using System.Diagnostics;
using System.ServiceProcess;
using System.Security.Principal;

namespace PrintServiceCLI;

/// <summary>
/// Manages Windows Service installation and verification
/// </summary>
public static class ServiceManager
{
    private const string ServiceName = "LAAPC Print Service";
    private const string ServiceInstallPath = @"C:\ProgramData\LAAPC";
    private const string ServiceExeName = "PrintService.exe";
    
    private static bool? _serviceAvailable = null; // Cache result

    /// <summary>
    /// Check if service is installed and running, with auto-install option
    /// </summary>
    public static bool EnsureServiceRunning(bool silent = false)
    {
        // Return cached result if already checked
        if (_serviceAvailable.HasValue)
            return _serviceAvailable.Value;

        try
        {
            // Check if service exists and is running
            using var service = new ServiceController(ServiceName);
            service.Refresh();

            if (service.Status == ServiceControllerStatus.Running)
            {
                _serviceAvailable = true;
                return true;
            }

            // Service exists but not running - try to start it
            if (service.Status == ServiceControllerStatus.Stopped)
            {
                if (!silent)
                    Console.WriteLine("Service is stopped. Starting...");
                
                service.Start();
                service.WaitForStatus(ServiceControllerStatus.Running, TimeSpan.FromSeconds(10));
                _serviceAvailable = true;
                return true;
            }

            _serviceAvailable = false;
            return false;
        }
        catch (InvalidOperationException)
        {
            // Service doesn't exist - offer to install
            if (silent)
            {
                _serviceAvailable = false;
                return false;
            }

            return PromptAndInstall();
        }
        catch (Exception ex)
        {
            if (!silent)
                Console.Error.WriteLine($"Error checking service: {ex.Message}");
            
            _serviceAvailable = false;
            return false;
        }
    }

    /// <summary>
    /// Prompt user and install service if they agree
    /// </summary>
    private static bool PromptAndInstall()
    {
        Console.WriteLine();
        Console.WriteLine("====================================================");
        Console.WriteLine("LAAPC Print Service is not installed on this PC.");
        Console.WriteLine("====================================================");
        Console.WriteLine();
        Console.WriteLine("The service must be installed locally to process print jobs.");
        Console.WriteLine("This is a one-time setup that requires administrator access.");
        Console.WriteLine();
        Console.Write("Install the service now? [Y/N]: ");
        
        var response = Console.ReadLine()?.Trim().ToUpper();
        
        if (response != "Y" && response != "YES")
        {
            Console.WriteLine("Installation cancelled. Service is required for printing.");
            _serviceAvailable = false;
            return false;
        }

        return InstallService();
    }

    /// <summary>
    /// Install and start the service with UAC elevation
    /// </summary>
    private static bool InstallService()
    {
        try
        {
            Console.WriteLine();
            Console.WriteLine("Installing service...");

            // Check if running as admin
            if (!IsAdministrator())
            {
                Console.WriteLine("Requesting administrator privileges...");
                return InstallWithElevation();
            }

            // Copy service files to local machine
            var cliPath = AppContext.BaseDirectory;
            var serviceSourcePath = Path.Combine(Path.GetDirectoryName(cliPath)!, ServiceExeName);

            if (!File.Exists(serviceSourcePath))
            {
                // Try relative path
                serviceSourcePath = Path.Combine(cliPath, "..", "PrintService", ServiceExeName);
                serviceSourcePath = Path.GetFullPath(serviceSourcePath);
            }

            if (!File.Exists(serviceSourcePath))
            {
                Console.Error.WriteLine($"ERROR: Could not find {ServiceExeName}");
                Console.Error.WriteLine($"Expected location: {serviceSourcePath}");
                _serviceAvailable = false;
                return false;
            }

            // Create installation directory
            Directory.CreateDirectory(ServiceInstallPath);

            // Copy service executable and dependencies
            var serviceDestPath = Path.Combine(ServiceInstallPath, ServiceExeName);
            CopyServiceFiles(Path.GetDirectoryName(serviceSourcePath)!, ServiceInstallPath);

            Console.WriteLine($"Files copied to: {ServiceInstallPath}");

            // Install Windows Service using sc.exe
            var scInstall = Process.Start(new ProcessStartInfo
            {
                FileName = "sc.exe",
                Arguments = $"create \"{ServiceName}\" binPath=\"{serviceDestPath}\" start=auto",
                UseShellExecute = false,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                CreateNoWindow = true
            });

            scInstall?.WaitForExit();

            if (scInstall?.ExitCode != 0)
            {
                Console.Error.WriteLine("ERROR: Failed to install service");
                _serviceAvailable = false;
                return false;
            }

            Console.WriteLine("Service installed successfully.");

            // Start the service
            Console.WriteLine("Starting service...");
            var scStart = Process.Start(new ProcessStartInfo
            {
                FileName = "sc.exe",
                Arguments = $"start \"{ServiceName}\"",
                UseShellExecute = false,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                CreateNoWindow = true
            });

            scStart?.WaitForExit();

            if (scStart?.ExitCode != 0)
            {
                Console.Error.WriteLine("WARNING: Service installed but failed to start");
                Console.Error.WriteLine("Try running: sc start \"LAAPC Print Service\"");
                _serviceAvailable = false;
                return false;
            }

            // Wait for service to be ready
            Thread.Sleep(2000);

            Console.WriteLine("Service started successfully!");
            Console.WriteLine();
            _serviceAvailable = true;
            return true;
        }
        catch (Exception ex)
        {
            Console.Error.WriteLine($"ERROR: Installation failed: {ex.Message}");
            _serviceAvailable = false;
            return false;
        }
    }

    /// <summary>
    /// Restart process with admin elevation
    /// </summary>
    private static bool InstallWithElevation()
    {
        try
        {
            var startInfo = new ProcessStartInfo
            {
                FileName = Process.GetCurrentProcess().MainModule?.FileName ?? "PrintServiceCLI.exe",
                Arguments = "--install-service",
                UseShellExecute = true,
                Verb = "runas" // Trigger UAC prompt
            };

            var process = Process.Start(startInfo);
            process?.WaitForExit();

            if (process?.ExitCode == 0)
            {
                Console.WriteLine("Service installed successfully.");
                _serviceAvailable = true;
                return true;
            }

            Console.Error.WriteLine("Installation was cancelled or failed.");
            _serviceAvailable = false;
            return false;
        }
        catch (Exception ex)
        {
            Console.Error.WriteLine($"ERROR: Could not elevate privileges: {ex.Message}");
            _serviceAvailable = false;
            return false;
        }
    }

    /// <summary>
    /// Copy service files from source to destination
    /// </summary>
    private static void CopyServiceFiles(string sourceDir, string destDir)
    {
        // Copy main executable
        var sourceExe = Path.Combine(sourceDir, ServiceExeName);
        var destExe = Path.Combine(destDir, ServiceExeName);
        File.Copy(sourceExe, destExe, overwrite: true);

        // Copy all DLLs and config files
        foreach (var file in Directory.GetFiles(sourceDir))
        {
            var fileName = Path.GetFileName(file);
            var ext = Path.GetExtension(file).ToLower();

            if (ext == ".dll" || ext == ".json" || ext == ".config")
            {
                var destFile = Path.Combine(destDir, fileName);
                File.Copy(file, destFile, overwrite: true);
            }
        }

        // Create necessary folders
        var capturesPath = Path.Combine(destDir, "Captures");
        var queuePath = Path.Combine(destDir, "Queue");
        var archivePath = Path.Combine(destDir, "Archive");
        var errorPath = Path.Combine(destDir, "Error");
        var outputPath = Path.Combine(destDir, "Output");

        Directory.CreateDirectory(capturesPath);
        Directory.CreateDirectory(queuePath);
        Directory.CreateDirectory(archivePath);
        Directory.CreateDirectory(errorPath);
        Directory.CreateDirectory(outputPath);
    }

    /// <summary>
    /// Check if running with administrator privileges
    /// </summary>
    private static bool IsAdministrator()
    {
        using var identity = WindowsIdentity.GetCurrent();
        var principal = new WindowsPrincipal(identity);
        return principal.IsInRole(WindowsBuiltInRole.Administrator);
    }
}