// 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.Diagnostics.CodeAnalysis;
using Microsoft.VisualStudio.Text.Editor;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.Editor.Shared.Extensions;
 
internal static partial class ITextViewExtensions
{
    private class AutoClosingViewProperty<TProperty, TTextView> where TTextView : ITextView
    {
        private readonly TTextView _textView;
        private readonly Dictionary<object, TProperty> _map = [];
 
        public static bool GetOrCreateValue(
            TTextView textView,
            object key,
            Func<TTextView, TProperty> valueCreator,
            out TProperty value)
        {
            Contract.ThrowIfTrue(textView.IsClosed);
 
            var properties = textView.Properties.GetOrCreateSingletonProperty(() => new AutoClosingViewProperty<TProperty, TTextView>(textView));
            if (!properties.TryGetValue(key, out var priorValue))
            {
                // Need to create it.
                value = valueCreator(textView);
                properties.Add(key, value);
                return true;
            }
 
            // Already there.
            value = priorValue;
            return false;
        }
 
        public static bool TryGetValue(
            TTextView textView,
            object key,
            [MaybeNullWhen(false)] out TProperty value)
        {
            Contract.ThrowIfTrue(textView.IsClosed);
 
            var properties = textView.Properties.GetOrCreateSingletonProperty(() => new AutoClosingViewProperty<TProperty, TTextView>(textView));
            return properties.TryGetValue(key, out value);
        }
 
        public static void AddValue(
            TTextView textView,
            object key,
            TProperty value)
        {
            Contract.ThrowIfTrue(textView.IsClosed);
 
            var properties = textView.Properties.GetOrCreateSingletonProperty(() => new AutoClosingViewProperty<TProperty, TTextView>(textView));
            properties.Add(key, value);
        }
 
        public static void RemoveValue(TTextView textView, object key)
        {
            if (textView.Properties.TryGetProperty(typeof(AutoClosingViewProperty<TProperty, TTextView>), out AutoClosingViewProperty<TProperty, TTextView> properties))
            {
                properties.Remove(key);
            }
        }
 
        private AutoClosingViewProperty(TTextView textView)
        {
            _textView = textView;
            _textView.Closed += OnTextViewClosed;
        }
 
        private void OnTextViewClosed(object? sender, EventArgs e)
        {
            _textView.Closed -= OnTextViewClosed;
            _textView.Properties.RemoveProperty(typeof(AutoClosingViewProperty<TProperty, TTextView>));
        }
 
        public bool TryGetValue(object key, [MaybeNullWhen(false)] out TProperty value)
            => _map.TryGetValue(key, out value);
 
        public void Add(object key, TProperty value)
            => _map[key] = value;
 
        public void Remove(object key)
            => _map.Remove(key);
    }
}