// 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.Collections.Generic;
using System.Linq;
using System.Text.Encodings.Web;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Html;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewComponents;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Xunit;

namespace Microsoft.AspNetCore.Mvc
{
    public class ViewComponentTests
    {
        [Fact]
        public void ViewComponent_ViewBag_UsesViewData()
        {
            // Arrange
            var viewComponent = new TestViewComponent();

            // Act
            viewComponent.ViewBag.A = "Alice";
            viewComponent.ViewBag.B = "Bob";

            // Assert
            Assert.Equal(2, viewComponent.ViewData.Count);
            Assert.Equal("Alice", viewComponent.ViewData["A"]);
            Assert.Equal("Bob", viewComponent.ViewData["B"]);
        }

        [Fact]
        public void ViewComponent_ViewData_StoresDataForViewBag()
        {
            // Arrange
            var viewComponent = new TestViewComponent();

            // Act
            viewComponent.ViewData["A"] = "Alice";
            viewComponent.ViewData["B"] = "Bob";

            // Assert
            Assert.Equal(2, viewComponent.ViewData.Count);
            Assert.Equal("Alice", viewComponent.ViewBag.A);
            Assert.Equal("Bob", viewComponent.ViewBag.B);
        }

        [Fact]
        public void ViewComponent_Content_SetsResultContentAndEncodedContent()
        {
            // Arrange
            var viewComponent = new TestViewComponent();
            var expectedContent = "TestContent&";
            var expectedEncodedContent = new HtmlString(HtmlEncoder.Default.Encode(expectedContent));

            // Act
            var actualResult = viewComponent.Content(expectedContent);

            // Assert
            Assert.IsType<ContentViewComponentResult>(actualResult);
            Assert.Same(expectedContent, actualResult.Content);
        }

        [Fact]
        public void ViewComponent_View_WithEmptyParameter_SetsResultViewWithDefaultViewName()
        {
            // Arrange
            var viewComponent = new TestViewComponent();

            // Act
            var actualResult = viewComponent.View();

            // Assert
            Assert.IsType<ViewViewComponentResult>(actualResult);
            Assert.NotSame(viewComponent.ViewData, actualResult.ViewData);
            Assert.Equal(new ViewDataDictionary<object>(viewComponent.ViewData), actualResult.ViewData);
            Assert.Null(actualResult.ViewData.Model);
            Assert.Null(actualResult.ViewName);
        }

        [Fact]
        public void ViewComponent_View_WithEmptyParameter_SetsViewDataModelWithDefaultViewName()
        {
            // Arrange
            var viewComponent = new TestViewComponent();
            var model = new object();
            viewComponent.ViewData.Model = model;

            // Act
            var actualResult = viewComponent.View();

            // Assert
            Assert.IsType<ViewViewComponentResult>(actualResult);
            Assert.NotSame(viewComponent.ViewData, actualResult.ViewData);
            Assert.Equal(new ViewDataDictionary<object>(viewComponent.ViewData), actualResult.ViewData);
            Assert.Same(model, actualResult.ViewData.Model);
            Assert.Null(actualResult.ViewName);
        }

        [Fact]
        public void ViewComponent_View_WithViewNameParameter_SetsResultViewWithCustomViewName()
        {
            // Arrange
            var viewComponent = new TestViewComponent();

            // Act
            var actualResult = viewComponent.View("CustomViewName");

            // Assert
            Assert.IsType<ViewViewComponentResult>(actualResult);
            Assert.IsType<ViewDataDictionary<object>>(actualResult.ViewData);
            Assert.NotSame(viewComponent.ViewData, actualResult.ViewData);
            Assert.Equal(new ViewDataDictionary<object>(viewComponent.ViewData), actualResult.ViewData);
            Assert.Null(actualResult.ViewData.Model);
            Assert.Equal("CustomViewName", actualResult.ViewName);
        }

        [Fact]
        public void ViewComponent_View_WithModelParameter_SetsResultViewWithDefaultViewNameAndModel()
        {
            // Arrange
            var viewComponent = new TestViewComponent();

            var model = new object();

            // Act
            var actualResult = viewComponent.View(model);

            // Assert
            Assert.IsType<ViewViewComponentResult>(actualResult);
            Assert.IsType<ViewDataDictionary<object>>(actualResult.ViewData);
            Assert.NotSame(viewComponent.ViewData, actualResult.ViewData);
            Assert.Equal(new ViewDataDictionary<object>(viewComponent.ViewData), actualResult.ViewData);
            Assert.Same(model, actualResult.ViewData.Model);
            Assert.Null(actualResult.ViewName);
        }

        [Fact]
        public void ViewComponent_View_WithNullModelParameter_SetsResultViewWithDefaultViewNameAndNullModel()
        {
            // Arrange
            var viewComponent = new TestViewComponent();
            viewComponent.ViewData.Model = new object();
            object model = null;

            // Act
            var actualResult = viewComponent.View(model: model);

            // Assert
            Assert.IsType<ViewViewComponentResult>(actualResult);
            Assert.IsType<ViewDataDictionary<object>>(actualResult.ViewData);
            Assert.NotSame(viewComponent.ViewData, actualResult.ViewData);
            Assert.Equal(new ViewDataDictionary<object>(viewComponent.ViewData), actualResult.ViewData);
            Assert.Null(actualResult.ViewData.Model);
            Assert.Null(actualResult.ViewName);
        }

        [Fact]
        public void ViewComponent_View_WithViewNameAndNullModelParameter_SetsResultViewWithViewNameAndNullModel()
        {
            // Arrange
            var viewComponent = new TestViewComponent();
            viewComponent.ViewData.Model = new object();

            // Act
            var actualResult = viewComponent.View<object>("CustomViewName", model: null);

            // Assert
            Assert.IsType<ViewViewComponentResult>(actualResult);
            Assert.IsType<ViewDataDictionary<object>>(actualResult.ViewData);
            Assert.NotSame(viewComponent.ViewData, actualResult.ViewData);
            Assert.Equal(new ViewDataDictionary<object>(viewComponent.ViewData), actualResult.ViewData);
            Assert.Null(actualResult.ViewData.Model);
            Assert.Equal("CustomViewName", actualResult.ViewName);
        }

        [Fact]
        public void ViewComponent_View_WithViewNameAndNonObjectNullModelParameter_SetsResultViewWithViewNameAndNullModel()
        {
            // Arrange
            var viewComponent = new TestViewComponent();
            viewComponent.ViewData.Model = "Hello World!";

            // Act
            var actualResult = viewComponent.View<string>("CustomViewName", model: null);

            // Assert
            Assert.IsType<ViewViewComponentResult>(actualResult);
            Assert.IsType<ViewDataDictionary<string>>(actualResult.ViewData);
            Assert.NotSame(viewComponent.ViewData, actualResult.ViewData);
            Assert.Equal(new ViewDataDictionary<string>(viewComponent.ViewData), actualResult.ViewData);
            Assert.Null(actualResult.ViewData.Model);
            Assert.Equal("CustomViewName", actualResult.ViewName);
        }

        [Fact]
        public void ViewComponent_View_WithViewNameAndModelParameters_SetsResultViewWithCustomViewNameAndModel()
        {
            // Arrange
            var viewComponent = new TestViewComponent();

            var model = new object();

            // Act
            var actualResult = viewComponent.View("CustomViewName", model);

            // Assert
            Assert.IsType<ViewViewComponentResult>(actualResult);
            Assert.IsType<ViewDataDictionary<object>>(actualResult.ViewData);
            Assert.NotSame(viewComponent.ViewData, actualResult.ViewData);
            Assert.Equal(new ViewDataDictionary<object>(viewComponent.ViewData), actualResult.ViewData);
            Assert.Same(model, actualResult.ViewData.Model);
            Assert.Equal("CustomViewName", actualResult.ViewName);
        }

        [Fact]
        public void ViewComponent_ViewContext_ViewData_ReturnsDefaultInstanceIfNull()
        {
            // Arrange && Act
            var viewComponent = new TestViewComponent();

            // Assert
            // ViewComponent.ViewContext returns the default instance for the unit test scenarios
            Assert.NotNull(viewComponent.ViewContext);
            Assert.NotNull(viewComponent.ViewContext.ViewData);
            Assert.Null(viewComponent.ViewContext.TempData);

            // ViewComponent.ViewData returns the default instance for the unit test scenarios
            Assert.Empty(viewComponent.ViewContext.ViewData);
            Assert.NotNull(viewComponent.ViewData);
            Assert.Empty(viewComponent.ViewData);
            Assert.Same(viewComponent.ViewData, viewComponent.ViewContext.ViewData);
        }

        [Fact]
        public void ViewComponent_ViewContext_TempData_ReturnsDefaultInstanceIfSessionActive()
        {
            // Arrange
            var httpContext = new DefaultHttpContext();
            httpContext.Features.Set<ISessionFeature>(new SessionFeature() { Session = new TestSession() });
            var viewContext = new ViewContext();
            viewContext.TempData = new TempDataDictionary(httpContext, new SessionStateTempDataProvider());
            var viewComponentContext = new ViewComponentContext();
            viewComponentContext.ViewContext = viewContext;

            // Act
            var viewComponent = new TestViewComponent();
            viewComponent.ViewComponentContext = viewComponentContext;

            // Assert
            Assert.NotNull(viewComponent.ViewContext.TempData);
            Assert.Empty(viewComponent.ViewContext.TempData);
            Assert.Same(viewComponent.TempData, viewComponent.ViewContext.TempData);
        }

        private class TestViewComponent : ViewComponent
        {
        }

        private class SessionFeature : ISessionFeature
        {
            public ISession Session { get; set; }
        }

        private class TestSession : ISession
        {
            private Dictionary<string, byte[]> _innerDictionary = new Dictionary<string, byte[]>();

            public IEnumerable<string> Keys { get { return _innerDictionary.Keys; } }

            public string Id => "TestId";

            public bool IsAvailable { get; } = true;

            public Task LoadAsync(CancellationToken cancellationToken = default(CancellationToken))
            {
                return Task.FromResult(0);
            }

            public Task CommitAsync(CancellationToken cancellationToken = default(CancellationToken))
            {
                return Task.FromResult(0);
            }

            public void Clear()
            {
                _innerDictionary.Clear();
            }

            public void Remove(string key)
            {
                _innerDictionary.Remove(key);
            }

            public void Set(string key, byte[] value)
            {
                _innerDictionary[key] = value.ToArray();
            }

            public bool TryGetValue(string key, out byte[] value)
            {
                return _innerDictionary.TryGetValue(key, out value);
            }
        }
    }
}