using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq.Expressions;
using System.Reactive.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using Avalonia.Collections;
using Avalonia.Data;
using Avalonia.Data.Core;
using Avalonia.Data.Core.ExpressionNodes;
using Avalonia.Diagnostics;
using Avalonia.Markup.Parsers;
using Avalonia.Threading;
using Avalonia.UnitTests;
using Avalonia.Utilities;
using Xunit;

#nullable enable

namespace Avalonia.Base.UnitTests.Data.Core;

public abstract class BindingExpressionTests_Indexer
{
    [Fact]
    public async Task Should_Get_Array_Value()
    {
        var data = new { Foo = new[] { "foo", "bar" } };
        var target = CreateTarget(data, o => o.Foo[1]).ToObservable();
        var result = await target.Take(1);

        Assert.Equal("bar", result);

        GC.KeepAlive(data);
    }

    [Fact]
    public async Task Should_Get_MultiDimensional_Array_Value()
    {
        var data = new { Foo = new[,] { { "foo", "bar" }, { "baz", "qux" } } };
        var target = CreateTarget(data, o => o.Foo[1, 1]).ToObservable();
        var result = await target.Take(1);

        Assert.Equal("qux", result);

        GC.KeepAlive(data);
    }

    [Fact]
    public async Task Should_Get_Value_For_String_Indexer()
    {
        var data = new { Foo = new Dictionary<string, string> { { "foo", "bar" }, { "baz", "qux" } } };
        var target = CreateTarget(data, o => o.Foo["foo"]).ToObservable();
        var result = await target.Take(1);

        Assert.Equal("bar", result);

        GC.KeepAlive(data);
    }

    [Fact]
    public async Task Should_Get_Value_For_Non_String_Indexer()
    {
        var data = new { Foo = new Dictionary<double, string> { { 1.0, "bar" }, { 2.0, "qux" } } };
        var target = CreateTarget(data, o => o.Foo[1.0]).ToObservable();
        var result = await target.Take(1);

        Assert.Equal("bar", result);

        GC.KeepAlive(data);
    }

    [Fact]
    public async Task Array_Out_Of_Bounds_Should_Return_UnsetValue()
    {
        var data = new { Foo = new[] { "foo", "bar" } };
        var target = CreateTarget(data, o => o.Foo[2]).ToObservable();
        var result = await target.Take(1);

        Assert.Equal(AvaloniaProperty.UnsetValue, BindingNotification.ExtractValue(result));

        GC.KeepAlive(data);
    }

    [Fact]
    public async Task List_Out_Of_Bounds_Should_Return_UnsetValue()
    {
        var data = new { Foo = new List<string> { "foo", "bar" } };
        var target = CreateTarget(data, o => o.Foo[2]).ToObservable();
        var result = await target.Take(1);

        Assert.Equal(AvaloniaProperty.UnsetValue, BindingNotification.ExtractValue(result));

        GC.KeepAlive(data);
    }

    [Fact]
    public async Task Should_Get_List_Value()
    {
        var data = new { Foo = new List<string> { "foo", "bar" } };
        var target = CreateTarget(data, o => o.Foo[1]).ToObservable();
        var result = await target.Take(1);

        Assert.Equal("bar", result);

        GC.KeepAlive(data);
    }

    [Fact]
    public void Should_Track_INCC_Add()
    {
        var data = new { Foo = new AvaloniaList<string> { "foo", "bar" } };
        var target = CreateTarget(data, o => o.Foo[2]).ToObservable();
        var result = new List<object?>();

        using (var sub = target.Subscribe(x => result.Add(BindingNotification.ExtractValue(x))))
        {
            data.Foo.Add("baz");
        }

        // Forces WeakEvent compact
        Dispatcher.UIThread.RunJobs();

        Assert.Equal(new[] { AvaloniaProperty.UnsetValue, "baz" }, result);
        Assert.Null(((INotifyCollectionChangedDebug)data.Foo).GetCollectionChangedSubscribers());

        GC.KeepAlive(data);
    }

    [Fact]
    public void Should_Track_INCC_Remove()
    {
        var data = new { Foo = new AvaloniaList<string> { "foo", "bar" } };
        var target = CreateTarget(data, o => o.Foo[0]).ToObservable();
        var result = new List<object?>();

        using (var sub = target.Subscribe(result.Add))
        {
            data.Foo.RemoveAt(0);
        }

        // Forces WeakEvent compact
        Dispatcher.UIThread.RunJobs();

        Assert.Equal(new[] { "foo", "bar" }, result);
        Assert.Null(((INotifyCollectionChangedDebug)data.Foo).GetCollectionChangedSubscribers());

        GC.KeepAlive(data);
    }

    [Fact]
    public void Should_Track_INCC_Replace()
    {
        var data = new { Foo = new AvaloniaList<string> { "foo", "bar" } };
        var target = CreateTarget(data, o => o.Foo[1]).ToObservable();
        var result = new List<object?>();

        using (var sub = target.Subscribe(result.Add))
        {
            data.Foo[1] = "baz";
        }

        // Forces WeakEvent compact
        Dispatcher.UIThread.RunJobs();

        Assert.Equal(new[] { "bar", "baz" }, result);
        Assert.Null(((INotifyCollectionChangedDebug)data.Foo).GetCollectionChangedSubscribers());

        GC.KeepAlive(data);
    }

    [Fact]
    public void Should_Track_INCC_Move()
    {
        // Using ObservableCollection here because AvaloniaList does not yet have a Move
        // method, but even if it did we need to test with ObservableCollection as well
        // as AvaloniaList as it implements PropertyChanged as an explicit interface event.
        var data = new { Foo = new ObservableCollection<string> { "foo", "bar" } };
        var target = CreateTarget(data, o => o.Foo[1]).ToObservable();
        var result = new List<object?>();

        var sub = target.Subscribe(result.Add);
        data.Foo.Move(0, 1);

        Assert.Equal(new[] { "bar", "foo" }, result);

        GC.KeepAlive(sub);
        GC.KeepAlive(data);
    }

    [Fact]
    public void Should_Track_INCC_Reset()
    {
        var data = new { Foo = new AvaloniaList<string> { "foo", "bar" } };
        var target = CreateTarget(data, o => o.Foo[1]).ToObservable();
        var result = new List<object?>();

        var sub = target.Subscribe(x => result.Add(BindingNotification.ExtractValue(x)));
        data.Foo.Clear();

        Assert.Equal(new[] { "bar", AvaloniaProperty.UnsetValue }, result);

        GC.KeepAlive(sub);
        GC.KeepAlive(data);
    }

    [Fact]
    public void Should_Track_NonIntegerIndexer()
    {
        var data = new { Foo = new NonIntegerIndexer() };
        data.Foo["foo"] = "bar";
        data.Foo["baz"] = "qux";

        var target = CreateTarget(data, o => o.Foo["foo"]).ToObservable();
        var result = new List<object?>();

        using (var sub = target.Subscribe(result.Add))
        {
            data.Foo["foo"] = "bar2";
        }

        // Forces WeakEvent compact
        Dispatcher.UIThread.RunJobs();

        var expected = new[] { "bar", "bar2" };
        Assert.Equal(expected, result);
        Assert.Equal(0, data.Foo.PropertyChangedSubscriptionCount);

        GC.KeepAlive(data);
    }

    [Fact]
    public void Should_SetArrayIndex()
    {
        var data = new { Foo = new[] { "foo", "bar" } };
        var target = CreateTarget(data, o => o.Foo[1]);

        using (target.ToObservable().Subscribe(_ => { }))
        {
            Assert.True(target.WriteValueToSource("baz"));
        }

        Assert.Equal("baz", data.Foo[1]);

        GC.KeepAlive(data);
    }

    [Fact]
    public void Should_Set_ExistingDictionaryEntry()
    {
        var data = new
        {
            Foo = new Dictionary<string, int>
            {
                {"foo", 1 }
            }
        };

        var target = CreateTarget(data, o => o.Foo["foo"]);
        using (target.ToObservable().Subscribe(_ => { }))
        {
            Assert.True(target.WriteValueToSource(4));
        }

        Assert.Equal(4, data.Foo["foo"]);

        GC.KeepAlive(data);
    }

    [Fact]
    public void Should_Add_NewDictionaryEntry()
    {
        var data = new
        {
            Foo = new Dictionary<string, int>
            {
                {"foo", 1 }
            }
        };

        var target = CreateTarget(data, o => o.Foo["bar"]);
        using (target.ToObservable().Subscribe(_ => { }))
        {
            Assert.True(target.WriteValueToSource(4));
        }

        Assert.Equal(4, data.Foo["bar"]);

        GC.KeepAlive(data);
    }

    [Fact]
    public void Should_Set_NonIntegerIndexer()
    {
        var data = new { Foo = new NonIntegerIndexer() };
        data.Foo["foo"] = "bar";
        data.Foo["baz"] = "qux";

        var target = CreateTarget(data, o => o.Foo["foo"]);

        using (target.ToObservable().Subscribe(_ => { }))
        {
            Assert.True(target.WriteValueToSource("bar2"));
        }

        Assert.Equal("bar2", data.Foo["foo"]);

        GC.KeepAlive(data);
    }

    [Fact]
    public async Task Indexer_Only_Binding_Works()
    {
        var data = new[] { 1, 2, 3 };

        var target = BindingExpression.Create(data, o => o[1]).ToObservable();

        var value = await target.Take(1);

        Assert.Equal(data[1], value);
    }

    private protected abstract BindingExpression CreateTarget<TIn, TOut>(
        TIn data,
        Expression<Func<TIn, TOut>> expression) where TIn : class?;

    public class Expressions : BindingExpressionTests_Indexer
    {
        private protected override BindingExpression CreateTarget<TIn, TOut>(
            TIn data,
            Expression<Func<TIn, TOut>> expression)
        {
            return BindingExpression.Create(data, expression);
        }
    }

    public class Reflection : BindingExpressionTests_Indexer
    {
        private protected override BindingExpression CreateTarget<TIn, TOut>(
            TIn data,
            Expression<Func<TIn, TOut>> expression)
        {
            var path = expression.Body.ToString();

            // Removes leading "o.".
            path = new Regex(@"^\w\.").Replace(path, "");

            // Replaces ".get_Item("x")" with "[x]".
            path = new Regex(@"\.get_Item\((.+)\)$").Replace(path, "[$1]");

            // Replaces ".Get(x)" with "[x]".
            path = new Regex(@"\.Get\((.+)\)$").Replace(path, "[$1]");

            // Remove quotes.
            path = path.Replace("\"", "");

            var reader = new CharacterReader(path);
            var (astNodes, sourceMode) = BindingExpressionGrammar.Parse(ref reader);
            var nodes = new List<ExpressionNode>();
            ExpressionNodeFactory.CreateFromAst(astNodes, null, null, nodes, out _);

            return new BindingExpression(data, nodes, AvaloniaProperty.UnsetValue);
        }
    }

    private class NonIntegerIndexer : NotifyingBase
    {
        private readonly Dictionary<string, string> _storage = new Dictionary<string, string>();

        public string this[string key]
        {
            get
            {
                return _storage[key];
            }
            set
            {
                _storage[key] = value;
                RaisePropertyChanged(CommonPropertyNames.IndexerName);
            }
        }
    }
}