/*

  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) 2009-2012 Michael Möller <mmoeller@openhardwaremonitor.org>

*/

using System;

using System.Collections.Generic;

using System.Globalization;

using System.IO;

using System.IO.Compression;

using OpenHardwareMonitor.Collections;

namespace OpenHardwareMonitor.Hardware {

  internal class Sensor : ISensor {

    private readonly string defaultName;

    private string name;

    private readonly int index;

    private readonly bool defaultHidden;

    private readonly SensorType sensorType;

    private readonly Hardware hardware;

    private readonly ReadOnlyArray<IParameter> parameters;

    private float? currentValue;

    private float? minValue;

    private float? maxValue;

    private readonly RingCollection<SensorValue> 

      values = new RingCollection<SensorValue>();

    private readonly ISettings settings;

    private IControl control;

    private float sum;

    private int count;

    public Sensor(string name, int index, SensorType sensorType,

      Hardware hardware, ISettings settings) : 

      this(name, index, sensorType, hardware, null, settings) { }

    public Sensor(string name, int index, SensorType sensorType,

      Hardware hardware, ParameterDescription[] parameterDescriptions, 

      ISettings settings) :

      this(name, index, false, sensorType, hardware,

        parameterDescriptions, settings) { }

    public Sensor(string name, int index, bool defaultHidden, 

      SensorType sensorType, Hardware hardware, 

      ParameterDescription[] parameterDescriptions, ISettings settings) 

    {           

      this.index = index;

      this.defaultHidden = defaultHidden;

      this.sensorType = sensorType;

      this.hardware = hardware;

      Parameter[] parameters = new Parameter[parameterDescriptions == null ?

        0 : parameterDescriptions.Length];

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

        parameters[i] = new Parameter(parameterDescriptions[i], this, settings);

      this.parameters = parameters;

      this.settings = settings;

      this.defaultName = name; 

      this.name = settings.GetValue(

        new Identifier(Identifier, "name").ToString(), name);

      GetSensorValuesFromSettings();      

      hardware.Closing += delegate(IHardware h) {

        SetSensorValuesToSettings();

      };

    }

    private void SetSensorValuesToSettings() {

      using (MemoryStream m = new MemoryStream()) {

        using (GZipStream c = new GZipStream(m, CompressionMode.Compress))

        using (BufferedStream b = new BufferedStream(c, 65536))

        using (BinaryWriter writer = new BinaryWriter(b)) {

          long t = 0;

          foreach (SensorValue sensorValue in values) {

            long v = sensorValue.Time.ToBinary();

            writer.Write(v - t);

            t = v;

            writer.Write(sensorValue.Value);

          }

          writer.Flush();

        }

        settings.SetValue(new Identifier(Identifier, "values").ToString(),

          Convert.ToBase64String(m.ToArray()));

      }

    }

    private void GetSensorValuesFromSettings() {

      string name = new Identifier(Identifier, "values").ToString();

      string s = settings.GetValue(name, null);

      try {

        byte[] array = Convert.FromBase64String(s);

        s = null;

        using (MemoryStream m = new MemoryStream(array))

        using (GZipStream c = new GZipStream(m, CompressionMode.Decompress))

        using (BinaryReader reader = new BinaryReader(c)) {

          try {

            long t = 0;

            while (true) {

              t += reader.ReadInt64();

              DateTime time = DateTime.FromBinary(t);              

              float value = reader.ReadSingle();

              AppendValue(value, time);

            }

          } catch (EndOfStreamException) { }

        }

      } catch { }

      if (values.Count > 0)

        AppendValue(float.NaN, DateTime.UtcNow);

      // remove the value string from the settings to reduce memory usage

      settings.Remove(name);

    }

    private void AppendValue(float value, DateTime time) {

      if (values.Count >= 2 && values.Last.Value == value && 

        values[values.Count - 2].Value == value) {

        values.Last = new SensorValue(value, time);

        return;

      } 

      values.Append(new SensorValue(value, time));

    }

    public IHardware Hardware {

      get { return hardware; }

    }

    public SensorType SensorType {

      get { return sensorType; }

    }

    public Identifier Identifier {

      get {

        return new Identifier(hardware.Identifier,

          sensorType.ToString().ToLowerInvariant(),

          index.ToString(CultureInfo.InvariantCulture));

      }

    }

    public string Name {

      get { 

        return name; 

      }

      set {

        if (!string.IsNullOrEmpty(value)) 

          name = value;          

        else 

          name = defaultName;

        settings.SetValue(new Identifier(Identifier, "name").ToString(), name);

      }

    }

    public int Index {

      get { return index; }

    }

    public bool IsDefaultHidden {

      get { return defaultHidden; }

    }

    public IReadOnlyArray<IParameter> Parameters {

      get { return parameters; }

    }

    public float? Value {

      get { 

        return currentValue; 

      }

      set {

        DateTime now = DateTime.UtcNow;

        while (values.Count > 0 && (now - values.First.Time).TotalDays > 1)

          values.Remove();

        if (value.HasValue) {

          sum += value.Value;

          count++;

          if (count == 4) {

            AppendValue(sum / count, now);

            sum = 0;

            count = 0;

          }

        }

        this.currentValue = value;

        if (minValue > value || !minValue.HasValue)

          minValue = value;

        if (maxValue < value || !maxValue.HasValue)

          maxValue = value;

      }

    }

    public float? Min { get { return minValue; } }

    public float? Max { get { return maxValue; } }

    public void ResetMin() {

      minValue = null;

    }

    public void ResetMax() {

      maxValue = null;

    }

    public IEnumerable<SensorValue> Values {

      get { return values; }

    }    

    public void Accept(IVisitor visitor) {

      if (visitor == null)

        throw new ArgumentNullException("visitor");

      visitor.VisitSensor(this);

    }

    public void Traverse(IVisitor visitor) {

      foreach (IParameter parameter in parameters)

        parameter.Accept(visitor);

    }

    public IControl Control {

      get {

        return control;

      }

      internal set {

        this.control = value;

      }

    }

  }

}