/*
 
  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();
        }
      }

    }
  }
}