package universalelectricity.core.path;

import java.util.HashSet;
import java.util.Set;

import universalelectricity.core.vector.Vector3;

/**
 * A class that allows flexible pathfinding for different positions. Compared to AStar pathfinding,
 * this version is faster but does not calculated the most optimal path.
 * 
 * @author Calclavia
 * 
 */
public class Pathfinder
{
	/**
	 * A pathfinding call back interface used to call back on paths.
	 */
	public IPathCallBack callBackCheck;

	/**
	 * A list of nodes that the pathfinder already went through.
	 */
	public Set<Vector3> closedSet;

	/**
	 * The resulted path found by the pathfinder. Could be null if no path was found.
	 */
	public Set<Vector3> results;

	public Pathfinder(IPathCallBack callBack)
	{
		this.callBackCheck = callBack;
		this.reset();
	}

	/**
	 * @return True on success finding, false on failure.
	 */
	public boolean findNodes(Vector3 currentNode)
	{
		this.closedSet.add(currentNode);

		if (this.callBackCheck.onSearch(this, currentNode))
		{
			return false;
		}

		for (Vector3 node : this.callBackCheck.getConnectedNodes(this, currentNode))
		{
			if (!this.closedSet.contains(node))
			{
				if (this.findNodes(node))
				{
					return true;
				}
			}
		}

		return false;
	}

	/**
	 * Called to execute the pathfinding operation.
	 */
	public Pathfinder init(Vector3 startNode)
	{
		this.findNodes(startNode);
		return this;
	}

	public Pathfinder reset()
	{
		this.closedSet = new HashSet<Vector3>();
		this.results = new HashSet<Vector3>();
		return this;
	}
}