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Create custom
Publisher
type ahead of support for more advanced beh…
…aviors
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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. | ||
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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 | ||
} | ||
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// 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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