// /**
//  * File: Variable.cs
//  * Author: haraldwolff
//  *
//  * This file and it's content is copyrighted by the Author and / or copyright holder.
//  * Any use wihtout proper permission is illegal and may lead to legal actions.
//  *
//  *
//  **/
using System;
using System.IO;
namespace ln.snmp.types
{
    public abstract class Variable
    {
        public Identifier Identifier { get; private set; }

        public Variable(Identifier identifier)
        {
            Identifier = identifier;
        }

        public abstract byte[] Bytes { get; set; }
        public abstract object Value { get; set; }

        public virtual void Write(Stream stream)
        {
            byte[] payload = Bytes;

            BasicEncodingRules.WriteIdentifier(stream,Identifier);
            BasicEncodingRules.WriteLength(stream, payload.Length);
            stream.Write(payload, 0, payload.Length);
        }

        public static Variable Read(Stream stream)
        {
            Variable variable = null;

            Identifier identifier = BasicEncodingRules.ReadIdentifier(stream);
            int length = BasicEncodingRules.ReadLength(stream);
            byte[] payload = new byte[length];
            stream.Read(payload, 0, length);

            variable = FromIdentifier(identifier);
            variable.Bytes = payload;

            return variable;
        }

        public static void Write(Stream stream,Variable variable)
        {
            variable.Write(stream);
        }


        public static Variable FromIdentifier(Identifier identifier)
        {
            if (identifier.IdentifierClass == IdentifierClass.UNIVERSAL)
            {
                switch (identifier.Number)
                {
                    case 0x02:
                        return new Integer();
                    case 0x04:
                        return new OctetString();
                    case 0x05:
                        return NullValue.Instance;
                    case 0x06:
                        return new ObjectIdentifier();
                    case 0x10:
                        return new Sequence();
                }
            } else if (identifier.IdentifierClass == IdentifierClass.CONTEXT)
            {
                switch (identifier.Number)
                {
                    case 0x00:
                        return new GetRequest();
                }
            }

            throw new NotSupportedException(String.Format("Unsupported ASN Type: {0}",identifier));
        }

    }

}