using System;
using System.Collections.Generic;
using M17N.Core;

namespace M17N.Core
{
  public sealed class MSymbol
  {
    private static Dictionary<string, MSymbol> pool
      = new Dictionary<string, MSymbol> ();

    public readonly string Name;
    private MPlist Plist;
    internal MProperty.Flags? flags;

    public static MSymbol nil = MSymbol.Of ("nil");
    public static MSymbol t = MSymbol.Of ("t");
    public static MSymbol symbol = MSymbol.Of ("symbol");
    public static MSymbol mtext = MSymbol.Of ("mtext");
    public static MSymbol plist = MSymbol.Of ("plist");
    public static MSymbol integer = MSymbol.Of ("integer");

    private MSymbol (string name)
    {
      Name = name;
    }

    public static MSymbol Of (string name)
    {
      lock (pool)
	{
	  MSymbol sym;

	  if (! pool.TryGetValue (name, out sym))
	    {
	      sym = new MSymbol (name);
	      pool[name] = sym;
	    }
	  return sym;
	}
    }

    public static MSymbol PropertyKey (string name)
    {
      MSymbol sym = MSymbol.Of (name);

      if (sym.flags == null)
	sym.flags = MProperty.Flags.None;;
      return sym;
    }

    public static MSymbol PropertyKey (string name, MProperty.Flags flags)
    {
      MSymbol sym = MSymbol.Of (name);

      if (sym.flags == null)
	sym.flags = flags;
      else if (sym.flags != flags)
	throw new Exception ("Flags of PropertyKey mismatch");
      return sym;
    }

    public override string ToString ()
    {
      string str = "";

      foreach (char c in Name)
	{
	  if (c == '\\' || c == ' ' || c == '\'' || c == '\"' || c == ':')
	    str += "\\";
	  str += c;
	}
      return str;
    }

    public MPlist Find (MSymbol key)
    {
      return (Plist == null ? null : Plist.Find (key));
    }

    public object Get (MSymbol key)
    {
      return (Plist == null ? null : Plist.Get (key));
    }

    public object Put (MSymbol key, object val)
    {
      if (Plist == null)
	Plist = new MPlist ();
      return Plist.Put (key, val);
    }
  }
}