Repository.cs

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using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
 
using LibGit2Sharp;
using LibGit2Sharp.Handlers;
 
using Microsoft.Extensions.Logging;
 
using Tgstation.Server.Api.Models;
using Tgstation.Server.Host.Components.Events;
using Tgstation.Server.Host.Configuration;
using Tgstation.Server.Host.Extensions;
using Tgstation.Server.Host.IO;
using Tgstation.Server.Host.Jobs;
using Tgstation.Server.Host.Utils;
 
namespace Tgstation.Server.Host.Components.Repository
{
#pragma warning disable CA1506 // TODO: Decomplexify
    sealed class Repository : DisposeInvoker, IRepository
    {
        public const string DefaultCommitterName = "tgstation-server";
 
        public const string DefaultCommitterEmail = "tgstation-server@users.noreply.github.com";
 
        public const string OriginTrackingErrorTemplate = "Unable to determine most recent origin commit of {sha}. Marking it as an origin commit. This may result in invalid git metadata until the next hard reset to an origin reference.";
 
        public const string RemoteTemporaryBranchName = "___TGSTempBranch";
 
        public const string NoReference = "(no branch)";
 
        const string UnknownReference = "<UNKNOWN>";
 
        public RemoteGitProvider? RemoteGitProvider => gitRemoteFeatures.RemoteGitProvider;
 
        public string? RemoteRepositoryOwner => gitRemoteFeatures.RemoteRepositoryOwner;
 
        public string? RemoteRepositoryName => gitRemoteFeatures.RemoteRepositoryName;
 
        public bool Tracking => Reference != null && libGitRepo.Head.IsTracking;
 
        public string Head => libGitRepo.Head.Tip.Sha;
 
        public string Reference => libGitRepo.Head.FriendlyName;
 
        public Uri Origin => new(libGitRepo.Network.Remotes.First().Url);
 
        readonly LibGit2Sharp.IRepository libGitRepo;
 
        readonly ILibGit2Commands commands;
 
        readonly IIOManager ioManager;
 
        readonly IEventConsumer eventConsumer;
 
        readonly ICredentialsProvider credentialsProvider;
 
        readonly IPostWriteHandler postWriteHandler;
 
        readonly IGitRemoteFeatures gitRemoteFeatures;
 
        readonly ILibGit2RepositoryFactory submoduleFactory;
 
        readonly ILogger<Repository> logger;
 
        readonly GeneralConfiguration generalConfiguration;
 
        public Repository(
            LibGit2Sharp.IRepository libGitRepo,
            ILibGit2Commands commands,
            IIOManager ioManager,
            IEventConsumer eventConsumer,
            ICredentialsProvider credentialsProvider,
            IPostWriteHandler postWriteHandler,
            IGitRemoteFeaturesFactory gitRemoteFeaturesFactory,
            ILibGit2RepositoryFactory submoduleFactory,
            ILogger<Repository> logger,
            GeneralConfiguration generalConfiguration,
            Action disposeAction)
            : base(disposeAction)
        {
            this.libGitRepo = libGitRepo ?? throw new ArgumentNullException(nameof(libGitRepo));
            this.commands = commands ?? throw new ArgumentNullException(nameof(commands));
            this.ioManager = ioManager ?? throw new ArgumentNullException(nameof(ioManager));
            this.eventConsumer = eventConsumer ?? throw new ArgumentNullException(nameof(eventConsumer));
            this.credentialsProvider = credentialsProvider ?? throw new ArgumentNullException(nameof(credentialsProvider));
            this.postWriteHandler = postWriteHandler ?? throw new ArgumentNullException(nameof(postWriteHandler));
            ArgumentNullException.ThrowIfNull(gitRemoteFeaturesFactory);
            this.submoduleFactory = submoduleFactory ?? throw new ArgumentNullException(nameof(submoduleFactory));
 
            this.logger = logger ?? throw new ArgumentNullException(nameof(logger));
            this.generalConfiguration = generalConfiguration ?? throw new ArgumentNullException(nameof(generalConfiguration));
 
            gitRemoteFeatures = gitRemoteFeaturesFactory.CreateGitRemoteFeatures(this);
        }
 
#pragma warning disable CA1506 // TODO: Decomplexify
        public async ValueTask<TestMergeResult> AddTestMerge(
            TestMergeParameters testMergeParameters,
            string committerName,
            string committerEmail,
            string? username,
            string? password,
            bool updateSubmodules,
            JobProgressReporter progressReporter,
            CancellationToken cancellationToken)
        {
            ArgumentNullException.ThrowIfNull(testMergeParameters);
            ArgumentNullException.ThrowIfNull(committerName);
            ArgumentNullException.ThrowIfNull(committerEmail);
            ArgumentNullException.ThrowIfNull(progressReporter);
 
            logger.LogDebug(
                "Begin AddTestMerge: #{prNumber} at {targetSha} ({comment}) by <{committerName} ({committerEmail})>",
                testMergeParameters.Number,
                testMergeParameters.TargetCommitSha?[..7],
                testMergeParameters.Comment,
                committerName,
                committerEmail);
 
            if (RemoteGitProvider == Api.Models.RemoteGitProvider.Unknown)
                throw new InvalidOperationException("Cannot test merge with an Unknown RemoteGitProvider!");
 
            var commitMessage = String.Format(
                CultureInfo.InvariantCulture,
                "TGS Test Merge (PR {0}){1}{2}",
                testMergeParameters.Number,
                testMergeParameters.Comment != null
                    ? Environment.NewLine
                    : String.Empty,
                testMergeParameters.Comment ?? String.Empty);
 
            var testMergeBranchName = String.Format(CultureInfo.InvariantCulture, "tm-{0}", testMergeParameters.Number);
            var localBranchName = String.Format(CultureInfo.InvariantCulture, gitRemoteFeatures.TestMergeLocalBranchNameFormatter, testMergeParameters.Number, testMergeBranchName);
 
            var refSpec = String.Format(CultureInfo.InvariantCulture, gitRemoteFeatures.TestMergeRefSpecFormatter, testMergeParameters.Number, testMergeBranchName);
            var refSpecList = new List<string> { refSpec };
            var logMessage = String.Format(CultureInfo.InvariantCulture, "Test merge #{0}", testMergeParameters.Number);
 
            var originalCommit = libGitRepo.Head;
 
            MergeResult? result = null;
 
            var progressFactor = 1.0 / (updateSubmodules ? 3 : 2);
 
            var sig = new Signature(new Identity(committerName, committerEmail), DateTimeOffset.UtcNow);
            List<string>? conflictedPaths = null;
            await Task.Factory.StartNew(
                () =>
                {
                    try
                    {
                        try
                        {
                            logger.LogTrace("Fetching refspec {refSpec}...", refSpec);
 
                            var remote = libGitRepo.Network.Remotes.First();
                            using var fetchReporter = progressReporter.CreateSection($"Fetch {refSpec}", progressFactor);
                            commands.Fetch(
                                libGitRepo,
                                refSpecList,
                                remote,
                                new FetchOptions().Hydrate(
                                    logger,
                                    fetchReporter,
                                    credentialsProvider.GenerateCredentialsHandler(username, password),
                                    cancellationToken),
                                logMessage);
                        }
                        catch (UserCancelledException ex)
                        {
                            logger.LogTrace(ex, "Suppressing fetch cancel exception");
                        }
                        catch (LibGit2SharpException ex)
                        {
                            credentialsProvider.CheckBadCredentialsException(ex);
                        }
 
                        cancellationToken.ThrowIfCancellationRequested();
 
                        libGitRepo.RemoveUntrackedFiles();
 
                        cancellationToken.ThrowIfCancellationRequested();
 
                        var objectName = testMergeParameters.TargetCommitSha ?? localBranchName;
                        var gitObject = libGitRepo.Lookup(objectName) ?? throw new JobException($"Could not find object to merge: {objectName}");
 
                        testMergeParameters.TargetCommitSha = gitObject.Sha;
 
                        cancellationToken.ThrowIfCancellationRequested();
 
                        logger.LogTrace("Merging {targetCommitSha} into {currentReference}...", testMergeParameters.TargetCommitSha[..7], Reference);
 
                        using var mergeReporter = progressReporter.CreateSection($"Merge {testMergeParameters.TargetCommitSha[..7]}", progressFactor);
                        result = libGitRepo.Merge(testMergeParameters.TargetCommitSha, sig, new MergeOptions
                        {
                            CommitOnSuccess = commitMessage == null,
                            FailOnConflict = false, // Needed to get conflicting files
                            FastForwardStrategy = FastForwardStrategy.NoFastForward,
                            SkipReuc = true,
                            OnCheckoutProgress = CheckoutProgressHandler(mergeReporter),
                        });
                    }
                    finally
                    {
                        libGitRepo.Branches.Remove(localBranchName);
                    }
 
                    cancellationToken.ThrowIfCancellationRequested();
 
                    if (result.Status == MergeStatus.Conflicts)
                    {
                        var repoStatus = libGitRepo.RetrieveStatus();
                        conflictedPaths = new List<string>();
                        foreach (var file in repoStatus)
                            if (file.State == FileStatus.Conflicted)
                                conflictedPaths.Add(file.FilePath);
 
                        var revertTo = originalCommit.CanonicalName ?? originalCommit.Tip.Sha;
                        logger.LogDebug("Merge conflict, aborting and reverting to {revertTarget}", revertTo);
                        progressReporter.ReportProgress(0);
                        using var revertReporter = progressReporter.CreateSection("Hard Reset to {revertTo}", 1.0);
                        RawCheckout(revertTo, false, revertReporter, cancellationToken);
                        cancellationToken.ThrowIfCancellationRequested();
                    }
 
                    libGitRepo.RemoveUntrackedFiles();
                },
                cancellationToken,
                DefaultIOManager.BlockingTaskCreationOptions,
                TaskScheduler.Current);
 
            if (result!.Status == MergeStatus.Conflicts)
            {
                var arguments = new List<string>
                {
                    originalCommit.Tip.Sha,
                    testMergeParameters.TargetCommitSha!,
                    originalCommit.FriendlyName ?? UnknownReference,
                    testMergeBranchName,
                };
 
                arguments.AddRange(conflictedPaths!);
 
                await eventConsumer.HandleEvent(
                    EventType.RepoMergeConflict,
                    arguments,
                    false,
                    cancellationToken);
                return new TestMergeResult
                {
                    Status = result.Status,
                    ConflictingFiles = conflictedPaths,
                };
            }
 
            if (result.Status != MergeStatus.UpToDate)
            {
                logger.LogTrace("Committing merge: \"{commitMessage}\"...", commitMessage);
                await Task.Factory.StartNew(
                    () => libGitRepo.Commit(commitMessage, sig, sig, new CommitOptions
                    {
                        PrettifyMessage = true,
                    }),
                    cancellationToken,
                    DefaultIOManager.BlockingTaskCreationOptions,
                    TaskScheduler.Current);
 
                if (updateSubmodules)
                {
                    using var progressReporter2 = progressReporter.CreateSection("Update Submodules", progressFactor);
                    await UpdateSubmodules(
                        progressReporter2,
                        username,
                        password,
                        false,
                        cancellationToken);
                }
            }
 
            await eventConsumer.HandleEvent(
                EventType.RepoAddTestMerge,
                new List<string?>
                {
                    testMergeParameters.Number.ToString(CultureInfo.InvariantCulture),
                    testMergeParameters.TargetCommitSha!,
                    testMergeParameters.Comment,
                },
                false,
                cancellationToken);
 
            return new TestMergeResult
            {
                Status = result.Status,
            };
        }
#pragma warning restore CA1506
 
        public async ValueTask CheckoutObject(
            string committish,
            string? username,
            string? password,
            bool updateSubmodules,
            bool moveCurrentReference,
            JobProgressReporter progressReporter,
            CancellationToken cancellationToken)
        {
            ArgumentNullException.ThrowIfNull(committish);
 
            logger.LogDebug("Checkout object: {committish}...", committish);
            await eventConsumer.HandleEvent(EventType.RepoCheckout, new List<string> { committish, moveCurrentReference.ToString() }, false, cancellationToken);
            await Task.Factory.StartNew(
                () =>
                {
                    libGitRepo.RemoveUntrackedFiles();
                    using var progressReporter3 = progressReporter.CreateSection(null, updateSubmodules ? 2.0 / 3 : 1.0);
                    RawCheckout(
                        committish,
                        moveCurrentReference,
                        progressReporter3,
                        cancellationToken);
                },
                cancellationToken,
                DefaultIOManager.BlockingTaskCreationOptions,
                TaskScheduler.Current);
 
            if (updateSubmodules)
            {
                using var progressReporter2 = progressReporter.CreateSection(null, 1.0 / 3);
                await UpdateSubmodules(
                    progressReporter2,
                    username,
                    password,
                    false,
                    cancellationToken);
            }
        }
 
        public async ValueTask FetchOrigin(
            JobProgressReporter progressReporter,
            string? username,
            string? password,
            bool deploymentPipeline,
            CancellationToken cancellationToken)
        {
            logger.LogDebug("Fetch origin...");
            await eventConsumer.HandleEvent(EventType.RepoFetch, Enumerable.Empty<string>(), deploymentPipeline, cancellationToken);
            await Task.Factory.StartNew(
                () =>
                {
                    var remote = libGitRepo.Network.Remotes.First();
                    try
                    {
                        using var subReporter = progressReporter.CreateSection("Fetch Origin", 1.0);
                        var fetchOptions = new FetchOptions
                        {
                            Prune = true,
                            TagFetchMode = TagFetchMode.All,
                        }.Hydrate(
                            logger,
                            subReporter,
                            credentialsProvider.GenerateCredentialsHandler(username, password),
                            cancellationToken);
 
                        commands.Fetch(
                            libGitRepo,
                            remote
                                .FetchRefSpecs
                                .Select(x => x.Specification),
                            remote,
                            fetchOptions,
                            "Fetch origin commits");
                    }
                    catch (UserCancelledException)
                    {
                        cancellationToken.ThrowIfCancellationRequested();
                    }
                    catch (LibGit2SharpException ex)
                    {
                        credentialsProvider.CheckBadCredentialsException(ex);
                    }
                },
                cancellationToken,
                DefaultIOManager.BlockingTaskCreationOptions,
                TaskScheduler.Current);
        }
 
        public async ValueTask ResetToOrigin(
            JobProgressReporter progressReporter,
            string? username,
            string? password,
            bool updateSubmodules,
            bool deploymentPipeline,
            CancellationToken cancellationToken)
        {
            ArgumentNullException.ThrowIfNull(progressReporter);
            if (!Tracking)
                throw new JobException(ErrorCode.RepoReferenceRequired);
            logger.LogTrace("Reset to origin...");
            var trackedBranch = libGitRepo.Head.TrackedBranch;
            await eventConsumer.HandleEvent(EventType.RepoResetOrigin, new List<string> { trackedBranch.FriendlyName, trackedBranch.Tip.Sha }, deploymentPipeline, cancellationToken);
 
            using (var progressReporter2 = progressReporter.CreateSection(null, updateSubmodules ? 2.0 / 3 : 1.0))
                await ResetToSha(
                    trackedBranch.Tip.Sha,
                    progressReporter2,
                    cancellationToken);
 
            if (updateSubmodules)
            {
                using var progressReporter3 = progressReporter.CreateSection(null, 1.0 / 3);
                await UpdateSubmodules(
                    progressReporter3,
                    username,
                    password,
                    deploymentPipeline,
                    cancellationToken);
            }
        }
 
        public Task ResetToSha(string sha, JobProgressReporter progressReporter, CancellationToken cancellationToken) => Task.Factory.StartNew(
            () =>
            {
                ArgumentNullException.ThrowIfNull(sha);
                ArgumentNullException.ThrowIfNull(progressReporter);
 
                logger.LogDebug("Reset to sha: {sha}", sha[..7]);
 
                libGitRepo.RemoveUntrackedFiles();
                cancellationToken.ThrowIfCancellationRequested();
 
                var gitObject = libGitRepo.Lookup(sha, ObjectType.Commit);
                cancellationToken.ThrowIfCancellationRequested();
 
                if (gitObject == null)
                    throw new InvalidOperationException(String.Format(CultureInfo.InvariantCulture, "Cannot reset to non-existent SHA: {0}", sha));
 
                libGitRepo.Reset(ResetMode.Hard, gitObject.Peel<Commit>(), new CheckoutOptions
                {
                    OnCheckoutProgress = CheckoutProgressHandler(progressReporter.CreateSection($"Reset to {gitObject.Sha}", 1.0)),
                });
            },
            cancellationToken,
            DefaultIOManager.BlockingTaskCreationOptions,
            TaskScheduler.Current);
 
        public async ValueTask CopyTo(string path, CancellationToken cancellationToken)
        {
            ArgumentNullException.ThrowIfNull(path);
            logger.LogTrace("Copying to {path}...", path);
            await ioManager.CopyDirectory(
                new List<string> { ".git" },
                (src, dest) =>
                {
                    if (postWriteHandler.NeedsPostWrite(src))
                        postWriteHandler.HandleWrite(dest);
 
                    return ValueTask.CompletedTask;
                },
                ioManager.ResolvePath(),
                path,
                generalConfiguration.GetCopyDirectoryTaskThrottle(),
                cancellationToken);
        }
 
        public Task<string> GetOriginSha(CancellationToken cancellationToken) => Task.Factory.StartNew(
            () =>
            {
                if (!Tracking)
                    throw new JobException(ErrorCode.RepoReferenceRequired);
 
                cancellationToken.ThrowIfCancellationRequested();
 
                return libGitRepo.Head.TrackedBranch.Tip.Sha;
            },
            cancellationToken,
            DefaultIOManager.BlockingTaskCreationOptions,
            TaskScheduler.Current);
 
        public async ValueTask<bool?> MergeOrigin(
            JobProgressReporter progressReporter,
            string committerName,
            string committerEmail,
            bool deploymentPipeline,
            CancellationToken cancellationToken)
        {
            ArgumentNullException.ThrowIfNull(progressReporter);
 
            MergeResult? result = null;
            Branch? trackedBranch = null;
 
            var oldHead = libGitRepo.Head;
            var oldTip = oldHead.Tip;
 
            await Task.Factory.StartNew(
                () =>
                {
                    if (!Tracking)
                        throw new JobException(ErrorCode.RepoReferenceRequired);
 
                    libGitRepo.RemoveUntrackedFiles();
 
                    cancellationToken.ThrowIfCancellationRequested();
 
                    trackedBranch = libGitRepo.Head.TrackedBranch;
                    logger.LogDebug(
                        "Merge origin/{trackedBranch}: <{committerName} ({committerEmail})>",
                        trackedBranch.FriendlyName,
                        committerName,
                        committerEmail);
                    result = libGitRepo.Merge(trackedBranch, new Signature(committerName, committerEmail, DateTimeOffset.UtcNow), new MergeOptions
                    {
                        CommitOnSuccess = true,
                        FailOnConflict = true,
                        FastForwardStrategy = FastForwardStrategy.Default,
                        SkipReuc = true,
                        OnCheckoutProgress = CheckoutProgressHandler(progressReporter.CreateSection("Merge Origin", 1.0)),
                    });
 
                    cancellationToken.ThrowIfCancellationRequested();
 
                    if (result.Status == MergeStatus.Conflicts)
                    {
                        logger.LogDebug("Merge conflict, aborting and reverting to {oldHeadFriendlyName}", oldHead.FriendlyName);
                        progressReporter.ReportProgress(0);
                        libGitRepo.Reset(ResetMode.Hard, oldTip, new CheckoutOptions
                        {
                            OnCheckoutProgress = CheckoutProgressHandler(progressReporter.CreateSection($"Hard Reset to {oldHead.FriendlyName}", 1.0)),
                        });
                        cancellationToken.ThrowIfCancellationRequested();
                    }
 
                    libGitRepo.RemoveUntrackedFiles();
                },
                cancellationToken,
                DefaultIOManager.BlockingTaskCreationOptions,
                TaskScheduler.Current);
 
            if (result!.Status == MergeStatus.Conflicts)
            {
                await eventConsumer.HandleEvent(
                    EventType.RepoMergeConflict,
                    new List<string>
                    {
                        oldTip.Sha,
                        trackedBranch!.Tip.Sha,
                        oldHead.FriendlyName ?? UnknownReference,
                        trackedBranch.FriendlyName,
                    },
                    deploymentPipeline,
                    cancellationToken);
                return null;
            }
 
            return result.Status == MergeStatus.FastForward;
        }
 
        public async ValueTask<bool> Synchronize(
            JobProgressReporter progressReporter,
            string? username,
            string? password,
            string committerName,
            string committerEmail,
            bool synchronizeTrackedBranch,
            bool deploymentPipeline,
            CancellationToken cancellationToken)
        {
            ArgumentNullException.ThrowIfNull(committerName);
            ArgumentNullException.ThrowIfNull(committerEmail);
            ArgumentNullException.ThrowIfNull(progressReporter);
 
            if (username == null && password == null)
            {
                logger.LogTrace("Not synchronizing due to lack of credentials!");
                return false;
            }
 
            logger.LogTrace("Begin Synchronize...");
 
            ArgumentNullException.ThrowIfNull(username);
            ArgumentNullException.ThrowIfNull(password);
 
            var startHead = Head;
 
            logger.LogTrace("Configuring <{committerName} ({committerEmail})> as author/committer", committerName, committerEmail);
            await Task.Factory.StartNew(
                () =>
                {
                    libGitRepo.Config.Set("user.name", committerName);
                    cancellationToken.ThrowIfCancellationRequested();
                    libGitRepo.Config.Set("user.email", committerEmail);
                },
                cancellationToken,
                DefaultIOManager.BlockingTaskCreationOptions,
                TaskScheduler.Current);
 
            cancellationToken.ThrowIfCancellationRequested();
            try
            {
                await eventConsumer.HandleEvent(
                    EventType.RepoPreSynchronize,
                    new List<string>
                    {
                        ioManager.ResolvePath(),
                    },
                    deploymentPipeline,
                    cancellationToken);
            }
            finally
            {
                logger.LogTrace("Resetting and cleaning untracked files...");
                await Task.Factory.StartNew(
                    () =>
                    {
                        using var resetProgress = progressReporter.CreateSection("Hard reset and remove untracked files", 0.1);
                        libGitRepo.Reset(ResetMode.Hard, libGitRepo.Head.Tip, new CheckoutOptions
                        {
                            OnCheckoutProgress = CheckoutProgressHandler(resetProgress),
                        });
                        cancellationToken.ThrowIfCancellationRequested();
                        libGitRepo.RemoveUntrackedFiles();
                    },
                    cancellationToken,
                    DefaultIOManager.BlockingTaskCreationOptions,
                    TaskScheduler.Current);
            }
 
            var remainingProgressFactor = 0.9;
            if (!synchronizeTrackedBranch)
            {
                using var progressReporter2 = progressReporter.CreateSection("Push to temporary branch", remainingProgressFactor);
                await PushHeadToTemporaryBranch(
                    username,
                    password,
                    progressReporter2,
                    cancellationToken);
                return false;
            }
 
            var sameHead = Head == startHead;
            if (sameHead || !Tracking)
            {
                logger.LogTrace("Aborted synchronize due to {abortReason}!", sameHead ? "lack of changes" : "not being on tracked reference");
                return false;
            }
 
            logger.LogInformation("Synchronizing with origin...");
 
            return await Task.Factory.StartNew(
                () =>
                {
                    var remote = libGitRepo.Network.Remotes.First();
                    try
                    {
                        using var pushReporter = progressReporter.CreateSection("Push to origin", remainingProgressFactor);
                        var (pushOptions, progressReporters) = GeneratePushOptions(
                            pushReporter,
                            username,
                            password,
                            cancellationToken);
                        try
                        {
                            libGitRepo.Network.Push(
                                libGitRepo.Head,
                                pushOptions);
                        }
                        finally
                        {
                            foreach (var progressReporter in progressReporters)
                                progressReporter.Dispose();
                        }
 
                        return true;
                    }
                    catch (NonFastForwardException)
                    {
                        logger.LogInformation("Synchronize aborted, non-fast forward!");
                        return false;
                    }
                    catch (UserCancelledException e)
                    {
                        cancellationToken.ThrowIfCancellationRequested();
                        throw new InvalidOperationException("Caught UserCancelledException without cancellationToken triggering", e);
                    }
                    catch (LibGit2SharpException e)
                    {
                        logger.LogWarning(e, "Unable to make synchronization push!");
                        return false;
                    }
                },
                cancellationToken,
                DefaultIOManager.BlockingTaskCreationOptions,
                TaskScheduler.Current);
        }
 
        public Task<bool> IsSha(string committish, CancellationToken cancellationToken) => Task.Factory.StartNew(
            () =>
            {
                // check if it's a tag
                var gitObject = libGitRepo.Lookup(committish, ObjectType.Tag);
                if (gitObject != null)
                    return false;
                cancellationToken.ThrowIfCancellationRequested();
 
                // check if it's a branch
                if (libGitRepo.Branches[committish] != null)
                    return false;
                cancellationToken.ThrowIfCancellationRequested();
 
                // err on the side of references, if we can't look it up, assume its a reference
                if (libGitRepo.Lookup<Commit>(committish) != null)
                    return true;
                return false;
            },
            cancellationToken,
            DefaultIOManager.BlockingTaskCreationOptions,
            TaskScheduler.Current);
 
        public Task<bool> CommittishIsParent(string committish, CancellationToken cancellationToken) => Task.Factory.StartNew(
            () =>
            {
                var targetObject = libGitRepo.Lookup(committish);
                if (targetObject == null)
                {
                    logger.LogTrace("Committish {committish} not found in repository", committish);
                    return false;
                }
 
                if (targetObject is not Commit targetCommit)
                {
                    if (targetObject is not TagAnnotation)
                    {
                        logger.LogTrace("Committish {committish} is a {type} and does not point to a commit!", committish, targetObject.GetType().Name);
                        return false;
                    }
 
                    targetCommit = targetObject.Peel<Commit>();
                    if (targetCommit == null)
                    {
                        logger.LogError(
                            "TagAnnotation {committish} was found but the commit associated with it could not be found in repository!",
                            committish);
                        return false;
                    }
                }
 
                cancellationToken.ThrowIfCancellationRequested();
                var startSha = Head;
                logger.LogTrace("Testing if {committish} is a parent of {startSha}...", committish, startSha);
                MergeResult mergeResult;
                try
                {
                    mergeResult = libGitRepo.Merge(
                        targetCommit,
                        new Signature(
                            DefaultCommitterName,
                            DefaultCommitterEmail,
                            DateTimeOffset.UtcNow),
                        new MergeOptions
                        {
                            FastForwardStrategy = FastForwardStrategy.FastForwardOnly,
                            FailOnConflict = true,
                        });
                }
                catch (NonFastForwardException ex)
                {
                    logger.LogTrace(ex, "{committish} is not a parent of {startSha}", committish, startSha);
                    return false;
                }
 
                if (mergeResult.Status == MergeStatus.UpToDate)
                    return true;
 
                logger.LogTrace("{committish} is not a parent of {startSha} ({mergeStatus}). Moving back...", committish, startSha, mergeResult.Status);
                commands.Checkout(
                    libGitRepo,
                    new CheckoutOptions
                    {
                        CheckoutModifiers = CheckoutModifiers.Force,
                    },
                    startSha);
 
                return false;
            },
            cancellationToken,
            DefaultIOManager.BlockingTaskCreationOptions,
            TaskScheduler.Current);
 
        public ValueTask<Models.TestMerge> GetTestMerge(
            TestMergeParameters parameters,
            RepositorySettings repositorySettings,
            CancellationToken cancellationToken) => gitRemoteFeatures.GetTestMerge(
                parameters,
                repositorySettings,
                cancellationToken);
 
        public Task<DateTimeOffset> TimestampCommit(string sha, CancellationToken cancellationToken) => Task.Factory.StartNew(
            () =>
            {
                ArgumentNullException.ThrowIfNull(sha);
 
                var commit = libGitRepo.Lookup<Commit>(sha) ?? throw new JobException($"Commit {sha} does not exist in the repository!");
                return commit.Committer.When.ToUniversalTime();
            },
            cancellationToken,
            DefaultIOManager.BlockingTaskCreationOptions,
            TaskScheduler.Current);
 
        protected override void DisposeImpl()
        {
            logger.LogTrace("Disposing...");
            libGitRepo.Dispose();
            base.DisposeImpl();
        }
 
        void RawCheckout(string committish, bool moveCurrentReference, JobProgressReporter progressReporter, CancellationToken cancellationToken)
        {
            logger.LogTrace("Checkout: {committish}", committish);
 
            var checkoutOptions = new CheckoutOptions
            {
                CheckoutModifiers = CheckoutModifiers.Force,
            };
 
            var stage = $"Checkout {committish}";
            using var newProgressReporter = progressReporter.CreateSection(stage, 1.0);
            newProgressReporter.ReportProgress(0);
            checkoutOptions.OnCheckoutProgress = CheckoutProgressHandler(newProgressReporter);
 
            cancellationToken.ThrowIfCancellationRequested();
 
            if (moveCurrentReference)
            {
                if (Reference == NoReference)
                    throw new InvalidOperationException("Cannot move current reference when not on reference!");
 
                var gitObject = libGitRepo.Lookup(committish);
                if (gitObject == null)
                    throw new JobException($"Could not find committish: {committish}");
 
                var commit = gitObject.Peel<Commit>();
 
                cancellationToken.ThrowIfCancellationRequested();
 
                libGitRepo.Reset(ResetMode.Hard, commit, checkoutOptions);
            }
            else
            {
                void RunCheckout() => commands.Checkout(
                    libGitRepo,
                    checkoutOptions,
                    committish);
 
                try
                {
                    RunCheckout();
                }
                catch (NotFoundException)
                {
                    // Maybe (likely) a remote?
                    var remoteName = $"origin/{committish}";
                    var remoteBranch = libGitRepo.Branches.FirstOrDefault(
                        branch => branch.FriendlyName.Equals(remoteName, StringComparison.Ordinal));
                    cancellationToken.ThrowIfCancellationRequested();
 
                    if (remoteBranch == default)
                        throw;
 
                    logger.LogDebug("Creating local branch for {remoteBranchFriendlyName}...", remoteBranch.FriendlyName);
                    var branch = libGitRepo.CreateBranch(committish, remoteBranch.Tip);
 
                    libGitRepo.Branches.Update(branch, branchUpdate => branchUpdate.TrackedBranch = remoteBranch.CanonicalName);
 
                    cancellationToken.ThrowIfCancellationRequested();
 
                    RunCheckout();
                }
            }
 
            cancellationToken.ThrowIfCancellationRequested();
 
            libGitRepo.RemoveUntrackedFiles();
        }
 
        Task PushHeadToTemporaryBranch(string username, string password, JobProgressReporter progressReporter, CancellationToken cancellationToken) => Task.Factory.StartNew(
            () =>
            {
                logger.LogInformation("Pushing changes to temporary remote branch...");
                var branch = libGitRepo.CreateBranch(RemoteTemporaryBranchName);
                try
                {
                    cancellationToken.ThrowIfCancellationRequested();
                    var remote = libGitRepo.Network.Remotes.First();
                    try
                    {
                        var forcePushString = String.Format(CultureInfo.InvariantCulture, "+{0}:{0}", branch.CanonicalName);
 
                        using (var mainPushReporter = progressReporter.CreateSection(null, 0.9))
                        {
                            var (pushOptions, progressReporters) = GeneratePushOptions(
                                mainPushReporter,
                                username,
                                password,
                                cancellationToken);
 
                            try
                            {
                                libGitRepo.Network.Push(remote, forcePushString, pushOptions);
                            }
                            finally
                            {
                                foreach (var progressReporter in progressReporters)
                                    progressReporter.Dispose();
                            }
                        }
 
                        var removalString = String.Format(CultureInfo.InvariantCulture, ":{0}", branch.CanonicalName);
                        using var forcePushReporter = progressReporter.CreateSection(null, 0.1);
                        var (forcePushOptions, forcePushReporters) = GeneratePushOptions(forcePushReporter, username, password, cancellationToken);
                        try
                        {
                            libGitRepo.Network.Push(remote, removalString, forcePushOptions);
                        }
                        finally
                        {
                            foreach (var subForcePushReporter in forcePushReporters)
                                forcePushReporter.Dispose();
                        }
                    }
                    catch (UserCancelledException)
                    {
                        cancellationToken.ThrowIfCancellationRequested();
                    }
                    catch (LibGit2SharpException e)
                    {
                        logger.LogWarning(e, "Unable to push to temporary branch!");
                    }
                }
                finally
                {
                    libGitRepo.Branches.Remove(branch);
                }
            },
            cancellationToken,
            DefaultIOManager.BlockingTaskCreationOptions,
            TaskScheduler.Current);
 
        (PushOptions PushOptions, IEnumerable<JobProgressReporter> SubProgressReporters) GeneratePushOptions(JobProgressReporter progressReporter, string username, string password, CancellationToken cancellationToken)
        {
            var packFileCountingReporter = progressReporter.CreateSection(null, 0.25);
            var packFileDeltafyingReporter = progressReporter.CreateSection(null, 0.25);
            var transferProgressReporter = progressReporter.CreateSection(null, 0.5);
 
            return (
                PushOptions: new PushOptions
                {
                    OnPackBuilderProgress = (stage, current, total) =>
                    {
                        if (total < current)
                            total = current;
 
                        var percentage = ((double)current) / total;
                        (stage == PackBuilderStage.Counting ? packFileCountingReporter : packFileDeltafyingReporter).ReportProgress(percentage);
                        return !cancellationToken.IsCancellationRequested;
                    },
                    OnNegotiationCompletedBeforePush = (a) => !cancellationToken.IsCancellationRequested,
                    OnPushTransferProgress = (a, sentBytes, totalBytes) =>
                    {
                        packFileCountingReporter.ReportProgress((double)sentBytes / totalBytes);
                        return !cancellationToken.IsCancellationRequested;
                    },
                    CredentialsProvider = credentialsProvider.GenerateCredentialsHandler(username, password),
                },
                SubProgressReporters: new List<JobProgressReporter>
                {
                    packFileCountingReporter,
                    packFileDeltafyingReporter,
                    transferProgressReporter,
                });
        }
 
        string GetRepositoryPath()
            => ioManager.GetDirectoryName(libGitRepo
                .Info
                .Path
                .TrimEnd(ioManager.DirectorySeparatorChar)
                .TrimEnd(ioManager.AltDirectorySeparatorChar));
 
        ValueTask UpdateSubmodules(
            JobProgressReporter progressReporter,
            string? username,
            string? password,
            bool deploymentPipeline,
            CancellationToken cancellationToken)
        {
            logger.LogTrace("Updating submodules {withOrWithout} credentials...", username == null ? "without" : "with");
 
            async ValueTask RecursiveUpdateSubmodules(LibGit2Sharp.IRepository parentRepository, JobProgressReporter currentProgressReporter, string parentGitDirectory)
            {
                var submoduleCount = libGitRepo.Submodules.Count();
                if (submoduleCount == 0)
                {
                    logger.LogTrace("No submodules, skipping update");
                    return;
                }
 
                var factor = 1.0 / submoduleCount / 3;
                foreach (var submodule in parentRepository.Submodules)
                {
                    logger.LogTrace("Entering submodule {name} ({path}) for recursive updates...", submodule.Name, submodule.Path);
                    var submoduleUpdateOptions = new SubmoduleUpdateOptions
                    {
                        Init = true,
                        OnCheckoutNotify = (_, _) => !cancellationToken.IsCancellationRequested,
                    };
 
                    using var fetchReporter = currentProgressReporter.CreateSection($"Fetch submodule {submodule.Name}", factor);
 
                    submoduleUpdateOptions.FetchOptions.Hydrate(
                        logger,
                        fetchReporter,
                        credentialsProvider.GenerateCredentialsHandler(username, password),
                        cancellationToken);
 
                    using var checkoutReporter = currentProgressReporter.CreateSection($"Checkout submodule {submodule.Name}", factor);
                    submoduleUpdateOptions.OnCheckoutProgress = CheckoutProgressHandler(checkoutReporter);
 
                    logger.LogDebug("Updating submodule {submoduleName}...", submodule.Name);
                    Task RawSubModuleUpdate() => Task.Factory.StartNew(
                        () => parentRepository.Submodules.Update(submodule.Name, submoduleUpdateOptions),
                        cancellationToken,
                        DefaultIOManager.BlockingTaskCreationOptions,
                        TaskScheduler.Current);
 
                    try
                    {
                        await RawSubModuleUpdate();
                    }
                    catch (LibGit2SharpException ex) when (parentRepository == libGitRepo)
                    {
                        // workaround for https://github.com/libgit2/libgit2/issues/3820
                        // kill off the modules/ folder in .git and try again
                        currentProgressReporter.ReportProgress(0);
                        credentialsProvider.CheckBadCredentialsException(ex);
                        logger.LogWarning(ex, "Initial update of submodule {submoduleName} failed. Deleting submodule directories and re-attempting...", submodule.Name);
 
                        await Task.WhenAll(
                            ioManager.DeleteDirectory($".git/modules/{submodule.Path}", cancellationToken),
                            ioManager.DeleteDirectory(submodule.Path, cancellationToken));
 
                        logger.LogTrace("Second update attempt for submodule {submoduleName}...", submodule.Name);
                        try
                        {
                            await RawSubModuleUpdate();
                        }
                        catch (UserCancelledException)
                        {
                            cancellationToken.ThrowIfCancellationRequested();
                        }
                        catch (LibGit2SharpException ex2)
                        {
                            credentialsProvider.CheckBadCredentialsException(ex2);
                            logger.LogTrace(ex2, "Retried update of submodule {submoduleName} failed!", submodule.Name);
                            throw new AggregateException(ex, ex2);
                        }
                    }
 
                    await eventConsumer.HandleEvent(
                        EventType.RepoSubmoduleUpdate,
                        new List<string> { submodule.Name },
                        deploymentPipeline,
                        cancellationToken);
 
                    var submodulePath = ioManager.ResolvePath(
                        ioManager.ConcatPath(
                            parentGitDirectory,
                            submodule.Path));
 
                    using var submoduleRepo = await submoduleFactory.CreateFromPath(
                        submodulePath,
                        cancellationToken);
 
                    using var submoduleReporter = currentProgressReporter.CreateSection($"Entering submodule \"{submodule.Name}\"...", factor);
                    await RecursiveUpdateSubmodules(
                        submoduleRepo,
                        submoduleReporter,
                        submodulePath);
                }
            }
 
            return RecursiveUpdateSubmodules(libGitRepo, progressReporter, GetRepositoryPath());
        }
 
        CheckoutProgressHandler CheckoutProgressHandler(JobProgressReporter progressReporter) => (a, completedSteps, totalSteps) =>
        {
            double? percentage;
 
            // short circuit initialization where totalSteps is 0
            if (completedSteps == 0)
                percentage = 0;
            else if (totalSteps < completedSteps || totalSteps == 0)
                percentage = null;
            else
            {
                percentage = ((double)completedSteps) / totalSteps;
                if (percentage < 0)
                    percentage = null;
            }
 
            if (percentage == null)
                logger.LogDebug(
                    "Bad checkout progress values (Please tell Dominion)! Completeds: {completed}, Total: {total}",
                    completedSteps,
                    totalSteps);
 
            progressReporter.ReportProgress(percentage);
        };
    }
#pragma warning restore CA1506
}