// 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.IO;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using Microsoft.AspNetCore.DataProtection.Internal;
using Microsoft.AspNetCore.DataProtection.KeyManagement;
using Microsoft.AspNetCore.DataProtection.Repositories;
using Microsoft.AspNetCore.DataProtection.Test.Shared;
using Microsoft.AspNetCore.Testing;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using Moq;
using Xunit;

namespace Microsoft.AspNetCore.DataProtection
{
    public class DataProtectionProviderTests
    {
        [Fact]
        public void System_UsesProvidedDirectory()
        {
            WithUniqueTempDirectory(directory =>
            {
                // Step 1: directory should be completely empty
                directory.Create();
                Assert.Empty(directory.GetFiles());

                // Step 2: instantiate the system and round-trip a payload
                var protector = DataProtectionProvider.Create(directory).CreateProtector("purpose");
                Assert.Equal("payload", protector.Unprotect(protector.Protect("payload")));

                // Step 3: validate that there's now a single key in the directory and that it's not protected
                var allFiles = directory.GetFiles();
                Assert.Single(allFiles);
                Assert.StartsWith("key-", allFiles[0].Name, StringComparison.OrdinalIgnoreCase);
                string fileText = File.ReadAllText(allFiles[0].FullName);
                Assert.Contains("Warning: the key below is in an unencrypted form.", fileText, StringComparison.Ordinal);
                Assert.DoesNotContain("Windows DPAPI", fileText, StringComparison.Ordinal);
            });
        }

        [Fact]
        public void System_NoKeysDirectoryProvided_UsesDefaultKeysDirectory()
        {
            var mock = new Mock<IDefaultKeyStorageDirectories>();
            var keysPath = Path.Combine(AppContext.BaseDirectory, Path.GetRandomFileName());
            mock.Setup(m => m.GetKeyStorageDirectory()).Returns(new DirectoryInfo(keysPath));

            // Step 1: Instantiate the system and round-trip a payload
            var provider = DataProtectionProvider.CreateProvider(
                keyDirectory: null,
                certificate: null,
                setupAction: builder =>
            {
                builder.SetApplicationName("TestApplication");
                builder.Services.AddSingleton<IKeyManager>(s =>
                    new XmlKeyManager(
                        s.GetRequiredService<IOptions<KeyManagementOptions>>(),
                        s.GetRequiredService<IActivator>(),
                        NullLoggerFactory.Instance,
                        mock.Object));
            });

            var protector = provider.CreateProtector("Protector");
            Assert.Equal("payload", protector.Unprotect(protector.Protect("payload")));

            // Step 2: Validate that there's now a single key in the directory
            var newFileName = Assert.Single(Directory.GetFiles(keysPath));
            var file = new FileInfo(newFileName);
            Assert.StartsWith("key-", file.Name, StringComparison.OrdinalIgnoreCase);
            var fileText = File.ReadAllText(file.FullName);
            // On Windows, validate that it's protected using Windows DPAPI.
            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
            {
                Assert.DoesNotContain("Warning: the key below is in an unencrypted form.", fileText, StringComparison.Ordinal);
                Assert.Contains("This key is encrypted with Windows DPAPI.", fileText, StringComparison.Ordinal);
            }
            else
            {
                Assert.Contains("Warning: the key below is in an unencrypted form.", fileText, StringComparison.Ordinal);
            }
        }

        [ConditionalFact]
        [ConditionalRunTestOnlyOnWindows]
        public void System_UsesProvidedDirectory_WithConfigurationCallback()
        {
            WithUniqueTempDirectory(directory =>
            {
                // Step 1: directory should be completely empty
                directory.Create();
                Assert.Empty(directory.GetFiles());

                // Step 2: instantiate the system and round-trip a payload
                var protector = DataProtectionProvider.Create(directory, configure =>
                {
                    configure.ProtectKeysWithDpapi();
                }).CreateProtector("purpose");
                Assert.Equal("payload", protector.Unprotect(protector.Protect("payload")));

                // Step 3: validate that there's now a single key in the directory and that it's protected with DPAPI
                var allFiles = directory.GetFiles();
                Assert.Single(allFiles);
                Assert.StartsWith("key-", allFiles[0].Name, StringComparison.OrdinalIgnoreCase);
                string fileText = File.ReadAllText(allFiles[0].FullName);
                Assert.DoesNotContain("Warning: the key below is in an unencrypted form.", fileText, StringComparison.Ordinal);
                Assert.Contains("Windows DPAPI", fileText, StringComparison.Ordinal);
            });
        }

        [ConditionalFact]
        [X509StoreIsAvailable(StoreName.My, StoreLocation.CurrentUser)]
        public void System_UsesProvidedDirectoryAndCertificate()
        {
            var filePath = Path.Combine(GetTestFilesPath(), "TestCert.pfx");
            using (var store = new X509Store(StoreName.My, StoreLocation.CurrentUser))
            {
                store.Open(OpenFlags.ReadWrite);
                store.Add(new X509Certificate2(filePath, "password", X509KeyStorageFlags.Exportable));
                store.Close();
            }

            WithUniqueTempDirectory(directory =>
            {
                var certificateStore = new X509Store(StoreName.My, StoreLocation.CurrentUser);
                certificateStore.Open(OpenFlags.ReadWrite);
                var certificate = certificateStore.Certificates.Find(X509FindType.FindBySubjectName, "TestCert", false)[0];
                Assert.True(certificate.HasPrivateKey, "Cert should have a private key");
                try
                {
                    // Step 1: directory should be completely empty
                    directory.Create();
                    Assert.Empty(directory.GetFiles());

                    // Step 2: instantiate the system and round-trip a payload
                    var protector = DataProtectionProvider.Create(directory, certificate).CreateProtector("purpose");
                    var data = protector.Protect("payload");

                    // add a cert without the private key to ensure the decryption will still fallback to the cert store
                    var certWithoutKey = new X509Certificate2(Path.Combine(GetTestFilesPath(), "TestCertWithoutPrivateKey.pfx"), "password");
                    var unprotector = DataProtectionProvider.Create(directory, o => o.UnprotectKeysWithAnyCertificate(certWithoutKey)).CreateProtector("purpose");
                    Assert.Equal("payload", unprotector.Unprotect(data));

                    // Step 3: validate that there's now a single key in the directory and that it's is protected using the certificate
                    var allFiles = directory.GetFiles();
                    Assert.Single(allFiles);
                    Assert.StartsWith("key-", allFiles[0].Name, StringComparison.OrdinalIgnoreCase);
                    string fileText = File.ReadAllText(allFiles[0].FullName);
                    Assert.DoesNotContain("Warning: the key below is in an unencrypted form.", fileText, StringComparison.Ordinal);
                    Assert.Contains("X509Certificate", fileText, StringComparison.Ordinal);
                }
                finally
                {
                    certificateStore.Remove(certificate);
                    certificateStore.Close();
                }
            });
        }

        [ConditionalFact]
        [X509StoreIsAvailable(StoreName.My, StoreLocation.CurrentUser)]
        public void System_UsesProvidedCertificateNotFromStore()
        {
            using (var store = new X509Store(StoreName.My, StoreLocation.CurrentUser))
            {
                store.Open(OpenFlags.ReadWrite);
                var certWithoutKey = new X509Certificate2(Path.Combine(GetTestFilesPath(), "TestCert3WithoutPrivateKey.pfx"), "password3", X509KeyStorageFlags.Exportable);
                Assert.False(certWithoutKey.HasPrivateKey, "Cert should not have private key");
                store.Add(certWithoutKey);
                store.Close();
            }

            WithUniqueTempDirectory(directory =>
            {
                using (var certificateStore = new X509Store(StoreName.My, StoreLocation.CurrentUser))
                {
                    certificateStore.Open(OpenFlags.ReadWrite);
                    var certInStore = certificateStore.Certificates.Find(X509FindType.FindBySubjectName, "TestCert", false)[0];
                    Assert.NotNull(certInStore);
                    Assert.False(certInStore.HasPrivateKey, "Cert should not have private key");

                    try
                    {
                        var certWithKey = new X509Certificate2(Path.Combine(GetTestFilesPath(), "TestCert3.pfx"), "password3");

                        var protector = DataProtectionProvider.Create(directory, certWithKey).CreateProtector("purpose");
                        var data = protector.Protect("payload");

                        var keylessUnprotector = DataProtectionProvider.Create(directory).CreateProtector("purpose");
                        Assert.Throws<CryptographicException>(() => keylessUnprotector.Unprotect(data));

                        var unprotector = DataProtectionProvider.Create(directory, o => o.UnprotectKeysWithAnyCertificate(certInStore, certWithKey)).CreateProtector("purpose");
                        Assert.Equal("payload", unprotector.Unprotect(data));
                    }
                    finally
                    {
                        certificateStore.Remove(certInStore);
                        certificateStore.Close();
                    }
                }
            });
        }

        [Fact]
        public void System_UsesInMemoryCertificate()
        {
            var filePath = Path.Combine(GetTestFilesPath(), "TestCert2.pfx");
            var certificate = new X509Certificate2(filePath, "password");

            AssetStoreDoesNotContain(certificate);

            WithUniqueTempDirectory(directory =>
            {
                // Step 1: directory should be completely empty
                directory.Create();
                Assert.Empty(directory.GetFiles());

                // Step 2: instantiate the system and round-trip a payload
                var protector = DataProtectionProvider.Create(directory, certificate).CreateProtector("purpose");
                Assert.Equal("payload", protector.Unprotect(protector.Protect("payload")));

                // Step 3: validate that there's now a single key in the directory and that it's is protected using the certificate
                var allFiles = directory.GetFiles();
                Assert.Single(allFiles);
                Assert.StartsWith("key-", allFiles[0].Name, StringComparison.OrdinalIgnoreCase);
                string fileText = File.ReadAllText(allFiles[0].FullName);
                Assert.DoesNotContain("Warning: the key below is in an unencrypted form.", fileText, StringComparison.Ordinal);
                Assert.Contains("X509Certificate", fileText, StringComparison.Ordinal);
            });
        }

        private static void AssetStoreDoesNotContain(X509Certificate2 certificate)
        {
            using (var store = new X509Store(StoreName.My, StoreLocation.CurrentUser))
            {
                try
                {
                    store.Open(OpenFlags.ReadOnly);
                }
                catch
                {
                    return;
                }

                // ensure this cert is not in the x509 store
                Assert.Empty(store.Certificates.Find(X509FindType.FindByThumbprint, certificate.Thumbprint, false));
            }
        }

        [Fact]
        public void System_CanUnprotectWithCert()
        {
            var filePath = Path.Combine(GetTestFilesPath(), "TestCert2.pfx");
            var certificate = new X509Certificate2(filePath, "password");

            WithUniqueTempDirectory(directory =>
            {
                // Step 1: directory should be completely empty
                directory.Create();
                Assert.Empty(directory.GetFiles());

                // Step 2: instantiate the system and create some data
                var protector = DataProtectionProvider
                    .Create(directory, certificate)
                    .CreateProtector("purpose");

                var data = protector.Protect("payload");

                // Step 3: validate that there's now a single key in the directory and that it's is protected using the certificate
                var allFiles = directory.GetFiles();
                Assert.Single(allFiles);
                Assert.StartsWith("key-", allFiles[0].Name, StringComparison.OrdinalIgnoreCase);
                string fileText = File.ReadAllText(allFiles[0].FullName);
                Assert.DoesNotContain("Warning: the key below is in an unencrypted form.", fileText, StringComparison.Ordinal);
                Assert.Contains("X509Certificate", fileText, StringComparison.Ordinal);

                // Step 4: setup a second system and validate it can decrypt keys and unprotect data
                var unprotector = DataProtectionProvider.Create(directory,
                    b => b.UnprotectKeysWithAnyCertificate(certificate));
                Assert.Equal("payload", unprotector.CreateProtector("purpose").Unprotect(data));
            });
        }

        /// <summary>
        /// Runs a test and cleans up the temp directory afterward.
        /// </summary>
        private static void WithUniqueTempDirectory(Action<DirectoryInfo> testCode)
        {
            string uniqueTempPath = Path.Combine(AppContext.BaseDirectory, Path.GetRandomFileName());
            var dirInfo = new DirectoryInfo(uniqueTempPath);
            try
            {
                testCode(dirInfo);
            }
            finally
            {
                // clean up when test is done
                if (dirInfo.Exists)
                {
                    dirInfo.Delete(recursive: true);
                }
            }
        }

        private static string GetTestFilesPath()
            => Path.Combine(AppContext.BaseDirectory, "TestFiles");
    }
}
