using System;
using System.Collections.Generic;

using Org.BouncyCastle.Asn1.Nist;
using Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Asn1.X509;

using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Asn1.Smime
{
    /**
     * Handler class for dealing with S/MIME Capabilities
     */
    public class SmimeCapabilities
        : Asn1Encodable
    {
        /**
         * general preferences
         */
        public static readonly DerObjectIdentifier PreferSignedData = PkcsObjectIdentifiers.PreferSignedData;
        public static readonly DerObjectIdentifier CannotDecryptAny = PkcsObjectIdentifiers.CannotDecryptAny;
        public static readonly DerObjectIdentifier SmimeCapabilitesVersions = PkcsObjectIdentifiers.SmimeCapabilitiesVersions;

		/**
         * encryption algorithms preferences
         */
        public static readonly DerObjectIdentifier Aes256Cbc = NistObjectIdentifiers.IdAes256Cbc;
        public static readonly DerObjectIdentifier Aes192Cbc = NistObjectIdentifiers.IdAes192Cbc;
        public static readonly DerObjectIdentifier Aes128Cbc = NistObjectIdentifiers.IdAes128Cbc;
        public static readonly DerObjectIdentifier IdeaCbc = new DerObjectIdentifier("1.3.6.1.4.1.188.7.1.1.2");
        public static readonly DerObjectIdentifier Cast5Cbc = new DerObjectIdentifier("1.2.840.113533.7.66.10");
        public static readonly DerObjectIdentifier DesCbc = new DerObjectIdentifier("1.3.14.3.2.7");
        public static readonly DerObjectIdentifier DesEde3Cbc = PkcsObjectIdentifiers.DesEde3Cbc;
        public static readonly DerObjectIdentifier RC2Cbc = PkcsObjectIdentifiers.RC2Cbc;

		private Asn1Sequence capabilities;

		/**
         * return an Attr object from the given object.
         *
         * @param o the object we want converted.
         * @exception ArgumentException if the object cannot be converted.
         */
        public static SmimeCapabilities GetInstance(
            object obj)
        {
            if (obj == null || obj is SmimeCapabilities)
            {
                return (SmimeCapabilities) obj;
            }

			if (obj is Asn1Sequence)
            {
                return new SmimeCapabilities((Asn1Sequence) obj);
            }

			if (obj is AttributeX509)
            {
                return new SmimeCapabilities(
                    (Asn1Sequence)(((AttributeX509) obj).AttrValues[0]));
            }

            throw new ArgumentException("unknown object in factory: " + Platform.GetTypeName(obj), "obj");
        }

		public SmimeCapabilities(
            Asn1Sequence seq)
        {
            capabilities = seq;
        }

        /**
         * returns an ArrayList with 0 or more objects of all the capabilities
         * matching the passed in capability Oid. If the Oid passed is null the
         * entire set is returned.
         */
        public IList<SmimeCapability> GetCapabilitiesForOid(DerObjectIdentifier capability)
        {
            var list = new List<SmimeCapability>();
            DoGetCapabilitiesForOid(capability, list);
			return list;
        }

        private void DoGetCapabilitiesForOid(DerObjectIdentifier capability, IList<SmimeCapability> list)
        {
            foreach (object o in capabilities)
            {
                SmimeCapability cap = SmimeCapability.GetInstance(o);

                if (capability == null || capability.Equals(cap.CapabilityID))
                {
                    list.Add(cap);
                }
            }
        }

        /**
         * Produce an object suitable for an Asn1OutputStream.
         * <pre>
         * SMIMECapabilities ::= Sequence OF SMIMECapability
         * </pre>
         */
        public override Asn1Object ToAsn1Object()
        {
            return capabilities;
        }
    }
}