EnclosedBlockedAreaFinderAlgorithm.java

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package jsettlers.algorithms.landmarks;

import jsettlers.algorithms.interfaces.IContainingProvider;
import jsettlers.algorithms.traversing.area.AreaTraversingAlgorithm;
import jsettlers.algorithms.traversing.area.IAreaVisitor;
import jsettlers.algorithms.traversing.borders.BorderTraversingAlgorithm;
import jsettlers.common.movable.EDirection;
import jsettlers.common.position.ShortPoint2D;

/**
 * Algorithm to correct the landmarks. For example if Pioneers set all landmarks around a lake, this Thread will recognize it and take over the area
 * of the lake.
 * 
 * @author Andreas Eberle
 * 
 */
public final class EnclosedBlockedAreaFinderAlgorithm {

	public static void checkLandmark(IEnclosedBlockedAreaFinderGrid grid, int startX, int startY) {
		if (grid.isPioneerBlockedAndWithoutTowerProtection(startX, startY)) {
			return;
		}

		final IContainingProvider containingProvider = grid::isPioneerBlockedAndWithoutTowerProtection;
		final short startPartition = grid.getPartitionAt(startX, startY);

		for (EDirection currDir : EDirection.VALUES) {
			ShortPoint2D currPos = currDir.getNextHexPoint(startX, startY);

			if (grid.isPioneerBlockedAndWithoutTowerProtection(currPos.x, currPos.y)) {
				if (needsRelabel(grid, containingProvider, currPos, startPartition)) {
					relabel(grid, containingProvider, currPos, startPartition);
				}
			}
		}
	}

	private static void relabel(final IEnclosedBlockedAreaFinderGrid grid, IContainingProvider containingProvider, ShortPoint2D blockedStartPos,
			final short newPartition) {
		IAreaVisitor visitor = (x, y) -> {
			grid.setPartitionAt(x, y, newPartition);
			return true;
		};
		AreaTraversingAlgorithm.traverseArea(containingProvider, visitor, blockedStartPos, grid.getWidth(), grid.getHeight());
	}

	/**
	 * Checks if the blocked partition given by the coordinates blockedX and blockedY is surrounded by the given partition.
	 * 
	 * @param grid
	 * @param containingProvider
	 * @param blockedStartPos
	 * @return
	 */
	private static boolean needsRelabel(final IEnclosedBlockedAreaFinderGrid grid, IContainingProvider containingProvider,
			ShortPoint2D blockedStartPos, final short partition) {
		return BorderTraversingAlgorithm.traverseBorder(containingProvider, blockedStartPos,
				(insideX, insideY, outsideX, outsideY) -> grid.getPartitionAt((short) outsideX, (short) outsideY) == partition, true);
	}
}