// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Components.Rendering;
using Microsoft.AspNetCore.Components.RenderTree;
using Xunit;

namespace Microsoft.AspNetCore.Components
{
    public partial class ParameterViewTest
    {
        [Fact]
        public void CanInitializeUsingComponentWithNoDescendants()
        {
            // Arrange
            var frames = new[]
            {
                RenderTreeFrame.ChildComponent(0, typeof(FakeComponent)).WithComponentSubtreeLength(1)
            };
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, frames, 0);

            // Assert
            Assert.Empty(ToEnumerable(parameters));
        }

        [Fact]
        public void CanInitializeUsingElementWithNoDescendants()
        {
            // Arrange
            var frames = new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(1)
            };
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, frames, 0);

            // Assert
            Assert.Empty(ToEnumerable(parameters));
        }

        [Fact]
        public void EnumerationStopsAtEndOfOwnerDescendants()
        {
            // Arrange
            var attribute1Value = new object();
            var attribute2Value = new object();
            var frames = new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(3),
                RenderTreeFrame.Attribute(1, "attribute 1", attribute1Value),
                RenderTreeFrame.Attribute(2, "attribute 2", attribute2Value),
                // Although RenderTreeBuilder doesn't let you add orphaned attributes like this,
                // still want to verify that parameters doesn't attempt to read past the
                // end of the owner's descendants
                RenderTreeFrame.Attribute(3, "orphaned attribute", "value")
            };
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, frames, 0);

            // Assert
            Assert.Collection(ToEnumerable(parameters),
                AssertParameter("attribute 1", attribute1Value, false),
                AssertParameter("attribute 2", attribute2Value, false));
        }

        [Fact]
        public void EnumerationStopsAtEndOfOwnerAttributes()
        {
            // Arrange
            var attribute1Value = new object();
            var attribute2Value = new object();
            var frames = new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(3),
                RenderTreeFrame.Attribute(1, "attribute 1", attribute1Value),
                RenderTreeFrame.Attribute(2, "attribute 2", attribute2Value),
                RenderTreeFrame.Element(3, "child element").WithElementSubtreeLength(2),
                RenderTreeFrame.Attribute(4, "child attribute", "some value")
            };
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, frames, 0);

            // Assert
            Assert.Collection(ToEnumerable(parameters),
                AssertParameter("attribute 1", attribute1Value, false),
                AssertParameter("attribute 2", attribute2Value, false));
        }

        [Fact]
        public void EnumerationIncludesCascadingParameters()
        {
            // Arrange
            var attribute1Value = new object();
            var attribute2Value = new object();
            var attribute3Value = new object();
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                RenderTreeFrame.Attribute(1, "attribute 1", attribute1Value)
            }, 0).WithCascadingParameters(new List<CascadingParameterState>
            {
                new CascadingParameterState("attribute 2", new TestCascadingValue(attribute2Value)),
                new CascadingParameterState("attribute 3", new TestCascadingValue(attribute3Value)),
            });

            // Assert
            Assert.Collection(ToEnumerable(parameters),
                AssertParameter("attribute 1", attribute1Value, false),
                AssertParameter("attribute 2", attribute2Value, true),
                AssertParameter("attribute 3", attribute3Value, true));
        }

        [Fact]
        public void CanTryGetNonExistingValue()
        {
            // Arrange
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                RenderTreeFrame.Attribute(1, "some other entry", new object())
            }, 0);

            // Act
            var didFind = parameters.TryGetValue<string>("nonexisting entry", out var value);

            // Assert
            Assert.False(didFind);
            Assert.Null(value);
        }

        [Fact]
        public void CanTryGetExistingValueWithCorrectType()
        {
            // Arrange
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                RenderTreeFrame.Attribute(1, "my entry", "hello")
            }, 0);

            // Act
            var didFind = parameters.TryGetValue<string>("my entry", out var value);

            // Assert
            Assert.True(didFind);
            Assert.Equal("hello", value);
        }

        [Fact]
        public void CanGetValueOrDefault_WithExistingValue()
        {
            // Arrange
            var myEntryValue = new object();
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                RenderTreeFrame.Attribute(1, "my entry", myEntryValue),
                RenderTreeFrame.Attribute(1, "my other entry", new object())
            }, 0);

            // Act
            var result = parameters.GetValueOrDefault<object>("my entry");

            // Assert
            Assert.Same(myEntryValue, result);
        }

        [Fact]
        public void CanGetValueOrDefault_WithMultipleMatchingValues()
        {
            // Arrange
            var myEntryValue = new object();
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(3),
                RenderTreeFrame.Attribute(1, "my entry", myEntryValue),
                RenderTreeFrame.Attribute(1, "my entry", new object()),
            }, 0);

            // Act
            var result = parameters.GetValueOrDefault<object>("my entry");

            // Assert: Picks first match
            Assert.Same(myEntryValue, result);
        }

        [Fact]
        public void CanGetValueOrDefault_WithNonExistingValue()
        {
            // Arrange
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                RenderTreeFrame.Attribute(1, "some other entry", new object())
            }, 0).WithCascadingParameters(new List<CascadingParameterState>
            {
                new CascadingParameterState("another entry", new TestCascadingValue(null))
            });

            // Act
            var result = parameters.GetValueOrDefault<DateTime>("nonexisting entry");

            // Assert
            Assert.Equal(default, result);
        }

        [Fact]
        public void CanGetValueOrDefault_WithNonExistingValueAndExplicitDefault()
        {
            // Arrange
            var explicitDefaultValue = new DateTime(2018, 3, 20);
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                RenderTreeFrame.Attribute(1, "some other entry", new object())
            }, 0);

            // Act
            var result = parameters.GetValueOrDefault("nonexisting entry", explicitDefaultValue);

            // Assert
            Assert.Equal(explicitDefaultValue, result);
        }

        [Fact]
        public void ThrowsIfTryGetExistingValueWithIncorrectType()
        {
            // Arrange
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                RenderTreeFrame.Attribute(1, "my entry", "hello")
            }, 0);

            // Act/Assert
            Assert.Throws<InvalidCastException>(() =>
            {
                parameters.TryGetValue<bool>("my entry", out var value);
            });
        }

        [Fact]
        public void FromDictionary_CanBeInitializedWithEmptyDictionary()
        {
            // Arrange
            var dictionary = new Dictionary<string, object>();

            // Act
            var collection = ParameterView.FromDictionary(dictionary);

            // Assert
            Assert.Empty(collection.ToDictionary());
        }

        [Fact]
        public void FromDictionary_RoundTrips()
        {
            // Arrange
            var dictionary = new Dictionary<string, object>
            {
                ["IntValue"] = 1,
                ["StringValue"] = "String"
            };

            // Act
            var collection = ParameterView.FromDictionary(dictionary);

            // Assert
            Assert.Equal(dictionary, collection.ToDictionary());
        }


        [Fact]
        public void CanConvertToReadOnlyDictionary()
        {
            // Arrange
            var entry2Value = new object();
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(3),
                RenderTreeFrame.Attribute(0, "entry 1", "value 1"),
                RenderTreeFrame.Attribute(0, "entry 2", entry2Value),
            }, 0);

            // Act
            IReadOnlyDictionary<string, object> dict = parameters.ToDictionary();

            // Assert
            Assert.Collection(dict,
                entry =>
                {
                    Assert.Equal("entry 1", entry.Key);
                    Assert.Equal("value 1", entry.Value);
                },
                entry =>
                {
                    Assert.Equal("entry 2", entry.Key);
                    Assert.Same(entry2Value, entry.Value);
                });
        }

        [Fact]
        public void CanGetValueOrDefault_WithMatchingCascadingParameter()
        {
            // Arrange
            var myEntryValue = new object();
            var parameters = new ParameterView(ParameterViewLifetime.Unbound, new[]
            {
                RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                RenderTreeFrame.Attribute(1, "unrelated value", new object())
            }, 0).WithCascadingParameters(new List<CascadingParameterState>
            {
                new CascadingParameterState("unrelated value 2", new TestCascadingValue(null)),
                new CascadingParameterState("my entry", new TestCascadingValue(myEntryValue)),
                new CascadingParameterState("unrelated value 3", new TestCascadingValue(null)),
            });

            // Act
            var result = parameters.GetValueOrDefault<object>("my entry");

            // Assert
            Assert.Same(myEntryValue, result);
        }

        [Fact]
        public void CannotReadAfterLifetimeExpiry()
        {
            // Arrange
            var builder = new RenderBatchBuilder();
            var lifetime = new ParameterViewLifetime(builder);
            var frames = new[]
            {
                RenderTreeFrame.ChildComponent(0, typeof(FakeComponent)).WithComponentSubtreeLength(1)
            };
            var parameterView = new ParameterView(lifetime, frames, 0);

            // Act
            builder.InvalidateParameterViews();

            // Assert
            Assert.Throws<InvalidOperationException>(() => parameterView.GetEnumerator());
            Assert.Throws<InvalidOperationException>(() => parameterView.GetValueOrDefault<object>("anything"));
            Assert.Throws<InvalidOperationException>(() => parameterView.SetParameterProperties(new object()));
            Assert.Throws<InvalidOperationException>(() => parameterView.ToDictionary());
            var ex = Assert.Throws<InvalidOperationException>(() => parameterView.TryGetValue<object>("anything", out _));

            // It's enough to assert about one of the messages
            Assert.Equal($"The {nameof(ParameterView)} instance can no longer be read because it has expired. {nameof(ParameterView)} can only be read synchronously and must not be stored for later use.", ex.Message);
        }

        private Action<ParameterValue> AssertParameter(string expectedName, object expectedValue, bool expectedIsCascading)
        {
            return parameter =>
            {
                Assert.Equal(expectedName, parameter.Name);
                Assert.Same(expectedValue, parameter.Value);
                Assert.Equal(expectedIsCascading, parameter.Cascading);
            };
        }

        public IEnumerable<ParameterValue> ToEnumerable(ParameterView parameters)
        {
            foreach (var item in parameters)
            {
                yield return item;
            }
        }

        private class FakeComponent : IComponent
        {
            public void Attach(RenderHandle renderHandle)
                => throw new NotImplementedException();

            public Task SetParametersAsync(ParameterView parameters)
                => throw new NotImplementedException();
        }

        private class TestCascadingValue : ICascadingValueComponent
        {
            public TestCascadingValue(object value)
            {
                CurrentValue = value;
            }

            public object CurrentValue { get; }

            public bool CurrentValueIsFixed => false;

            public bool CanSupplyValue(Type valueType, string valueName)
                => throw new NotImplementedException();

            public void Subscribe(ComponentState subscriber)
                => throw new NotImplementedException();

            public void Unsubscribe(ComponentState subscriber)
                => throw new NotImplementedException();
        }
    }
}
