using System;
using System.IO;

namespace NBitcoin.BouncyCastle.Asn1
{
    internal abstract class Asn1Object
        : Asn1Encodable
    {
        /// <summary>Create a base ASN.1 object from a byte array.</summary>
        /// <param name="data">The byte array to parse.</param>
        /// <returns>The base ASN.1 object represented by the byte array.</returns>
        /// <exception cref="IOException">If there is a problem parsing the data.</exception>
        public static Asn1Object FromByteArray(
            byte[] data)
        {
            try
            {
                var input = new MemoryStream(data, false);
                var asn1 = new Asn1InputStream(input, data.Length);
                Asn1Object result = asn1.ReadObject();
                if(input.Position != input.Length)
                    throw new IOException("extra data found after object");
                return result;
            }
            catch(InvalidCastException)
            {
                throw new IOException("cannot recognise object in byte array");
            }
        }

        /// <summary>Read a base ASN.1 object from a stream.</summary>
        /// <param name="inStr">The stream to parse.</param>
        /// <returns>The base ASN.1 object represented by the byte array.</returns>
        /// <exception cref="IOException">If there is a problem parsing the data.</exception>
        public static Asn1Object FromStream(
            Stream inStr)
        {
            try
            {
                return new Asn1InputStream(inStr).ReadObject();
            }
            catch(InvalidCastException)
            {
                throw new IOException("cannot recognise object in stream");
            }
        }

        public sealed override Asn1Object ToAsn1Object()
        {
            return this;
        }

        internal abstract void Encode(DerOutputStream derOut);

        protected abstract bool Asn1Equals(Asn1Object asn1Object);
        protected abstract int Asn1GetHashCode();

        internal bool CallAsn1Equals(Asn1Object obj)
        {
            return Asn1Equals(obj);
        }

        internal int CallAsn1GetHashCode()
        {
            return Asn1GetHashCode();
        }
    }
}
