From 99ded566559941b8a51cbf8a9b3ee1e35b9510e6 Mon Sep 17 00:00:00 2001
From: Daniel-I-Am <djdecloet@gmail.com>
Date: Thu, 4 Jun 2020 17:51:21 +0200
Subject: [PATCH] Add Timer service

---
 ChaosBot/Services/Timer.cs | 117 +++++++++++++++++++++++++++++++++++++
 1 file changed, 117 insertions(+)
 create mode 100644 ChaosBot/Services/Timer.cs

diff --git a/ChaosBot/Services/Timer.cs b/ChaosBot/Services/Timer.cs
new file mode 100644
index 0000000..2300a17
--- /dev/null
+++ b/ChaosBot/Services/Timer.cs
@@ -0,0 +1,117 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace ChaosBot.Services
+{
+    public static class Timer
+    {
+        private static Dictionary<int, System.Threading.Timer> _timers = new Dictionary<int, System.Threading.Timer>();
+
+        private static int _nextTimerIndex = 0;
+        private static int NextTimerIndex
+        {
+            get
+            {
+                _nextTimerIndex++;
+                return _nextTimerIndex;
+            }
+        }
+        
+        public static int RunAt(Action toRun, DateTime deadlineTime)
+        {
+            DateTime current = DateTime.Now;
+            TimeSpan timeToGo = deadlineTime - current;
+            if (timeToGo < TimeSpan.Zero)
+            {
+                return -1; //time already passed
+            }
+
+            int timerIndex = NextTimerIndex;
+            _timers.Add(timerIndex, new System.Threading.Timer(x =>
+            {
+                toRun();
+                _timers.Remove(timerIndex);
+            }, null, timeToGo, Timeout.InfiniteTimeSpan));
+
+            return timerIndex;
+        }
+
+        public static int RunIn(Action toRun, TimeSpan dueTime)
+        {
+            DateTime current = DateTime.Now;
+            if (dueTime < TimeSpan.Zero)
+            {
+                return -1; //time already passed
+            }
+
+            int timerIndex = NextTimerIndex;
+            _timers.Add(timerIndex, new System.Threading.Timer(x =>
+            {
+                toRun();
+                _timers.Remove(timerIndex);
+            }, null, dueTime, Timeout.InfiniteTimeSpan));
+
+            return timerIndex;
+        }
+
+        public static int RunTimer(Action toRun, TimeSpan interval)
+        {
+            return RunTimer(toRun, interval, TimeSpan.Zero);
+        }
+
+        public static int RunTimer(Action toRun, TimeSpan interval, TimeSpan offset)
+        {
+            DateTime current = DateTime.Now;
+            if (offset < TimeSpan.Zero)
+            {
+                return -1; //time already passed
+            }
+
+            int timerIndex = NextTimerIndex;
+
+            void Callback()
+            {
+                toRun();
+
+                if (_timers.ContainsKey(timerIndex))
+                    _timers.Remove(timerIndex);
+                _timers.Add(timerIndex, new System.Threading.Timer(x => { Callback(); }, null, interval, Timeout.InfiniteTimeSpan));
+            }
+
+            if (offset > TimeSpan.Zero)
+            {
+                _timers.Add(timerIndex, new System.Threading.Timer(x => { Callback(); }, null, offset, Timeout.InfiniteTimeSpan));
+            }
+            else
+            {
+                Callback();
+            }
+
+            return timerIndex;
+        }
+
+        public static void CancelTimer(int id)
+        {
+            if (id < 0) return;
+
+            if (!_timers.ContainsKey(id)) return;
+
+            _timers.GetValueOrDefault(id)?.Dispose();
+
+            if (_timers.ContainsKey(id))
+                _timers.Remove(id);
+        }
+
+        public static void Join(int id)
+        {
+            if (id < 0) return;
+            
+            while (_timers.ContainsKey(id))
+            {
+                Thread.Sleep(500);
+            }
+        }
+    }
+}
\ No newline at end of file