using System.Diagnostics;
using Microsoft.AspNetCore.Mvc;
using w4c_workflows.Filters;
using w4c_workflows.Services;

namespace w4c_workflows.Controllers;

/// <summary>
/// Workflow file management endpoints. Provides CRUD operations for the
/// workflow YAML definitions and their sibling code files (shell scripts,
/// JS, Python, etc.) that live in the tenant's per-tenant workflow repository.
///
/// The repository is the single source of truth for a tenant's workflow content:
/// the workflows module edits files here and <c>POST /api/workflows/sync</c>
/// recompiles them (see <see cref="WorkflowSyncService"/>). Edits land in the
/// SAME directory <see cref="IWorkflowSource"/> reads from, so the "edit in the
/// workflows module" and "the engine runs it" paths are always coherent.
///
/// Works in both storage modes:
///   - <b>Forgejo-backed</b> (Forgejo:AdminToken set): files live in a private
///     per-user Forgejo repo <c>{login}/workflows-{login}</c>, cloned locally.
///     <c>/commit</c> and <c>/pull</c> sync to/from the remote.
///   - <b>Filesystem-only</b> (no AdminToken): files live under
///     <c>{CopiesRoot}/{tenantId}/</c> with no remote. <c>/commit</c> and
///     <c>/pull</c> are no-ops.
/// </summary>
[ApiController]
[Route("api/workflow-files")]
public class WorkflowFilesController : ControllerBase
{
    public WorkflowFilesController(
        WorkflowSourceFactory sourceFactory,
        WorkflowRepoStore repoStore,
        WorkflowSyncService sync,
        RealtimeEventHub events,
        ILogger<WorkflowFilesController> logger)
    {
        _sourceFactory = sourceFactory;
        _repoStore = repoStore;
        _sync = sync;
        _events = events;
        _logger = logger;
    }

    private readonly WorkflowSourceFactory _sourceFactory;
    private readonly WorkflowRepoStore _repoStore;
    private readonly WorkflowSyncService _sync;
    private readonly RealtimeEventHub _events;
    private readonly ILogger<WorkflowFilesController> _logger;

    private string TenantId => (string?)HttpContext.Items["TenantId"]
        ?? throw new InvalidOperationException("TenantId not resolved by auth middleware");

    /// <summary>
    /// The user's Forgejo login when the middleware resolved it (Forgejo-backed
    /// mode succeeded). Null when in filesystem-only mode OR when the Forgejo
    /// login could not be resolved (the request then falls back to the filesystem
    /// source, so file CRUD must target the filesystem dir to stay consistent).
    /// </summary>
    private string? MaybeForgejoLogin =>
        HttpContext.Items.TryGetValue("ForgejoLogin", out var v) ? v as string : null;

    /// <summary>
    /// The on-disk directory holding the tenant's workflow files. In Forgejo-backed
    /// mode (login resolved) it is the per-user clone dir; otherwise it is the
    /// per-tenant directory. Both are exactly the root <see cref="IWorkflowSource"/>
    /// reads from, so file edits made through these endpoints are what get compiled
    /// on sync.
    /// </summary>
    private string SourceDir => _sourceFactory.ResolveTenantSourceDir(
        TenantId, MaybeForgejoLogin, CurrentRepo);

    /// <summary>The tenant's current workflow repo name (set by the source middleware).</summary>
    private string CurrentRepo =>
        (HttpContext.Items["WorkflowRepo"] as string)
        ?? (_sourceFactory.Forgejo?.WorkflowRepoName ?? "workflows");

    /// <summary>Returns the Forgejo repo info for this tenant's workflow files.</summary>
    [HttpGet("repo")]
    [RequireScope("read")]
    public IActionResult GetRepoInfo()
    {
        if (_sourceFactory.Forgejo == null)
            return StatusCode(503, new { error = "Forgejo-backed workflow mode is not configured." });
        var login = MaybeForgejoLogin;
        if (string.IsNullOrWhiteSpace(login))
            return StatusCode(503, new { error = "Forgejo login not resolved for this tenant." });

        var repoName = _repoStore.DefaultName;
        try { repoName = CurrentRepo; } catch { /* keep default */ }
        var cloneDir = _sourceFactory.Forgejo.TenantCloneDir(TenantId, login, repoName);
        var fullName = _sourceFactory.Forgejo.RepoFullNameForLogin(login, repoName);
        var exists = Directory.Exists(Path.Combine(cloneDir, ".git"));

        return Ok(new
        {
            repoName,
            repoFullName = fullName,
            cloneDir,
            cloned = exists,
            forgejoUrl = $"{_sourceFactory.Forgejo.ForgejoBaseUrl}/{fullName}",
        });
    }

    /// <summary>
    /// Sets the tenant's workflow repository (basename, e.g. <c>workflows</c> or
    /// a user-selected repo) and re-syncs. Switching repos unloads workflows
    /// compiled from any previously-selected repo (they are no longer listed).
    /// </summary>
    [HttpPut("repo")]
    [RequireScope("manage")]
    public async Task<IActionResult> SetRepo([FromBody] SetWorkflowRepoRequest? request, CancellationToken ct)
    {
        if (request == null || string.IsNullOrWhiteSpace(request.RepoName))
            return BadRequest(new { error = "repoName is required" });

        // A workflow repo is always owned by the caller's own Forgejo account, so
        // only a single safe name segment is accepted (no owner prefix / traversal).
        if (!WorkflowRepoStore.TryNormalizeName(request.RepoName, out var repoName))
            return BadRequest(new { error = "Invalid repository name. Use a single repository name (letters, digits, '.', '_', '-')." });

        var login = MaybeForgejoLogin;

        // Materialize the selected repo BEFORE persisting the switch. An
        // unreachable/missing repo must fail loudly instead of being saved as the
        // tenant's selection (which would strand the workflows module on a dead repo).
        if (_sourceFactory.Forgejo != null && !string.IsNullOrWhiteSpace(login))
        {
            try
            {
                await _sourceFactory.Forgejo.EnsureCloneAsync(TenantId, login, repoName, ct);
                await _sourceFactory.Forgejo.PullAsync(TenantId, login, repoName, ct);
            }
            catch (Exception ex)
            {
                _logger.LogWarning(ex, "Workflow repo switch for tenant {TenantId} to {Repo} failed", TenantId, repoName);
                return BadRequest(new { error = $"Repository '{repoName}' could not be opened: {ex.Message}" });
            }
        }

        await _repoStore.SetNameAsync(TenantId, repoName, ct);

        // Re-sync workflows for the newly selected repo so the list reflects it.
        var syncResult = await _sync.SyncAsync(TenantId, repoName, ct);

        string? fullName = null, cloneDir = null;
        if (_sourceFactory.Forgejo != null && !string.IsNullOrWhiteSpace(login))
        {
            cloneDir = _sourceFactory.Forgejo.TenantCloneDir(TenantId, login, repoName);
            fullName = _sourceFactory.Forgejo.RepoFullNameForLogin(login, repoName);
        }

        return Ok(new
        {
            repoName,
            repoFullName = fullName,
            cloneDir,
            compiled = syncResult.Compiled,
            removed = syncResult.Removed,
            errors = syncResult.Errors,
        });
    }

    /// <summary>
    /// Lists all files under a directory (recursive, excluding .git), plus the
    /// top-level subdirectories. Returns repo-relative paths.
    /// </summary>
    [HttpGet]
    [RequireScope("read")]
    public IActionResult ListFiles([FromQuery] string? path = null)
    {
        var sourceDir = SourceDir;
        if (!Directory.Exists(sourceDir))
            return Ok(new { files = Array.Empty<object>() });

        var dir = string.IsNullOrWhiteSpace(path)
            ? sourceDir
            : Path.Combine(sourceDir, path.Replace('/', Path.DirectorySeparatorChar));

        var fullDir = Path.GetFullPath(dir);
        if (!IsWithin(sourceDir, fullDir))
            return BadRequest(new { error = "Invalid path" });

        if (!Directory.Exists(fullDir))
            return NotFound(new { error = $"Directory not found: {path}" });

        var files = new List<object>();
        foreach (var full in Directory.EnumerateFiles(fullDir, "*", SearchOption.AllDirectories))
        {
            var rel = Path.GetRelativePath(sourceDir, full).Replace(Path.DirectorySeparatorChar, '/');
            if (rel.StartsWith(".git", StringComparison.OrdinalIgnoreCase))
                continue;
            var info = new FileInfo(full);
            files.Add(new { path = rel, name = Path.GetFileName(full), size = info.Length, modified = info.LastWriteTimeUtc });
        }

        foreach (var full in Directory.EnumerateDirectories(fullDir))
        {
            var name = Path.GetFileName(full);
            if (name == ".git") continue;
            var rel = Path.GetRelativePath(sourceDir, full).Replace(Path.DirectorySeparatorChar, '/');
            files.Add(new { path = rel, name, isDir = true });
        }

        return Ok(new { files });
    }

    /// <summary>Returns the content of a specific file.</summary>
    [HttpGet("content")]
    [RequireScope("read")]
    public IActionResult GetContent([FromQuery] string path)
    {
        if (string.IsNullOrWhiteSpace(path))
            return BadRequest(new { error = "path is required" });

        var full = ResolveSafeFile(path, out var status);
        if (status.HasValue)
            return BadRequest(new { error = "Invalid path" });

        if (!System.IO.File.Exists(full))
            return NotFound(new { error = $"File not found: {path}" });

        var content = System.IO.File.ReadAllText(full);
        var info = new FileInfo(full);
        return Ok(new { path, content, size = info.Length, modified = info.LastWriteTimeUtc });
    }

    /// <summary>
    /// Saves content to a file in the tenant's workflow repo. Writes to the local
    /// working tree (no commit/push — use POST /commit in Forgejo mode for that).
    /// </summary>
    [HttpPost("save")]
    [RequireScope("manage")]
    public IActionResult SaveFile([FromBody] SaveWorkflowFileRequest request)
    {
        if (string.IsNullOrWhiteSpace(request.Path))
            return BadRequest(new { error = "path is required" });

        var full = ResolveSafeFile(request.Path, out var status);
        if (status.HasValue)
            return BadRequest(new { error = "Invalid path" });

        try
        {
            var dir = Path.GetDirectoryName(full);
            if (dir != null && !Directory.Exists(dir))
                Directory.CreateDirectory(dir);

            System.IO.File.WriteAllText(full, request.Content ?? string.Empty, new System.Text.UTF8Encoding(false));
            _logger.LogInformation("Saved workflow file {Path} for tenant {TenantId} ({Login})",
                request.Path, TenantId, MaybeForgejoLogin ?? "-");
            // Notify any open workflow editor that the file changed server-side (frontend is optional:
            // the AI can write it via the backend while no page is open, then the page reloads on next visit).
            _events.Publish(TenantId, "workflow", request.Path, DateTime.UtcNow);
            return Ok(new { success = true, path = request.Path });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to save workflow file {Path}", request.Path);
            return BadRequest(new { error = ex.Message });
        }
    }

    /// <summary>
    /// Deletes files/directories from the tenant's workflow repo. Used to remove a
    /// whole workflow (its folder) or an individual file. Returns the paths deleted.
    /// </summary>
    [HttpPost("delete")]
    [RequireScope("manage")]
    public IActionResult DeleteFiles([FromBody] DeleteWorkflowFileRequest? request)
    {
        if (request == null || request.Paths == null || request.Paths.Length == 0)
            return BadRequest(new { error = "paths is required" });

        var sourceDir = SourceDir;
        var fullSourceDir = Path.GetFullPath(sourceDir);
        var deleted = new List<string>();

        foreach (var raw in request.Paths)
        {
            if (string.IsNullOrWhiteSpace(raw)) continue;
            var full = Path.GetFullPath(Path.Combine(sourceDir, raw.Replace('/', Path.DirectorySeparatorChar)));
            if (full == fullSourceDir || !IsWithin(sourceDir, full))
                continue;

            if (Directory.Exists(full))
                Directory.Delete(full, recursive: true);
            else if (System.IO.File.Exists(full))
                System.IO.File.Delete(full);
            else
                continue;
            deleted.Add(raw);
        }

        _logger.LogInformation("Deleted workflow files for tenant {TenantId}: {Paths}",
            TenantId, string.Join(", ", deleted));
        return Ok(new { success = true, deleted });
    }

    /// <summary>Returns the git status of the tenant's workflow repo (Forgejo-backed mode only).</summary>
    [HttpGet("status")]
    [RequireScope("read")]
    public IActionResult GetStatus()
    {
        if (_sourceFactory.Forgejo == null)
            return StatusCode(503, new { error = "Forgejo-backed workflow mode is not configured." });
        var login = MaybeForgejoLogin;
        if (string.IsNullOrWhiteSpace(login))
            return StatusCode(503, new { error = "Forgejo login not resolved for this tenant." });

        var cloneDir = _sourceFactory.Forgejo.TenantCloneDir(TenantId, login, CurrentRepo);
        if (!Directory.Exists(Path.Combine(cloneDir, ".git")))
            return Ok(new { branch = "", changed = Array.Empty<object>(), untracked = Array.Empty<object>() });

        var branch = RunGit(cloneDir, "rev-parse", "--abbrev-ref", "HEAD")?.Trim() ?? "";
        var statusOutput = RunGit(cloneDir, "status", "--porcelain") ?? "";

        var changed = new List<object>();
        var untracked = new List<object>();

        foreach (var line in statusOutput.Split('\n', StringSplitOptions.RemoveEmptyEntries))
        {
            if (line.Length < 4) continue;
            var statusCode = line[..2].Trim();
            var filePath = line[3..].Trim();

            if (statusCode == "??")
                untracked.Add(new { path = filePath, status = "untracked" });
            else
                changed.Add(new { path = filePath, status = statusCode });
        }

        var head = RunGit(cloneDir, "rev-parse", "--short", "HEAD")?.Trim() ?? "";
        return Ok(new { branch, head, changed, untracked });
    }

    /// <summary>
    /// Commits and pushes all changes to Forgejo. A no-op (returns success) in
    /// filesystem-only mode. After committing, call POST /api/workflows/sync to
    /// recompile.
    /// </summary>
    [HttpPost("commit")]
    [RequireScope("manage")]
    public async Task<IActionResult> CommitAndPush([FromBody] CommitWorkflowRequest? request = null)
    {
        if (_sourceFactory.Forgejo == null)
            return Ok(new { success = true, output = "filesystem mode — no remote to push" });
        var login = MaybeForgejoLogin;
        if (string.IsNullOrWhiteSpace(login))
            return StatusCode(503, new { error = "Forgejo login not resolved for this tenant." });

        var message = string.IsNullOrWhiteSpace(request?.Message)
            ? $"Update workflow files ({DateTime.UtcNow:yyyy-MM-dd HH:mm:ss} UTC)"
            : request!.Message;

        var (success, output) = await _sourceFactory.Forgejo.CommitAndPushAsync(
            TenantId, login, message, CurrentRepo, HttpContext.RequestAborted);

        _logger.LogInformation("Commit/push for login {Login}: {Success} ({Output})",
            login, success, output?.Trim() ?? "");

        return Ok(new { success, output });
    }

    /// <summary>Pulls the latest changes from Forgejo (no-op in filesystem-only mode).</summary>
    [HttpPost("pull")]
    [RequireScope("manage")]
    public async Task<IActionResult> Pull()
    {
        if (_sourceFactory.Forgejo == null)
            return Ok(new { success = true, output = "filesystem mode — no remote to pull" });
        var login = MaybeForgejoLogin;
        if (string.IsNullOrWhiteSpace(login))
            return StatusCode(503, new { error = "Forgejo login not resolved for this tenant." });

        var ok = await _sourceFactory.Forgejo.PullAsync(TenantId, login, CurrentRepo, HttpContext.RequestAborted);
        return Ok(new { success = ok });
    }

    /// <summary>Resolves a repo-relative path to an absolute path inside the tenant source dir.</summary>
    private string ResolveSafeFile(string path, out int? status)
    {
        var sourceDir = SourceDir;
        var full = Path.GetFullPath(Path.Combine(sourceDir, path.Replace('/', Path.DirectorySeparatorChar)));
        if (!IsWithin(sourceDir, full))
        {
            status = 400;
            return full;
        }
        status = null;
        return full;
    }

    /// <summary>
    /// True when <paramref name="candidate"/> is the root directory or a path
    /// inside it. Uses a trailing separator so a sibling directory whose name
    /// merely shares the root's prefix (e.g. ".../workflows-evil") can't escape.
    /// </summary>
    private static bool IsWithin(string root, string candidate)
    {
        var fullRoot = Path.GetFullPath(root).TrimEnd(Path.DirectorySeparatorChar);
        var fullCandidate = Path.GetFullPath(candidate);
        if (string.Equals(fullCandidate, fullRoot, StringComparison.Ordinal))
            return true;
        return fullCandidate.StartsWith(fullRoot + Path.DirectorySeparatorChar, StringComparison.Ordinal);
    }

    private string? RunGit(string workDir, params string[] args)
    {
        try
        {
            var psi = new ProcessStartInfo("git")
            {
                WorkingDirectory = workDir,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                UseShellExecute = false,
            };
            foreach (var arg in args) psi.ArgumentList.Add(arg);

            using var process = Process.Start(psi);
            if (process == null) return null;

            var output = process.StandardOutput.ReadToEnd();
            if (!process.WaitForExit(5000))
            {
                process.Kill(entireProcessTree: true);
                return null;
            }

            return process.ExitCode == 0 ? output.Trim() : null;
        }
        catch (Exception ex)
        {
            _logger.LogDebug(ex, "git invocation failed in {Dir}", workDir);
            return null;
        }
    }
}

public sealed record SetWorkflowRepoRequest(string? RepoName);
public sealed record SaveWorkflowFileRequest(string Path, string? Content);
public sealed record CommitWorkflowRequest(string? Message);
public sealed record DeleteWorkflowFileRequest(string[] Paths);