Rename UserSuggestion module as CompletionSuggestion

RiotSwiftUI/Modules/Room/CompletionSuggestion/Service/CompletionSuggestionService.swift

@@ -0,0 +1,189 @@
+//
+// Copyright 2021 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Combine
+import Foundation
+import WysiwygComposer
+
+struct RoomMembersProviderMember {
+    var userId: String
+    var displayName: String
+    var avatarUrl: String
+}
+
+struct CommandsProviderCommand {
+    var name: String
+}
+
+class CompletionSuggestionUserID: NSObject {
+    /// A special case added for suggesting `@room` mentions.
+    @objc static let room = "@room"
+}
+
+protocol RoomMembersProviderProtocol {
+    var canMentionRoom: Bool { get }
+    func fetchMembers(_ members: @escaping ([RoomMembersProviderMember]) -> Void)
+}
+
+protocol CommandsProviderProtocol {
+    func fetchCommands(_ commands: @escaping ([CommandsProviderCommand]) -> Void)
+}
+
+struct CompletionSuggestionServiceUserItem: CompletionSuggestionUserItemProtocol {
+    let userId: String
+    let displayName: String?
+    let avatarUrl: String?
+}
+
+struct CompletionSuggestionServiceCommandItem: CompletionSuggestionCommandItemProtocol {
+    let name: String
+}
+
+class CompletionSuggestionService: CompletionSuggestionServiceProtocol {
+    // MARK: - Properties
+    
+    // MARK: Private
+    
+    private let roomMemberProvider: RoomMembersProviderProtocol
+    private let commandProvider: CommandsProviderProtocol
+    
+    private var suggestionItems: [CompletionSuggestionItem] = []
+    private let currentTextTriggerSubject = CurrentValueSubject<String?, Never>(nil)
+    private var cancellables = Set<AnyCancellable>()
+    
+    // MARK: Public
+    
+    var items = CurrentValueSubject<[CompletionSuggestionItem], Never>([])
+    
+    var currentTextTrigger: String? {
+        currentTextTriggerSubject.value
+    }
+    
+    // MARK: - Setup
+    
+    init(roomMemberProvider: RoomMembersProviderProtocol,
+         commandProvider: CommandsProviderProtocol,
+         shouldDebounce: Bool = true) {
+        self.roomMemberProvider = roomMemberProvider
+        self.commandProvider = commandProvider
+        
+        if shouldDebounce {
+            currentTextTriggerSubject
+                .debounce(for: 0.5, scheduler: RunLoop.main)
+                .removeDuplicates()
+                .sink { [weak self] in self?.fetchAndFilterMembersForTextTrigger($0) }
+                .store(in: &cancellables)
+        } else {
+            currentTextTriggerSubject
+                .sink { [weak self] in self?.fetchAndFilterMembersForTextTrigger($0) }
+                .store(in: &cancellables)
+        }
+    }
+    
+    // MARK: - CompletionSuggestionServiceProtocol
+    
+    func processTextMessage(_ textMessage: String?) {
+        guard let textMessage = textMessage,
+              textMessage.count > 0,
+              let lastComponent = textMessage.components(separatedBy: .whitespaces).last,
+              lastComponent.prefix(while: { $0 == "@" || $0 == "/" }).count == 1 // Partial username should start with one and only one "@" character
+        else {
+            items.send([])
+            currentTextTriggerSubject.send(nil)
+            return
+        }
+        
+        currentTextTriggerSubject.send(lastComponent)
+    }
+
+    func processSuggestionPattern(_ suggestionPattern: SuggestionPattern?) {
+        guard let suggestionPattern else {
+            items.send([])
+            currentTextTriggerSubject.send(nil)
+            return
+        }
+
+        switch suggestionPattern.key {
+        case .at:
+            currentTextTriggerSubject.send("@" + suggestionPattern.text)
+        case .hash:
+            // No room suggestion support yet
+            items.send([])
+            currentTextTriggerSubject.send(nil)
+        case .slash:
+            currentTextTriggerSubject.send("/" + suggestionPattern.text)
+        }
+    }
+    
+    // MARK: - Private
+    
+    private func fetchAndFilterMembersForTextTrigger(_ textTrigger: String?) {
+        guard var partialName = textTrigger else {
+            return
+        }
+
+        switch partialName.first {
+        case "@":
+            partialName.removeFirst() // remove the '@' prefix
+
+            roomMemberProvider.fetchMembers { [weak self] members in
+                guard let self = self else {
+                    return
+                }
+
+                self.suggestionItems = members.withRoom(self.roomMemberProvider.canMentionRoom).map { member in
+                    CompletionSuggestionItem.user(value: CompletionSuggestionServiceUserItem(userId: member.userId, displayName: member.displayName, avatarUrl: member.avatarUrl))
+                }
+
+                self.items.send(self.suggestionItems.filter { item in
+                    guard case let .user(completionSuggestionUserItem) = item else { return false }
+
+                    let containedInUsername = completionSuggestionUserItem.userId.lowercased().contains(partialName.lowercased())
+                    let containedInDisplayName = (completionSuggestionUserItem.displayName ?? "").lowercased().contains(partialName.lowercased())
+
+                    return (containedInUsername || containedInDisplayName)
+                })
+            }
+        case "/":
+            // TODO: send all commands if only text is "/"
+            partialName.removeFirst()
+
+            commandProvider.fetchCommands { [weak self] commands in
+                guard let self else { return }
+
+                self.suggestionItems = commands.map { command in
+                    CompletionSuggestionItem.command(value: CompletionSuggestionServiceCommandItem(name: command.name))
+                }
+
+                self.items.send(self.suggestionItems.filter { item in
+                    guard case let .command(commandSuggestion) = item else { return false }
+
+                    return commandSuggestion.name.lowercased().contains(partialName.lowercased())
+                })
+            }
+        default:
+            return
+        }
+    }
+}
+
+extension Array where Element == RoomMembersProviderMember {
+    /// Returns the array with an additional member that represents an `@room` mention.
+    func withRoom(_ canMentionRoom: Bool) -> Self {
+        guard canMentionRoom else { return self }
+        return self + [RoomMembersProviderMember(userId: CompletionSuggestionUserID.room, displayName: "Everyone", avatarUrl: "")]
+    }
+}