Show instance info if available

ServiceLayer/Sources/ServiceLayer/Services/InstanceURLService.swift

@@ -4,18 +4,54 @@ import CodableBloomFilter
 import Combine
 import Foundation
 import HTTP
+import Mastodon
+import MastodonAPI
 
 public struct InstanceURLService {
     private let httpClient: HTTPClient
     private var userDefaultsClient: UserDefaultsClient
 
     public init(environment: AppEnvironment) {
-        httpClient = HTTPClient(session: environment.session, decoder: JSONDecoder())
+        httpClient = HTTPClient(session: environment.session, decoder: MastodonDecoder())
         userDefaultsClient = UserDefaultsClient(userDefaults: environment.userDefaults)
     }
 }
 
 public extension InstanceURLService {
+    static func url(text: String) -> URL? {
+        guard text.count >= shortestPossibleURLLength else { return nil }
+
+        if text.hasPrefix(httpsPrefix), let prefixedURL = URL(string: text) {
+            return prefixedURL
+        } else if let unprefixedURL = URL(string: httpsPrefix + text) {
+            return unprefixedURL
+        }
+
+        return nil
+    }
+
+    func instance(url: URL) -> AnyPublisher<Instance?, Never> {
+        httpClient.request(
+            MastodonAPITarget(
+                baseURL: url,
+                endpoint: InstanceEndpoint.instance,
+                accessToken: nil))
+            .map { $0 as Instance? }
+            .catch { _ in Just(nil) }
+            .eraseToAnyPublisher()
+    }
+
+    func isPublicTimelineAvailable(url: URL) -> AnyPublisher<Bool, Never> {
+        httpClient.request(
+            MastodonAPITarget(
+                baseURL: url,
+                endpoint: TimelinesEndpoint.public(local: true),
+                accessToken: nil))
+            .map { _ in true }
+            .catch { _ in Just(false) }
+            .eraseToAnyPublisher()
+    }
+
     func isFiltered(url: URL) -> Bool {
         guard let host = url.host else { return true }
 
@@ -55,11 +91,8 @@ private struct UpdatedFilterTarget: DecodableTarget {
 }
 
 private extension InstanceURLService {
-    var filter: BloomFilter<String> {
+    static let httpsPrefix = "https://"
-        userDefaultsClient.updatedInstanceFilter ?? Self.defaultFilter
+    static let shortestPossibleURLLength = 4
-    }
-
-    static let updatedFilterUserDefaultsKey = "updatedFilter"
     // Ugly, but baking this into the compiled app instead of loading the data from the bundle is more secure
     // swiftlint:disable line_length
     static let defaultFilterData = #"{"hashes":["djb232","djb2a32","fnv132","fnv1a32","sdbm32"],"data":"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAgAIAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAAAAgAAAAAQAAAAAABAAACAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAAABAAAEAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAIAAAAAABAAAAAAAAAAAAAAAAAAAAAQAAAAAAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAIAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAIAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAAAAIAAAQAAAAAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAQAAAAAAAQAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAADAAAAAAAAAAAAA=="}"#
@@ -68,4 +101,7 @@ private extension InstanceURLService {
     // swiftlint:disable force_try
     static let defaultFilter = try! JSONDecoder().decode(BloomFilter<String>.self, from: defaultFilterData)
     // swiftlint:enable force_try
+    var filter: BloomFilter<String> {
+        userDefaultsClient.updatedInstanceFilter ?? Self.defaultFilter
+    }
 }

ViewModels/Sources/ViewModels/AddIdentityViewModel.swift

@@ -2,6 +2,7 @@
 
 import Combine
 import Foundation
+import Mastodon
 import ServiceLayer
 
 public enum AddIdentityError: Error {
@@ -12,6 +13,8 @@ public final class AddIdentityViewModel: ObservableObject {
     @Published public var urlFieldText = ""
     @Published public var alertItem: AlertItem?
     @Published public private(set) var loading = false
+    @Published public private(set) var instance: Instance?
+    @Published public private(set) var isPublicTimelineAvailable = false
     public let addedIdentityID: AnyPublisher<UUID, Never>
 
     private let allIdentitiesService: AllIdentitiesService
@@ -23,6 +26,21 @@ public final class AddIdentityViewModel: ObservableObject {
         self.allIdentitiesService = allIdentitiesService
         self.instanceURLService = instanceURLService
         addedIdentityID = addedIdentityIDSubject.eraseToAnyPublisher()
+
+        let url = $urlFieldText
+            .debounce(for: 0.5, scheduler: DispatchQueue.main)
+            .removeDuplicates()
+            .compactMap(InstanceURLService.url(text:))
+            .filter { !instanceURLService.isFiltered(url: $0) }
+            .share()
+
+        url.flatMap(instanceURLService.instance(url:))
+            .receive(on: DispatchQueue.main)
+            .assign(to: &$instance)
+
+        url.flatMap(instanceURLService.isPublicTimelineAvailable(url:))
+            .receive(on: DispatchQueue.main)
+            .assign(to: &$isPublicTimelineAvailable)
     }
 }
 
@@ -43,23 +61,10 @@ public extension AddIdentityViewModel {
 }
 
 private extension AddIdentityViewModel {
-    private static let filteredURL = URL(string: "https://filtered")!
-    private static let HTTPSPrefix = "https://"
-
-    static func url(fieldText: String) -> URL? {
-        if fieldText.hasPrefix(HTTPSPrefix), let prefixedURL = URL(string: fieldText) {
-            return prefixedURL
-        } else if let unprefixedURL = URL(string: HTTPSPrefix + fieldText) {
-            return unprefixedURL
-        }
-
-        return nil
-    }
-
     func addIdentity(authenticated: Bool) {
         let identityID = UUID()
 
-        guard let url = Self.url(fieldText: urlFieldText) else {
+        guard let url = InstanceURLService.url(text: urlFieldText) else {
             alertItem = AlertItem(error: AddIdentityError.unableToConnectToInstance)
 
             return
@@ -81,27 +86,29 @@ private extension AddIdentityViewModel {
             url: url,
             authenticated: authenticated)
             .receive(on: DispatchQueue.main)
-            .catch { [weak self] error -> Empty<Never, Never> in
-                if case AuthenticationError.canceled = error {
-                    // no-op
-                } else {
-                    let displayedError = error is URLError ? AddIdentityError.unableToConnectToInstance : error
-
-                    self?.alertItem = AlertItem(error: displayedError)
-                }
-
-                return Empty()
-            }
             .handleEvents(receiveSubscription: { [weak self] _ in self?.loading = true })
             .sink { [weak self] in
                 guard let self = self else { return }
 
                 self.loading = false
 
-                if case .finished = $0 {
+                switch $0 {
+                case .finished:
                     self.addedIdentityIDSubject.send(identityID)
+                case let .failure(error):
+                    if case AuthenticationError.canceled = error {
+                        return
+                    }
+
+                    let displayedError = error is URLError ? AddIdentityError.unableToConnectToInstance : error
+
+                    self.alertItem = AlertItem(error: displayedError)
                 }
             } receiveValue: { _ in }
             .store(in: &cancellables)
     }
+
+    func checkIfPublicTimelineAvailable(url: URL) -> AnyPublisher<Bool, Never> {
+        Just(false).eraseToAnyPublisher()
+    }
 }

Views/AddIdentityView.swift

@@ -1,5 +1,6 @@
 // Copyright © 2020 Metabolist. All rights reserved.
 
+import KingfisherSwiftUI
 import SwiftUI
 import ViewModels
 
@@ -9,7 +10,8 @@ struct AddIdentityView: View {
 
     var body: some View {
         Form {
-            urlTextField
+            Section {
+                TextField("add-identity.instance-url", text: $viewModel.urlFieldText)
                     .autocapitalization(.none)
                     .disableAutocorrection(true)
                     .keyboardType(.URL)
@@ -19,12 +21,35 @@ struct AddIdentityView: View {
                     } else {
                         Button("add-identity.log-in",
                                action: viewModel.logInTapped)
+                        if viewModel.isPublicTimelineAvailable {
                             Button("add-identity.browse-anonymously", action: viewModel.browseAnonymouslyTapped)
-                        .frame(maxWidth: .infinity, alignment: .center)
+                        }
                     }
                 }
                 .frame(maxWidth: .infinity, alignment: .center)
             }
+            Section {
+                if let instance = viewModel.instance {
+                    KFImage(instance.thumbnail)
+                        .placeholder {
+                            ProgressView()
+                        }
+                        .resizable()
+                        .scaledToFit()
+                        .listRowInsets(EdgeInsets())
+                    VStack(alignment: .center) {
+                        Text(instance.title)
+                            .font(.headline)
+                        Text(instance.uri)
+                            .font(.subheadline)
+                            .foregroundColor(.secondary)
+                    }
+                    .frame(maxWidth: .infinity, alignment: .center)
+                    .listRowInsets(EdgeInsets())
+                }
+            }
+        }
+        .animation(.default)
         .alertItem($viewModel.alertItem)
         .onReceive(viewModel.addedIdentityID) { id in
             withAnimation {
@@ -35,12 +60,6 @@ struct AddIdentityView: View {
     }
 }
 
-extension AddIdentityView {
-    private var urlTextField: some View {
-        TextField("add-identity.instance-url", text: $viewModel.urlFieldText)
-    }
-}
-
 extension AddIdentityError: LocalizedError {
     public var errorDescription: String? {
         NSLocalizedString("add-identity.unable-to-connect-to-instance", comment: "")