using System;
using System.Text;

using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Asn1
{
    /**
     * Der UniversalString object.
     */
    public class DerUniversalString
        : DerStringBase
    {
        private static readonly char[] table = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

		private readonly byte[] str;

		/**
         * return a Universal string from the passed in object.
         *
         * @exception ArgumentException if the object cannot be converted.
         */
        public static DerUniversalString GetInstance(
            object obj)
        {
            if (obj == null || obj is DerUniversalString)
            {
                return (DerUniversalString)obj;
            }

            throw new ArgumentException("illegal object in GetInstance: " + Platform.GetTypeName(obj));
        }

        /**
         * return a Universal string from a tagged object.
         *
         * @param obj the tagged object holding the object we want
         * @param explicitly true if the object is meant to be explicitly
         *              tagged false otherwise.
         * @exception ArgumentException if the tagged object cannot
         *               be converted.
         */
        public static DerUniversalString GetInstance(
            Asn1TaggedObject	obj,
            bool				isExplicit)
        {
			Asn1Object o = obj.GetObject();

			if (isExplicit || o is DerUniversalString)
			{
				return GetInstance(o);
			}

			return new DerUniversalString(Asn1OctetString.GetInstance(o).GetOctets());
        }

        /**
         * basic constructor - byte encoded string.
         */
        public DerUniversalString(
            byte[] str)
        {
			if (str == null)
				throw new ArgumentNullException("str");

			this.str = str;
        }

        public override string GetString()
        {
			StringBuilder buffer = new StringBuilder("#");
			byte[] enc = GetDerEncoded();

			for (int i = 0; i != enc.Length; i++)
			{
				uint ubyte = enc[i];
				buffer.Append(table[(ubyte >> 4) & 0xf]);
				buffer.Append(table[enc[i] & 0xf]);
			}

            return buffer.ToString();
        }

		public byte[] GetOctets()
        {
            return (byte[]) str.Clone();
        }

		internal override void Encode(
            DerOutputStream derOut)
        {
            derOut.WriteEncoded(Asn1Tags.UniversalString, this.str);
        }

		protected override bool Asn1Equals(
			Asn1Object asn1Object)
		{
			DerUniversalString other = asn1Object as DerUniversalString;

			if (other == null)
				return false;

//			return this.GetString().Equals(other.GetString());
			return Arrays.AreEqual(this.str, other.str);
        }
    }
}