MultiTerm/MultiTerm.Core/ViewModel/ShellViewModel.cs

using Common.AppSettings;
using Common.Logging;
using Common.Helpers;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using MultiTerm.Core.Factories;
using System.Collections.ObjectModel;
using MultiTerm.Core.Types;
using MultiTerm.Protocols.Types;
using CommunityToolkit.Mvvm.Messaging;
using Common.Messaging;
using System.Timers;

namespace MultiTerm.Core.ViewModel;

public partial class ShellViewModel : ObservableObject, IRecipient<IUserInterfaceMessage>
{
    private const string defaultReceiveNewlineSeparatorAppSettingsKey = "DefaultReceiveNewlineSeparator";
    private const string defaultSendNewlineSeparatorAppSettingsKey = "DefaultSendNewlineSeparator";
    private const int statusBarMessageDurationMs = 12000;   // how long the status bar shall be displayed

    #region Terminal collection
    [ObservableProperty]
    private ObservableCollection<ITerminalViewModel> terminalViewModels = new();

    [ObservableProperty]
    private ITerminalViewModel? selectedTerminalViewModel;
    #endregion

    #region Settings Menu Bar
    [ObservableProperty]
    private NewlineSeparatorType defaultReceiveNewlineSeparator = NewlineSeparatorType.None;

    [ObservableProperty]
    private NewlineSeparatorType defaultSendNewlineSeparator = NewlineSeparatorType.None;
    #endregion

    #region New Terminal Context Menu
    [ObservableProperty]
    private TerminalViewType selectedTerminalViewType = TerminalViewType.SendReceive;
    #endregion

    #region Status Bar
    private System.Timers.Timer? statusBarMessageTimer;
    private const int statusBarMessageTimerIntervalMs = 100;   // After x milliseconds the timer shall be called

    [ObservableProperty]
    private string statusBarMessage = "";

    [ObservableProperty]
    private MessageImportance statusBarMessageImportance = MessageImportance.Normal;

    [ObservableProperty]
    private double statusBarMessageDurationPercentage = 0;
    #endregion

    private readonly ITerminalViewModelFactory terminalViewModelFactory;
    private readonly ILogger logger;
    private readonly IAppSettingsProvider appSettings;
    private readonly IMessenger messenger;

    public ShellViewModel(ITerminalViewModelFactory terminalViewModelFactory, ILogger logger, IAppSettingsProvider appSettings, IMessenger messenger)
    {
        this.terminalViewModelFactory = terminalViewModelFactory;
        this.logger = logger;
        this.appSettings = appSettings;
        this.messenger = messenger;

        // intialize values from app settings
        this.LoadFromAppSettings();

        // register to messages
        this.messenger.Register(this);
    }

    /// <summary>
    /// Forcefully close all <see cref="TerminalViewModel"/>s.
    /// </summary>
    public void Teardown()
    {
        // iterate through all terminals
        foreach (ITerminalViewModel terminal in this.TerminalViewModels)
        {
            // forcefully close
            terminal.ForceClose();
            // do not remove from collection, otherwise the collection was changed
        }
    }

    [RelayCommand]
    private void AppendTerminalWithSelectedViewType(ProtocolType protocolType)
    {
        this.logger.LogInfo($"Adding new Terminal with ViewType '{this.SelectedTerminalViewType}' and ProtocolType '{protocolType}'", nameof(ShellViewModel));
        this.AppendConfiguredTerminal(this.terminalViewModelFactory.Create(this.SelectedTerminalViewType, protocolType));
    }

    private void AppendConfiguredTerminal(ITerminalViewModel? newTerminal)
    {
        // guard null value
        if(newTerminal == null) { return; }

        // add to collection and register closing event handler
        this.TerminalViewModels.Add(newTerminal);
        newTerminal.ClosingEvent += Terminal_ClosingEvent;

        // set as selected
        this.SelectedTerminalViewModel = newTerminal;
    }

    private void Terminal_ClosingEvent(object? sender, EventArgs e)
    {
        if(sender is not ITerminalViewModel tvm) { throw new ArgumentException($"{nameof(Terminal_ClosingEvent)} failed to convert sender to {nameof(ITerminalViewModel)}"); }
        this.RemoveTerminal(tvm);
    }

    private void RemoveTerminal(ITerminalViewModel terminalToRemove)
    {
        // guard null value
        if(terminalToRemove == null) { return; }

        this.TerminalViewModels.Remove(terminalToRemove);
    }

    #region App Settings handling
    private void LoadFromAppSettings()
    {
        // initialize newline separators from persistent settings
        this.appSettings.TryReadSettingOrAddDefault(defaultReceiveNewlineSeparatorAppSettingsKey, out string settingValueReceiveNLSep, NewlineSeparatorType.None.ToString());
        this.DefaultReceiveNewlineSeparator = EnumHelpers.ParseEnum<NewlineSeparatorType>(settingValueReceiveNLSep);
        this.appSettings.TryReadSettingOrAddDefault(defaultSendNewlineSeparatorAppSettingsKey, out string settingValueSendNLSep, NewlineSeparatorType.None.ToString());
        this.DefaultSendNewlineSeparator = EnumHelpers.ParseEnum<NewlineSeparatorType>(settingValueSendNLSep);
    }

    partial void OnDefaultReceiveNewlineSeparatorChanged(NewlineSeparatorType value)
    {
        // update setting in app settings
        this.appSettings.WriteSetting(defaultReceiveNewlineSeparatorAppSettingsKey, value.ToString());
    }

    partial void OnDefaultSendNewlineSeparatorChanged(NewlineSeparatorType value)
    {
        // update setting in app settings
        this.appSettings.WriteSetting(defaultSendNewlineSeparatorAppSettingsKey, value.ToString());
    }
    #endregion

    #region Messaging handling
    public void Receive(IUserInterfaceMessage message)
    {
        // reset percentage
        this.StatusBarMessageDurationPercentage = 100;

        // display message
        this.StatusBarMessage = message.ToString();
        this.StatusBarMessageImportance = message.Importance;

        // start timer
        if(this.statusBarMessageTimer == null)
        {
            this.statusBarMessageTimer = new System.Timers.Timer(statusBarMessageTimerIntervalMs);
            this.statusBarMessageTimer.Elapsed += StatusBarMessageTimer_Elapsed;
            this.statusBarMessageTimer.AutoReset = true;  // restart after elapsed
            this.statusBarMessageTimer.Enabled = true;    // start timer
        }
    }

    private void StatusBarMessageTimer_Elapsed(object? sender, ElapsedEventArgs e)
    {
        float differencePercentage = (statusBarMessageDurationMs / statusBarMessageTimerIntervalMs) / 100;

        // if not yet done
        if(this.StatusBarMessageDurationPercentage - differencePercentage > 0)
        {
            this.StatusBarMessageDurationPercentage -= differencePercentage;
            return;
        }

        // clear message and kill timer when finished
        this.StatusBarMessage = "";
        this.StatusBarMessageDurationPercentage = 0;
        this.statusBarMessageTimer!.Enabled = false;
        this.statusBarMessageTimer.Dispose();
        this.statusBarMessageTimer = null;
    }
    #endregion
}