// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
#nullable disable
 
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Diagnostics;
using System.Linq;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CodeStyle;
using Microsoft.CodeAnalysis.Options;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation.Options;
 
/// <summary>
/// This class represents the view model for a <see cref="CodeStyleOption2{T}"/>
/// that binds to the codestyle options UI.  Note that the T here is expected to be an enum
/// type.  
/// 
/// Important.  The order of the previews and preferences provided should match the order
/// of enum members of T.  
/// </summary>
internal sealed class EnumCodeStyleOptionViewModel<T> : AbstractCodeStyleOptionViewModel
    where T : struct
{
    static EnumCodeStyleOptionViewModel()
        => Contract.ThrowIfFalse(typeof(T).IsEnum);
 
    private readonly ImmutableArray<T> _enumValues;
    private readonly ImmutableArray<string> _previews;
 
    private CodeStylePreference _selectedPreference;
    private NotificationOptionViewModel _selectedNotificationPreference;
 
    public EnumCodeStyleOptionViewModel(
        IOption2 option,
        string description,
        T[] enumValues,
        string[] previews,
        AbstractOptionPreviewViewModel info,
        OptionStore optionStore,
        string groupName,
        List<CodeStylePreference> preferences)
        : base(option, description, info, groupName, preferences)
    {
        Debug.Assert(preferences.Count == enumValues.Length);
        Debug.Assert(previews.Length == enumValues.Length);
 
        _enumValues = [.. enumValues];
        _previews = [.. previews];
 
        var codeStyleOption = optionStore.GetOption<CodeStyleOption2<T>>(option, option.IsPerLanguage ? info.Language : null);
 
        var enumIndex = _enumValues.IndexOf(codeStyleOption.Value);
        if (enumIndex < 0 || enumIndex >= Preferences.Count)
        {
            enumIndex = 0;
        }
 
        _selectedPreference = Preferences[enumIndex];
 
        var notificationViewModel = NotificationPreferences.Single(i => i.Notification.Severity == codeStyleOption.Notification.Severity);
        _selectedNotificationPreference = NotificationPreferences.Single(p => p.Notification.Severity == notificationViewModel.Notification.Severity);
 
        NotifyPropertyChanged(nameof(SelectedPreference));
        NotifyPropertyChanged(nameof(SelectedNotificationPreference));
    }
 
    public override string GetPreview()
    {
        var index = Preferences.IndexOf(SelectedPreference);
        return _previews[index];
    }
 
    public override CodeStylePreference SelectedPreference
    {
        get => _selectedPreference;
 
        set
        {
            if (SetProperty(ref _selectedPreference, value))
            {
                var index = Preferences.IndexOf(value);
                var enumValue = _enumValues[index];
 
                Info.SetOptionAndUpdatePreview(
                    new CodeStyleOption2<T>(
                        enumValue, _selectedNotificationPreference.Notification),
                    Option, GetPreview());
            }
        }
    }
 
    public override NotificationOptionViewModel SelectedNotificationPreference
    {
        get => _selectedNotificationPreference;
 
        set
        {
            if (SetProperty(ref _selectedNotificationPreference, value))
            {
                var index = Preferences.IndexOf(SelectedPreference);
                var enumValue = _enumValues[index];
 
                Info.SetOptionAndUpdatePreview(
                    new CodeStyleOption2<T>(
                        enumValue, _selectedNotificationPreference.Notification),
                    Option, GetPreview());
            }
        }
    }
}