diff -r 07d44b20bbd4 -r 46c056e76130 Utilities/Logger.cs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Utilities/Logger.cs	Sun Aug 11 21:26:56 2013 +0000
@@ -0,0 +1,169 @@
+/*
+ 
+  This Source Code Form is subject to the terms of the Mozilla Public
+  License, v. 2.0. If a copy of the MPL was not distributed with this
+  file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ 
+	Copyright (C) 2013 Michael Möller <mmoeller@openhardwaremonitor.org>
+
+*/
+
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.IO;
+using System.Linq;
+using OpenHardwareMonitor.Hardware;
+
+namespace OpenHardwareMonitor.Utilities {
+  public class Logger {
+
+    private const string fileNameFormat = 
+      "OpenHardwareMonitorLog-{0:yyyy-MM-dd}.csv";
+
+    private readonly IComputer computer;
+
+    private DateTime day = DateTime.MinValue;
+    private string fileName;
+    private ISensor[] sensors;
+
+    public Logger(IComputer computer) {
+      this.computer = computer;
+      this.computer.HardwareAdded += HardwareAdded;
+      this.computer.HardwareRemoved += HardwareRemoved;    
+    }
+
+    private void HardwareRemoved(IHardware hardware) {
+      hardware.SensorRemoved -= SensorRemoved;
+      foreach (ISensor sensor in hardware.Sensors)
+        SensorRemoved(sensor);
+      foreach (IHardware subHardware in hardware.SubHardware)
+        HardwareRemoved(subHardware);
+    }
+
+    private void HardwareAdded(IHardware hardware) {
+      hardware.SensorRemoved += SensorRemoved;
+      foreach (IHardware subHardware in hardware.SubHardware)
+        HardwareAdded(subHardware);
+    }
+
+    private void SensorRemoved(ISensor sensor) {
+      for (int i = 0; i < sensors.Length; i++) {
+        if (sensor == sensors[i])
+          sensors[i] = null;
+      }
+    }
+
+    private static string GetFileName(DateTime date) {
+      return AppDomain.CurrentDomain.BaseDirectory +
+        Path.DirectorySeparatorChar + string.Format(fileNameFormat, date);
+    }
+
+    private void AddSensorRemovedHandler() {
+      for (int i = 0; i < sensors.Length; i++) {
+        ISensor sensor = sensors[i];
+        int index = i;
+        SensorEventHandler handler = null;        
+        handler = s => {
+          if (s != sensor) 
+            return;
+
+          sensors[index] = null;
+          sensor.Hardware.SensorRemoved -= handler;          
+        };
+        sensor.Hardware.SensorRemoved += handler;
+      }
+    }
+
+    private bool OpenExistingLogFile() {
+      if (!File.Exists(fileName))
+        return false;
+
+      string[] identifiers;
+      try {
+        String line;
+        using (StreamReader reader = new StreamReader(fileName)) 
+          line = reader.ReadLine(); 
+       
+        if (string.IsNullOrEmpty(line))
+          return false;
+        
+        identifiers = line.Split(',').Skip(1).ToArray();
+      } catch {
+        return false;
+      }
+
+      if (identifiers.Length == 0)
+        return false;
+
+      sensors = new ISensor[identifiers.Length];
+      SensorVisitor visitor = new SensorVisitor(sensor => {
+        for (int i = 0; i < identifiers.Length; i++)
+          if (sensor.Identifier.ToString() == identifiers[i])
+            sensors[i] = sensor;
+      });
+      visitor.VisitComputer(computer);
+      return true;
+    }
+
+    private void CreateNewLogFile() {
+      IList<ISensor> list = new List<ISensor>();
+      SensorVisitor visitor = new SensorVisitor(sensor => {
+        list.Add(sensor);
+      });
+      visitor.VisitComputer(computer);
+      sensors = list.ToArray();      
+
+      using (StreamWriter writer = new StreamWriter(fileName, false)) {
+        writer.Write(",");
+        for (int i = 0; i < sensors.Length; i++) {
+          writer.Write(sensors[i].Identifier);
+          if (i < sensors.Length - 1)
+            writer.Write(",");
+          else
+            writer.WriteLine();
+        }
+
+        writer.Write("Time,");
+        for (int i = 0; i < sensors.Length; i++) {
+          writer.Write('"');
+          writer.Write(sensors[i].Name);
+          writer.Write('"');
+          if (i < sensors.Length - 1)
+            writer.Write(",");
+          else
+            writer.WriteLine();
+        }
+      }
+    }
+
+    public void Log() {
+      var now = DateTime.Now;
+      if (day != now.Date) {
+        day = now.Date;
+        fileName = GetFileName(day);
+
+        if (!OpenExistingLogFile())
+          CreateNewLogFile();
+      }
+
+      using (StreamWriter writer = new StreamWriter(fileName, true)) {
+        writer.Write(now.ToString("G", CultureInfo.InvariantCulture));
+        writer.Write(",");
+        for (int i = 0; i < sensors.Length; i++) {
+          if (sensors[i] != null) {
+            float? value = sensors[i].Value;
+            if (value.HasValue)
+              writer.Write(
+                value.Value.ToString("R", CultureInfo.InvariantCulture));
+          }
+          if (i < sensors.Length - 1)
+            writer.Write(",");
+          else
+            writer.WriteLine();
+        }
+      }
+
+    }
+  }
+}