117 lines
4.2 KiB
Swift
117 lines
4.2 KiB
Swift
// Copyright © 2020 Metabolist. All rights reserved.
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import Combine
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import Foundation
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import Mastodon
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import MastodonAPI
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public enum AuthenticationError: Error {
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case canceled
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}
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struct AuthenticationService {
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private let mastodonAPIClient: MastodonAPIClient
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private let webAuthSessionType: WebAuthSession.Type
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private let webAuthSessionContextProvider = WebAuthSessionContextProvider()
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init(url: URL, environment: AppEnvironment) {
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mastodonAPIClient = MastodonAPIClient(session: environment.session, instanceURL: url)
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webAuthSessionType = environment.webAuthSessionType
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}
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}
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extension AuthenticationService {
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func authenticate() -> AnyPublisher<(AppAuthorization, AccessToken), Error> {
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let appAuthorization = mastodonAPIClient.request(
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AppAuthorizationEndpoint.apps(
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clientName: OAuth.clientName,
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redirectURI: OAuth.callbackURL.absoluteString,
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scopes: OAuth.scopes,
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website: OAuth.website))
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.share()
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return appAuthorization
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.zip(appAuthorization.flatMap(authenticate(appAuthorization:)))
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.eraseToAnyPublisher()
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}
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}
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private extension AuthenticationService {
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struct OAuth {
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static let clientName = "Metatext"
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static let scopes = "read write follow push"
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static let codeCallbackQueryItemName = "code"
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static let grantType = "authorization_code"
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static let callbackURLScheme = "metatext"
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static let callbackURL = URL(string: "\(callbackURLScheme)://oauth.callback")!
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static let website = URL(string: "https://metabolist.com/metatext")!
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}
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enum OAuthError: Error {
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case codeNotFound
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}
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static func extractCode(oauthCallbackURL: URL) throws -> String {
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guard let queryItems = URLComponents(
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url: oauthCallbackURL,
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resolvingAgainstBaseURL: true)?.queryItems,
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let code = queryItems.first(where: {
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$0.name == OAuth.codeCallbackQueryItemName
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})?.value
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else { throw OAuthError.codeNotFound }
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return code
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}
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func authorizationURL(appAuthorization: AppAuthorization) throws -> URL {
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guard var authorizationURLComponents = URLComponents(
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url: mastodonAPIClient.instanceURL,
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resolvingAgainstBaseURL: true)
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else { throw URLError(.badURL) }
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authorizationURLComponents.path = "/oauth/authorize"
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authorizationURLComponents.queryItems = [
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.init(name: "client_id", value: appAuthorization.clientId),
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.init(name: "scope", value: OAuth.scopes),
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.init(name: "response_type", value: "code"),
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.init(name: "redirect_uri", value: OAuth.callbackURL.absoluteString)
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]
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guard let authorizationURL = authorizationURLComponents.url else {
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throw URLError(.badURL)
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}
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return authorizationURL
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}
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func authenticate(appAuthorization: AppAuthorization) -> AnyPublisher<AccessToken, Error> {
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Just(appAuthorization)
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.tryMap(authorizationURL(appAuthorization:))
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.flatMap {
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webAuthSessionType.publisher(
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url: $0,
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callbackURLScheme: OAuth.callbackURLScheme,
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presentationContextProvider: webAuthSessionContextProvider)
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}
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.mapError { error -> Error in
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if (error as? WebAuthSessionError)?.code == .canceledLogin {
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return AuthenticationError.canceled as Error
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}
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return error
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}
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.tryMap(Self.extractCode(oauthCallbackURL:))
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.flatMap {
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mastodonAPIClient.request(
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AccessTokenEndpoint.oauthToken(
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clientID: appAuthorization.clientId,
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clientSecret: appAuthorization.clientSecret,
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code: $0,
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grantType: OAuth.grantType,
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scopes: OAuth.scopes,
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redirectURI: OAuth.callbackURL.absoluteString))
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}
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.eraseToAnyPublisher()
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}
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}
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