package bjc.utils.funcutils;

import java.io.IOException;
import java.nio.file.FileVisitResult;
import java.nio.file.Path;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.function.BiPredicate;

/**
 * Functional implementation of a file visitor.
 *
 * @author Ben Culkin
 */
final class FunctionalFileVisitor extends SimpleFileVisitor<Path> {
	/* Our predicate to pick files. */
	private final BiPredicate<Path, BasicFileAttributes> predicate;
	/* Our action to aply to files. */
	private final BiPredicate<Path, BasicFileAttributes> action;

	/**
	 * Create a new file visitor, powered by functions.
	 *
	 * @param predicate
	 *                  The predicate to use to pick which files to traverse.
	 *
	 * @param action
	 *                  The function to execute on every file.
	 */
	public FunctionalFileVisitor(final BiPredicate<Path, BasicFileAttributes> predicate,
			final BiPredicate<Path, BasicFileAttributes> action) {
		this.predicate = predicate;
		this.action = action;
	}

	@Override
	public FileVisitResult preVisitDirectory(final Path dir,
			final BasicFileAttributes attrs) throws IOException {
		if (predicate.test(dir, attrs))
			return FileVisitResult.CONTINUE;

		return FileVisitResult.SKIP_SUBTREE;
	}

	@Override
	public FileVisitResult visitFile(final Path file, final BasicFileAttributes attrs)
			throws IOException {
		if (action.test(file, attrs))
			return FileVisitResult.CONTINUE;

		return FileVisitResult.TERMINATE;
	}
}