using System.Diagnostics;
using System.ServiceProcess;
using SpdUp.Core;
using SpdUp.Models;

namespace SpdUp.Services;

/// <summary>
/// Manages the full boost lifecycle: activate → monitor → restore.
/// </summary>
public sealed class OptimizationService
{
    private readonly RamOptimizationService _ramService = new();
    private readonly AppSettings _settings;

    private readonly List<string> _stoppedServices = new();
    private uint _previousTimerResolution;
    private bool _timerResolutionChanged;
    private string? _boostedProcessName;
    private bool _isBoosted;

    public bool IsBoosted => _isBoosted;
    public string? BoostedProcessName => _boostedProcessName;

    public event Action<string>? BoostActivated;
    public event Action? BoostDeactivated;

    public OptimizationService(AppSettings settings)
    {
        _settings = settings;
    }

    /// <summary>
    /// Activate all boost optimizations. Thread-safe.
    /// </summary>
    public async Task<BoostResult> ActivateBoostAsync(string? gameProcessName = null)
    {
        if (_isBoosted) return new BoostResult(false, "Boost is already active.");

        var messages = new List<string>();

        try
        {
            // 1. Enable required privileges
            NativeMethods.EnablePrivilege(NativeMethods.SE_DEBUG_NAME);
            NativeMethods.EnablePrivilege(NativeMethods.SE_INC_BASE_PRIORITY_NAME);
            NativeMethods.EnablePrivilege(NativeMethods.SE_PROF_SINGLE_PROCESS_NAME);

            // 2. RAM Cleanup
            await Task.Run(() =>
            {
                var result = _ramService.FullCleanup();
                messages.Add($"RAM: trimmed {result.TrimmedCount} processes, standby purge {(result.StandbyPurged > 0 ? "OK" : "skipped")}.");
            });

            // 3. Stop non-critical services
            await Task.Run(() =>
            {
                foreach (var svcName in _settings.ServicesToStop)
                {
                    try
                    {
                        using var sc = new ServiceController(svcName);
                        if (sc.Status == ServiceControllerStatus.Running)
                        {
                            sc.Stop();
                            _stoppedServices.Add(svcName);
                            messages.Add($"Stopped service: {sc.DisplayName}");
                        }
                    }
                    catch (Exception ex)
                    {
                        Logger.Warn($"Could not stop {svcName}: {ex.Message}");
                    }
                }
            });

            // 4. Set game to HIGH priority
            if (!string.IsNullOrEmpty(gameProcessName))
            {
                _boostedProcessName = gameProcessName;
                await Task.Run(() => SetProcessPriority(gameProcessName, ProcessPriorityClass.High));
                messages.Add($"Set {gameProcessName} to HIGH priority.");
            }

            // 5. Reduce timer resolution (0.5 ms)
            await Task.Run(() =>
            {
                NativeMethods.NtQueryTimerResolution(out _, out _, out _previousTimerResolution);
                int status = NativeMethods.NtSetTimerResolution(5000, true, out _);
                _timerResolutionChanged = status == 0;
                if (_timerResolutionChanged)
                    messages.Add("Timer resolution set to 0.5 ms.");
            });

            _isBoosted = true;
            BoostActivated?.Invoke(string.Join("\n", messages));
            Logger.Info("Boost activated: " + string.Join(" | ", messages));

            return new BoostResult(true, string.Join("\n", messages));
        }
        catch (Exception ex)
        {
            Logger.Error("Boost activation failed", ex);
            return new BoostResult(false, $"Error: {ex.Message}");
        }
    }

    /// <summary>
    /// Restore all changes made during boost.
    /// </summary>
    public async Task DeactivateBoostAsync()
    {
        if (!_isBoosted) return;

        try
        {
            // 1. Restore timer resolution
            if (_timerResolutionChanged)
            {
                NativeMethods.NtSetTimerResolution(_previousTimerResolution, true, out _);
                _timerResolutionChanged = false;
                Logger.Info("Timer resolution restored.");
            }

            // 2. Restart stopped services
            await Task.Run(() =>
            {
                foreach (var svcName in _stoppedServices)
                {
                    try
                    {
                        using var sc = new ServiceController(svcName);
                        if (sc.Status == ServiceControllerStatus.Stopped)
                        {
                            sc.Start();
                            Logger.Info($"Restarted service: {sc.DisplayName}");
                        }
                    }
                    catch (Exception ex)
                    {
                        Logger.Warn($"Could not restart {svcName}: {ex.Message}");
                    }
                }
                _stoppedServices.Clear();
            });

            // 3. Restore process priority
            if (_boostedProcessName is not null)
            {
                await Task.Run(() => SetProcessPriority(_boostedProcessName, ProcessPriorityClass.Normal));
                _boostedProcessName = null;
            }

            _isBoosted = false;
            BoostDeactivated?.Invoke();
            Logger.Info("Boost deactivated – all settings restored.");
        }
        catch (Exception ex)
        {
            Logger.Error("Boost deactivation error", ex);
        }
    }

    /// <summary>
    /// Set priority class for a process by name.
    /// </summary>
    public static void SetProcessPriority(string processName, ProcessPriorityClass priority)
    {
        foreach (var proc in Process.GetProcessesByName(processName))
        {
            try
            {
                proc.PriorityClass = priority;
                Logger.Info($"Set {processName} (PID {proc.Id}) priority to {priority}.");
            }
            catch (Exception ex)
            {
                Logger.Warn($"Cannot set priority for {processName}: {ex.Message}");
            }
            finally
            {
                proc.Dispose();
            }
        }
    }

    /// <summary>
    /// Kill a process by PID.
    /// </summary>
    public static bool KillProcess(int pid)
    {
        try
        {
            using var proc = Process.GetProcessById(pid);
            proc.Kill(entireProcessTree: true);
            Logger.Info($"Killed process {proc.ProcessName} (PID {pid}).");
            return true;
        }
        catch (Exception ex)
        {
            Logger.Error($"Failed to kill PID {pid}", ex);
            return false;
        }
    }
}

public record BoostResult(bool Success, string Message);