letro-ios/ElementX/Sources/Screens/HomeScreen/View/HomeScreen.swift

// 
// 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 SwiftUI
import Kingfisher

struct HomeScreen: View {
    
    @ObservedObject var context: HomeScreenViewModel.Context
    
    // MARK: Views
    
    var body: some View {
        VStack(spacing: 16.0) {
            if context.viewState.isLoadingRooms {
                VStack {
                    Text("Loading rooms")
                    ProgressView()
                }
            } else {
                List {
                    Section("Rooms") {
                        ForEach(context.viewState.unencryptedRooms) { room in
                            RoomCell(room: room, context: context)
                        }
                        
                        let other = context.viewState.encryptedRooms
                        
                        if other.count > 0 {
                            DisclosureGroup("Encrypted") {
                                ForEach(other) { room in
                                    RoomCell(room: room, context: context)
                                }
                            }
                        }
                    }
                    
                    Section("People") {
                        ForEach(context.viewState.unencryptedDMs) { room in
                            RoomCell(room: room, context: context)
                        }
                        
                        let other = context.viewState.encryptedDMs
                        
                        if other.count > 0 {
                            DisclosureGroup("Encrypted") {
                                ForEach(other) { room in
                                    RoomCell(room: room, context: context)
                                }
                            }
                        }
                    }
                }
                .listStyle(.plain)
            }
            
            Spacer()
        }
        .ignoresSafeArea(.all, edges: .bottom)
        .navigationBarTitleDisplayMode(.inline)
        .toolbar {
            ToolbarItem(placement: .navigationBarLeading) {
                HStack {
                    if let avatar = context.viewState.userAvatar {
                        Image(uiImage: avatar)
                            .resizable()
                            .scaledToFill()
                            .frame(width: 40, height: 40, alignment: .center)
                            .mask(Circle())
                    } else {
                        let _ = context.send(viewAction: .loadUserAvatar)
                    }
                    Text("Hello, \(context.viewState.userDisplayName)!")
                        .font(.subheadline)
                        .fontWeight(.bold)
                }
            }
            ToolbarItem(placement: .navigationBarTrailing) {
                Button("Logout") {
                    context.send(viewAction: .logout)
                }
            }
        }
    }
}

struct RoomCell: View {
    
    let room: HomeScreenRoom
    let context: HomeScreenViewModel.Context
    
    var body: some View {
        Button {
            context.send(viewAction: .selectRoom(roomIdentifier: room.id))
        } label: {
            HStack(spacing: 16.0) {
                if let avatar = room.avatar {
                    Image(uiImage: avatar)
                        .resizable()
                        .scaledToFill()
                        .frame(width: 40, height: 40)
                        .mask(Circle())
                } else {
                    Image(systemName: "person.3")
                        .frame(width: 40, height: 40)
                }
                
                VStack(alignment: .leading, spacing: 4.0) {
                    Text(roomName(room))
                        .font(.headline)
                        .fontWeight(.regular)
                    
                    if let roomTopic = room.topic, roomTopic.count > 0 {
                        Text(roomTopic)
                            .font(.footnote)
                            .fontWeight(.bold)
                            .lineLimit(1)
                    }
                    
                    if let lastMessage = room.lastMessage {
                        Text(lastMessage)
                            .font(.footnote)
                            .fontWeight(.medium)
                            .lineLimit(1)
                    }
                }
            }
            .frame(minHeight: 60.0)
            .onAppear {
                context.send(viewAction: .loadRoomData(roomIdentifier: room.id))
            }
        }
    }
    
    private func roomName(_ room: HomeScreenRoom) -> String {
        room.displayName ?? room.id + (room.isEncrypted ? "🛡": "")
    }
}

// MARK: - Previews

struct HomeScreen_Previews: PreviewProvider {
    static var previews: some View {
        let viewModel = HomeScreenViewModel(userDisplayName: "Johnny Appleseed", imageCache: ImageCache.default)
        
        let rooms = [MockRoomProxy(displayName: "Alfa"),
                     MockRoomProxy(displayName: "Beta"),
                     MockRoomProxy(displayName: "Omega")]
        
        viewModel.updateWithRoomList(rooms)
        
        viewModel.updateWithUserAvatar(UIImage(systemName: "person.fill.questionmark"))
        
        return HomeScreen(context: viewModel.context)
    }
}