// Copyright (c) The Avalonia Project. All rights reserved.
// Licensed under the MIT license. See licence.md file in the project root for full license information.

using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using Avalonia.Data;
using Avalonia.Markup.Data.Plugins;
using Xunit;

namespace Avalonia.Markup.UnitTests.Data
{
    public class IndeiValidatorTests
    {
        [Fact]
        public void Setting_Non_Validating_Does_Not_Trigger_Validation()
        {
            var inpcAccessorPlugin = new InpcPropertyAccessorPlugin();
            var validatorPlugin = new IndeiValidationPlugin();
            var data = new Data();
            var accessor = inpcAccessorPlugin.Start(new WeakReference(data), nameof(data.NonValidated));
            var validator = validatorPlugin.Start(new WeakReference(data), nameof(data.NonValidated), accessor);
            var results = new List<object>();

            validator.Subscribe(x => results.Add(x));
            validator.SetValue(5, BindingPriority.LocalValue);

            Assert.Equal(
                new[]
                {
                   new BindingNotification(0),
                   new BindingNotification(5),
                }, results);
        }

        [Fact]
        public void Setting_Validating_Property_To_Valid_Value_Returns_Successful_BindingNotification()
        {
            var inpcAccessorPlugin = new InpcPropertyAccessorPlugin();
            var validatorPlugin = new IndeiValidationPlugin();
            var data = new Data { MustBePositive = 1 };
            var accessor = inpcAccessorPlugin.Start(new WeakReference(data), nameof(data.MustBePositive));
            var validator = validatorPlugin.Start(new WeakReference(data), nameof(data.MustBePositive), accessor);
            var results = new List<object>();

            validator.Subscribe(x => results.Add(x));
            validator.SetValue(5, BindingPriority.LocalValue);

            Assert.Equal(
                new[]
                {
                   new BindingNotification(1),
                   new BindingNotification(5),
                }, results);
        }

        [Fact]
        public void Setting_Validating_Property_To_Invalid_Value_Returns_DataValidationError()
        {
            var inpcAccessorPlugin = new InpcPropertyAccessorPlugin();
            var validatorPlugin = new IndeiValidationPlugin();
            var data = new Data { MustBePositive = 1 };
            var accessor = inpcAccessorPlugin.Start(new WeakReference(data), nameof(data.MustBePositive));
            var validator = validatorPlugin.Start(new WeakReference(data), nameof(data.MustBePositive), accessor);
            var results = new List<object>();

            validator.Subscribe(x => results.Add(x));
            validator.SetValue(-5, BindingPriority.LocalValue);

            Assert.Equal(
                new[]
                {
                   new BindingNotification(1),
                   new BindingNotification(new Exception("MustBePositive must be positive"), BindingErrorType.DataValidationError, -5),
                }, results);
        }

        public class Data : INotifyPropertyChanged, INotifyDataErrorInfo
        {
            private int nonValidated;

            public int NonValidated
            {
                get { return nonValidated; }
                set { nonValidated = value; NotifyPropertyChanged(); }
            }

            private int mustBePositive;

            public int MustBePositive
            {
                get { return mustBePositive; }
                set
                {
                    mustBePositive = value;
                    NotifyErrorsChanged();
                }
            }

            public bool HasErrors
            {
                get
                {
                    return MustBePositive > 0;
                }
            }

            public event PropertyChangedEventHandler PropertyChanged;
            public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;

            private void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
            {
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
            }

            private void NotifyErrorsChanged([CallerMemberName] string propertyName = "")
            {
                ErrorsChanged?.Invoke(this, new DataErrorsChangedEventArgs(propertyName));
            }

            public IEnumerable GetErrors(string propertyName)
            {
                if (propertyName == nameof(MustBePositive) && MustBePositive <= 0)
                {
                    yield return $"{nameof(MustBePositive)} must be positive";
                }
            }
        }
    }
}