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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

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 *

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package build.tools.publicsuffixlist;

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.InputStreamReader;

import java.io.IOException;

import java.io.OutputStreamWriter;

import java.nio.file.attribute.FileTime;

import java.util.HashMap;

import java.util.LinkedList;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.regex.Pattern;

import java.util.stream.Collectors;

import java.util.zip.ZipEntry;

import java.util.zip.ZipOutputStream;

/**

 * This tool takes the original Mozilla public suffix rule list as input

 * and slices it into a set of files, one for each top-level domain.

 * Each file contains only the rules for that domain. Lines containing comments

 * or only whitespace are not copied. Each of these files are then combined

 * into the target zipfile.

 *

 * Usage: java GeneratePublicSuffixList mozilla_file destination_zipfile

 */

public final class GeneratePublicSuffixList {

    // patterns

    private static final String COMMENT = "//";

    private static final String BEGIN_PRIVATE = "// ===BEGIN PRIVATE DOMAINS===";

    private static final Pattern WHITESPACE = Pattern.compile("\\s*");

    private static final byte ICANN = 0x00;

    private static final byte PRIVATE = 0x01;

    private static class Domain {

        final String name;

        final byte type;

        Domain(String name, byte type) {

            this.name = name;

            this.type = type;

        }

    }

    public static void main(String[] args) throws Exception {

        if (args.length != 2) {

            throw new Exception("2 args required: input_file output_file");

        }

        try (FileInputStream fis = new FileInputStream(args[0]);

             ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(args[1])))

        {

            BufferedReader br =

                new BufferedReader(new InputStreamReader(fis, "UTF-8"));

            List<Domain> domains = new LinkedList<>();

            byte type = ICANN;

            String line;

            while ((line = br.readLine()) != null) {

                if (line.startsWith(COMMENT)) {

                    if (line.startsWith(BEGIN_PRIVATE)) {

                        type = PRIVATE;

                    }

                    continue;

                }

                if (WHITESPACE.matcher(line).matches()) {

                    continue;

                }

                domains.add(new Domain(line, type));

            }

            // have a list of rules now

            // Map of TLD names to rules with the same TLD

            Map<String, List<Domain>> rules = addDomains(domains);

            // stream for writing the file contents

            BufferedWriter bw =

                new BufferedWriter(new OutputStreamWriter(zos, "UTF-8"));

            // now output each map entry to its own file,

            // whose filename is the TLD

            writeRules(zos, bw, rules);

        }

    }

    private static Map<String, List<Domain>> addDomains(List<Domain> domains) {

        Map<String, List<Domain>> rules = new HashMap<>();

        for (Domain domain : domains) {

            String tld = getTLD(domain.name);

            rules.compute(tld, (k, v) -> {

                if (v == null) {

                    List<Domain> newV = new LinkedList<>();

                    newV.add(domain);

                    return newV;

                } else {

                    v.add(domain);

                    return v;

                }

            });

        }

        return rules;

    }

    private static void writeRules(ZipOutputStream zos, BufferedWriter bw,

                                   Map<String, List<Domain>> rules)

                                   throws IOException {

        // Sort keys for deterministic output

        List<String> tlds = rules.keySet().stream().sorted().collect(Collectors.toList());

        for (String tld : tlds) {

            List<Domain> entries = rules.get(tld);

            ZipEntry ze = new ZipEntry(tld);

            ze.setLastModifiedTime(FileTime.fromMillis(0));

            zos.putNextEntry(ze);

            for (Domain entry : entries) {

                bw.write(entry.type);

                bw.write(entry.name, 0, entry.name.length());

                bw.newLine();

            }

            bw.flush();

        }

    }

    private static String getTLD(String line) {

        int dotIndex = line.lastIndexOf('.');

        return (dotIndex == -1) ? line : line.substring(dotIndex + 1);

    }

}