// 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;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Linq;
using Roslyn.Utilities;
using Xunit;
 
namespace Microsoft.CodeAnalysis.Editor.UnitTests.Collections.Immutable.Maps;
 
public class MapTests
{
    [Fact]
    public void TestEnumerator()
    {
        var map = ImmutableDictionary.Create<string, int>().Add("1", 1);
        foreach (var v in map)
        {
            Assert.Equal("1", v.Key);
            Assert.Equal(1, v.Value);
        }
 
        foreach (var v in (IEnumerable)map)
        {
            Assert.Equal("1", ((KeyValuePair<string, int>)v).Key);
            Assert.Equal(1, ((KeyValuePair<string, int>)v).Value);
        }
    }
 
    [Fact]
    public void TestCounts()
    {
        var map = ImmutableDictionary.Create<string, int>()
            .Add("1", 1)
            .Add("2", 2)
            .Add("3", 3)
            .Add("4", 4)
            .Add("5", 5);
 
        Assert.Equal(5, map.Count);
        Assert.Equal(5, map.Keys.Count());
        Assert.Equal(5, map.Values.Count());
    }
 
    [Fact]
    public void TestRemove()
    {
        var map = ImmutableDictionary.Create<string, int>()
            .Add("1", 1)
            .Add("2", 2)
            .Add("3", 3)
            .Add("4", 4)
            .Add("5", 5);
 
        map = map.Remove("0");
        Assert.Equal(5, map.Count);
 
        map = map.Remove("1");
        Assert.Equal(4, map.Count);
 
        map = map.Remove("1");
        Assert.Equal(4, map.Count);
 
        map = map.Remove("2");
        Assert.Equal(3, map.Count);
 
        map = map.Remove("3");
        Assert.Equal(2, map.Count);
 
        map = map.Remove("4");
        Assert.Equal(1, map.Count);
 
        map = map.Remove("5");
        Assert.Equal(0, map.Count);
    }
 
    [Fact]
    public void TestPathology()
    {
        var map = ImmutableDictionary.Create<string, int>(new PathologicalComparer<string>())
            .Add("1", 1)
            .Add("2", 2)
            .Add("3", 3)
            .Add("4", 4)
            .Add("5", 5);
 
        Assert.Equal(5, map.Count);
        Assert.Equal(1, map["1"]);
        Assert.Equal(2, map["2"]);
        Assert.Equal(3, map["3"]);
 
        map = map.Remove("0");
        Assert.Equal(5, map.Count);
 
        map = map.Remove("3");
        Assert.Equal(4, map.Count);
 
        map = map.Remove("3");
        Assert.Equal(4, map.Count);
 
        map = map.Remove("2");
        Assert.Equal(3, map.Count);
 
        map = map.Remove("1");
        Assert.Equal(2, map.Count);
 
        map = map.Remove("4");
        Assert.Equal(1, map.Count);
 
        map = map.Remove("6");
        Assert.Equal(1, map.Count);
 
        map = map.Remove("5");
        Assert.Equal(0, map.Count);
    }
 
    private class PathologicalComparer<T> : IEqualityComparer<T>
    {
        public bool Equals(T x, T y)
            => EqualityComparer<T>.Default.Equals(x, y);
 
        public int GetHashCode(T obj)
            => 0;
    }
}