/*
 * Graph.cs
 * Authors:
 * Copyright (c) 2007-2008 Cornell University

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2
 of the License, or (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/

using System;
using System.Collections.Generic;
using System.Text;
using ColonySim.Structures;

namespace ColonySim.Graphs
{
	/// <summary>
	/// Represents the graph that makes up the connections for mapping the
	/// flow and gathering of resources through the Colony.
	/// </summary>
	internal abstract class Graph
	{
		#region Fields

		// The list of all nodes in the graph
		protected List<Node> mNodes = new List<Node>();

		#endregion

		#region Collection

		/// <summary>
		/// Add the node to the graph.
		/// </summary>
		/// <param name="pNode">The node for the graph.</param>
		public virtual void AddNode(Node pNode)
		{
			// Add the node if we don't have it
			if (!mNodes.Contains(pNode))
			{
				// Add the node
				mNodes.Add(pNode);
			}
		}

		/// <summary>
		/// Remove the given node from the graph.
		/// </summary>
		/// <param name="pNode">The node to remove.</param>
		/// <returns>Whether the node was removed successfully or not.</returns>
		public virtual bool RemoveNode(Node pNode)
		{
			// Remove it from the list of nodes
			bool retVal = mNodes.Remove(pNode);

			// Remove this from each of the adjacent nodes adjacencies
			foreach (Node node in pNode.Adjacencies)
			{
				// Remove the adjacency
				node.RemoveAdjacency(pNode);
			}

			// Return
			return retVal;
		}

		#endregion

		#region Utility

		/// <summary>
		/// Creates and edge between the two nodes by adding them to the
		/// correct adjacency lists.
		/// </summary>
		/// <param name="pA">The first node.</param>
		/// <param name="pB">The second node.</param>
		public abstract void CreateEdge(Node pA, Node pB);

		/// <summary>
		/// Removes an edge from the two nodes by removing the adjacencies that
		/// link them together.
		/// </summary>
		/// <param name="pA">The first node.</param>
		/// <param name="pB">The second node.</param>
		public abstract void DestroyEdge(Node pA, Node pB);

		#endregion
	}
}