StreamChatChannelSearch.swift

import Combine
import StreamChat
import SwiftUI

struct CustomChannelSearchView: View {
    @StateObject var viewModel: ViewModel
    
    init(client: ChatClient) {
        _viewModel = StateObject(wrappedValue: ViewModel(client: client))
    }
    
    var body: some View {
        NavigationView {
            List(viewModel.results, id: \.cid) { channel in
                VStack(alignment: .leading) {
                    Text(channel.name ?? "<Not set>")
                        .font(.headline)
                    Text(channel.cid.rawValue)
                        .font(.subheadline)
                        .foregroundColor(.secondary)
                }
            }
            .navigationTitle("Channels")
            .searchable(text: $viewModel.searchText, prompt: "Search for Channels")
            // TODO: Implement pagination
        }
    }
}

extension CustomChannelSearchView {
    @MainActor final class ViewModel: ObservableObject {
        @Published private(set) var results = [ChatChannel]()
        @Published var searchText = ""
        private var cancellables = Set<AnyCancellable>()
        private var channelList: ChannelList?
        private let client: ChatClient
        private var searchTask: Task<Void, Error>?
        private var channelListCancellable: AnyCancellable?
        
        init(client: ChatClient) {
            self.client = client
            $searchText
                .removeDuplicates()
                .sink { [weak self] text in
                    self?.search(text)
                }
                .store(in: &cancellables)
        }
        
        private func search(_ text: String) {
            guard let currentUserId = client.currentUserId else { return }
            searchTask?.cancel()
            
            guard text.count > 2 else {
                results = []
                return
            }
            
            var query = ChannelListQuery(
                filter: .and([
                    .autocomplete(.name, text: text),
                    .containMembers(userIds: [currentUserId])
                ])
            )
            query.options = [] // disable watching channels aka web-socket updates
            let channelList = client.makeChannelList(with: query)
            searchTask = Task {
                do {
                    try await channelList.get()
                    guard !Task.isCancelled else { return }
                    setActiveChannelList(channelList)
                } catch {
                    // TODO: handle errors
                }
            }
        }
        
        private func setActiveChannelList(_ channelList: ChannelList) {
            self.channelList = channelList
            channelListCancellable = channelList.state
                .$channels
                .sink { [weak self] results in
                self?.results = Array(results)
            }
        }
    }
}