using System.Diagnostics;
using System.Linq;
using System.Windows;
using AxCopilot.Models;

namespace AxCopilot.Services;

/// <summary>
/// 예약 작업을 백그라운드에서 점검하고 조건이 맞으면 액션을 실행합니다.
/// 활성 일정이 없을 때는 타이머를 돌리지 않아 유휴 CPU 사용을 줄입니다.
/// </summary>
public sealed class SchedulerService : IDisposable
{
    private readonly SettingsService _settings;
    private Timer? _timer;
    private bool _disposed;

    public SchedulerService(SettingsService settings)
    {
        _settings = settings;
    }

    public void Start()
    {
        if (_disposed || _timer != null) return;

        _timer = new Timer(OnTick, null, TimeSpan.FromSeconds(10), TimeSpan.FromSeconds(30));
        LogService.Info("SchedulerService 시작");
    }

    public void Stop()
    {
        if (_timer == null) return;

        _timer.Dispose();
        _timer = null;
        LogService.Info("SchedulerService 중지");
    }

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

        if (HasEnabledSchedules())
        {
            Start();
            return;
        }

        Stop();
    }

    public void Dispose()
    {
        if (_disposed) return;
        _disposed = true;
        Stop();
    }

    private void OnTick(object? _)
    {
        try
        {
            if (!HasEnabledSchedules())
            {
                Stop();
                return;
            }

            var now = DateTime.Now;
            var schedules = _settings.Settings.Schedules;
            var dirty = false;

            foreach (var entry in schedules.ToList())
            {
                if (!ShouldFire(entry, now)) continue;

                LogService.Info($"스케줄 실행: '{entry.Name}' ({entry.TriggerType} {entry.TriggerTime})");
                ExecuteAction(entry);

                entry.LastRun = now;
                dirty = true;

                if (entry.TriggerType == "once")
                    entry.Enabled = false;
            }

            if (dirty)
            {
                _settings.Save();
                Refresh();
            }
        }
        catch (Exception ex)
        {
            LogService.Error($"SchedulerService 오류: {ex.Message}");
        }
    }

    private bool HasEnabledSchedules() =>
        _settings.Settings.Schedules.Any(entry => entry.Enabled);

    private static bool ShouldFire(ScheduleEntry entry, DateTime now)
    {
        if (!entry.Enabled) return false;
        if (!TimeSpan.TryParse(entry.TriggerTime, out var triggerTime)) return false;

        var targetDt = now.Date + triggerTime;
        if (Math.Abs((now - targetDt).TotalMinutes) > 1.0) return false;

        if (entry.TriggerType != "once" &&
            entry.LastRun.HasValue &&
            entry.LastRun.Value.Date == now.Date)
        {
            return false;
        }

        var typeMatch = entry.TriggerType switch
        {
            "daily" => true,
            "weekdays" => now.DayOfWeek >= DayOfWeek.Monday &&
                          now.DayOfWeek <= DayOfWeek.Friday,
            "weekly" => entry.WeekDays.Count > 0 &&
                        entry.WeekDays.Contains((int)now.DayOfWeek),
            "once" => !entry.LastRun.HasValue &&
                      entry.TriggerDate != null &&
                      DateTime.TryParse(entry.TriggerDate, out var d) &&
                      now.Date == d.Date,
            _ => false
        };

        if (!typeMatch) return false;

        if (!string.IsNullOrWhiteSpace(entry.ConditionProcess))
        {
            var procName = entry.ConditionProcess.Trim()
                .Replace(".exe", "", StringComparison.OrdinalIgnoreCase);

            var isRunning = Process.GetProcessesByName(procName).Length > 0;

            if (entry.ConditionProcessMustRun && !isRunning) return false;
            if (!entry.ConditionProcessMustRun && isRunning) return false;
        }

        return true;
    }

    private static void ExecuteAction(ScheduleEntry entry)
    {
        try
        {
            switch (entry.ActionType)
            {
                case "app":
                    if (!string.IsNullOrWhiteSpace(entry.ActionTarget))
                    {
                        Process.Start(new ProcessStartInfo
                        {
                            FileName = entry.ActionTarget,
                            Arguments = entry.ActionArgs ?? "",
                            UseShellExecute = true
                        });
                    }
                    break;

                case "notification":
                    var msg = string.IsNullOrWhiteSpace(entry.ActionTarget)
                        ? entry.Name
                        : entry.ActionTarget;
                    Application.Current?.Dispatcher.Invoke(() =>
                        NotificationService.Notify($"[일정] {entry.Name}", msg));
                    break;
            }
        }
        catch (Exception ex)
        {
            LogService.Warn($"스케줄 액션 실행 실패 '{entry.Name}': {ex.Message}");
        }
    }

    public static DateTime? ComputeNextRun(ScheduleEntry entry)
    {
        if (!entry.Enabled) return null;
        if (!TimeSpan.TryParse(entry.TriggerTime, out var t)) return null;

        var now = DateTime.Now;

        return entry.TriggerType switch
        {
            "once" when
                !entry.LastRun.HasValue &&
                entry.TriggerDate != null &&
                DateTime.TryParse(entry.TriggerDate, out var d) &&
                (now.Date + t) >= now =>
                d.Date + t,

            "daily" => NextOccurrence(now, t, _ => true),

            "weekdays" => NextOccurrence(now, t, dt =>
                dt.DayOfWeek >= DayOfWeek.Monday && dt.DayOfWeek <= DayOfWeek.Friday),

            "weekly" when entry.WeekDays.Count > 0 => NextOccurrence(now, t, dt =>
                entry.WeekDays.Contains((int)dt.DayOfWeek)),

            _ => null
        };
    }

    private static DateTime? NextOccurrence(DateTime now, TimeSpan t, Func<DateTime, bool> dayFilter)
    {
        for (var i = 0; i <= 7; i++)
        {
            var candidate = now.Date.AddDays(i) + t;
            if (candidate > now && dayFilter(candidate))
                return candidate;
        }

        return null;
    }

    public static string TriggerLabel(ScheduleEntry e) => e.TriggerType switch
    {
        "daily" => "매일",
        "weekdays" => "주중(월~금)",
        "weekly" => WeekDayLabel(e.WeekDays),
        "once" => $"한번({e.TriggerDate})",
        _ => e.TriggerType
    };

    private static readonly string[] DayShort = ["일", "월", "화", "수", "목", "금", "토"];

    private static string WeekDayLabel(List<int> days) =>
        days.Count == 0
            ? "매주(요일 미지정)"
            : "매주 " + string.Join(", ", days.OrderBy(d => d).Select(d => DayShort[d]));
}