/*

 * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.

 * 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,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.File;

import java.io.Reader;

import java.nio.charset.Charset;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

/**

 * This file was originally a copy of CommandLine.java in

 * com.sun.tools.javac.main.

 * It should track changes made to that file.

 */

/**

 * Various utility methods for processing Java tool command line arguments.

 *

 *  <p><b>This is NOT part of any supported API.

 *  If you write code that depends on this, you do so at your own risk.

 *  This code and its internal interfaces are subject to change or

 *  deletion without notice.</b>

 */

class CommandLine {

    /**

     * Process Win32-style command files for the specified command line

     * arguments and return the resulting arguments. A command file argument

     * is of the form '@file' where 'file' is the name of the file whose

     * contents are to be parsed for additional arguments. The contents of

     * the command file are parsed using StreamTokenizer and the original

     * '@file' argument replaced with the resulting tokens. Recursive command

     * files are not supported. The '@' character itself can be quoted with

     * the sequence '@@'.

     * @param args the arguments that may contain @files

     * @return the arguments, with @files expanded

     * @throws IOException if there is a problem reading any of the @files

     */

    public static String[] parse(String[] args) throws IOException {

        List<String> newArgs = new ArrayList<>();

        appendParsedCommandArgs(newArgs, Arrays.asList(args));

        return newArgs.toArray(new String[newArgs.size()]);

    }

    private static void appendParsedCommandArgs(List<String> newArgs,

            List<String> args) throws IOException {

        for (String arg : args) {

            if (arg.length() > 1 && arg.charAt(0) == '@') {

                arg = arg.substring(1);

                if (arg.charAt(0) == '@') {

                    newArgs.add(arg);

                } else {

                    loadCmdFile(arg, newArgs);

                }

            } else {

                newArgs.add(arg);

            }

        }

    }

    private static void loadCmdFile(String name, List<String> args)

            throws IOException {

        if (!Files.isReadable(Path.of(name))) {

            throw new FileNotFoundException(name);

        }

        try (Reader r = Files.newBufferedReader(Paths.get(name),

                Charset.defaultCharset())) {

            Tokenizer t = new Tokenizer(r);

            String s;

            while ((s = t.nextToken()) != null) {

                args.add(s);

            }

        }

    }

    public static class Tokenizer {

        private final Reader in;

        private int ch;

        public Tokenizer(Reader in) throws IOException {

            this.in = in;

            ch = in.read();

        }

        public String nextToken() throws IOException {

            skipWhite();

            if (ch == -1) {

                return null;

            }

            StringBuilder sb = new StringBuilder();

            char quoteChar = 0;

            while (ch != -1) {

                switch (ch) {

                    case ' ':

                    case '\t':

                    case '\f':

                        if (quoteChar == 0) {

                            return sb.toString();

                        }

                        sb.append((char) ch);

                        break;

                    case '\n':

                    case '\r':

                        return sb.toString();

                    case '\'':

                    case '"':

                        if (quoteChar == 0) {

                            quoteChar = (char) ch;

                        } else if (quoteChar == ch) {

                            quoteChar = 0;

                        } else {

                            sb.append((char) ch);

                        }

                        break;

                    case '\\':

                        if (quoteChar != 0) {

                            ch = in.read();

                            switch (ch) {

                                case '\n':

                                case '\r':

                                    while (ch == ' ' || ch == '\n'

                                            || ch == '\r' || ch == '\t'

                                            || ch == '\f') {

                                        ch = in.read();

                                    }

                                    continue;

                                case 'n':

                                    ch = '\n';

                                    break;

                                case 'r':

                                    ch = '\r';

                                    break;

                                case 't':

                                    ch = '\t';

                                    break;

                                case 'f':

                                    ch = '\f';

                                    break;

                            }

                        }

                        sb.append((char) ch);

                        break;

                    default:

                        sb.append((char) ch);

                }

                ch = in.read();

            }

            return sb.toString();

        }

        void skipWhite() throws IOException {

            while (ch != -1) {

                switch (ch) {

                    case ' ':

                    case '\t':

                    case '\n':

                    case '\r':

                    case '\f':

                        break;

                    case '#':

                        ch = in.read();

                        while (ch != '\n' && ch != '\r' && ch != -1) {

                            ch = in.read();

                        }

                        break;

                    default:

                        return;

                }

                ch = in.read();

            }

        }

    }

}