/*
 * Copyright 2012-2017 Red Hat, Inc.
 *
 * This file is part of Thermostat.
 *
 * Thermostat 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, or (at your
 * option) any later version.
 *
 * Thermostat 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 Thermostat; see the file COPYING.  If not see
 * <http://www.gnu.org/licenses/>.
 *
 * Linking this code with other modules is making a combined work
 * based on this code.  Thus, the terms and conditions of the GNU
 * General Public License cover the whole combination.
 *
 * As a special exception, the copyright holders of this code give
 * you permission to link this code with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also
 * meet, for each linked independent module, the terms and conditions
 * of the license of that module.  An independent module is a module
 * which is not derived from or based on this code.  If you modify
 * this code, you may extend this exception to your version of the
 * library, but you are not obligated to do so.  If you do not wish
 * to do so, delete this exception statement from your version.
 */

package com.redhat.thermostat.setup.command.internal.model;

import com.redhat.thermostat.shared.config.CommonPaths;

import java.io.File;
import java.io.IOException;

public class CredentialFinder {

    private final CommonPaths paths;

    public CredentialFinder(CommonPaths paths) {
        this.paths = paths;
    }

    public File getConfiguration(String name) {
        File systemFile = getConfigurationFile(paths.getSystemConfigurationDirectory(), name);
        if (isUsable(systemFile)) {
            return systemFile;
        }
        File userFile = getConfigurationFile(paths.getUserConfigurationDirectory(), name);
        if (isUsable(userFile)) {
            return userFile;
        }
        return null;
    }

    //package-private for testing
    File getConfigurationFile(File directory, String name) {
        return new File(directory, name);
    }

    //package-private for testing
    boolean isUsable(File file) {
        if (file.exists()) {
            return file.isFile() && file.canRead() && file.canWrite();
        } else {
            try {
                //Check that the parent directory is not read-only,
                //so file can be created
                File canonicalFile = file.getCanonicalFile();
                return canonicalFile.getParentFile().canWrite();
            } catch (IOException e) {
                return false;
            }
        }
    }
}