another.im-ios/ConversationsClassic/View/Screens/Conversation/ConversationScreen.swift

import Combine
import Foundation
import Martin
import SwiftUI

struct ConversationScreen: View {
    @EnvironmentObject var store: AppStore

    @State private var autoScroll = true

    var body: some View {
        ZStack {
            // Background color
            Color.Main.backgroundLight
                .ignoresSafeArea()

            // Content
            VStack(spacing: 0) {
                // Header
                ConversationHeader()

                // Msg list
                let messages = store.state.conversationsState.currentMessages
                if !messages.isEmpty {
                    ScrollViewReader { proxy in
                        List {
                            ForEach(messages) { message in
                                ConversationMessageRow(message: message)
                                    .id(message.id)
                                    .onAppear {
                                        if message.id == messages.first?.id {
                                            autoScroll = true
                                        }
                                    }
                                    .onDisappear {
                                        if message.id == messages.first?.id {
                                            autoScroll = false
                                        }
                                    }
                            }
                            .rotationEffect(.degrees(180))
                        }
                        .rotationEffect(.degrees(180))
                        .listStyle(.plain)
                        .background(Color.Main.backgroundLight)
                        .scrollDismissesKeyboard(.immediately)
                        .scrollIndicators(.hidden)
                        .onChange(of: autoScroll) { new in
                            if new {
                                withAnimation {
                                    proxy.scrollTo(messages.first?.id, anchor: .top)
                                }
                            }
                        }
                    }
                } else {
                    Spacer()
                }
            }
            .onTapGesture {
                UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder), to: nil, from: nil, for: nil)
            }

            // Jump to last button
            if !autoScroll {
                VStack {
                    Spacer()
                    HStack {
                        Spacer()
                        Button {
                            autoScroll = true
                        } label: {
                            ZStack {
                                Circle()
                                    .fill(Color.Main.white)
                                Image(systemName: "arrow.down")
                                    .foregroundColor(.Tango.blueLight)
                            }
                            .frame(width: 40, height: 40)
                            .shadow(color: .Main.black.opacity(0.2), radius: 4)
                            .padding(.trailing, 8)
                            .padding(.bottom, 8)
                        }
                    }
                }
            }
        }
        .safeAreaInset(edge: .bottom, spacing: 0) {
            ConversationTextInput()
        }
    }
}

// Preview
#if DEBUG
    struct ConversationScreen_Previews: PreviewProvider {
        static var previews: some View {
            ConversationScreen()
                .environmentObject(pStore)
        }

        static var pStore: AppStore {
            let state = pState
            return AppStore(initialState: state, reducer: AppState.reducer, middlewares: [])
        }

        static var pState: AppState {
            var state = AppState()

            let acc = "user@test.com"
            let contact = "some@test.com"

            state.conversationsState.currentChat = Chat(id: "1", account: acc, participant: contact, type: .chat)
            state.conversationsState.currentMessages = [
                Message(
                    id: "1",
                    type: .chat,
                    contentType: .text,
                    from: contact,
                    to: acc,
                    body: "this is for test sdgdsfg dsfg dsfgdg dsfgdfgsdgsdfgdfg sdfgdsfgdfsg dsfgdsfgsdfg dsfgdfgsdg fgf fgfg sdfsdf sdfsdf sdf  sdfsdf sdf sdfsdf sdfsdfsdf sdfsdf ",
                    subject: nil,
                    thread: nil,
                    oobUrl: nil,
                    date: Date(),
                    pending: true, sentError: false
                ),
                Message(
                    id: "2",
                    type: .chat,
                    contentType: .text,
                    from: contact,
                    to: acc,
                    body: "this is for testsdfsdf sdfsdf sdfs sdf sdffsdf  sdf sdf  sdf sdf sdf sdff sdfffwwe ",
                    subject: nil,
                    thread: nil,
                    oobUrl: nil,
                    date: Date(),
                    pending: false,
                    sentError: false
                ),
                Message(id: "3", type: .chat, contentType: .text, from: contact, to: acc, body: "this is for test", subject: nil, thread: nil, oobUrl: nil, date: Date(), pending: false, sentError: true),
                Message(
                    id: "4",
                    type: .chat,
                    contentType: .text,
                    from: acc,
                    to: contact,
                    body: "this is for test  sdfkjwek jwkjfh jwerf   jdfhskjdhf  jsdhfjhwefh sjdhfh  fsdjhfh sd ",
                    subject: nil,
                    thread: nil,
                    oobUrl: nil,
                    date: Date(),
                    pending: false,
                    sentError: false
                ),
                Message(id: "5", type: .chat, contentType: .text, from: contact, to: acc, body: "this is for test sdfjkkeke kekkddjw;;  w;edkdjfj l kjwekrjfk wef", subject: nil, thread: nil, oobUrl: nil, date: Date(), pending: false, sentError: false),
                Message(id: "6", type: .chat, contentType: .text, from: acc, to: contact, body: "this is for testsdf dsdkkekkddn  wejkjfj  ", subject: nil, thread: nil, oobUrl: nil, date: Date(), pending: false, sentError: false),
                Message(
                    id: "7",
                    type: .chat,
                    contentType: .text,
                    from: acc,
                    to: contact,

                    body: "this is for test sdgdsfg dsfg dsfgdg dsfgdfgsdgsdfgdfg sdfgdsfgdfsg dsfgdsfgsdfg dsfgdfgsdg fgf fgfg sdfsdf sdfsdf sdf  sdfsdf sdf sdfsdf sdfsdfsdf sdfsdf ",
                    subject: nil,
                    thread: nil,
                    oobUrl: nil,
                    date: Date(), pending: false, sentError: false
                ),
                Message(id: "8", type: .chat, contentType: .text, from: acc, to: contact, body: "so test", subject: nil, thread: nil, oobUrl: nil, date: Date(), pending: false, sentError: false),
                Message(id: "9", type: .chat, contentType: .text, from: contact, to: acc, body: "so test", subject: nil, thread: nil, oobUrl: nil, date: Date(), pending: false, sentError: false),
                Message(id: "10", type: .chat, contentType: .text, from: acc, to: contact, body: "so test so test so test", subject: nil, thread: nil, oobUrl: nil, date: Date(), pending: false, sentError: false),
                Message(id: "11", type: .chat, contentType: .text, from: contact, to: acc, body: "xD", subject: nil, thread: nil, oobUrl: nil, date: Date(), pending: false, sentError: false)
            ]

            state.conversationsState.replyText = "> Some Text here! And if it a long and very long text sdfsadfsadfsafsadfsadfsadfsadfassadfsadfsafsafdsadfsafdsadfsadfas sdf sdf asdf  sdfasdfsd sdfasdf sdfsdfdsasdfsdfa dsafsaf"

            return state
        }
    }
#endif