using System;

using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Asn1.Cms
{
    public class KeyAgreeRecipientIdentifier
		: Asn1Encodable, IAsn1Choice
	{
        public static KeyAgreeRecipientIdentifier GetInstance(object obj)
        {
			if (obj == null)
				return null;

			if (obj is KeyAgreeRecipientIdentifier keyAgreeRecipientIdentifier)
				return keyAgreeRecipientIdentifier;

			if (obj is IssuerAndSerialNumber issuerAndSerialNumber)
				return new KeyAgreeRecipientIdentifier(issuerAndSerialNumber);

            if (obj is Asn1Sequence sequence)
                return new KeyAgreeRecipientIdentifier(IssuerAndSerialNumber.GetInstance(sequence));

            if (obj is Asn1TaggedObject taggedObject)
            {
                if (taggedObject.HasContextTag(0))
                    return new KeyAgreeRecipientIdentifier(RecipientKeyIdentifier.GetInstance(taggedObject, false));
            }

			throw new ArgumentException("Invalid KeyAgreeRecipientIdentifier: " + Platform.GetTypeName(obj), nameof(obj));
        }

        public static KeyAgreeRecipientIdentifier GetInstance(Asn1TaggedObject obj, bool isExplicit)
		{
            return Asn1Utilities.GetInstanceFromChoice(obj, isExplicit, GetInstance);
		}

		private readonly IssuerAndSerialNumber m_issuerSerial;
		private readonly RecipientKeyIdentifier m_rKeyID;

        public KeyAgreeRecipientIdentifier(IssuerAndSerialNumber issuerSerial)
        {
            m_issuerSerial = issuerSerial ?? throw new ArgumentNullException(nameof(issuerSerial));
        }

        public KeyAgreeRecipientIdentifier(RecipientKeyIdentifier rKeyID)
        {
            m_rKeyID = rKeyID ?? throw new ArgumentNullException(nameof(rKeyID));
        }

		public IssuerAndSerialNumber IssuerAndSerialNumber => m_issuerSerial;

		public RecipientKeyIdentifier RKeyID => m_rKeyID;

		/** 
		 * Produce an object suitable for an Asn1OutputStream.
		 * <pre>
		 * KeyAgreeRecipientIdentifier ::= CHOICE {
		 *     issuerAndSerialNumber IssuerAndSerialNumber,
		 *     rKeyId [0] IMPLICIT RecipientKeyIdentifier
		 * }
		 * </pre>
		 */
		public override Asn1Object ToAsn1Object()
		{
			if (m_issuerSerial != null)
				return m_issuerSerial.ToAsn1Object();

			return new DerTaggedObject(false, 0, m_rKeyID);
		}
	}
}