// DataflowMessageHeader.cs
//
// Copyright (c) 2011 Jérémie "garuma" Laval
// Copyright (c) 2012 Petr Onderka
//
// 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.

namespace System.Threading.Tasks.Dataflow {
	public struct DataflowMessageHeader : IEquatable<DataflowMessageHeader> {
		readonly long id;

		public DataflowMessageHeader (long id)
		{
			if (id == 0)
				throw new ArgumentException("The value of 0 can't be used as an id for a valid header.");

			this.id = id;
		}

		public long Id {
			get {
				return id;
			}
		}

		public bool IsValid {
			get {
				return id != 0;
			}
		}

		public override bool Equals (object obj)
		{
			return obj is DataflowMessageHeader && Equals ((DataflowMessageHeader)obj);
		}

		public bool Equals (DataflowMessageHeader other)
		{
			return other.id == id;
		}

		public override int GetHashCode ()
		{
			return id.GetHashCode ();
		}

		public static bool operator== (DataflowMessageHeader left, DataflowMessageHeader right)
		{
			return left.Equals (right);
		}

		public static bool operator!= (DataflowMessageHeader left, DataflowMessageHeader right)
		{
			return !left.Equals (right);
		}
	}
}