/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.fontbox.util.autodetect;

import java.io.File;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Native font finder base class. This class is based on a class provided by Apache FOP. see
 * org.apache.fop.fonts.autodetect.NativeFontDirFinder
 */
public abstract class NativeFontDirFinder implements FontDirFinder
{

    private static final Log LOG = LogFactory.getLog(NativeFontDirFinder.class);

    /**
     * Generic method used by Mac and Unix font finders.
     * 
     * @return list of natively existing font directories {@inheritDoc}
     */
    @Override
    public List<File> find()
    {
        List<File> fontDirList = new java.util.ArrayList<>();
        String[] searchableDirectories = getSearchableDirectories();
        if (searchableDirectories != null)
        {
            for (String searchableDirectorie : searchableDirectories)
            {
                File fontDir = new File(searchableDirectorie);
                try
                {
                    if (fontDir.exists() && fontDir.canRead())
                    {
                        fontDirList.add(fontDir);
                    }
                }
                catch (SecurityException e)
                {
                    LOG.debug("Couldn't get native font directories - ignoring", e);
                    // should continue if this fails
                }
            }
        }
        return fontDirList;
    }

    /**
     * Returns an array of directories to search for fonts in.
     * 
     * @return an array of directories
     */
    protected abstract String[] getSearchableDirectories();

}
