﻿// 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.

using System;
using System.Collections.Generic;
using System.Linq;

namespace Microsoft.VisualStudio.LanguageServices.EditorConfigSettings.Common
{
    internal abstract class EnumSettingViewModel<T> : IEnumSettingViewModel
        where T : Enum
    {
        private readonly IReadOnlyDictionary<string, T> _mapping;

        public string[] EnumValues => GetValueDescriptions();

        public string ToolTip => ServicesVSResources.Value;
        public string AutomationName => ServicesVSResources.Value;

        private string? _selectedEnumValue;

        public string SelectedEnumValue
        {
            get
            {
                if (_selectedEnumValue is null)
                {
                    var values = EnumValues;
                    var index = GetValueIndex();
                    _selectedEnumValue = values[index];
                }

                return _selectedEnumValue;
            }
            set => _selectedEnumValue = value;
        }

        protected EnumSettingViewModel()
        {
            _mapping = GetValuesAndDescriptions();
        }

        public void ChangeProperty(string propertyDescription)
        {
            if (_mapping.TryGetValue(propertyDescription, out var value))
            {
                ChangePropertyTo(value);
            }
        }

        public string[] GetValueDescriptions()
            => _mapping.Keys.ToArray();

        public int GetValueIndex()
        {
            var value = GetCurrentValue();
            return _mapping.Values.ToList().IndexOf(value);
        }

        protected abstract IReadOnlyDictionary<string, T> GetValuesAndDescriptions();
        protected abstract void ChangePropertyTo(T newValue);
        protected abstract T GetCurrentValue();
    }
}
