//-----------------------------------------------------------------------
// <copyright file="DataBag.cs" company="Outercurve Foundation">
//     Copyright (c) Outercurve Foundation. All rights reserved.
// </copyright>
//-----------------------------------------------------------------------

namespace DotNetOpenAuth.Messaging {
	using System;
	using System.Collections.Generic;
	using System.Diagnostics.CodeAnalysis;
	using System.Diagnostics.Contracts;

	/// <summary>
	/// A collection of message parts that will be serialized into a single string,
	/// to be set into a larger message.
	/// </summary>
	public abstract class DataBag : IMessage {
		/// <summary>
		/// The default version for DataBags.
		/// </summary>
		private static readonly Version DefaultVersion = new Version(1, 0);

		/// <summary>
		/// The backing field for the <see cref="IMessage.Version"/> property.
		/// </summary>
		private Version version;

		/// <summary>
		/// A dictionary to contain extra message data.
		/// </summary>
		private Dictionary<string, string> extraData = new Dictionary<string, string>();

		/// <summary>
		/// Initializes a new instance of the <see cref="DataBag"/> class.
		/// </summary>
		protected DataBag()
			: this(DefaultVersion) {
		}

		/// <summary>
		/// Initializes a new instance of the <see cref="DataBag"/> class.
		/// </summary>
		/// <param name="version">The DataBag version.</param>
		protected DataBag(Version version) {
			Requires.NotNull(version, "version");
			this.version = version;
		}

		#region IMessage Properties

		/// <summary>
		/// Gets the version of the protocol or extension this message is prepared to implement.
		/// </summary>
		/// <remarks>
		/// Implementations of this interface should ensure that this property never returns null.
		/// </remarks>
		Version IMessage.Version {
			get { return this.version; }
		}

		/// <summary>
		/// Gets the extra, non-standard Protocol parameters included in the message.
		/// </summary>
		/// <value></value>
		/// <remarks>
		/// Implementations of this interface should ensure that this property never returns null.
		/// </remarks>
		public IDictionary<string, string> ExtraData {
			get { return this.extraData; }
		}

		#endregion

		/// <summary>
		/// Gets or sets the nonce.
		/// </summary>
		/// <value>The nonce.</value>
		[MessagePart]
		internal byte[] Nonce { get; set; }

		/// <summary>
		/// Gets or sets the UTC creation date of this token.
		/// </summary>
		/// <value>The UTC creation date.</value>
		[MessagePart("ts", IsRequired = true, Encoder = typeof(TimestampEncoder))]
		internal DateTime UtcCreationDate { get; set; }

		/// <summary>
		/// Gets or sets the signature.
		/// </summary>
		/// <value>The signature.</value>
		internal byte[] Signature { get; set; }

		/// <summary>
		/// Gets or sets the message that delivered this DataBag instance to this host.
		/// </summary>
		protected internal IProtocolMessage ContainingMessage { get; set; }

		/// <summary>
		/// Gets the type of this instance.
		/// </summary>
		/// <value>The type of the bag.</value>
		/// <remarks>
		/// This ensures that one token cannot be misused as another kind of token.
		/// </remarks>
		[SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode", Justification = "Accessed by reflection")]
		[MessagePart("t", IsRequired = true, AllowEmpty = false)]
		protected virtual Type BagType {
			get { return this.GetType(); }
		}

		#region IMessage Methods

		/// <summary>
		/// Checks the message state for conformity to the protocol specification
		/// and throws an exception if the message is invalid.
		/// </summary>
		/// <remarks>
		/// 	<para>Some messages have required fields, or combinations of fields that must relate to each other
		/// in specialized ways.  After deserializing a message, this method checks the state of the
		/// message to see if it conforms to the protocol.</para>
		/// 	<para>Note that this property should <i>not</i> check signatures or perform any state checks
		/// outside this scope of this particular message.</para>
		/// </remarks>
		/// <exception cref="ProtocolException">Thrown if the message is invalid.</exception>
		void IMessage.EnsureValidMessage() {
			this.EnsureValidMessage();
		}

		#endregion

		/// <summary>
		/// Checks the message state for conformity to the protocol specification
		/// and throws an exception if the message is invalid.
		/// </summary>
		/// <remarks>
		/// 	<para>Some messages have required fields, or combinations of fields that must relate to each other
		/// in specialized ways.  After deserializing a message, this method checks the state of the
		/// message to see if it conforms to the protocol.</para>
		/// 	<para>Note that this property should <i>not</i> check signatures or perform any state checks
		/// outside this scope of this particular message.</para>
		/// </remarks>
		/// <exception cref="ProtocolException">Thrown if the message is invalid.</exception>
		protected virtual void EnsureValidMessage() {
		}
	}
}