--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ServerMonitor/Objects/Logger.cs	Mon Dec 31 18:32:14 2018 -0500
@@ -0,0 +1,63 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace ServerMonitorApp
+{
+    public class Logger
+    {
+        private const int logVersion = 1;
+        private readonly string logFile;
+        
+        public Logger(string file)
+        {
+            logFile = file;
+        }
+
+        public async void Log(string logString)
+        {
+            if (!File.Exists(logFile))
+                logString = "Server Monitor log version " + logVersion + Environment.NewLine + logString;
+            using (FileStream stream = new FileStream(logFile, FileMode.Append, FileAccess.Write, FileShare.Read, 4096, true))
+            using (StreamWriter writer = new StreamWriter(stream, Encoding.UTF8))
+            {
+                await writer.WriteLineAsync(logString);
+            }
+        }
+
+        public void Log(CheckResult result)
+        {
+            Log(result.ToLogString());
+        }
+
+        public IList<CheckResult> Read(Server server)
+        {
+            Dictionary<int, Check> checks = server.Checks.ToDictionary(c => c.Id);
+            List<CheckResult> results = new List<CheckResult>();
+            using (FileStream stream = new FileStream(logFile, FileMode.Open, FileAccess.Read, FileShare.Read))
+            using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))
+            {
+                while (true)
+                {
+                    try
+                    {
+                        string line = reader.ReadLine();
+                        if (line == null)
+                            break;
+                        if (int.TryParse(line.Substring(0, 5), out int id) && checks.TryGetValue(id, out Check check))
+                        {
+                            results.Add(CheckResult.FromLogString(check, line));
+                        }
+                    }
+                    catch (Exception) { }
+                }
+            }
+            results.Reverse();
+            return results;
+        }
+    }
+}