// 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.Linq;
using System.Xml.Linq;
using Microsoft.AspNetCore.DataProtection.Internal;
using Microsoft.Extensions.DependencyInjection;
using Moq;
using Xunit;

namespace Microsoft.AspNetCore.DataProtection.XmlEncryption
{
    public class XmlEncryptionExtensionsTests
    {
        [Fact]
        public void DecryptElement_NothingToDecrypt_ReturnsOriginalElement()
        {
            // Arrange
            var original = XElement.Parse(@"<element />");

            // Act
            var retVal = original.DecryptElement(activator: null);

            // Assert
            Assert.Same(original, retVal);
            XmlAssert.Equal("<element />", original); // unmutated
        }

        [Fact]
        public void DecryptElement_RootNodeRequiresDecryption_Success()
        {
            // Arrange
            var original = XElement.Parse(@"
                <x:encryptedSecret decryptorType='theDecryptor' xmlns:x='http://schemas.asp.net/2015/03/dataProtection'>
                  <node />
                </x:encryptedSecret>");

            var mockActivator = new Mock<IActivator>();
            mockActivator.ReturnDecryptedElementGivenDecryptorTypeNameAndInput("theDecryptor", "<node />", "<newNode />");

            var serviceCollection = new ServiceCollection();
            serviceCollection.AddSingleton<IActivator>(mockActivator.Object);
            var services = serviceCollection.BuildServiceProvider();
            var activator = services.GetActivator();

            // Act
            var retVal = original.DecryptElement(activator);

            // Assert
            XmlAssert.Equal("<newNode />", retVal);
        }

        [Fact]
        public void DecryptElement_MultipleNodesRequireDecryption_AvoidsRecursion_Success()
        {
            // Arrange
            var original = XElement.Parse(@"
                <rootNode xmlns:x='http://schemas.asp.net/2015/03/dataProtection'>
                  <x:encryptedSecret decryptorType='myDecryptor'>
                    <node1 />
                  </x:encryptedSecret>
                  <node2 x:requiresEncryption='false'>
                    <![CDATA[This data should stick around.]]>
                    <x:encryptedSecret decryptorType='myDecryptor'>
                      <node3 />
                    </x:encryptedSecret>
                  </node2>
                </rootNode>");

            var expected = @"
                <rootNode xmlns:x='http://schemas.asp.net/2015/03/dataProtection'>
                  <node1_decrypted>
                    <x:encryptedSecret>nested</x:encryptedSecret>
                  </node1_decrypted>
                  <node2 x:requiresEncryption='false'>
                    <![CDATA[This data should stick around.]]>
                      <node3_decrypted>
                        <x:encryptedSecret>nested</x:encryptedSecret>
                      </node3_decrypted>
                  </node2>
                </rootNode>";

            var mockDecryptor = new Mock<IXmlDecryptor>();
            mockDecryptor
                .Setup(o => o.Decrypt(It.IsAny<XElement>()))
                .Returns<XElement>(el => new XElement(el.Name.LocalName + "_decrypted", new XElement(XmlConstants.EncryptedSecretElementName, "nested")));

            var mockActivator = new Mock<IActivator>();
            mockActivator.Setup(o => o.CreateInstance(typeof(IXmlDecryptor), "myDecryptor")).Returns(mockDecryptor.Object);

            var serviceCollection = new ServiceCollection();
            serviceCollection.AddSingleton<IActivator>(mockActivator.Object);
            var services = serviceCollection.BuildServiceProvider();
            var activator = services.GetActivator();

            // Act
            var retVal = original.DecryptElement(activator);

            // Assert
            XmlAssert.Equal(expected, retVal);
        }

        [Fact]
        public void EncryptIfNecessary_NothingToEncrypt_ReturnsNull()
        {
            // Arrange
            var original = XElement.Parse(@"<element />");
            var xmlEncryptor = new Mock<IXmlEncryptor>(MockBehavior.Strict).Object;

            // Act
            var retVal = xmlEncryptor.EncryptIfNecessary(original);

            // Assert
            Assert.Null(retVal);
            XmlAssert.Equal("<element />", original); // unmutated
        }

        [Fact]
        public void EncryptIfNecessary_RootNodeRequiresEncryption_Success()
        {
            // Arrange
            var original = XElement.Parse(@"<rootNode x:requiresEncryption='true' xmlns:x='http://schemas.asp.net/2015/03/dataProtection' />");
            var mockXmlEncryptor = new Mock<IXmlEncryptor>();
            mockXmlEncryptor.Setup(o => o.Encrypt(It.IsAny<XElement>())).Returns(new EncryptedXmlInfo(new XElement("theElement"), typeof(MyXmlDecryptor)));

            // Act
            var retVal = mockXmlEncryptor.Object.EncryptIfNecessary(original);

            // Assert
            XmlAssert.Equal(@"<rootNode x:requiresEncryption='true' xmlns:x='http://schemas.asp.net/2015/03/dataProtection' />", original); // unmutated
            Assert.Equal(XmlConstants.EncryptedSecretElementName, retVal.Name);
            Assert.Equal(typeof(MyXmlDecryptor).AssemblyQualifiedName, (string)retVal.Attribute(XmlConstants.DecryptorTypeAttributeName));
            XmlAssert.Equal("<theElement />", retVal.Descendants().Single());
        }

        [Fact]
        public void EncryptIfNecessary_MultipleNodesRequireEncryption_Success()
        {
            // Arrange
            var original = XElement.Parse(@"
                <rootNode xmlns:x='http://schemas.asp.net/2015/03/dataProtection'>
                  <node1 x:requiresEncryption='true'>
                    <![CDATA[This data should be encrypted.]]>
                  </node1>
                  <node2 x:requiresEncryption='false'>
                    <![CDATA[This data should stick around.]]>
                    <node3 x:requiresEncryption='true'>
                      <node4 x:requiresEncryption='true' />
                    </node3>
                  </node2>
                </rootNode>");

            var expected = String.Format(@"
                <rootNode xmlns:x='http://schemas.asp.net/2015/03/dataProtection'>
                  <x:encryptedSecret decryptorType='{0}'>
                    <node1_encrypted />
                  </x:encryptedSecret>
                  <node2 x:requiresEncryption='false'>
                    <![CDATA[This data should stick around.]]>
                    <x:encryptedSecret decryptorType='{0}'>
                      <node3_encrypted />
                    </x:encryptedSecret>
                  </node2>
                </rootNode>",
                typeof(MyXmlDecryptor).AssemblyQualifiedName);

            var mockXmlEncryptor = new Mock<IXmlEncryptor>();
            mockXmlEncryptor
                .Setup(o => o.Encrypt(It.IsAny<XElement>()))
                .Returns<XElement>(element => new EncryptedXmlInfo(new XElement(element.Name.LocalName + "_encrypted"), typeof(MyXmlDecryptor)));

            // Act
            var retVal = mockXmlEncryptor.Object.EncryptIfNecessary(original);

            // Assert
            XmlAssert.Equal(expected, retVal);
        }

        [Fact]
        public void EncryptIfNecessary_NullEncryptorWithRecursion_NoStackDive_Success()
        {
            // Arrange
            var original = XElement.Parse(@"
                <rootNode xmlns:x='http://schemas.asp.net/2015/03/dataProtection'>
                  <node1 x:requiresEncryption='true'>
                    <![CDATA[This data should be encrypted.]]>
                  </node1>
                  <node2 x:requiresEncryption='false'>
                    <![CDATA[This data should stick around.]]>
                    <node3 x:requiresEncryption='true'>
                      <node4 x:requiresEncryption='true' />
                    </node3>
                  </node2>
                </rootNode>");

            var expected = String.Format(@"
                <rootNode xmlns:x='http://schemas.asp.net/2015/03/dataProtection'>
                  <x:encryptedSecret decryptorType='{0}'>
                    <node1 x:requiresEncryption='true'>
                      <![CDATA[This data should be encrypted.]]>
                    </node1>
                  </x:encryptedSecret>
                  <node2 x:requiresEncryption='false'>
                    <![CDATA[This data should stick around.]]>
                    <x:encryptedSecret decryptorType='{0}'>
                      <node3 x:requiresEncryption='true'>
                          <node4 x:requiresEncryption='true' />
                      </node3>
                    </x:encryptedSecret>
                  </node2>
                </rootNode>",
                typeof(MyXmlDecryptor).AssemblyQualifiedName);

            var mockXmlEncryptor = new Mock<IXmlEncryptor>();
            mockXmlEncryptor
                .Setup(o => o.Encrypt(It.IsAny<XElement>()))
                .Returns<XElement>(element => new EncryptedXmlInfo(new XElement(element), typeof(MyXmlDecryptor)));

            // Act
            var retVal = mockXmlEncryptor.Object.EncryptIfNecessary(original);

            // Assert
            XmlAssert.Equal(expected, retVal);
        }

        private sealed class MyXmlDecryptor : IXmlDecryptor
        {
            public XElement Decrypt(XElement encryptedElement)
            {
                throw new NotImplementedException();
            }
        }
    }
}