HAcontrol/SettingsWindow.axaml.cs

using Avalonia.Controls;
using Avalonia.Interactivity;
using System;
using System.IO;
using System.Text.Json;

namespace HAcontrol;

public partial class SettingsWindow : Window
{
    public static readonly string SettingsFile =
        Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), "ha_control_settings.json");

    public SettingsWindow()
    {
        InitializeComponent();
        LoadSettings();
    }

    private void LoadSettings()
    {
        if (File.Exists(SettingsFile))
        {
            var json = File.ReadAllText(SettingsFile);
            var settings = JsonSerializer.Deserialize<Settings>(json);
            if (settings != null)
            {
                UrlBox.Text = settings.HomeAssistantUrl;
                TokenBox.Text = settings.AccessToken;
                WebhookBox.Text = settings.WebhookId;
                EntityBox.Text = settings.Entity;
            }
        }
    }

    private void Save_Click(object? sender, RoutedEventArgs e)
    {
        var settings = new Settings
        {
            HomeAssistantUrl = UrlBox.Text ?? string.Empty,
            AccessToken = TokenBox.Text ?? string.Empty,
            WebhookId = WebhookBox.Text ?? string.Empty,
            Entity = EntityBox.Text ?? string.Empty
        };
        var json = JsonSerializer.Serialize(settings, new JsonSerializerOptions { WriteIndented = true });
        File.WriteAllText(SettingsFile, json);
        this.Close();

        MainWindow.Self.LoadSettings();
    }
}

public class Settings
{
    public string HomeAssistantUrl { get; set; } = string.Empty;
    public string AccessToken { get; set; } = string.Empty;
    public string WebhookId { get; set; } = string.Empty;
    public string Entity { get; set; } = string.Empty;
}