// SNMP variable binding type.
// Copyright (C) 2008-2010 Malcolm Crowe, Lex Li, and other contributors.
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

/*
 * Created by SharpDevelop.
 * User: lextm
 * Date: 2008/4/25
 * Time: 20:30
 * 
 * To change this template use Tools | Options | Coding | Edit Standard Headers.
 */

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;

namespace GSF.Net.Snmp
{
    /// <summary>
    /// Variable bind.
    /// </summary>
    /// <remarks>
    /// <para>Represents SNMP variable bind.</para>
    /// </remarks>
    public sealed class Variable
    {
        /// <summary>
        /// Creates a <see cref="Variable"/> instance with a specific <see cref="ObjectIdentifier"/>.
        /// </summary>
        /// <param name="id">Object identifier</param>
        public Variable(ObjectIdentifier id) : this(id, null)     
        { 
        }
      
        /// <summary>
        /// Creates a <see cref="Variable"/> instance with a specific object identifier.
        /// </summary>
        /// <param name="id">Object identifier</param>
        [CLSCompliant(false)]
        public Variable(uint[] id) : this(new ObjectIdentifier(id)) 
        {
        }
        
        /// <summary>
        /// Creates a <see cref="Variable"/> instance with a specific <see cref="ObjectIdentifier"/> and <see cref="ISnmpData"/>.
        /// </summary>
        /// <param name="id">Object identifier</param>
        /// <param name="data">Data</param>
        /// <remarks>If you set <c>null</c> to <paramref name="data"/>, you get a <see cref="Variable"/> instance whose <see cref="Data"/> is a <see cref="Null"/> instance.</remarks>
        [CLSCompliant(false)]
        public Variable(uint[] id, ISnmpData data) : this(new ObjectIdentifier(id), data) 
        { 
        }
        
        /// <summary>
        /// Creates a <see cref="Variable"/> instance with a specific object identifier and data.
        /// </summary>
        /// <param name="id">Object identifier</param>
        /// <param name="data">Data</param>
        /// <remarks>If you set <c>null</c> to <paramref name="data"/>, you get a <see cref="Variable"/> instance whose <see cref="Data"/> is a <see cref="Null"/> instance.</remarks>
        public Variable(ObjectIdentifier id, ISnmpData data)
        {
            if (id == null)
            {
                throw new ArgumentNullException(nameof(id));
            }

            Id = id;
            Data = data ?? new Null();
        }

        /// <summary>
        /// Variable object identifier.
        /// </summary>
        public ObjectIdentifier Id { get; private set; }

        /// <summary>
        /// Variable data.
        /// </summary>
        public ISnmpData Data { get; private set; }

        /// <summary>
        /// Converts variable binds section to variable binds list.
        /// </summary>
        /// <param name="varbindSection"></param>
        /// <returns></returns>
        internal static IList<Variable> Transform(Sequence varbindSection)
        {
            if (varbindSection == null)
            {
                throw new ArgumentNullException(nameof(varbindSection));
            }

            IList<Variable> result = new List<Variable>(varbindSection.Length);
            foreach (ISnmpData item in varbindSection)
            {
                if (item.TypeCode != SnmpType.Sequence)
                {
                    throw new ArgumentException($"Invalid varbind section data type: {item.TypeCode}.", nameof(varbindSection));
                }
                
                Sequence varbind = (Sequence)item;
                if (varbind.Length != 2)
                {
                    throw new ArgumentException($"Invalid varbind data length: {varbind.Length}.", nameof(varbindSection));
                }
                
                if (varbind[0].TypeCode != SnmpType.ObjectIdentifier)
                {
                    throw new ArgumentException($"Invalid varbind first data type: {varbind[0].TypeCode}.", nameof(varbindSection));
                }
                    
                result.Add(new Variable((ObjectIdentifier)varbind[0], varbind[1]));
            }
            
            return result;
        }
        
        /// <summary>
        /// Converts variable binds to variable binds section.
        /// </summary>
        /// <param name="variables"></param>
        /// <returns></returns>
        internal static Sequence Transform(IList<Variable> variables)
        {
            // TODO: use IEnumerable instead of IList.
            if (variables == null)
            {
                throw new ArgumentNullException(nameof(variables));
            }

            List<ISnmpData> varbinds = new List<ISnmpData>(variables.Count);
            varbinds.AddRange(variables.Select(v => new Sequence(null, v.Id, v.Data)).Cast<ISnmpData>());

            Sequence result = new Sequence(varbinds);
            return result;
        }
        
        /// <summary>
        /// Returns a <see cref="string"/> that represents this <see cref="Variable"/>.
        /// </summary>
        /// <returns></returns>
        public override string ToString()
        {
            return string.Format(CultureInfo.InvariantCulture, "Variable: Id: {0}; Data: {1}", Id, Data);
        }
    }
}