// 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.Text;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Primitives;
using Microsoft.Net.Http.Headers;
using Moq;
using Xunit;

namespace Microsoft.AspNetCore.Mvc.Formatters
{
    public class TextOutputFormatterTests
    {
        public static IEnumerable<object[]> SelectResponseCharacterEncodingData
        {
            get
            {
                // string acceptEncodings, string requestEncoding, string[] supportedEncodings, string expectedEncoding
                yield return new object[] { "", new string[] { "utf-8", "utf-16" }, "utf-8" };

                yield return new object[] { "utf-8", new string[] { "utf-8", "utf-16" }, "utf-8" };
                yield return new object[] { "utf-16", new string[] { "utf-8", "utf-16" }, "utf-16" };
                yield return new object[] { "utf-16; q=0.5", new string[] { "utf-8", "utf-16" }, "utf-16" };

                yield return new object[] { "utf-8; q=0.0", new string[] { "utf-8", "utf-16" }, "utf-8" };
                yield return new object[] { "utf-8; q=0.0, utf-16; q=0.0", new string[] { "utf-8", "utf-16" }, "utf-8" };

                yield return new object[] { "*; q=0.0", new string[] { "utf-8", "utf-16" }, "utf-8" };
            }
        }

        [Theory]
        [MemberData(nameof(SelectResponseCharacterEncodingData))]
        public void SelectResponseCharacterEncoding_SelectsEncoding(
            string acceptCharsetHeaders,
            string[] supportedEncodings,
            string expectedEncoding)
        {
            // Arrange
            var httpContext = new Mock<HttpContext>();
            var httpRequest = new DefaultHttpContext().Request;
            httpRequest.Headers[HeaderNames.AcceptCharset] = acceptCharsetHeaders;
            httpRequest.Headers[HeaderNames.Accept] = "application/acceptCharset";
            httpContext.SetupGet(o => o.Request).Returns(httpRequest);

            var formatter = new TestOutputFormatter();
            foreach (string supportedEncoding in supportedEncodings)
            {
                formatter.SupportedEncodings.Add(Encoding.GetEncoding(supportedEncoding));
            }

            var context = new OutputFormatterWriteContext(
                httpContext.Object,
                new TestHttpResponseStreamWriterFactory().CreateWriter,
                typeof(string),
                "someValue")
            {
                ContentType = new StringSegment(httpRequest.Headers[HeaderNames.Accept]),
            };

            // Act
            var actualEncoding = formatter.SelectCharacterEncoding(context);

            // Assert
            Assert.Equal(Encoding.GetEncoding(expectedEncoding), actualEncoding);
        }

        [Theory]
        [InlineData("application/json; charset=utf-16", "application/json; charset=utf-32")]
        [InlineData("application/json; charset=utf-16; format=indent", "application/json; charset=utf-32; format=indent")]
        public void WriteResponse_OverridesCharset_IfDifferentFromContentTypeCharset(
            string contentType,
            string expectedContentType)
        {
            // Arrange
            var formatter = new OverrideEncodingFormatter(Encoding.UTF32);

            var formatterContext = new OutputFormatterWriteContext(
                new DefaultHttpContext(),
                new TestHttpResponseStreamWriterFactory().CreateWriter,
                objectType: null,
                @object: null)
            {
                ContentType = new StringSegment(contentType),
            };

            // Act
            formatter.WriteAsync(formatterContext);

            // Assert
            Assert.Equal(new StringSegment(expectedContentType), formatterContext.ContentType);
        }

        [Fact]
        public void WriteResponse_GetMediaTypeWithCharsetReturnsMediaTypeFromCache_IfEncodingIsUtf8()
        {
            // Arrange
            var formatter = new TestOutputFormatter();

            var formatterContext = new OutputFormatterWriteContext(
                new DefaultHttpContext(),
                new TestHttpResponseStreamWriterFactory().CreateWriter,
                objectType: null,
                @object: null)
            {
                ContentType = new StringSegment("application/json"),
            };

            formatter.SupportedMediaTypes.Add("application/json");
            formatter.SupportedEncodings.Add(Encoding.UTF8);

            // Act
            formatter.WriteAsync(formatterContext);
            var firstContentType = formatterContext.ContentType;

            formatterContext.ContentType = new StringSegment("application/json");

            formatter.WriteAsync(formatterContext);
            var secondContentType = formatterContext.ContentType;

            // Assert
            Assert.Same(firstContentType.Buffer, secondContentType.Buffer);
        }

        [Fact]
        public void WriteResponse_GetMediaTypeWithCharsetReplacesCharset_IfDifferentThanEncoding()
        {
            // Arrange
            var formatter = new TestOutputFormatter();

            var formatterContext = new OutputFormatterWriteContext(
                new DefaultHttpContext(),
                new TestHttpResponseStreamWriterFactory().CreateWriter,
                objectType: null,
                @object: null)
            {
                ContentType = new StringSegment("application/json; charset=utf-7"),
            };

            formatter.SupportedMediaTypes.Add("application/json");
            formatter.SupportedEncodings.Add(Encoding.UTF8);

            // Act
            formatter.WriteAsync(formatterContext);

            // Assert
            Assert.Equal(new StringSegment("application/json; charset=utf-8"), formatterContext.ContentType);
        }

        [Fact]
        public void WriteResponse_GetMediaTypeWithCharsetReturnsSameString_IfCharsetEqualToEncoding()
        {
            // Arrange
            var formatter = new TestOutputFormatter();

            var contentType = "application/json; charset=utf-16";
            var formatterContext = new OutputFormatterWriteContext(
                new DefaultHttpContext(),
                new TestHttpResponseStreamWriterFactory().CreateWriter,
                objectType: null,
                @object: null)
            {
                ContentType = new StringSegment(contentType),
            };

            formatter.SupportedMediaTypes.Add("application/json");
            formatter.SupportedEncodings.Add(Encoding.Unicode);

            // Act
            formatter.WriteAsync(formatterContext);

            // Assert
            Assert.Same(contentType, formatterContext.ContentType.Buffer);
        }

        [Fact]
        public void WriteResponseContentHeaders_NoSupportedEncodings_NoEncodingIsSet()
        {
            // Arrange
            var formatter = new TestOutputFormatter();

            var testContentType = new StringSegment("text/json");

            formatter.SupportedEncodings.Clear();
            formatter.SupportedMediaTypes.Clear();
            formatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/json"));

            var context = new OutputFormatterWriteContext(
                new DefaultHttpContext(),
                new TestHttpResponseStreamWriterFactory().CreateWriter,
                objectType: null,
                @object: null)
            {
                ContentType = testContentType,
            };

            // Act
            formatter.WriteResponseHeaders(context);

            // Assert
            Assert.Null(MediaTypeHeaderValue.Parse(context.ContentType.Value).Encoding);
            Assert.Equal(testContentType, context.ContentType);

            // If we had set an encoding, it would be part of the content type header
            Assert.Equal(MediaTypeHeaderValue.Parse(testContentType.Value), context.HttpContext.Response.GetTypedHeaders().ContentType);
        }

        [Fact]
        public async Task WriteAsync_ReturnsNotAcceptable_IfSelectCharacterEncodingReturnsNull()
        {
            // Arrange
            var formatter = new OverrideEncodingFormatter(encoding: null);

            var testContentType = new StringSegment("text/json");
            formatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/json"));

            var context = new OutputFormatterWriteContext(
                new DefaultHttpContext(),
                new TestHttpResponseStreamWriterFactory().CreateWriter,
                objectType: null,
                @object: null)
            {
                ContentType = testContentType,
            };

            // Act
            await formatter.WriteAsync(context);

            // Assert
            Assert.Equal(StatusCodes.Status406NotAcceptable, context.HttpContext.Response.StatusCode);
        }

        private class TestOutputFormatter : TextOutputFormatter
        {
            public TestOutputFormatter()
            {
                SupportedMediaTypes.Add("application/acceptCharset");
            }

            public override Task WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)
            {
                return Task.FromResult(true);
            }
        }

        private class OverrideEncodingFormatter : TextOutputFormatter
        {
            private readonly Encoding _encoding;

            public OverrideEncodingFormatter(Encoding encoding)
            {
                _encoding = encoding;
            }

            public override Encoding SelectCharacterEncoding(OutputFormatterWriteContext context)
            {
                return _encoding;
            }

            public override Task WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)
            {
                return Task.FromResult(true);
            }
        }
    }
}
