using System;
using System.Diagnostics;
using System.Timers;

namespace WebMvcEF
{
    /// <summary>
    /// 監控程序是否卡死
    /// </summary>
    public sealed class ProcessKiller : IDisposable
    {
        private readonly Timer Timer;
        private Process[] ProcessList;
        private readonly string ProcessName;

        public static ProcessKiller StartNew(string processName, int interval)
        {
            var process = new ProcessKiller(processName, interval);
            process.Start();
            return process;
        }

        /// <summary>
        /// 產生計時器去監控指定程序
        /// </summary>
        /// <param name="processName">程序名稱</param>
        /// <param name="interval">每幾秒檢查一次</param>
        private ProcessKiller(string processName, int interval)
        {
            // 設定時間及監控程序名
            Timer = new Timer(interval * 1000);
            ProcessList = Array.Empty<Process>();
            ProcessName = processName;

            // 計時檢查程序卡死問題
            Timer.Elapsed += new ElapsedEventHandler(CheckProcess);
            Timer.AutoReset = true;
        }

        private void CheckProcess(object sender, ElapsedEventArgs e)
        {
            // 判斷是不是為空
            if (ProcessList.Length >= 1)
            {
                // 把當下電腦執行soffice取回來
                var currentProcesses = Process.GetProcessesByName(ProcessName);

                if (currentProcesses.Length > 0)
                {
                    try
                    {
                        // 把上次抓的List跟當下抓的List做比對
                        for (var i = 0; i < ProcessList.Length; i++)
                        {
                            for (var j = 0; j < currentProcesses.Length; j++)
                            {
                                // 如果有相同id的就刪除
                                if (ProcessList[i].Id == currentProcesses[j].Id)
                                {
                                    ProcessList[i].Kill();
                                    break;
                                }
                            }
                        }
                    }
                    catch (Exception)
                    {
                        // 關不掉也沒關係
                    }
                }
            }
            // 重抓一次程序，下一次可以比對
            ProcessList = Process.GetProcessesByName(ProcessName);
        }

        public void Start()
        {
            Timer.Start();
        }

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

        public void Dispose()
        {
            Timer?.Dispose();
        }
    }
}