using System.Text;
using NuGet.Versioning;
using Velopack.Core;
using Velopack.Exceptions;
using Velopack.Locators;
using Velopack.Sources;
using Velopack.Tests.TestHelpers;
using Velopack.Util;

namespace Velopack.Tests;

public class UpdateManagerTests
{
    private readonly ITestOutputHelper _output;

    public UpdateManagerTests(ITestOutputHelper output)
    {
        _output = output;
    }

    private FakeDownloader GetMockDownloaderNoDelta()
    {
        var feed = new VelopackAssetFeed() {
            Assets = new VelopackAsset[] {
                new VelopackAsset() {
                    PackageId = "MyCoolApp",
                    Version = new SemanticVersion(1, 1, 0),
                    Type = VelopackAssetType.Full,
                    FileName = $"MyCoolApp-1.1.0.nupkg",
                    SHA1 = "3a2eadd15dd984e4559f2b4d790ec8badaeb6a39",
                    Size = 1040561,
                },
                new VelopackAsset() {
                    PackageId = "MyCoolApp",
                    Version = new SemanticVersion(1, 0, 0),
                    Type = VelopackAssetType.Full,
                    FileName = $"MyCoolApp-1.0.0.nupkg",
                    SHA1 = "94689fede03fed7ab59c24337673a27837f0c3ec",
                    Size = 1004502,
                },
            }
        };
        var json = SimpleJson.SerializeObject(feed);
        return new FakeDownloader() { MockedResponseBytes = Encoding.UTF8.GetBytes(json) };
    }

    private FakeDownloader GetMockDownloaderWith2Delta()
    {
        var feed = new VelopackAssetFeed {
            Assets = new VelopackAsset[] {
                new VelopackAsset() {
                    PackageId = "MyCoolApp",
                    Version = new SemanticVersion(1, 1, 0),
                    Type = VelopackAssetType.Full,
                    FileName = $"MyCoolApp-1.1.0.nupkg",
                    SHA1 = "3a2eadd15dd984e4559f2b4d790ec8badaeb6a39",
                    Size = 1040561,
                },
                new VelopackAsset() {
                    PackageId = "MyCoolApp",
                    Version = new SemanticVersion(1, 0, 0),
                    Type = VelopackAssetType.Full,
                    FileName = $"MyCoolApp-1.0.0.nupkg",
                    SHA1 = "94689fede03fed7ab59c24337673a27837f0c3ec",
                    Size = 1004502,
                },
                new VelopackAsset() {
                    PackageId = "MyCoolApp",
                    Version = new SemanticVersion(1, 1, 0),
                    Type = VelopackAssetType.Delta,
                    FileName = $"MyCoolApp-1.1.0-delta.nupkg",
                    SHA1 = "14db31d2647c6d2284882a2e101924a9c409ee67",
                    Size = 80396,
                },
                new VelopackAsset() {
                    PackageId = "MyCoolApp",
                    Version = new SemanticVersion(1, 0, 0),
                    Type = VelopackAssetType.Delta,
                    FileName = $"MyCoolApp-1.0.0-delta.nupkg",
                    SHA1 = "14db31d2647c6d2284882a2e101924a9c409ee67",
                    Size = 80396,
                },
                new VelopackAsset() {
                    PackageId = "MyCoolApp",
                    Version = new SemanticVersion(1, 2, 0),
                    Type = VelopackAssetType.Delta,
                    FileName = $"MyCoolApp-1.2.0-delta.nupkg",
                    SHA1 = "14db31d2647c6d2284882a2e101924a9c409ee67",
                    Size = 80396,
                },
                new VelopackAsset() {
                    PackageId = "MyCoolApp",
                    Version = new SemanticVersion(1, 2, 0),
                    Type = VelopackAssetType.Full,
                    FileName = $"MyCoolApp-1.2.0.nupkg",
                    SHA1 = "3a2eadd15dd984e4559f2b4d790ec8badaeb6a39",
                    Size = 1040561,
                },
            }
        };
        var json = SimpleJson.SerializeObject(feed);
        return new FakeDownloader() { MockedResponseBytes = Encoding.UTF8.GetBytes(json) };
    }

    [Fact]
    public void CanDownloadFilesAsUrl()
    {
        var fixture = PathHelper.GetFixture("AvaloniaCrossPlat-1.0.11-win-full.nupkg");

        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var dl = new FakeDownloader() {
            MockedResponseBytes = Encoding.UTF8.GetBytes(
                SimpleJson.SerializeObject(
                    new VelopackAssetFeed {
                        Assets = new VelopackAsset[] {
                            new VelopackAsset() {
                                PackageId = "AvaloniaCrossPlat",
                                Version = new SemanticVersion(1, 0, 11),
                                Type = VelopackAssetType.Full,
                                FileName = $"https://mysite.com/releases/AvaloniaCrossPlat$-1.1.0.nupkg",
                                SHA1 = IoUtil.CalculateFileSHA1(fixture),
                                Size = new FileInfo(fixture).Length,
                            }
                        }
                    }))
        };
        var source = new SimpleWebSource("http://any.com", dl);
        var locator = new TestVelopackLocator("MyCoolApp", "1.0.0", tempPath, logger.ToVelopackLogger());
        var um = new UpdateManager(source, null, locator);
        var info = um.CheckForUpdates();
        Assert.NotNull(info);
        Assert.True(new SemanticVersion(1, 0, 11) == info.TargetFullRelease.Version);
        Assert.Equal(0, info.DeltasToTarget.Count());
        Assert.False(info.IsDowngrade);
        Assert.StartsWith($"http://any.com/releases.{VelopackRuntimeInfo.SystemOs.GetOsShortName()}.json?", dl.LastUrl);

        dl.MockedResponseBytes = File.ReadAllBytes(fixture);
        dl.WriteMockLocalFile = true;
        um.DownloadUpdates(info);

        Assert.True(File.Exists(Path.Combine(tempPath, "AvaloniaCrossPlat$-1.1.0.nupkg")));
        Assert.Equal(Path.Combine(tempPath, "AvaloniaCrossPlat$-1.1.0.nupkg.partial"), dl.LastLocalFile);
        Assert.Equal("https://mysite.com/releases/AvaloniaCrossPlat$-1.1.0.nupkg", dl.LastUrl);
    }

    [Fact]
    public void DownloadFullUpdateFromFixtures()
    {
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var packagesPath);
        using var _2 = TempUtil.GetTempDirectory(out var feedPath);

        var locator = new TestVelopackLocator("MyCoolApp", "1.0.0", packagesPath, logger.ToVelopackLogger());

        File.Copy(PathHelper.GetFixture("testfeed.json"), Path.Combine(feedPath, "releases.beta.json"), true);
        File.Copy(PathHelper.GetFixture("AvaloniaCrossPlat-1.0.11-win-full.nupkg"), Path.Combine(feedPath, "AvaloniaCrossPlat-1.0.11-full.nupkg"), true);

        var options = new UpdateOptions() {
            ExplicitChannel = "beta",
            AllowVersionDowngrade = false,
            MaximumDeltasBeforeFallback = 10,
        };

        var um = new UpdateManager(feedPath, options, locator);
        var updateInfo = um.CheckForUpdates();
        Assert.NotNull(updateInfo);
        um.DownloadUpdates(updateInfo);
        Assert.True(File.Exists(Path.Combine(packagesPath, "AvaloniaCrossPlat-1.0.11-full.nupkg")));
    }

    [Fact]
    public void CheckFromLocal()
    {
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var dl = GetMockDownloaderNoDelta();
        var source = new SimpleWebSource("http://any.com", dl);
        var locator = new TestVelopackLocator("MyCoolApp", "1.0.0", tempPath, logger.ToVelopackLogger());
        var um = new UpdateManager(source, null, locator);
        var info = um.CheckForUpdates();
        Assert.NotNull(info);
        Assert.True(new SemanticVersion(1, 1, 0) == info.TargetFullRelease.Version);
        Assert.Equal(0, info.DeltasToTarget.Count());
        Assert.False(info.IsDowngrade);
        Assert.StartsWith($"http://any.com/releases.{VelopackRuntimeInfo.SystemOs.GetOsShortName()}.json?", dl.LastUrl);
    }

    [Fact]
    public void CheckFromLocalWithChannel()
    {
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var dl = GetMockDownloaderNoDelta();
        var source = new SimpleWebSource("http://any.com", dl);
        var locator = new TestVelopackLocator("MyCoolApp", "1.0.0", tempPath, logger.ToVelopackLogger());
        var opt = new UpdateOptions { ExplicitChannel = "experimental" };
        var um = new UpdateManager(source, opt, locator);
        var info = um.CheckForUpdates();
        Assert.NotNull(info);
        Assert.True(new SemanticVersion(1, 1, 0) == info.TargetFullRelease.Version);
        Assert.Equal(0, info.DeltasToTarget.Count());
        Assert.False(info.IsDowngrade);
        Assert.StartsWith("http://any.com/releases.experimental.json?", dl.LastUrl);
    }

    [Fact]
    public void CheckForSameAsInstalledVersion()
    {
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var dl = GetMockDownloaderWith2Delta();
        var myVer = new VelopackAsset() {
            PackageId = "MyCoolApp",
            Version = new SemanticVersion(1, 2, 0),
            Type = VelopackAssetType.Full,
            FileName = $"MyCoolApp-1.2.0.nupkg",
            SHA1 = "3a2eadd15dd984e4559f2b4d790ec8badaeb6a39",
            Size = 1040561,
        };
        var source = new SimpleWebSource("http://any.com", dl);
        var locator = new TestVelopackLocator(
            "MyCoolApp",
            "1.2.0",
            tempPath,
            null,
            null,
            null,
            logger: logger.ToVelopackLogger(),
            localPackage: myVer,
            channel: "stable");

        // checking for same version should return null
        var um = new UpdateManager(source, null, locator);
        var info = um.CheckForUpdates();
        Assert.Null(info);
        Assert.StartsWith("http://any.com/releases.stable.json?", dl.LastUrl);

        // checking for same version WITHOUT explicit channel should return null
        var opt = new UpdateOptions { AllowVersionDowngrade = true };
        um = new UpdateManager(source, opt, locator);
        Assert.Null(info);
        Assert.StartsWith("http://any.com/releases.stable.json?", dl.LastUrl);

        // checking for same version with explicit channel & downgrade allowed should return version
        opt = new UpdateOptions { ExplicitChannel = "experimental", AllowVersionDowngrade = true };
        um = new UpdateManager(source, opt, locator);
        info = um.CheckForUpdates();
        Assert.True(info.IsDowngrade);
        Assert.NotNull(info);
        Assert.True(new SemanticVersion(1, 2, 0) == info.TargetFullRelease.Version);
        Assert.StartsWith("http://any.com/releases.experimental.json?", dl.LastUrl);
        Assert.Equal(0, info.DeltasToTarget.Count());
    }

    [Fact]
    public void CheckForLowerThanInstalledVersion()
    {
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var dl = GetMockDownloaderWith2Delta();
        var myVer = new VelopackAsset() {
            PackageId = "MyCoolApp",
            Version = new SemanticVersion(2, 0, 0),
            Type = VelopackAssetType.Full,
            FileName = $"MyCoolApp-2.0.0.nupkg",
            SHA1 = "3a2eadd15dd984e4559f2b4d790ec8badaeb6a39",
            Size = 1040561,
        };
        var source = new SimpleWebSource("http://any.com", dl);
        var locator = new TestVelopackLocator(
            "MyCoolApp",
            "2.0.0",
            tempPath,
            null,
            null,
            null,
            logger: logger.ToVelopackLogger(),
            localPackage: myVer,
            channel: "stable");

        // checking for lower version should return null
        var um = new UpdateManager(source, null, locator);
        var info = um.CheckForUpdates();
        Assert.Null(info);
        Assert.StartsWith("http://any.com/releases.stable.json?", dl.LastUrl);

        // checking for lower version with downgrade allowed should return lower version
        var opt = new UpdateOptions { AllowVersionDowngrade = true };
        um = new UpdateManager(source, opt, locator);
        info = um.CheckForUpdates();
        Assert.True(info.IsDowngrade);
        Assert.NotNull(info);
        Assert.True(new SemanticVersion(1, 2, 0) == info.TargetFullRelease.Version);
        Assert.StartsWith("http://any.com/releases.stable.json?", dl.LastUrl);
        Assert.Equal(0, info.DeltasToTarget.Count());
    }

    [Fact]
    public void CheckFromLocalWithDelta()
    {
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var dl = GetMockDownloaderWith2Delta();
        var myVer = new VelopackAsset() {
            PackageId = "MyCoolApp",
            Version = new SemanticVersion(1, 0, 0),
            Type = VelopackAssetType.Full,
            FileName = $"MyCoolApp-1.0.0.nupkg",
            SHA1 = "94689fede03fed7ab59c24337673a27837f0c3ec",
            Size = 1004502,
        };
        var source = new SimpleWebSource("http://any.com", dl);

        var locator = new TestVelopackLocator("MyCoolApp", "1.0.0", tempPath, null, null, null, logger: logger.ToVelopackLogger(), localPackage: myVer);
        var um = new UpdateManager(source, null, locator);
        var info = um.CheckForUpdates();
        Assert.False(info.IsDowngrade);
        Assert.NotNull(info);
        Assert.True(new SemanticVersion(1, 2, 0) == info.TargetFullRelease.Version);
        Assert.Equal(2, info.DeltasToTarget.Count());
    }

    [Fact]
    public void CheckSumShouldUseSha256()
    {
        string id = "Clowd";
        string version = "3.4.287";

        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var packagesDir);
        var repo = new FakeFixtureRepository(id, false);
        var source = new SimpleWebSource("http://any.com", repo);
        var locator = new TestVelopackLocator(id, "1.0.0", packagesDir, logger.ToVelopackLogger());
        var um = new UpdateManager(source, null, locator);

        var info = um.CheckForUpdates();
        Assert.NotNull(info);
        Assert.True(SemanticVersion.Parse(version) == info.TargetFullRelease.Version);
        Assert.Equal(0, info.DeltasToTarget.Count());

        string actualHash = info.TargetFullRelease.SHA256;
        string modifiedHash = info.TargetFullRelease.SHA256.ToLowerInvariant();
        info.TargetFullRelease.SHA256 = modifiedHash;

        var ex = Assert.Throws<ChecksumFailedException>(() => um.DownloadUpdates(info));

        Assert.Contains("SHA256 doesn't match", ex.Message);
        Assert.Contains(actualHash, ex.Message);
        Assert.Contains(modifiedHash, ex.Message);

        // Restore SHA256 hash, it should not work even if SHA1 is changed
        info.TargetFullRelease.SHA256 = actualHash;
        info.TargetFullRelease.SHA1 = "wrong";
        um.DownloadUpdates(info);
    }

    [Fact]
    public void CheckSumShouldFallbackToSha1()
    {
        string id = "Clowd";
        string version = "3.4.287";

        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var packagesDir);
        var repo = new FakeFixtureRepository(id, false);
        var source = new SimpleWebSource("http://any.com", repo);
        var locator = new TestVelopackLocator(id, "1.0.0", packagesDir, logger.ToVelopackLogger());
        var um = new UpdateManager(source, null, locator);

        var info = um.CheckForUpdates();
        Assert.NotNull(info);
        Assert.True(SemanticVersion.Parse(version) == info.TargetFullRelease.Version);
        Assert.Equal(0, info.DeltasToTarget.Count());

        info.TargetFullRelease.SHA256 = null;
        um.DownloadUpdates(info);

        Directory.EnumerateFiles(packagesDir, "*.nupkg", SearchOption.TopDirectoryOnly).ForEach(File.Delete);

        // change hash, it should now fail
        string actualHash = info.TargetFullRelease.SHA1;
        string modifiedHash = info.TargetFullRelease.SHA1.Substring(1) + "A";
        info.TargetFullRelease.SHA1 = modifiedHash;

        var ex = Assert.Throws<ChecksumFailedException>(() => um.DownloadUpdates(info));

        Assert.Contains("SHA1 doesn't match", ex.Message);
        Assert.Contains(actualHash, ex.Message);
        Assert.Contains(modifiedHash, ex.Message);
    }

    [Fact]
    public void NoDeltaIfNoBasePackage()
    {
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var dl = GetMockDownloaderWith2Delta();
        var source = new SimpleWebSource("http://any.com", dl);
        var locator = new TestVelopackLocator("MyCoolApp", "1.0.0", tempPath, logger: logger.ToVelopackLogger());
        var um = new UpdateManager(source, null, locator);
        var info = um.CheckForUpdates();
        Assert.NotNull(info);
        Assert.False(info.IsDowngrade);
        Assert.True(new SemanticVersion(1, 2, 0) == info.TargetFullRelease.Version);
        Assert.Equal(0, info.DeltasToTarget.Count());
    }

    [Fact]
    public void CheckFromLocalWithDeltaNoLocalPackage()
    {
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var dl = GetMockDownloaderWith2Delta();
        var source = new SimpleWebSource("http://any.com", dl);
        var locator = new TestVelopackLocator("MyCoolApp", "1.0.0", tempPath, logger: logger.ToVelopackLogger());
        var um = new UpdateManager(source, null, locator);
        var info = um.CheckForUpdates();
        Assert.NotNull(info);
        Assert.False(info.IsDowngrade);
        Assert.True(new SemanticVersion(1, 2, 0) == info.TargetFullRelease.Version);
        Assert.Equal(0, info.DeltasToTarget.Count());
    }

    [Fact(Skip = "Consumes API Quota")]
    public void CheckGithub()
    {
        // https://github.com/caesay/SquirrelCustomLauncherTestApp
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var locator = new TestVelopackLocator("MyCoolApp", "1.0.0", tempPath, logger.ToVelopackLogger());
        var source = new GithubSource("https://github.com/caesay/SquirrelCustomLauncherTestApp", null, false);
        var um = new UpdateManager(source, null, locator);
        var info = um.CheckForUpdates();
        Assert.NotNull(info);
        Assert.True(new SemanticVersion(1, 0, 1) == info.TargetFullRelease.Version);
        Assert.Equal(0, info.DeltasToTarget.Count());
    }

    [Fact(Skip = "Consumes API Quota")]
    public void CheckGithubWithNonExistingChannel()
    {
        // https://github.com/caesay/SquirrelCustomLauncherTestApp
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var locator = new TestVelopackLocator("MyCoolApp", "1.0.0", tempPath, logger.ToVelopackLogger());
        var source = new GithubSource("https://github.com/caesay/SquirrelCustomLauncherTestApp", null, false);
        var opt = new UpdateOptions { ExplicitChannel = "hello" };
        var um = new UpdateManager(source, opt, locator);
        Assert.Throws<ArgumentException>(() => um.CheckForUpdates());
    }

    [Fact(Skip = "Consumes API Quota")]
    public void CheckGitea()
    {
        // https://github.com/caesay/SquirrelCustomLauncherTestApp
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var locator = new TestVelopackLocator("MyCoolApp", "1.0.0", tempPath, logger.ToVelopackLogger());
        var source = new GiteaSource("https://gitea.com/remco1271/VeloPackTest", null, false);
        var um = new UpdateManager(source, null, locator);
        var info = um.CheckForUpdates();
        Assert.NotNull(info);
        Assert.True(new SemanticVersion(1, 0, 1) == info.TargetFullRelease.Version);
        Assert.Equal(0, info.DeltasToTarget.Count());
    }

    [Fact]
    public void CheckFromEmptyFileSource()
    {
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var source = new SimpleFileSource(new DirectoryInfo(tempPath));
        var locator = new TestVelopackLocator("MyCoolApp", "1.0.0", tempPath, logger.ToVelopackLogger());
        var um = new UpdateManager(source, null, locator);
        var info = um.CheckForUpdates();
        Assert.Null(info);
    }

    [Fact]
    public void NoUpdatesIfCurrentEqualsRemoteVersion()
    {
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var dl = GetMockDownloaderNoDelta();
        var source = new SimpleWebSource("http://any.com", dl);
        var locator = new TestVelopackLocator("MyCoolApp", "1.1.0", tempPath, logger.ToVelopackLogger());
        var um = new UpdateManager(source, null, locator);
        var info = um.CheckForUpdates();
        Assert.Null(info);
    }

    [Fact]
    public void NoUpdatesIfCurrentGreaterThanRemoteVersion()
    {
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var tempPath);
        var dl = GetMockDownloaderNoDelta();
        var source = new SimpleWebSource("http://any.com", dl);
        var locator = new TestVelopackLocator("MyCoolApp", "1.2.0", tempPath, logger.ToVelopackLogger());
        var um = new UpdateManager(source, null, locator);
        var info = um.CheckForUpdates();
        Assert.Null(info);
    }

    [Theory]
    [InlineData("Clowd", "3.4.287")]
    [InlineData("slack", "1.1.8")]
    public void DownloadsLatestFullVersion(string id, string version)
    {
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var packagesDir);
        var repo = new FakeFixtureRepository(id, false);
        var source = new SimpleWebSource("http://any.com", repo);
        var locator = new TestVelopackLocator(id, "1.0.0", packagesDir, logger.ToVelopackLogger());
        var um = new UpdateManager(source, null, locator);

        var info = um.CheckForUpdates();
        Assert.NotNull(info);
        Assert.True(SemanticVersion.Parse(version) == info.TargetFullRelease.Version);
        Assert.Equal(0, info.DeltasToTarget.Count());

        um.DownloadUpdates(info);

        var target = Path.Combine(packagesDir, $"{id}-{version}-full.nupkg");
        Assert.True(File.Exists(target));
        um.VerifyPackageChecksum(info.TargetFullRelease);
    }

    [SkippableTheory]
    [InlineData("Clowd", "3.4.287", "3.4.293")]
    //[InlineData("slack", "1.1.8", "1.2.2")]
    public async Task DownloadsDeltasAndCreatesFullVersion(string id, string fromVersion, string toVersion)
    {
        Skip.If(VelopackRuntimeInfo.IsLinux);
        using var logger = _output.BuildLoggerFor<UpdateManagerTests>();
        using var _1 = TempUtil.GetTempDirectory(out var packagesDir);
        var repo = new FakeFixtureRepository(id, true);
        var source = new SimpleWebSource("http://any.com", repo);

        var feed = await source.GetReleaseFeed(logger.ToVelopackLogger(), id, VelopackRuntimeInfo.SystemOs.GetOsShortName());
        var basePkg = feed.Assets
            .Where(x => x.Type == VelopackAssetType.Full)
            .Single(x => x.Version == SemanticVersion.Parse(fromVersion));
        var basePkgFixturePath = PathHelper.GetFixture(basePkg.FileName);
        var basePkgPath = Path.Combine(packagesDir, basePkg.FileName);
        File.Copy(basePkgFixturePath, basePkgPath);

        var updateExe = PathHelper.CopyUpdateTo(packagesDir);
        var locator = new TestVelopackLocator(
            id,
            fromVersion,
            packagesDir,
            null,
            null,
            updateExe,
            null,
            logger.ToVelopackLogger());
        var um = new UpdateManager(source, null, locator);

        var info = await um.CheckForUpdatesAsync();
        Assert.NotNull(info);
        Assert.True(SemanticVersion.Parse(toVersion) == info.TargetFullRelease.Version);
        Assert.Equal(4, info.DeltasToTarget.Count());
        Assert.NotNull(info.BaseRelease);

        await um.DownloadUpdatesAsync(info);
        var target = Path.Combine(packagesDir, $"{id}-{toVersion}-full.nupkg");
        Assert.True(File.Exists(target));
    }
}