/*

  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 string[] identifiers;

    private ISensor[] sensors;

    private DateTime lastLoggedTime = DateTime.MinValue;

    public Logger(IComputer computer) {

      this.computer = computer;

      this.computer.HardwareAdded += HardwareAdded;

      this.computer.HardwareRemoved += HardwareRemoved;      

    }

    private void HardwareRemoved(IHardware hardware) {

      hardware.SensorAdded -= SensorAdded;

      hardware.SensorRemoved -= SensorRemoved;

      foreach (ISensor sensor in hardware.Sensors)

        SensorRemoved(sensor);

      foreach (IHardware subHardware in hardware.SubHardware)

        HardwareRemoved(subHardware);

    }

    private void HardwareAdded(IHardware hardware) {

      foreach (ISensor sensor in hardware.Sensors)

        SensorAdded(sensor);

      hardware.SensorAdded += SensorAdded;

      hardware.SensorRemoved += SensorRemoved;

      foreach (IHardware subHardware in hardware.SubHardware)

        HardwareAdded(subHardware);

    }

    private void SensorAdded(ISensor sensor) {

      if (sensors == null)

        return;

      for (int i = 0; i < sensors.Length; i++) {

        if (sensor.Identifier.ToString() == identifiers[i])

          sensors[i] = sensor;

      }

    }

    private void SensorRemoved(ISensor sensor) {

      if (sensors == null)

        return;

      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 bool OpenExistingLogFile() {

      if (!File.Exists(fileName))

        return false;

      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 {

        identifiers = null;

        return false;

      }

      if (identifiers.Length == 0) {

        identifiers = null;

        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();

      identifiers = sensors.Select(s => s.Identifier.ToString()).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 TimeSpan LoggingInterval { get; set; }

    public void Log() {      

      var now = DateTime.Now;

      if (lastLoggedTime + LoggingInterval - new TimeSpan(5000000) > now)

        return;      

      if (day != now.Date || !File.Exists(fileName)) {

        day = now.Date;

        fileName = GetFileName(day);

        if (!OpenExistingLogFile())

          CreateNewLogFile();

      }

      try {

        using (StreamWriter writer = new StreamWriter(new FileStream(fileName,

          FileMode.Append, FileAccess.Write, FileShare.ReadWrite))) {

          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();

          }

        }

      } catch (IOException) { }

      lastLoggedTime = now;

    }

  }

}