using System.Collections.Concurrent;
using MarketAlly.LibGit2Sharp;
using MarketAlly.GitCommitEditor.Models;
using MarketAlly.GitCommitEditor.Resources;

namespace MarketAlly.GitCommitEditor.Services;

public sealed class GitOperationsService : IGitOperationsService
{
    private readonly ConcurrentDictionary<string, CachedRepository> _repoCache = new();
    private readonly Timer _cleanupTimer;
    private readonly int _maxCacheSize;
    private readonly TimeSpan _cacheTtl;
    private bool _disposed;

    private sealed class CachedRepository(Repository repository)
    {
        public Repository Repository { get; } = repository;
        public DateTime LastAccessed { get; set; } = DateTime.UtcNow;
    }

    public GitOperationsService(int maxCacheSize = 20, TimeSpan? cacheTtl = null)
    {
        _maxCacheSize = maxCacheSize;
        _cacheTtl = cacheTtl ?? TimeSpan.FromMinutes(30);
        _cleanupTimer = new Timer(CleanupExpiredRepositories, null, TimeSpan.FromMinutes(5), TimeSpan.FromMinutes(5));
    }

    private void CleanupExpiredRepositories(object? state)
    {
        var expiredKeys = _repoCache
            .Where(kvp => DateTime.UtcNow - kvp.Value.LastAccessed > _cacheTtl)
            .Select(kvp => kvp.Key)
            .ToList();

        foreach (var key in expiredKeys)
        {
            if (_repoCache.TryRemove(key, out var cached))
            {
                cached.Repository.Dispose();
            }
        }
    }

    /// <summary>
    /// Normalizes a path for consistent cache key comparison.
    /// On Windows, paths are case-insensitive, so we normalize to lowercase.
    /// </summary>
    private static string NormalizePath(string path)
    {
        // Get full path to resolve any relative paths or ../ segments
        var fullPath = Path.GetFullPath(path);

        // On Windows, normalize to lowercase for case-insensitive comparison
        if (OperatingSystem.IsWindows())
        {
            return fullPath.ToLowerInvariant();
        }

        return fullPath;
    }

    private Repository GetRepository(string path)
    {
        var normalizedPath = NormalizePath(path);

        // Evict oldest if at capacity
        while (_repoCache.Count >= _maxCacheSize)
        {
            var oldest = _repoCache
                .OrderBy(kvp => kvp.Value.LastAccessed)
                .FirstOrDefault();

            if (oldest.Key != null && _repoCache.TryRemove(oldest.Key, out var removed))
            {
                removed.Repository.Dispose();
            }
        }

        // Use normalized path for cache key, but original path for Repository constructor
        var cached = _repoCache.GetOrAdd(normalizedPath, _ => new CachedRepository(new Repository(path)));
        cached.LastAccessed = DateTime.UtcNow;
        return cached.Repository;
    }

    /// <summary>
    /// Invalidates the cached Repository for the given path, forcing a fresh instance on next access.
    /// Call this after operations that modify git history (rewrite, rebase, etc.)
    /// </summary>
    public void InvalidateCache(string path)
    {
        var normalizedPath = NormalizePath(path);
        if (_repoCache.TryRemove(normalizedPath, out var cached))
        {
            cached.Repository.Dispose();
        }
    }

    public IEnumerable<string> DiscoverRepositories(string rootPath, int maxDepth = 3)
    {
        ArgumentNullException.ThrowIfNull(rootPath);

        if (!Directory.Exists(rootPath))
            yield break;

        var queue = new Queue<(string Path, int Depth)>();
        queue.Enqueue((rootPath, 0));

        while (queue.Count > 0)
        {
            var (currentPath, depth) = queue.Dequeue();

            var gitDir = Path.Combine(currentPath, ".git");
            if (Directory.Exists(gitDir) || File.Exists(gitDir))
            {
                yield return currentPath;
                continue;
            }

            if (depth >= maxDepth)
                continue;

            try
            {
                foreach (var subDir in Directory.GetDirectories(currentPath))
                {
                    var name = Path.GetFileName(subDir);
                    if (name.StartsWith('.') ||
                        name is "node_modules" or "bin" or "obj" or "packages" or ".git")
                        continue;

                    queue.Enqueue((subDir, depth + 1));
                }
            }
            catch (UnauthorizedAccessException)
            {
                // Skip directories we can't access
            }
            catch (DirectoryNotFoundException)
            {
                // Skip directories that were deleted during enumeration
            }
        }
    }

    public ManagedRepo CreateManagedRepo(string repoPath)
    {
        ArgumentNullException.ThrowIfNull(repoPath);

        using var repo = new Repository(repoPath);

        var remoteUrl = repo.Network.Remotes.FirstOrDefault()?.Url;
        var currentBranch = repo.Head.FriendlyName;
        var name = Path.GetFileName(repoPath);

        return new ManagedRepo
        {
            Name = name,
            Path = repoPath,
            RemoteUrl = remoteUrl,
            CurrentBranch = currentBranch
        };
    }

    public IEnumerable<BranchInfo> GetBranches(string repoPath)
    {
        ArgumentNullException.ThrowIfNull(repoPath);

        var repo = GetRepository(repoPath);

        foreach (var branch in repo.Branches)
        {
            yield return new BranchInfo
            {
                Name = branch.FriendlyName,
                FullName = branch.CanonicalName,
                IsRemote = branch.IsRemote,
                IsCurrentHead = branch.IsCurrentRepositoryHead,
                LastCommitSha = branch.Tip?.Sha,
                LastCommitDate = branch.Tip?.Author.When,
                RemoteName = branch.IsRemote ? branch.RemoteName : null
            };
        }
    }

    public IEnumerable<CommitAnalysis> AnalyzeCommits(
        ManagedRepo managedRepo,
        ICommitMessageAnalyzer analyzer,
        int maxCommits = 100,
        DateTimeOffset? since = null,
        string[]? excludeAuthors = null)
    {
        ArgumentNullException.ThrowIfNull(managedRepo);
        ArgumentNullException.ThrowIfNull(analyzer);

        // Always invalidate cache before analyzing to ensure we see the latest commits
        // This is critical after rewrite operations that change commit history
        InvalidateCache(managedRepo.Path);

        var repo = GetRepository(managedRepo.Path);
        var headTip = repo.Head.Tip;
        var headSha = headTip?.Sha;

        if (headTip == null)
            yield break;

        // Explicitly walk from HEAD to avoid picking up unreachable commits
        // After a rewrite, old commits still exist in the object database but are unreachable from HEAD
        var commitFilter = new CommitFilter
        {
            IncludeReachableFrom = headTip,
            SortBy = CommitSortStrategies.Topological | CommitSortStrategies.Time
        };

        var commits = since.HasValue
            ? repo.Commits.QueryBy(commitFilter).Where(c => c.Author.When >= since.Value).Take(maxCommits)
            : repo.Commits.QueryBy(commitFilter).Take(maxCommits);

        foreach (var commit in commits)
        {
            if (excludeAuthors?.Contains(commit.Author.Email, StringComparer.OrdinalIgnoreCase) == true)
                continue;

            var parent = commit.Parents.FirstOrDefault();
            var changes = repo.Diff.Compare<TreeChanges>(parent?.Tree, commit.Tree);
            var patch = repo.Diff.Compare<Patch>(parent?.Tree, commit.Tree);

            var context = new CommitContext
            {
                FilesChanged = changes.Count(),
                LinesAdded = patch.LinesAdded,
                LinesDeleted = patch.LinesDeleted,
                FileNames = changes.Select(c => c.Path).ToList()
            };

            var quality = analyzer.Analyze(commit.Message, context);

            // Build per-file diffs dictionary
            var fileDiffs = new Dictionary<string, string>();
            foreach (var patchEntry in patch)
            {
                fileDiffs[patchEntry.Path] = TruncateDiff(patchEntry.Patch, 100);
            }

            yield return new CommitAnalysis
            {
                RepoId = managedRepo.Id,
                RepoName = managedRepo.Name,
                RepoPath = managedRepo.Path,
                CommitHash = commit.Sha,
                OriginalMessage = commit.Message.Trim(),
                CommitDate = commit.Author.When,
                Author = commit.Author.Name,
                AuthorEmail = commit.Author.Email,
                Quality = quality,
                FilesChanged = changes.Select(c => c.Path).ToList(),
                DiffSummary = TruncateDiff(patch.Content, 200),
                FileDiffs = fileDiffs,
                LinesAdded = patch.LinesAdded,
                LinesDeleted = patch.LinesDeleted,
                IsLatestCommit = commit.Sha == headSha
            };
        }
    }

    public RewriteOperation AmendLatestCommit(ManagedRepo managedRepo, string newMessage)
    {
        ArgumentNullException.ThrowIfNull(managedRepo);
        ArgumentNullException.ThrowIfNull(newMessage);

        var repo = GetRepository(managedRepo.Path);
        var head = repo.Head.Tip ?? throw new InvalidOperationException(Str.Git_NoCommits);

        var operation = new RewriteOperation
        {
            RepoId = managedRepo.Id,
            RepoPath = managedRepo.Path,
            CommitHash = head.Sha,
            OriginalMessage = head.Message,
            NewMessage = newMessage,
            IsLatestCommit = true
        };

        try
        {
            var amended = repo.Commit(
                newMessage,
                head.Author,
                head.Committer,
                new CommitOptions { AmendPreviousCommit = true });

            operation.NewCommitHash = amended.Sha;
            operation.Status = OperationStatus.Applied;
            operation.AppliedAt = DateTimeOffset.UtcNow;
        }
        catch (LibGit2SharpException ex)
        {
            operation.Status = OperationStatus.Failed;
            operation.ErrorMessage = Str.Git_Error(ex.Message);
        }
        catch (Exception ex)
        {
            operation.Status = OperationStatus.Failed;
            operation.ErrorMessage = ex.Message;
        }

        return operation;
    }

    public RewriteOperation RewordOlderCommit(ManagedRepo managedRepo, string commitHash, string newMessage)
    {
        ArgumentNullException.ThrowIfNull(managedRepo);
        ArgumentNullException.ThrowIfNull(commitHash);
        ArgumentNullException.ThrowIfNull(newMessage);

        var repo = GetRepository(managedRepo.Path);

        var targetCommit = repo.Lookup<Commit>(commitHash)
            ?? throw new ArgumentException(Str.Git_CommitNotFound(commitHash), nameof(commitHash));

        var operation = new RewriteOperation
        {
            RepoId = managedRepo.Id,
            RepoPath = managedRepo.Path,
            CommitHash = commitHash,
            OriginalMessage = targetCommit.Message,
            NewMessage = newMessage,
            IsLatestCommit = repo.Head.Tip?.Sha == commitHash
        };

        if (operation.IsLatestCommit)
        {
            return AmendLatestCommit(managedRepo, newMessage);
        }

        try
        {
            var commitsToRewrite = repo.Commits
                .QueryBy(new CommitFilter
                {
                    IncludeReachableFrom = repo.Head.Tip,
                    ExcludeReachableFrom = targetCommit.Parents
                })
                .Reverse()
                .ToList();

            if (!commitsToRewrite.Any(c => c.Sha == targetCommit.Sha))
                throw new InvalidOperationException(Str.Git_NotAncestor);

            var rewriteMap = new Dictionary<string, Commit>();
            Commit? newHead = null;

            foreach (var oldCommit in commitsToRewrite)
            {
                var message = oldCommit.Sha == targetCommit.Sha
                    ? newMessage
                    : oldCommit.Message;

                var newParents = oldCommit.Parents
                    .Select(p => rewriteMap.TryGetValue(p.Sha, out var mapped) ? mapped : p)
                    .ToList();

                var newCommit = repo.ObjectDatabase.CreateCommit(
                    oldCommit.Author,
                    oldCommit.Committer,
                    message,
                    oldCommit.Tree,
                    newParents,
                    prettifyMessage: false);

                rewriteMap[oldCommit.Sha] = newCommit;
                newHead = newCommit;
            }

            if (newHead != null)
            {
                repo.Refs.UpdateTarget(repo.Head.CanonicalName, newHead.Id.Sha);
            }

            operation.NewCommitHash = rewriteMap.TryGetValue(commitHash, out var rewritten)
                ? rewritten.Sha
                : null;
            operation.Status = OperationStatus.Applied;
            operation.AppliedAt = DateTimeOffset.UtcNow;
        }
        catch (LibGit2SharpException ex)
        {
            operation.Status = OperationStatus.Failed;
            operation.ErrorMessage = Str.Git_Error(ex.Message);
        }
        catch (Exception ex)
        {
            operation.Status = OperationStatus.Failed;
            operation.ErrorMessage = ex.Message;
        }

        return operation;
    }

    public List<RewriteOperation> RewordMultipleCommits(ManagedRepo managedRepo, Dictionary<string, string> rewrites)
    {
        ArgumentNullException.ThrowIfNull(managedRepo);
        ArgumentNullException.ThrowIfNull(rewrites);

        var operations = new List<RewriteOperation>();

        if (rewrites.Count == 0)
            return operations;

        // Disable libgit2's internal object cache to prevent stale objects during rewrite
        GlobalSettings.SetEnableCaching(false);

        // Use a fresh Repository (not cached) to ensure changes are flushed to disk
        // The cached repo might have stale state or not flush properly
        InvalidateCache(managedRepo.Path);
        var repo = new Repository(managedRepo.Path);

        // Validate all commits exist and build operation list
        // Cache OriginalMessage now because commit objects become stale after cache invalidation
        var commitInfos = new List<(string OriginalHash, string OriginalMessage, string NewMessage)>();
        foreach (var (hash, newMessage) in rewrites)
        {
            var commit = repo.Lookup<Commit>(hash);
            if (commit == null)
            {
                operations.Add(new RewriteOperation
                {
                    RepoId = managedRepo.Id,
                    RepoPath = managedRepo.Path,
                    CommitHash = hash,
                    OriginalMessage = "",
                    NewMessage = newMessage,
                    Status = OperationStatus.Failed,
                    ErrorMessage = Str.Git_CommitNotFound(hash)
                });
                continue;
            }
            commitInfos.Add((hash, commit.Message, newMessage));
        }

        if (commitInfos.Count == 0)
            return operations;

        try
        {
            // Find the oldest commit in git ancestry by walking from HEAD
            // The commit that appears LAST when walking from HEAD is the oldest ancestor
            var commitHashes = new HashSet<string>(commitInfos.Select(c => c.OriginalHash));

            Commit? oldestCommit = null;
            foreach (var commit in repo.Commits.QueryBy(new CommitFilter { IncludeReachableFrom = repo.Head.Tip }))
            {
                if (commitHashes.Contains(commit.Sha))
                {
                    oldestCommit = commit; // Keep updating - last one found is oldest
                }
            }

            // Fallback: if none found in walk (shouldn't happen), look up first commit
            if (oldestCommit == null && commitInfos.Count > 0)
            {
                oldestCommit = repo.Lookup<Commit>(commitInfos[0].OriginalHash);
            }

            if (oldestCommit == null)
            {
                throw new InvalidOperationException(Str.Git_NoTargetCommits);
            }

            // Get all commits from oldest's parents to HEAD
            // CRITICAL: Use Topological+Reverse to ensure parents come before children
            // This is essential for rewriting - we must process parents first so their
            // new hashes are in rewriteMap when we process their children
            // Topological alone = children before parents (git default for log)
            // Topological | Reverse = parents before children (what we need for rewriting)
            var commitsToRewrite = repo.Commits
                .QueryBy(new CommitFilter
                {
                    IncludeReachableFrom = repo.Head.Tip,
                    ExcludeReachableFrom = oldestCommit.Parents,
                    SortBy = CommitSortStrategies.Topological | CommitSortStrategies.Reverse
                })
                .ToList();

            // Build a lookup of commits to rewrite
            var rewriteLookup = commitInfos.ToDictionary(c => c.OriginalHash, c => c);

            // Rewrite all commits in a single pass
            var rewriteMap = new Dictionary<string, Commit>();
            Commit? newHead = null;

            foreach (var oldCommit in commitsToRewrite)
            {
                // Use new message if this commit is being rewritten, otherwise keep original
                var message = rewriteLookup.TryGetValue(oldCommit.Sha, out var info)
                    ? info.NewMessage
                    : oldCommit.Message;

                // Map parents to their rewritten versions
                var newParents = oldCommit.Parents
                    .Select(p => rewriteMap.TryGetValue(p.Sha, out var mapped) ? mapped : p)
                    .ToList();

                var newCommit = repo.ObjectDatabase.CreateCommit(
                    oldCommit.Author,
                    oldCommit.Committer,
                    message,
                    oldCommit.Tree,
                    newParents,
                    prettifyMessage: false);

                // Verify the created commit has the correct parents
                var createdParents = newCommit.Parents.Select(p => p.Sha).ToList();
                var expectedParents = newParents.Select(p => p.Sha).ToList();
                if (!createdParents.SequenceEqual(expectedParents))
                {
                    throw new InvalidOperationException(Str.Git_ParentMismatch(oldCommit.Sha[..7]));
                }

                rewriteMap[oldCommit.Sha] = newCommit;
                newHead = newCommit;
            }

            // Update HEAD to new commit chain using hard reset
            // This is more robust than just updating refs because it also syncs index and working tree
            if (newHead != null)
            {
                // Hard reset updates HEAD, index, AND working tree atomically
                repo.Reset(ResetMode.Hard, newHead);

                // Verify the HEAD was actually updated
                var verifyHead = repo.Head.Tip;
                if (verifyHead?.Sha != newHead.Sha)
                {
                    throw new InvalidOperationException(Str.Git_HeadUpdateFailed(newHead.Sha[..7]));
                }
            }

            // Store the expected new HEAD SHA before disposing (null if no commits rewritten)
            var expectedHeadSha = newHead?.Sha;

            // Explicitly dispose repository to flush changes to disk
            repo.Dispose();
            repo = null!;

            // Invalidate cache to ensure fresh state
            InvalidateCache(managedRepo.Path);

            // Verify the changes persisted to disk and no old commits are reachable
            if (expectedHeadSha != null)
            {
                using (var verifyRepo = new Repository(managedRepo.Path))
                {
                    var diskHead = verifyRepo.Head.Tip;
                    if (diskHead?.Sha != expectedHeadSha)
                    {
                        throw new InvalidOperationException(Str.Git_VerificationFailed(expectedHeadSha[..7], diskHead?.Sha?[..7] ?? "null"));
                    }

                    // Walk the new chain and verify no original hashes appear
                    var originalHashes = new HashSet<string>(commitsToRewrite.Select(c => c.Sha));
                    var walkCount = 0;
                    var maxWalk = commitsToRewrite.Count + 10;
                    foreach (var c in verifyRepo.Commits.QueryBy(new CommitFilter { IncludeReachableFrom = diskHead }))
                    {
                        if (walkCount++ > maxWalk) break;

                        if (originalHashes.Contains(c.Sha))
                        {
                            throw new InvalidOperationException(Str.Git_OldCommitReachable(c.Sha[..7]));
                        }
                    }
                }
            }

            // Build successful operation results
            foreach (var (originalHash, originalMessage, newMessage) in commitInfos)
            {
                var newHash = rewriteMap.TryGetValue(originalHash, out var rewritten)
                    ? rewritten.Sha
                    : null;

                operations.Add(new RewriteOperation
                {
                    RepoId = managedRepo.Id,
                    RepoPath = managedRepo.Path,
                    CommitHash = originalHash,
                    OriginalMessage = originalMessage,
                    NewMessage = newMessage,
                    NewCommitHash = newHash,
                    Status = OperationStatus.Applied,
                    AppliedAt = DateTimeOffset.UtcNow
                });
            }

            // Re-enable libgit2 caching after successful rewrite
            GlobalSettings.SetEnableCaching(true);
        }
        catch (LibGit2SharpException ex)
        {
            // Ensure repo is disposed even on error
            repo?.Dispose();
            InvalidateCache(managedRepo.Path);

            // Re-enable libgit2 caching on error
            GlobalSettings.SetEnableCaching(true);

            // Mark all remaining as failed
            foreach (var (originalHash, originalMessage, newMessage) in commitInfos)
            {
                if (!operations.Any(o => o.CommitHash == originalHash))
                {
                    operations.Add(new RewriteOperation
                    {
                        RepoId = managedRepo.Id,
                        RepoPath = managedRepo.Path,
                        CommitHash = originalHash,
                        OriginalMessage = originalMessage,
                        NewMessage = newMessage,
                        Status = OperationStatus.Failed,
                        ErrorMessage = Str.Git_Error(ex.Message)
                    });
                }
            }
        }
        catch (Exception ex)
        {
            // Ensure repo is disposed even on error
            repo?.Dispose();
            InvalidateCache(managedRepo.Path);

            // Re-enable libgit2 caching on error
            GlobalSettings.SetEnableCaching(true);

            foreach (var (originalHash, originalMessage, newMessage) in commitInfos)
            {
                if (!operations.Any(o => o.CommitHash == originalHash))
                {
                    operations.Add(new RewriteOperation
                    {
                        RepoId = managedRepo.Id,
                        RepoPath = managedRepo.Path,
                        CommitHash = originalHash,
                        OriginalMessage = originalMessage,
                        NewMessage = newMessage,
                        Status = OperationStatus.Failed,
                        ErrorMessage = ex.Message
                    });
                }
            }
        }

        return operations;
    }

    public bool IsCommitPushed(string repoPath, string commitHash)
    {
        ArgumentNullException.ThrowIfNull(repoPath);
        ArgumentNullException.ThrowIfNull(commitHash);

        try
        {
            var repo = GetRepository(repoPath);
            var commit = repo.Lookup<Commit>(commitHash);
            if (commit == null) return false;

            var head = repo.Head;
            if (!head.IsTracking || head.TrackedBranch?.Tip == null)
                return false;

            var remoteTip = head.TrackedBranch.Tip;
            var filter = new CommitFilter { IncludeReachableFrom = remoteTip };

            return repo.Commits.QueryBy(filter).Any(c => c.Sha == commitHash);
        }
        catch (LibGit2SharpException)
        {
            return false;
        }
    }

    public TrackingInfo GetTrackingInfo(string repoPath)
    {
        ArgumentNullException.ThrowIfNull(repoPath);

        try
        {
            var repo = GetRepository(repoPath);
            var head = repo.Head;

            if (!head.IsTracking)
                return TrackingInfo.None;

            var tracking = head.TrackingDetails;
            return new TrackingInfo(
                head.TrackedBranch?.FriendlyName,
                tracking.AheadBy,
                tracking.BehindBy);
        }
        catch (LibGit2SharpException)
        {
            return TrackingInfo.None;
        }
    }

    public GitPushResult ForcePush(string repoPath, PushOptions? options = null)
    {
        ArgumentNullException.ThrowIfNull(repoPath);

        try
        {
            var repo = GetRepository(repoPath);
            var head = repo.Head;
            var branchName = head.FriendlyName;

            Remote remote;
            string forceRefSpec;

            if (head.IsTracking)
            {
                // Branch has upstream - force push to tracked remote
                remote = repo.Network.Remotes[head.RemoteName];
                if (remote == null)
                    return GitPushResult.Fail(Str.Git_RemoteNotFound(head.RemoteName));

                forceRefSpec = $"+{head.CanonicalName}:{head.UpstreamBranchCanonicalName}";
            }
            else
            {
                // No upstream - try to push to origin
                remote = repo.Network.Remotes["origin"];
                if (remote == null)
                    return GitPushResult.Fail(Str.Git_NoUpstreamNoOrigin(branchName));

                // Force push to origin with the same branch name
                forceRefSpec = $"+{head.CanonicalName}:refs/heads/{branchName}";
            }

            // Use provided options or create default with credentials handler
            var pushOptions = options ?? CreateDefaultPushOptions();

            repo.Network.Push(remote, forceRefSpec, pushOptions);

            return GitPushResult.Ok(head.IsTracking
                ? Str.Git_ForcePushSuccess
                : Str.Git_ForcePushedTo(branchName));
        }
        catch (LibGit2SharpException ex)
        {
            // Provide more helpful error message for auth failures
            if (ex.Message.Contains("authentication") || ex.Message.Contains("credential"))
            {
                // Try using system git as fallback
                return ForcePushViaGitCommand(repoPath);
            }
            return GitPushResult.Fail(Str.Git_Error(ex.Message));
        }
        catch (Exception ex)
        {
            return GitPushResult.Fail(ex.Message);
        }
    }

    private static GitPushResult ForcePushViaGitCommand(string repoPath)
    {
        try
        {
            var startInfo = new System.Diagnostics.ProcessStartInfo
            {
                FileName = "git",
                Arguments = "push --force-with-lease",
                WorkingDirectory = repoPath,
                UseShellExecute = false,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                CreateNoWindow = true
            };

            using var process = System.Diagnostics.Process.Start(startInfo);
            if (process == null)
                return GitPushResult.Fail(Str.Git_ProcessFailed);

            var output = process.StandardOutput.ReadToEnd();
            var error = process.StandardError.ReadToEnd();
            process.WaitForExit(30000); // 30 second timeout

            if (process.ExitCode == 0)
            {
                return GitPushResult.Ok(Str.Git_ForcePushSuccessCmd);
            }
            else
            {
                // Git often outputs progress to stderr even on success
                var message = !string.IsNullOrEmpty(error) ? error : output;
                return GitPushResult.Fail(Str.Git_PushFailed(message.Trim()));
            }
        }
        catch (Exception ex)
        {
            return GitPushResult.Fail(Str.Git_CommandFailed(ex.Message));
        }
    }

    private static PushOptions CreateDefaultPushOptions()
    {
        return new PushOptions
        {
            CredentialsProvider = (url, usernameFromUrl, types) =>
            {
                // Try to use default credentials (works with Git Credential Manager on Windows)
                return new DefaultCredentials();
            }
        };
    }

    public GitPushResult Push(string repoPath, PushOptions? options = null)
    {
        ArgumentNullException.ThrowIfNull(repoPath);

        try
        {
            var repo = GetRepository(repoPath);
            var head = repo.Head;

            if (!head.IsTracking)
                return GitPushResult.Fail(Str.Git_NoUpstream);

            var pushOptions = options ?? CreateDefaultPushOptions();
            repo.Network.Push(head, pushOptions);
            return GitPushResult.Ok();
        }
        catch (NonFastForwardException)
        {
            return GitPushResult.Fail(Str.Git_NonFastForward);
        }
        catch (LibGit2SharpException ex)
        {
            if (ex.Message.Contains("authentication") || ex.Message.Contains("credential"))
            {
                // Try using system git as fallback
                return PushViaGitCommand(repoPath);
            }
            return GitPushResult.Fail(Str.Git_Error(ex.Message));
        }
        catch (Exception ex)
        {
            return GitPushResult.Fail(ex.Message);
        }
    }

    private static GitPushResult PushViaGitCommand(string repoPath)
    {
        try
        {
            var startInfo = new System.Diagnostics.ProcessStartInfo
            {
                FileName = "git",
                Arguments = "push",
                WorkingDirectory = repoPath,
                UseShellExecute = false,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                CreateNoWindow = true
            };

            using var process = System.Diagnostics.Process.Start(startInfo);
            if (process == null)
                return GitPushResult.Fail(Str.Git_ProcessFailed);

            var output = process.StandardOutput.ReadToEnd();
            var error = process.StandardError.ReadToEnd();
            process.WaitForExit(30000);

            if (process.ExitCode == 0)
            {
                return GitPushResult.Ok(Str.Git_PushSuccessCmd);
            }
            else
            {
                var message = !string.IsNullOrEmpty(error) ? error : output;
                return GitPushResult.Fail(Str.Git_PushFailed(message.Trim()));
            }
        }
        catch (Exception ex)
        {
            return GitPushResult.Fail(Str.Git_CommandFailed(ex.Message));
        }
    }

    public bool UndoCommitAmend(string repoPath, string originalCommitHash)
    {
        ArgumentNullException.ThrowIfNull(repoPath);
        ArgumentNullException.ThrowIfNull(originalCommitHash);

        try
        {
            var repo = GetRepository(repoPath);
            var originalCommit = repo.Lookup<Commit>(originalCommitHash);

            if (originalCommit == null)
            {
                var reflog = repo.Refs.Log(repo.Head.CanonicalName);
                var entry = reflog?.FirstOrDefault(e => e.To.Sha == originalCommitHash);
                if (entry != null)
                {
                    originalCommit = repo.Lookup<Commit>(entry.To);
                }
            }

            if (originalCommit == null)
                return false;

            repo.Reset(ResetMode.Soft, originalCommit);
            return true;
        }
        catch (LibGit2SharpException)
        {
            return false;
        }
    }

    private static string TruncateDiff(string diff, int maxLines)
    {
        var lines = diff.Split('\n');
        if (lines.Length <= maxLines)
            return diff;

        return string.Join('\n', lines.Take(maxLines)) + $"\n... ({lines.Length - maxLines} more lines)";
    }

    public IEnumerable<BackupBranchInfo> GetBackupBranches(string repoPath)
    {
        ArgumentNullException.ThrowIfNull(repoPath);

        // Use a fresh repository to ensure we get the latest branch state
        // Don't use cache here as branches may have been deleted
        using var repo = new Repository(repoPath);
        var branches = repo.Branches
            .Where(b => !b.IsRemote && b.FriendlyName.StartsWith("backup/"))
            .ToList(); // Materialize to avoid enumeration issues with using

        foreach (var branch in branches)
        {
            yield return new BackupBranchInfo(
                branch.FriendlyName,
                branch.CanonicalName,
                branch.Tip?.Author.When,
                branch.Tip?.Sha);
        }
    }

    public bool DeleteBranch(string repoPath, string branchName)
    {
        ArgumentNullException.ThrowIfNull(repoPath);
        ArgumentNullException.ThrowIfNull(branchName);

        // Clear the cached repository BEFORE deletion to avoid stale state
        if (_repoCache.TryRemove(repoPath, out var cached))
        {
            cached.Repository.Dispose();
        }

        try
        {
            // Use a fresh repository instance
            using var repo = new Repository(repoPath);
            var branch = repo.Branches[branchName];

            if (branch == null)
                return false;

            if (branch.IsCurrentRepositoryHead)
                return false; // Can't delete current branch

            repo.Branches.Remove(branch);

            // Verify the branch was actually deleted
            var verifyBranch = repo.Branches[branchName];
            return verifyBranch == null;
        }
        catch (LibGit2SharpException)
        {
            return false;
        }
    }

    public void Dispose()
    {
        if (_disposed) return;

        _cleanupTimer.Dispose();

        foreach (var cached in _repoCache.Values)
        {
            cached.Repository.Dispose();
        }
        _repoCache.Clear();
        _disposed = true;
    }
}