using System;
using System.Text;

namespace GemCard
{
	/// <summary>
	/// This class represents the APDU response sent by the card
	/// </summary>
	public class APDUResponse
	{
		/// <summary>
		///	Status bytes length
		/// </summary>
		public const int SW_LENGTH = 2;

        /// <summary>
        /// Response data. Contains the data sent by the card minus the 2 status bytes (SW1, SW2)
        /// null if no data were sent by the card
        /// </summary>
        public byte[] Data;
        public byte SW1;
        public byte SW2;

        /// <summary>
        /// Status get property
        /// </summary>
        public ushort Status
        {
            get { return (ushort)(((short)SW1 << 8) + (short)SW2); }
        }

		/// <summary>
		/// Constructor from the byte data sent back by the card
		/// </summary>
		/// <param name="baData">Buffer of data from the card</param>
		public APDUResponse(byte[] baData)
		{
			if (baData.Length > SW_LENGTH)
			{
				Data = new byte[baData.Length - SW_LENGTH];

                for (int nI = 0; nI < baData.Length - SW_LENGTH; nI++)
                {
                    this.Data[nI] = baData[nI];
                }
			}

            this.SW1 = baData[baData.Length - 2];
            this.SW2 = baData[baData.Length - 1];
		}

        /// <summary>
        /// Overrides the ToString method to format to a string the APDUResponse object
        /// </summary>
        /// <returns></returns>
        public override string ToString()
        {
            if (Data != null)
            {
                StringBuilder sData = new StringBuilder(Data.Length * 2);
                for (int nI = 0; nI < Data.Length; nI++)
                {
                    sData.AppendFormat("{0:X02}", Data[nI]);
                }

                return sData.ToString();
            }
            else
            {
                return string.Empty;
            }
        }
	}
}