// Copyright (c) Microsoft Open Technologies, Inc. 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.Reflection;
using System.Threading.Tasks;
using Microsoft.AspNet.Mvc.HeaderValueAbstractions;
using Microsoft.AspNet.Mvc.ModelBinding;
using Microsoft.AspNet.Mvc.Routing;
using Moq;
using Xunit;

namespace Microsoft.AspNet.Mvc.Description
{
    public class DefaultApiDescriptionProviderTest
    {
        [Fact]
        public void GetApiDescription_IgnoresNonReflectedActionDescriptor()
        {
            // Arrange
            var action = new ActionDescriptor();
            action.SetProperty(new ApiDescriptionActionData());

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            Assert.Empty(descriptions);
        }

        [Fact]
        public void GetApiDescription_IgnoresActionWithoutApiExplorerData()
        {
            // Arrange
            var action = new ReflectedActionDescriptor();

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            Assert.Empty(descriptions);
        }

        [Fact]
        public void GetApiDescription_PopulatesActionDescriptor()
        {
            // Arrange
            var action = CreateActionDescriptor();

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Same(action, description.ActionDescriptor);
        }

        [Fact]
        public void GetApiDescription_PopulatesGroupName()
        {
            // Arrange
            var action = CreateActionDescriptor();
            action.GetProperty<ApiDescriptionActionData>().GroupName = "Customers";

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Equal("Customers", description.GroupName);
        }

        [Fact]
        public void GetApiDescription_HttpMethodIsNullWithoutConstraint()
        {
            // Arrange
            var action = CreateActionDescriptor();

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Null(description.HttpMethod);
        }


        [Fact]
        public void GetApiDescription_CreatesMultipleDescriptionsForMultipleHttpMethods()
        {
            // Arrange
            var action = CreateActionDescriptor();
            action.MethodConstraints = new List<HttpMethodConstraint>()
            {
                new HttpMethodConstraint(new string[] { "PUT", "POST" }),
                new HttpMethodConstraint(new string[] { "GET" }),
            };

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            Assert.Equal(3, descriptions.Count);

            Assert.Single(descriptions, d => d.HttpMethod == "PUT");
            Assert.Single(descriptions, d => d.HttpMethod == "POST");
            Assert.Single(descriptions, d => d.HttpMethod == "GET");
        }

        // This is a test for the placeholder behavior - see #886
        [Fact]
        public void GetApiDescription_PopulatesParameters()
        {
            // Arrange
            var action = CreateActionDescriptor();
            action.Parameters = new List<ParameterDescriptor>()
            {
                new ParameterDescriptor()
                {
                    Name = "id",
                    IsOptional = true,
                    ParameterBindingInfo = new ParameterBindingInfo("id", typeof(int)),
                },
                new ParameterDescriptor()
                {
                    Name = "username",
                    BodyParameterInfo = new BodyParameterInfo(typeof(string)),
                }
            };

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Equal(2, description.ParameterDescriptions.Count);

            var id = Assert.Single(description.ParameterDescriptions, p => p.Name == "id");
            Assert.NotNull(id.ModelMetadata);
            Assert.True(id.IsOptional);
            Assert.Same(action.Parameters[0], id.ParameterDescriptor);
            Assert.Equal(ApiParameterSource.Query, id.Source);
            Assert.Equal(typeof(int), id.Type);

            var username = Assert.Single(description.ParameterDescriptions, p => p.Name == "username");
            Assert.NotNull(username.ModelMetadata);
            Assert.False(username.IsOptional);
            Assert.Same(action.Parameters[1], username.ParameterDescriptor);
            Assert.Equal(ApiParameterSource.Body, username.Source);
            Assert.Equal(typeof(string), username.Type);
        }

        // This is a placeholder based on current functionality - see #885
        [Fact]
        public void GetApiDescription_PopluatesRelativePath()
        {
            // Arrange
            var action = CreateActionDescriptor();
            action.AttributeRouteInfo = new AttributeRouteInfo();
            action.AttributeRouteInfo.Template = "api/Products/{id}";

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Equal("api/Products/{id}", description.RelativePath);
        }

        [Fact]
        public void GetApiDescription_PopluatesResponseType_WithProduct()
        {
            // Arrange
            var action = CreateActionDescriptor(nameof(ReturnsProduct));

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Equal(typeof(Product), description.ResponseType);
            Assert.NotNull(description.ResponseModelMetadata);
        }

        [Fact]
        public void GetApiDescription_PopluatesResponseType_WithTaskOfProduct()
        {
            // Arrange
            var action = CreateActionDescriptor(nameof(ReturnsTaskOfProduct));

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Equal(typeof(Product), description.ResponseType);
            Assert.NotNull(description.ResponseModelMetadata);
        }

        [Theory]
        [InlineData(nameof(ReturnsObject))]
        [InlineData(nameof(ReturnsActionResult))]
        [InlineData(nameof(ReturnsJsonResult))]
        [InlineData(nameof(ReturnsTaskOfObject))]
        [InlineData(nameof(ReturnsTaskOfActionResult))]
        [InlineData(nameof(ReturnsTaskOfJsonResult))]
        public void GetApiDescription_DoesNotPopluatesResponseInformation_WhenUnknown(string methodName)
        {
            // Arrange
            var action = CreateActionDescriptor(methodName);

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Null(description.ResponseType);
            Assert.Null(description.ResponseModelMetadata);
            Assert.Empty(description.SupportedResponseFormats);
        }

        [Theory]
        [InlineData(nameof(ReturnsVoid))]
        [InlineData(nameof(ReturnsTask))]
        public void GetApiDescription_DoesNotPopluatesResponseInformation_WhenVoid(string methodName)
        {
            // Arrange
            var action = CreateActionDescriptor(methodName);

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Equal(typeof(void), description.ResponseType);
            Assert.Null(description.ResponseModelMetadata);
            Assert.Empty(description.SupportedResponseFormats);
        }

        [Theory]
        [InlineData(nameof(ReturnsObject))]
        [InlineData(nameof(ReturnsVoid))]
        [InlineData(nameof(ReturnsActionResult))]
        [InlineData(nameof(ReturnsJsonResult))]
        [InlineData(nameof(ReturnsTaskOfObject))]
        [InlineData(nameof(ReturnsTask))]
        [InlineData(nameof(ReturnsTaskOfActionResult))]
        [InlineData(nameof(ReturnsTaskOfJsonResult))]
        public void GetApiDescription_PopluatesResponseInformation_WhenSetByFilter(string methodName)
        {
            // Arrange
            var action = CreateActionDescriptor(methodName);
            var filter = new ContentTypeAttribute("text/*")
            {
                Type = typeof(Order)
            };

            action.FilterDescriptors = new List<FilterDescriptor>();
            action.FilterDescriptors.Add(new FilterDescriptor(filter, FilterScope.Action));

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Equal(typeof(Order), description.ResponseType);
            Assert.NotNull(description.ResponseModelMetadata);
        }

        [Fact]
        public void GetApiDescription_IncludesResponseFormats()
        {
            // Arrange
            var action = CreateActionDescriptor(nameof(ReturnsProduct));

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Equal(4, description.SupportedResponseFormats.Count);

            var formats = description.SupportedResponseFormats;
            Assert.Single(formats, f => f.MediaType.RawValue == "text/json");
            Assert.Single(formats, f => f.MediaType.RawValue == "application/json");
            Assert.Single(formats, f => f.MediaType.RawValue == "text/xml");
            Assert.Single(formats, f => f.MediaType.RawValue == "application/xml");
        }

        [Fact]
        public void GetApiDescription_IncludesResponseFormats_FilteredByAttribute()
        {
            // Arrange
            var action = CreateActionDescriptor(nameof(ReturnsProduct));

            action.FilterDescriptors = new List<FilterDescriptor>();
            action.FilterDescriptors.Add(new FilterDescriptor(new ContentTypeAttribute("text/*"), FilterScope.Action));

            // Act
            var descriptions = GetApiDescriptions(action);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Equal(2, description.SupportedResponseFormats.Count);

            var formats = description.SupportedResponseFormats;
            Assert.Single(formats, f => f.MediaType.RawValue == "text/json");
            Assert.Single(formats, f => f.MediaType.RawValue == "text/xml");
        }

        [Fact]
        public void GetApiDescription_IncludesResponseFormats_FilteredByType()
        {
            // Arrange
            var action = CreateActionDescriptor(nameof(ReturnsObject));
            var filter = new ContentTypeAttribute("text/*")
            {
                Type = typeof(Order)
            };

            action.FilterDescriptors = new List<FilterDescriptor>();
            action.FilterDescriptors.Add(new FilterDescriptor(filter, FilterScope.Action));

            var formatters = CreateFormatters();
            
            // This will just format Order
            formatters[0].SupportedTypes.Add(typeof(Order));

            // This will just format Product
            formatters[1].SupportedTypes.Add(typeof(Product));

            // Act
            var descriptions = GetApiDescriptions(action, formatters);

            // Assert
            var description = Assert.Single(descriptions);
            Assert.Equal(1, description.SupportedResponseFormats.Count);
            Assert.Equal(typeof(Order), description.ResponseType);
            Assert.NotNull(description.ResponseModelMetadata);

            var formats = description.SupportedResponseFormats;
            Assert.Single(formats, f => f.MediaType.RawValue == "text/json");
            Assert.Same(formatters[0], formats[0].Formatter);
        }

        private IReadOnlyList<ApiDescription> GetApiDescriptions(ActionDescriptor action)
        {
            return GetApiDescriptions(action, CreateFormatters());
        }

        private IReadOnlyList<ApiDescription> GetApiDescriptions(ActionDescriptor action, List<MockFormatter> formatters)
        {
            var context = new ApiDescriptionProviderContext(new ActionDescriptor[] { action });

            var formattersProvider = new Mock<IOutputFormattersProvider>(MockBehavior.Strict);
            formattersProvider.Setup(fp => fp.OutputFormatters).Returns(formatters);

            var modelMetadataProvider = new Mock<IModelMetadataProvider>(MockBehavior.Strict);
            modelMetadataProvider
                .Setup(mmp => mmp.GetMetadataForType(null, It.IsAny<Type>()))
                .Returns((Func<object> accessor, Type type) =>
                {
                    return new ModelMetadata(modelMetadataProvider.Object, null, accessor, type, null);
                });

            var provider = new DefaultApiDescriptionProvider(formattersProvider.Object, modelMetadataProvider.Object);
            provider.Invoke(context, () => { });
            return context.Results;
        }

        private List<MockFormatter> CreateFormatters()
        {
            // Include some default formatters that look reasonable, some tests will override this.
            var formatters = new List<MockFormatter>()
            {
                new MockFormatter(),
                new MockFormatter(),
            };

            formatters[0].SupportedMediaTypes.Add(MediaTypeHeaderValue.Parse("application/json"));
            formatters[0].SupportedMediaTypes.Add(MediaTypeHeaderValue.Parse("text/json"));

            formatters[1].SupportedMediaTypes.Add(MediaTypeHeaderValue.Parse("application/xml"));
            formatters[1].SupportedMediaTypes.Add(MediaTypeHeaderValue.Parse("text/xml"));

            return formatters;
        }

        private ReflectedActionDescriptor CreateActionDescriptor(string methodName = null)
        {
            var action = new ReflectedActionDescriptor();
            action.SetProperty(new ApiDescriptionActionData());

            action.MethodInfo = GetType().GetMethod(
                methodName ?? "ReturnsObject",
                BindingFlags.Instance | BindingFlags.NonPublic);


            return action;
        }

        private object ReturnsObject()
        {
            return null;
        }

        private void ReturnsVoid()
        {

        }

        private IActionResult ReturnsActionResult()
        {
            return null;
        }

        private JsonResult ReturnsJsonResult()
        {
            return null;
        }

        private Task<Product> ReturnsTaskOfProduct()
        {
            return null;
        }

        private Task<object> ReturnsTaskOfObject()
        {
            return null;
        }

        private Task ReturnsTask()
        {
            return null;
        }

        private Task<IActionResult> ReturnsTaskOfActionResult()
        {
            return null;
        }

        private Task<JsonResult> ReturnsTaskOfJsonResult()
        {
            return null;
        }

        private Product ReturnsProduct()
        {
            return null;
        }

        private class Product
        {
        }

        private class Order
        {
        }

        private class MockFormatter : OutputFormatter
        {
            public List<Type> SupportedTypes { get; } = new List<Type>();

            public override Task WriteResponseBodyAsync(OutputFormatterContext context)
            {
                throw new NotImplementedException();
            }

            protected override bool CanWriteType(Type declaredType, Type actualType)
            {
                if (SupportedTypes.Count == 0)
                {
                    return true;
                }
                else if ((actualType ?? declaredType) == null)
                {
                    return false;
                }
                else
                {
                    return SupportedTypes.Contains(actualType ?? declaredType);
                }
            }
        }

        private class ContentTypeAttribute : Attribute, IFilter, IApiResponseMetadataProvider
        {
            public ContentTypeAttribute(string mediaType)
            {
                ContentTypes.Add(MediaTypeHeaderValue.Parse(mediaType));
            }

            public List<MediaTypeHeaderValue> ContentTypes { get; } = new List<MediaTypeHeaderValue>();

            public Type Type { get; set; }

            public void SetContentTypes(IList<MediaTypeHeaderValue> contentTypes)
            {
                contentTypes.Clear();
                foreach (var contentType in ContentTypes)
                {
                    contentTypes.Add(contentType);
                }
            }
        }
    }
}