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A library to reliably execute external processes from within the JVM
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/*
 * 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
 *
 *      https://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.commons.exec.util;

import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.StringTokenizer;

/**
 * Supplement of commons-lang, the stringSubstitution() was in a simpler implementation available in an older commons-lang implementation.
 *
 * This class is not part of the public API and could change without warning.
 */
public class StringUtils {

    private static final String[] EMPTY_STRING_ARRAY = {};
    private static final String SINGLE_QUOTE = "\'";
    private static final String DOUBLE_QUOTE = "\"";
    private static final char SLASH_CHAR = '/';
    private static final char BACKSLASH_CHAR = '\\';

    /**
     * Fixes the file separator char for the target platform using the following replacement.
     * 
     * '/' → File.separatorChar
     * '\\' → File.separatorChar
     * 
     *
     * @param arg the argument to fix.
     * @return the transformed argument.
     */
    public static String fixFileSeparatorChar(final String arg) {
        return arg.replace(SLASH_CHAR, File.separatorChar).replace(BACKSLASH_CHAR, File.separatorChar);
    }

    /**
     * Determines if this is a quoted argument - either single or double quoted.
     *
     * @param argument the argument to check.
     * @return true when the argument is quoted.
     */
    public static boolean isQuoted(final String argument) {
        return argument.startsWith(SINGLE_QUOTE) && argument.endsWith(SINGLE_QUOTE) || argument.startsWith(DOUBLE_QUOTE) && argument.endsWith(DOUBLE_QUOTE);
    }

    /**
     * Put quotes around the given String if necessary.
     * 
     * If the argument doesn't include spaces or quotes, return it as is. If it contains double quotes, use single quotes - else surround the argument by double
     * quotes.
     * 
     *
     * @param argument the argument to be quoted.
     * @return the quoted argument.
     * @throws IllegalArgumentException If argument contains both types of quotes.
     */
    public static String quoteArgument(final String argument) {

        String cleanedArgument = argument.trim();

        // strip the quotes from both ends
        while (cleanedArgument.startsWith(SINGLE_QUOTE) || cleanedArgument.startsWith(DOUBLE_QUOTE)) {
            cleanedArgument = cleanedArgument.substring(1);
        }

        while (cleanedArgument.endsWith(SINGLE_QUOTE) || cleanedArgument.endsWith(DOUBLE_QUOTE)) {
            cleanedArgument = cleanedArgument.substring(0, cleanedArgument.length() - 1);
        }

        final StringBuilder buf = new StringBuilder();
        if (cleanedArgument.contains(DOUBLE_QUOTE)) {
            if (cleanedArgument.contains(SINGLE_QUOTE)) {
                throw new IllegalArgumentException("Can't handle single and double quotes in same argument");
            }
            return buf.append(SINGLE_QUOTE).append(cleanedArgument).append(SINGLE_QUOTE).toString();
        }
        if (cleanedArgument.contains(SINGLE_QUOTE) || cleanedArgument.contains(" ")) {
            return buf.append(DOUBLE_QUOTE).append(cleanedArgument).append(DOUBLE_QUOTE).toString();
        }
        return cleanedArgument;
    }

    /**
     * Split a string into an array of strings based on a separator.
     *
     * @param input     what to split.
     * @param splitChar what to split on.
     * @return the array of strings.
     */
    public static String[] split(final String input, final String splitChar) {
        final StringTokenizer tokens = new StringTokenizer(input, splitChar);
        final List strList = new ArrayList<>();
        while (tokens.hasMoreTokens()) {
            strList.add(tokens.nextToken());
        }
        return strList.toArray(EMPTY_STRING_ARRAY);
    }

    /**
     * Perform a series of substitutions.
     * 
     * The substitutions are performed by replacing ${variable} in the target string with the value of provided by the key "variable" in the provided hash
     * table.
     * 
     * 
     * A key consists of the following characters:
     * 
     * 
     * letter
     * 
digit
     * 
dot character
     * 
hyphen character
     * 
plus character
     * 
underscore character
     * 
     *
     * @param argStr    the argument string to be processed.
     * @param vars      name/value pairs used for substitution.
     * @param isLenient ignore a key not found in vars or throw a RuntimeException?
     * @return String target string with replacements.
     */
    public static StringBuffer stringSubstitution(final String argStr, final Map vars, final boolean isLenient) {

        final StringBuffer argBuf = new StringBuffer();

        if (argStr == null || argStr.isEmpty()) {
            return argBuf;
        }

        if (vars == null || vars.isEmpty()) {
            return argBuf.append(argStr);
        }

        final int argStrLength = argStr.length();

        for (int cIdx = 0; cIdx < argStrLength;) {

            char ch = argStr.charAt(cIdx);
            char del = ' ';

            switch (ch) {

            case '$':
                final StringBuilder nameBuf = new StringBuilder();
                del = argStr.charAt(cIdx + 1);
                if (del == '{') {
                    cIdx++;

                    for (++cIdx; cIdx < argStr.length(); ++cIdx) {
                        ch = argStr.charAt(cIdx);
                        if (ch != '_' && ch != '.' && ch != '-' && ch != '+' && !Character.isLetterOrDigit(ch)) {
                            break;
                        }
                        nameBuf.append(ch);
                    }

                    if (nameBuf.length() >= 0) {

                        String value;
                        final Object temp = vars.get(nameBuf.toString());

                        if (temp instanceof File) {
                            // for a file we have to fix the separator chars to allow
                            // cross-platform compatibility
                            value = fixFileSeparatorChar(((File) temp).getAbsolutePath());
                        } else {
                            value = Objects.toString(temp, null);
                        }

                        if (value != null) {
                            argBuf.append(value);
                        } else {
                            if (!isLenient) {
                                // complain that no variable was found
                                throw new IllegalArgumentException("No value found for : " + nameBuf);
                            }
                            // just append the unresolved variable declaration
                            argBuf.append("${").append(nameBuf.toString()).append("}");
                        }

                        del = argStr.charAt(cIdx);

                        if (del != '}') {
                            throw new IllegalArgumentException("Delimiter not found for : " + nameBuf);
                        }
                    }
                } else {
                    argBuf.append(ch);
                }
                cIdx++;

                break;

            default:
                argBuf.append(ch);
                ++cIdx;
                break;
            }
        }

        return argBuf;
    }

    /**
     * Concatenates an array of string using a separator.
     *
     * @param strings   the strings to concatenate.
     * @param separator the separator between two strings.
     * @return the concatenated strings.
     * @deprecated Use {@link String#join(CharSequence, CharSequence...)}.
     */
    @Deprecated
    public static String toString(final String[] strings, final String separator) {
        return String.join(separator, strings);
    }

    /**
     * Constructs a new instance.
     *
     * @deprecated Will be private in the next major version.
     */
    @Deprecated
    public StringUtils() {
        // empty
    }
}