Add user search for dm chats (#739)

* Add searchUsers in ClientProxy

* Add UserSearchProtocol

* Delete UserSearch file

* Add search

* Refine StartChatScreen

* Improve StartChatViewModel

* Add localizations

* Fix no result style

* Update localizations

* Add UTs

* Add UI tests

* Cleanup

* Refine tests

* Add changelog.d file

* Naming refactor

* Refactor ClientProxyProtocol api

* Fix typo

* Add mark

* Rename tests

* Update Dangerfile

* Improve UI test code

* Refactor search api

* Improve style

* Improve combine chain

* Add comment

* Improve StartChatScreen

* Improve updateState

* Add extension Published.Publisher

* Improve UI tests

* Remove Combine import

* Cleanup

* Remove “proxy” wording

* Delete extra extensions

* Refactor Publisher api

ElementX/Sources/Screens/StartChat/StartChatModels.swift

@@ -24,18 +24,21 @@ enum StartChatViewModelAction {
 
 struct StartChatViewState: BindableState {
     var bindings = StartChatScreenViewStateBindings()
-    
+    var usersSection: StartChatUsersSection = .init(type: .suggestions, users: [])
+
     var isSearching: Bool {
         !bindings.searchQuery.isEmpty
     }
     
-    var usersSection: StartChatUsersSection = .init(type: .suggestions, users: [])
+    var hasEmptySearchResults: Bool {
+        isSearching && usersSection.type == .searchResult && usersSection.users.isEmpty
+    }
 }
 
-enum StartChatUserSectionType {
+enum StartChatUserSectionType: Equatable {
     case searchResult
     case suggestions
-    
+
     var title: String? {
         switch self {
         case .searchResult:
@@ -47,8 +50,8 @@ enum StartChatUserSectionType {
 }
 
 struct StartChatUsersSection {
-    var type: StartChatUserSectionType
-    var users: [UserProfileProxy]
+    let type: StartChatUserSectionType
+    let users: [UserProfile]
 }
 
 struct StartChatScreenViewStateBindings {
@@ -62,5 +65,5 @@ enum StartChatViewAction {
     case close
     case createRoom
     case inviteFriends
-    case selectUser(UserProfileProxy)
+    case selectUser(UserProfile)
 }

ElementX/Sources/Screens/StartChat/StartChatViewModel.swift

@@ -24,6 +24,9 @@ class StartChatViewModel: StartChatViewModelType, StartChatViewModelProtocol {
     
     var callback: ((StartChatViewModelAction) -> Void)?
     weak var userIndicatorController: UserIndicatorControllerProtocol?
+    var searchTask: Task<Void, Error>? {
+        didSet { oldValue?.cancel() }
+    }
     
     init(userSession: UserSessionProtocol, userIndicatorController: UserIndicatorControllerProtocol?) {
         self.userSession = userSession
@@ -31,7 +34,7 @@ class StartChatViewModel: StartChatViewModelType, StartChatViewModelProtocol {
         super.init(initialViewState: StartChatViewState(), imageProvider: userSession.mediaProvider)
         
         setupBindings()
-        fetchSuggestion()
+        fetchSuggestions()
     }
     
     // MARK: - Public
@@ -82,28 +85,36 @@ class StartChatViewModel: StartChatViewModelType, StartChatViewModelProtocol {
     private func setupBindings() {
         context.$viewState
             .map(\.bindings.searchQuery)
-            .debounce(for: .milliseconds(300), scheduler: DispatchQueue.main)
+            .map { query in
+                // debounce search queries but make sure clearing the search updates immediately
+                let milliseconds = query.isEmpty ? 0 : 500
+                return Just(query).delay(for: .milliseconds(milliseconds), scheduler: DispatchQueue.main)
+            }
+            .switchToLatest()
             .removeDuplicates()
-            .sink { [weak self] searchQuery in
-                if searchQuery.isEmpty {
-                    self?.fetchSuggestion()
-                } else if MatrixEntityRegex.isMatrixUserIdentifier(searchQuery) {
-                    self?.state.usersSection.type = .searchResult
-                    self?.state.usersSection.users = [UserProfileProxy(userID: searchQuery, displayName: nil, avatarURL: nil)]
-                } else {
-                    self?.state.usersSection.type = .searchResult
-                    self?.state.usersSection.users = []
-                }
+            .sink { [weak self] query in
+                self?.updateState(searchQuery: query)
             }
             .store(in: &cancellables)
     }
     
-    private func fetchSuggestion() {
-        state.usersSection.type = .suggestions
-        state.usersSection.users = [.mockAlice, .mockBob, .mockCharlie]
+    private func updateState(searchQuery: String) {
+        searchTask = nil
+        
+        if searchQuery.count < 3 {
+            fetchSuggestions()
+        } else if MatrixEntityRegex.isMatrixUserIdentifier(searchQuery) {
+            state.usersSection = .init(type: .searchResult, users: [UserProfile(userID: searchQuery)])
+        } else {
+            searchUsers(searchTerm: searchQuery)
+        }
     }
     
-    private func createDirectRoom(with user: UserProfileProxy) async {
+    private func fetchSuggestions() {
+        state.usersSection = .init(type: .suggestions, users: [.mockAlice, .mockBob, .mockCharlie])
+    }
+    
+    private func createDirectRoom(with user: UserProfile) async {
         showLoadingIndicator()
         let result = await userSession.clientProxy.createDirectRoom(with: user.userID)
         hideLoadingIndicator()
@@ -115,6 +126,19 @@ class StartChatViewModel: StartChatViewModelType, StartChatViewModelProtocol {
         }
     }
     
+    private func searchUsers(searchTerm: String) {
+        searchTask = Task { @MainActor in
+            guard
+                case let .success(result) = await userSession.clientProxy.searchUsers(searchTerm: searchTerm, limit: 5),
+                !Task.isCancelled
+            else {
+                return
+            }
+            
+            state.usersSection = .init(type: .searchResult, users: result.results)
+        }
+    }
+    
     // MARK: Loading indicator
     
     static let loadingIndicatorIdentifier = "StartChatLoading"

ElementX/Sources/Screens/StartChat/View/StartChatScreen.swift

@@ -22,10 +22,10 @@ struct StartChatScreen: View {
     var body: some View {
         Form {
             if !context.viewState.isSearching {
-                createRoomSection
-                inviteFriendsSection
+                mainContent
+            } else {
+                searchContent
             }
-            usersSection
         }
         .scrollContentBackground(.hidden)
         .background(Color.element.formBackground.ignoresSafeArea())
@@ -39,6 +39,26 @@ struct StartChatScreen: View {
         .searchable(text: $context.searchQuery, placement: .navigationBarDrawer(displayMode: .always), prompt: L10n.commonSearchForSomeone)
         .alert(item: $context.alertInfo) { $0.alert }
     }
+
+    // MARK: - Private
+
+    /// The content shown in the form when the search query is empty.
+    @ViewBuilder
+    private var mainContent: some View {
+        createRoomSection
+        inviteFriendsSection
+        usersSection
+    }
+    
+    /// The content shown in the form when a search query has been entered.
+    @ViewBuilder
+    private var searchContent: some View {
+        if context.viewState.hasEmptySearchResults {
+            noResultsContent
+        } else {
+            usersSection
+        }
+    }
     
     private var createRoomSection: some View {
         Section {
@@ -77,6 +97,15 @@ struct StartChatScreen: View {
         .formSectionStyle()
     }
     
+    private var noResultsContent: some View {
+        Text(L10n.commonNoResults)
+            .font(.element.body)
+            .foregroundColor(.element.tertiaryContent)
+            .frame(maxWidth: .infinity)
+            .listRowBackground(Color.clear)
+            .accessibilityIdentifier(A11yIdentifiers.startChatScreen.searchNoResults)
+    }
+    
     private var closeButton: some View {
         Button(L10n.actionCancel, action: close)
             .accessibilityIdentifier(A11yIdentifiers.startChatScreen.closeStartChat)

ElementX/Sources/Screens/StartChat/View/StartChatSuggestedUserCell.swift

@@ -17,7 +17,7 @@
 import SwiftUI
 
 struct StartChatSuggestedUserCell: View {
-    let user: UserProfileProxy
+    let user: UserProfile
     let imageProvider: ImageProviderProtocol?
     
     var body: some View {