PathUtils.java

/*
 * Copyright (C) 2021 INRAE AgroClim
 *
 * This file is part of Indicators.
 *
 * Indicators 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 3 of the License, or
 * (at your option) any later version.
 *
 * Indicators 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 Indicators. If not, see <http://www.gnu.org/licenses/>.
 */
package fr.inrae.agroclim.indicators.util;

import java.nio.file.Path;
import java.nio.file.Paths;

/**
 * Helper methods for file paths.
 *
 * Last changed : $Date$
 *
 * @author $Author$
 * @version $Revision$
 */
public abstract class PathUtils {
    /**
     * The UNIX separator.
     */
    private static final String UNIX_SEP = "/";

    /**
     * Constructs a relative path between a base path and another path.
     *
     * <p> Relativization is the inverse of {@link #resolve(java.lang.String, java.lang.String) resolution}.
     * This method attempts to construct a {@link Path#isAbsolute relative} path that when
     * {@link #resolve(java.lang.String, java.lang.String) resolved} against this path, yields a path that locates
     * the same file as the given path.</p>
     *
     * @param basePath absolute path of base directory
     * @param absolutePath absolute path to relativize
     * @return relative path
     */
    public static String relativize(final String basePath, final String absolutePath) {
        if (absolutePath == null) {
            return null;
        }
        final Path base = Paths.get(basePath);
        final Path absolute = Paths.get(absolutePath);
        // example "."
        if (base.getRoot() == null) {
            return absolutePath;
        }
        if (UNIX_SEP.equals(base.getRoot().toString())) {
            if (!base.getName(0).equals(absolute.getName(0))) {
                return absolutePath;
            }
        } else if (!base.getRoot().equals(absolute.getRoot())) {
            return absolutePath;
        }
        final Path path = base.relativize(absolute);
        return path.toString();
    }

    /**
     * Resolve the given path against this path.
     *
     * <p> Resolution is the inverse of {@link #relativize(java.lang.String, java.lang.String) relativization}.
     * If the {@code relativePath} parameter is an {@link Path#isAbsolute() absolute}  path then this method trivially
     * returns {@code relativePath}.</p>
     *
     * @param basePath absolute path of base directory
     * @param relativePath relative path to resolve
     * @return absolute path
     */
    public static String resolve(final String basePath, final String relativePath) {
        if (relativePath == null) {
            return null;
        }
        if (Paths.get(relativePath).isAbsolute()) {
            return relativePath;
        }
        final Path path = Paths.get(basePath).resolve(relativePath).normalize();
        return path.toString();
    }

    /**
     * No constructor for helper class.
     */
    private PathUtils() {
        //
    }

}