using System;
using System.IO;
using System.Xml;

namespace Server.Engines.Reports
{
  public abstract class PersistanceReader
  {
    public abstract bool HasChild{ get; }
    public abstract int GetInt32(string key);
    public abstract bool GetBoolean(string key);
    public abstract string GetString(string key);
    public abstract DateTime GetDateTime(string key);

    public abstract bool BeginChildren();
    public abstract void FinishChildren();
    public abstract PersistableObject GetChild();

    public abstract void ReadDocument(PersistableObject root);
    public abstract void Close();
  }

  public class XmlPersistanceReader : PersistanceReader
  {
    private bool m_HasChild;
    private StreamReader m_Reader;
    private string m_Title;

    private bool m_WasEmptyElement;
    private XmlTextReader m_Xml;

    public XmlPersistanceReader(string filePath, string title)
    {
      m_Reader = new StreamReader(filePath);
      m_Xml = new XmlTextReader(m_Reader);
      m_Xml.WhitespaceHandling = WhitespaceHandling.None;
      m_Title = title;
    }

    public override bool HasChild => m_HasChild;

    public override int GetInt32(string key)
    {
      return XmlConvert.ToInt32(m_Xml.GetAttribute(key));
    }

    public override bool GetBoolean(string key)
    {
      return XmlConvert.ToBoolean(m_Xml.GetAttribute(key));
    }

    public override string GetString(string key)
    {
      return m_Xml.GetAttribute(key);
    }

    public override DateTime GetDateTime(string key)
    {
      string val = m_Xml.GetAttribute(key);

      if (val == null)
        return DateTime.MinValue;

      return XmlConvert.ToDateTime(val, XmlDateTimeSerializationMode.Utc);
    }

    public override bool BeginChildren()
    {
      m_HasChild = !m_WasEmptyElement;

      m_Xml.Read();

      return m_HasChild;
    }

    public override void FinishChildren()
    {
      m_Xml.Read();
    }

    public override PersistableObject GetChild()
    {
      PersistableType type = PersistableTypeRegistry.Find(m_Xml.Name);
      PersistableObject obj = type.Constructor();

      m_WasEmptyElement = m_Xml.IsEmptyElement;

      obj.Deserialize(this);

      m_HasChild = m_Xml.NodeType == XmlNodeType.Element;

      return obj;
    }

    public override void ReadDocument(PersistableObject root)
    {
      Console.Write("Reports: {0}: Loading...", m_Title);
      m_Xml.Read();
      m_Xml.Read();
      m_HasChild = !m_Xml.IsEmptyElement;
      root.Deserialize(this);
      Console.WriteLine("done");
    }

    public override void Close()
    {
      m_Xml.Close();
      m_Reader.Close();
    }
  }
}