demand += 1 | ||
| failWithMalformedComponents() | ||
| return | ||
| } | ||
|
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| urlComponents.path = "\(urlComponents.path)\(requestPublisher.request.path)" | ||
| if !requestPublisher.request.query.isEmpty { | ||
| urlComponents.queryItems = requestPublisher.request.query | ||
| } | ||
|
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| guard let finalURL = urlComponents.url else { | ||
| self.demand += 1 | ||
| failWithMalformedComponents() | ||
| return | ||
| } | ||
|
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| var request = URLRequest(url: finalURL) | ||
| request.httpMethod = requestPublisher.request.method.rawValue | ||
| if let body = requestPublisher.request.body { | ||
| do { | ||
| request.httpBody = try requestPublisher.request.requestEncoder.encode(body) | ||
| } catch { | ||
| self.demand += 1 | ||
| failWithMalformedComponents() | ||
| return | ||
| } | ||
| } | ||
|
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| var headers = requestPublisher.request.headers | ||
| .reduce([String: String]()) { prev, pair in | ||
| let (key, value) = pair | ||
| var next = prev | ||
| next[key.description] = value.description | ||
| return next | ||
| } | ||
|
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| headers = requestPublisher.injectedHeaders | ||
| .reduce(headers) { prev, pair in | ||
| let (key, value) = pair | ||
| var next = prev | ||
| next[key.description] = value.description | ||
| return next | ||
| } | ||
|
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| if let authentication = requestPublisher.request.authentication ?? requestPublisher.backupAuthentication { | ||
| headers[authentication.headerKey.description] = authentication.headerValue.description | ||
| } | ||
|
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| request.allHTTPHeaderFields = headers | ||
|
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| request.timeoutInterval = requestPublisher.request.timeoutInterval | ||
|
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| if self.task == nil { | ||
| let task = requestPublisher.session.dataTask(with: request, | ||
| completionHandler: handleResponse(data:response:error:)) | ||
| self.task = task | ||
| } | ||
|
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| guard let log = requestPublisher.log else { return } | ||
| var message = "Making Request" | ||
| if let urlString = request.url?.absoluteString { | ||
| message.append("\nURL: \(urlString)") | ||
| } | ||
| if let method = request.requestMethod { | ||
| message.append("\nMethod: \(method)") | ||
| } | ||
| if let headers = request.allHTTPHeaderFields { | ||
| message.append("\nHeaders:\n\(headers.description)") | ||
| } | ||
| if let body = requestPublisher.request.body { | ||
| message.append("\nBody:\n\(String(describing: body))") | ||
| } | ||
| if let encodedBody = request.httpBody { | ||
| message.append("\nEncoded Body:\n\(String(describing: encodedBody))") | ||
| } | ||
| os_log(.debug, log: log, "%@", message) | ||
|
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| self.demand += 1 | ||
| let task = self.task! | ||
| lock.unlock() | ||
| task.resume() | ||
| } | ||
|
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| func cancel() { | ||
| lock.lock() | ||
| guard requestPublisher != nil else { | ||
| lock.unlock() | ||
| return | ||
| } | ||
| requestPublisher = nil | ||
| downstream = nil | ||
| demand = .max(0) | ||
| let task = self.task | ||
| self.task = nil | ||
| lock.unlock() | ||
| task?.cancel() | ||
| } | ||
|
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| // MARK: - Private | ||
|
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| private let lock: Lock | ||
| private var requestPublisher: RequestPublisher<RequestBody, ResponseBody, ResponseError>? | ||
| private var downstream: Downstream? | ||
| private var demand: Subscribers.Demand | ||
| private var task: URLSessionDataTask! | ||
|
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| private func failWithMalformedComponents() { | ||
| lock.lock() | ||
| guard demand > 0, | ||
| requestPublisher != nil, | ||
| let downstream = downstream else { | ||
| lock.unlock() | ||
| return | ||
| } | ||
|
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| requestPublisher = nil | ||
| self.downstream = nil | ||
| demand = .max(0) | ||
| task = nil | ||
| lock.unlock() | ||
| downstream.receive(completion: .failure(.malformedRequest)) | ||
| } | ||
|
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| private func handleResponse(data: Data?, response: URLResponse?, error: Error?) { | ||
| lock.lock() | ||
| guard demand > 0, | ||
| requestPublisher != nil, | ||
| let downstream = downstream, | ||
| let request = requestPublisher?.request else { | ||
| lock.unlock() | ||
| return | ||
| } | ||
|
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| let log = requestPublisher?.log | ||
| requestPublisher = nil | ||
| self.downstream = nil | ||
|
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| demand = .max(0) | ||
| task = nil | ||
| lock.unlock() | ||
|
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| if let response = response, | ||
| error == nil { | ||
| do { | ||
| let body = try request.responseDecoder.decode(data) | ||
| let finalResponse: RequestResponse<ResponseBody> | ||
| if let response = response as? HTTPURLResponse { | ||
| let headers = response.allHeaderFields.reduce(RequestHeaders()) { headers, pair in | ||
| let (field, value) = pair | ||
| var next = headers | ||
| next[.init(String(describing: field))] = .init(String(describing: value)) | ||
| return next | ||
| } | ||
| finalResponse = .init(url: response.url, headers: headers, statusCode: response.statusCode, body: body) | ||
| } else { | ||
| finalResponse = .init(url: response.url, headers: nil, statusCode: nil, body: body) | ||
| } | ||
|
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| guard let log = log else { return } | ||
| var message = "" | ||
| if let urlString = response.url?.absoluteString { | ||
| message.append("Received Response from \(urlString)") | ||
| } else { | ||
| message.append("Received Response") | ||
| } | ||
| if let code = finalResponse.statusCode { | ||
| message.append("\nStatus Code: \(code.description)") | ||
| } | ||
| if let headers = finalResponse.headers { | ||
| message.append("\nHeaders:\n\(headers.description)") | ||
| } | ||
| if let body = finalResponse.body { | ||
| message.append("\nBody:\n\(String(describing: body))") | ||
| } | ||
| os_log(.debug, log: log, "%@", message) | ||
|
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| _ = downstream.receive(finalResponse) | ||
| } catch { | ||
| downstream.receive(completion: .failure(.decodingError(error))) | ||
| } | ||
| } else { | ||
| if let urlError = error as? URLError { | ||
| if urlError.code == .timedOut { | ||
| downstream.receive(completion: .failure(.timedOut)) | ||
| } | ||
| downstream.receive(completion: .failure(.urlSessionFailed(urlError))) | ||
| } else { | ||
| downstream.receive(completion: .failure(.unknownError)) | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
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| private final class Lock { | ||
| private var isLocked: Bool = false | ||
|
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| func lock() { | ||
| isLocked = true | ||
| } | ||
|
|
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| func unlock() { | ||
| isLocked = false | ||
| } | ||
| } |
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