using System;
using System.Windows.Forms;

namespace TimerApp
{
    public enum MonitorState
    {
        Idle,
        Working,
        Resting
    }

    public class ActivityMonitor
    {
        private System.Windows.Forms.Timer _timer;
        private DateTime _lastWorkStartTime;
        private TimeSpan _accumulatedWorkTime;
        private DateTime _restStartTime;
        private int _restElapsedSeconds; // 休息已过秒数（用于避免时间计算导致的跳变）

        // 配置 (默认值)
        public TimeSpan WorkDuration { get; set; } = TimeSpan.FromMinutes(20);
        public TimeSpan RestDuration { get; set; } = TimeSpan.FromMinutes(1);
        public TimeSpan IdleThreshold { get; set; } = TimeSpan.FromSeconds(30);

        public MonitorState CurrentState { get; private set; } = MonitorState.Idle;

        // 事件
        public event EventHandler<TimeSpan> WorkProgressChanged; // 剩余工作时间
        public event EventHandler<TimeSpan> RestProgressChanged; // 剩余休息时间
        public event EventHandler RestStarted;
        public event EventHandler RestEnded;
        public event EventHandler StateChanged;

        public ActivityMonitor()
        {
            _timer = new System.Windows.Forms.Timer();
            _timer.Interval = 1000; // 1秒检查一次
            _timer.Tick += Timer_Tick;
        }

        public void Start()
        {
            _timer.Start();
            ResetWork();
        }

        public void Stop()
        {
            _timer.Stop();
        }

        private void ResetWork()
        {
            _accumulatedWorkTime = TimeSpan.Zero;
            _lastWorkStartTime = DateTime.Now;
            ChangeState(MonitorState.Idle);
        }

        private void ChangeState(MonitorState newState)
        {
            if (CurrentState != newState)
            {
                CurrentState = newState;
                StateChanged?.Invoke(this, EventArgs.Empty);
            }
        }

        private void Timer_Tick(object sender, EventArgs e)
        {
            long idleMs = NativeMethods.GetIdleTime();
            TimeSpan idleTime = TimeSpan.FromMilliseconds(idleMs);

            if (CurrentState == MonitorState.Resting)
            {
                // 休息模式逻辑
                // 使用计数器而不是时间差，避免秒数跳变
                _restElapsedSeconds++;
                int totalRestSeconds = (int)RestDuration.TotalSeconds;
                int remainingSeconds = totalRestSeconds - _restElapsedSeconds;

                if (remainingSeconds <= 0)
                {
                    // 休息结束
                    RestEnded?.Invoke(this, EventArgs.Empty);
                    ResetWork(); // 重新开始工作周期
                }
                else
                {
                    TimeSpan remainingRest = TimeSpan.FromSeconds(remainingSeconds);
                    RestProgressChanged?.Invoke(this, remainingRest);
                }
            }
            else
            {
                // 检测是否有视频/媒体正在播放
                bool isMediaPlaying = NativeMethods.IsMediaPlaying();

                // 工作/空闲模式逻辑
                if (idleTime > IdleThreshold || isMediaPlaying)
                {
                    // 用户离开了或正在播放视频
                    if (CurrentState == MonitorState.Working)
                    {
                        // 如果正在工作，但离开了，暂停工作计时？
                        // 简单起见，如果离开时间过长，可以视为一种“休息”，或者只是暂停累积
                        // 这里我们简单处理：如果空闲时间超过阈值，状态变为空闲
                        ChangeState(MonitorState.Idle);
                    }

                    // 如果在 Idle 状态，且空闲时间非常长（比如超过了休息时间），
                    // 是否应该重置工作计时器？
                    // 假设用户去开会了1小时，回来应该重新计算20分钟。
                    if (idleTime > RestDuration)
                    {
                         _accumulatedWorkTime = TimeSpan.Zero;
                    }

                    // 如果正在播放视频，不累加工作时间，但保持当前状态
                    if (isMediaPlaying && CurrentState == MonitorState.Working)
                    {
                        // 保持当前剩余时间不变（不累加，也不减少）
                        TimeSpan remainingWork = WorkDuration - _accumulatedWorkTime;
                        WorkProgressChanged?.Invoke(this, remainingWork);
                    }
                }
                else
                {
                    // 用户在活动且没有播放视频
                    if (CurrentState == MonitorState.Idle)
                    {
                        // 从空闲变为工作
                        ChangeState(MonitorState.Working);
                        _lastWorkStartTime = DateTime.Now;
                    }

                    // 累加工作时间
                    // 简单的累加逻辑：这一秒是工作的
                    _accumulatedWorkTime += TimeSpan.FromSeconds(1);

                    // 检查是否达到工作时长
                    TimeSpan remainingWork = WorkDuration - _accumulatedWorkTime;

                    if (remainingWork <= TimeSpan.Zero)
                    {
                        // 触发休息
                        _restStartTime = DateTime.Now;
                        _restElapsedSeconds = 0; // 重置休息计数器
                        ChangeState(MonitorState.Resting);
                        RestStarted?.Invoke(this, EventArgs.Empty);
                    }
                    else
                    {
                        WorkProgressChanged?.Invoke(this, remainingWork);
                    }
                }
            }
        }

        // 用于强制重置或测试
        public void ForceRest()
        {
             _restStartTime = DateTime.Now;
             _restElapsedSeconds = 0; // 重置休息计数器
             ChangeState(MonitorState.Resting);
             RestStarted?.Invoke(this, EventArgs.Empty);
        }

        public void RefreshStatus()
        {
             if (CurrentState == MonitorState.Working)
             {
                 TimeSpan remaining = WorkDuration - _accumulatedWorkTime;
                 WorkProgressChanged?.Invoke(this, remaining);
             }
             else if (CurrentState == MonitorState.Resting)
             {
                 // 使用计数器计算剩余时间，保持一致性
                 int totalRestSeconds = (int)RestDuration.TotalSeconds;
                 int remainingSeconds = totalRestSeconds - _restElapsedSeconds;
                 if (remainingSeconds < 0) remainingSeconds = 0;
                 TimeSpan remaining = TimeSpan.FromSeconds(remainingSeconds);
                 RestProgressChanged?.Invoke(this, remaining);
             }
        }

        public void Restart()
        {
            _accumulatedWorkTime = TimeSpan.Zero;
            _lastWorkStartTime = DateTime.Now;

            // Ensure timer is running
            if (!_timer.Enabled) _timer.Start();

            // Force state to Working since user manually restarted
            ChangeState(MonitorState.Working);

            // Immediately refresh UI to show full duration
            RefreshStatus();
        }
    }
}