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/* ZipFileIterator.java
 *
 * Created: 2011-10-10 (Year-Month-Day)
 * Character encoding: UTF-8
 *
 ****************************************** LICENSE *******************************************
 *
 * Copyright (c) 2011 - 2013 XIAM Solutions B.V. (http://www.xiam.nl)
 * Copyright 2014 dorkbox, llc
 *
 * Licensed 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 dorkbox.annotation;

import java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

/**
 * {@code ZipFileIterator} is used to iterate over all entries in a given {@code zip} or
 * {@code jar} file and returning the {@link InputStream} of these entries.
 * 
 * It is possible to specify an (optional) entry name filter.
 * 
 * The most efficient way of iterating is used, see benchmark in test classes.
 *
 * @author Ronald K. Muller
 * @since annotation-detector 3.0.0
 *
 * @author dorkbox, llc
 */
final
class ZipFileIterator {

    private final File file;
    private final ZipFile zipFile;
    private final String[] entryNameFilter;
    private final Enumeration entries;

    private ZipEntry current;

    /**
     * Create a new {@code ZipFileIterator} instance.
     *
     * @param file         The ZIP file used to iterate over all entries
     * @param entryNameFilter (optional) file name filter. Only entry names starting with
     *                        one of the specified names in the filter are returned
     */
    ZipFileIterator(final File file, final String[] entryNameFilter) throws IOException {
        this.file = file;
        this.zipFile = new ZipFile(file);
        this.entryNameFilter = entryNameFilter;

        this.entries = this.zipFile.entries();
    }

    public
    ZipEntry getEntry() {
        return this.current;
    }

    public
    InputStream next(final FilenameFilter filter) throws IOException {
        while (this.entries.hasMoreElements()) {
            this.current = this.entries.nextElement();
            if (filter == null || accept(this.current, filter)) {
                return this.zipFile.getInputStream(this.current);
            }
        }
        // no more entries in this ZipFile, so close ZipFile
        try {
            // zipFile is never null here
            this.zipFile.close();
        } catch (IOException ex) {
            // suppress IOException, otherwise close() is called twice
        }
        return null;
    }

    private
    boolean accept(final ZipEntry entry, final FilenameFilter filter) {
        if (entry.isDirectory()) {
            return false;
        }
        final String name = entry.getName();
        if (name.endsWith(".class") && filter.accept(this.file, name)) {
            if (this.entryNameFilter == null) {
                return true;
            }
            for (final String entryName : this.entryNameFilter) {
                if (name.startsWith(entryName)) {
                    return true;
                }
            }
        }
        return false;
    }
}