/*
 * 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.text;

import java.util.HashSet;
import java.util.Locale;
import java.util.Set;
import java.util.function.IntUnaryOperator;
import java.util.function.Predicate;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.Strings;
import org.apache.commons.lang3.Validate;

/**
 * Operations on Strings that contain words.
 *
 * <p>
 * This class tries to handle {@code null} input gracefully. An exception will not be thrown for a
 * {@code null} input. Each method documents its behavior in more detail.
 * </p>
 *
 * @since 1.1
 */
public class WordUtils {

    /**
     * Abbreviates the words nicely.
     * <p>
     * This method searches for the first space after the lower limit and abbreviates the String there. It will also append any String passed as a parameter to
     * the end of the String. The upper limit can be specified to forcibly abbreviate a String.
     * </p>
     *
     * <pre>
     * WordUtils.abbreviate("Now is the time for all good men", 0, 40, null));     = "Now"
     * WordUtils.abbreviate("Now is the time for all good men", 10, 40, null));    = "Now is the"
     * WordUtils.abbreviate("Now is the time for all good men", 20, 40, null));    = "Now is the time for all"
     * WordUtils.abbreviate("Now is the time for all good men", 0, 40, ""));       = "Now"
     * WordUtils.abbreviate("Now is the time for all good men", 10, 40, ""));      = "Now is the"
     * WordUtils.abbreviate("Now is the time for all good men", 20, 40, ""));      = "Now is the time for all"
     * WordUtils.abbreviate("Now is the time for all good men", 0, 40, " ..."));   = "Now ..."
     * WordUtils.abbreviate("Now is the time for all good men", 10, 40, " ..."));  = "Now is the ..."
     * WordUtils.abbreviate("Now is the time for all good men", 20, 40, " ..."));  = "Now is the time for all ..."
     * WordUtils.abbreviate("Now is the time for all good men", 0, -1, ""));       = "Now"
     * WordUtils.abbreviate("Now is the time for all good men", 10, -1, ""));      = "Now is the"
     * WordUtils.abbreviate("Now is the time for all good men", 20, -1, ""));      = "Now is the time for all"
     * WordUtils.abbreviate("Now is the time for all good men", 50, -1, ""));      = "Now is the time for all good men"
     * WordUtils.abbreviate("Now is the time for all good men", 1000, -1, ""));    = "Now is the time for all good men"
     * WordUtils.abbreviate("Now is the time for all good men", 9, -10, null));    = Throws {@link IllegalArgumentException}
     * WordUtils.abbreviate("Now is the time for all good men", 10, 5, null));     = Throws {@link IllegalArgumentException}
     * </pre>
     *
     * @param str         The string to be abbreviated. If null is passed, null is returned. If the empty String is passed, the empty string is returned.
     * @param lower       The lower limit; negative value is treated as zero.
     * @param upper       The upper limit; specify -1 if no limit is desired. The upper limit cannot be lower than the lower limit.
     * @param appendToEnd The String to be appended to the end of the abbreviated string. This is appended ONLY if the string was indeed abbreviated. The append
     *                    does not count towards the lower or upper limits.
     * @return The abbreviated String.
     */
    public static String abbreviate(final String str, int lower, int upper, final String appendToEnd) {
        Validate.isTrue(upper >= -1, "upper value cannot be less than -1");
        Validate.isTrue(upper >= lower || upper == -1, "upper value is less than lower value");
        if (StringUtils.isEmpty(str)) {
            return str;
        }
        // if the lower value is greater than the length of the string,
        // set to the length of the string
        if (lower > str.length()) {
            lower = str.length();
        }
        // if the upper value is -1 (i.e. no limit) or is greater
        // than the length of the string, set to the length of the string
        if (upper == -1 || upper > str.length()) {
            upper = str.length();
        }
        final StringBuilder result = new StringBuilder();
        final int index = Strings.CS.indexOf(str, " ", lower);
        if (index == -1) {
            result.append(str, 0, upper);
            // only if abbreviation has occurred do we append the appendToEnd value
            if (upper != str.length()) {
                result.append(StringUtils.defaultString(appendToEnd));
            }
        } else {
            result.append(str, 0, Math.min(index, upper));
            result.append(StringUtils.defaultString(appendToEnd));
        }
        return result.toString();
    }

    /**
     * Applies a function to the first character of each word in a String.
     * <p>
     * This is used by {@link #capitalize(String, char...)} and {@link #uncapitalize(String, char...)}. The {@code transform} function is applied to the first
     * code point of each word; all other code points are passed through unchanged.
     * </p>
     *
     * @param str        The String to transform, may be null.
     * @param delimiters The set of characters to determine word boundaries, null means whitespace.
     * @param transform  The casing function to apply to the first code point of each word (e.g., {@code Character::toTitleCase} or
     *                   {@code Character::toLowerCase}).
     * @return The transformed String, or {@code null}/{@code ""} if the input is null/empty.
     */
    private static String applyWordCaseTransform(final String str, final char[] delimiters, final IntUnaryOperator transform) {
        if (StringUtils.isEmpty(str)) {
            return str;
        }
        final Predicate<Integer> isDelimiter = generateIsDelimiterFunction(delimiters);
        final int strLen = str.length();
        final int[] newCodePoints = new int[strLen];
        int outOffset = 0;
        boolean transformNext = true;
        for (int index = 0; index < strLen;) {
            final int codePoint = str.codePointAt(index);
            if (isDelimiter.test(codePoint)) {
                transformNext = true;
                newCodePoints[outOffset++] = codePoint;
                index += Character.charCount(codePoint);
            } else if (transformNext) {
                final int transformed = transform.applyAsInt(codePoint);
                newCodePoints[outOffset++] = transformed;
                index += Character.charCount(transformed);
                transformNext = false;
            } else {
                newCodePoints[outOffset++] = codePoint;
                index += Character.charCount(codePoint);
            }
        }
        return new String(newCodePoints, 0, outOffset);
    }

    /**
     * Capitalizes all the whitespace separated words in a String. Only the first character of each word is changed. To convert the rest of each word to
     * lowercase at the same time, use {@link #capitalizeFully(String)}.
     * <p>
     * Whitespace is defined by {@link Character#isWhitespace(char)}. A {@code null} input String returns {@code null}. Capitalization uses the Unicode title
     * case, normally equivalent to upper case.
     * </p>
     *
     * <pre>
     * WordUtils.capitalize(null)        = null
     * WordUtils.capitalize("")          = ""
     * WordUtils.capitalize("i am FINE") = "I Am FINE"
     * </pre>
     *
     * @param str The String to capitalize, may be null.
     * @return A new Capitalized String, or {@code null} if null String input.
     * @see #uncapitalize(String)
     * @see #capitalizeFully(String)
     */
    public static String capitalize(final String str) {
        return capitalize(str, null);
    }

    /**
     * Capitalizes all the delimiter separated words in a String. Only the first character of each word is changed. To convert the rest of each word to
     * lowercase at the same time, use {@link #capitalizeFully(String, char[])}.
     * <p>
     * The delimiters represent a set of characters understood to separate words. The first string character and the first non-delimiter character after a
     * delimiter will be capitalized.
     * </p>
     * <p>
     * A {@code null} input String returns {@code null}. Capitalization uses the Unicode title case, normally equivalent to upper case.
     * </p>
     *
     * <pre>
     * WordUtils.capitalize(null, *)            = null
     * WordUtils.capitalize("", *)              = ""
     * WordUtils.capitalize(*, new char[0])     = *
     * WordUtils.capitalize("i am fine", null)  = "I Am Fine"
     * WordUtils.capitalize("i aM.fine", {'.'}) = "I aM.Fine"
     * WordUtils.capitalize("i am fine", new char[]{}) = "I am fine"
     * </pre>
     *
     * @param str        The String to capitalize, may be null.
     * @param delimiters The Set of characters to determine capitalization, null means whitespace.
     * @return A new Capitalized String, or {@code null} if null String input.
     * @see #uncapitalize(String)
     * @see #capitalizeFully(String)
     */
    public static String capitalize(final String str, final char... delimiters) {
        return applyWordCaseTransform(str, delimiters, Character::toTitleCase);
    }

    /**
     * Converts all the whitespace separated words in a String into capitalized words,
     * that is each word is made up of a titlecase character and then a series of
     * lowercase characters.
     *
     * <p>Whitespace is defined by {@link Character#isWhitespace(char)}.
     * A {@code null} input String returns {@code null}.
     * Capitalization uses the Unicode title case, normally equivalent to
     * upper case.</p>
     *
     * <pre>
     * WordUtils.capitalizeFully(null)        = null
     * WordUtils.capitalizeFully("")          = ""
     * WordUtils.capitalizeFully("i am FINE") = "I Am Fine"
     * </pre>
     *
     * @param str  The String to capitalize, may be null.
     * @return A new capitalized String, or {@code null} if null String input.
     */
    public static String capitalizeFully(final String str) {
        return capitalizeFully(str, null);
    }

    /**
     * Converts all the delimiter separated words in a String into capitalized words,
     * that is each word is made up of a titlecase character and then a series of
     * lowercase characters.
     *
     * <p>The delimiters represent a set of characters understood to separate words.
     * The first string character and the first non-delimiter character after a
     * delimiter will be capitalized.</p>
     *
     * <p>A {@code null} input String returns {@code null}.
     * Capitalization uses the Unicode title case, normally equivalent to
     * upper case.</p>
     *
     * <pre>
     * WordUtils.capitalizeFully(null, *)            = null
     * WordUtils.capitalizeFully("", *)              = ""
     * WordUtils.capitalizeFully(*, null)            = *
     * WordUtils.capitalizeFully(*, new char[0])     = *
     * WordUtils.capitalizeFully("i aM.fine", {'.'}) = "I am.Fine"
     * </pre>
     *
     * @param str  The String to capitalize, may be null.
     * @param delimiters  The Set of characters to determine capitalization, null means whitespace.
     * @return A new capitalized String, or {@code null} if null String input.
     */
    public static String capitalizeFully(final String str, final char... delimiters) {
        return StringUtils.isEmpty(str) ? str : capitalize(str.toLowerCase(Locale.ROOT), delimiters);
    }

    /**
     * Checks if the String contains all words in the given array.
     *
     * <p>
     * A {@code null} String will return {@code false}. A {@code null}, zero
     * length search array or if one element of array is null will return {@code false}.
     * </p>
     *
     * <pre>
     * WordUtils.containsAllWords(null, *)            = false
     * WordUtils.containsAllWords("", *)              = false
     * WordUtils.containsAllWords(*, null)            = false
     * WordUtils.containsAllWords(*, [])              = false
     * WordUtils.containsAllWords("abcd", "ab", "cd") = false
     * WordUtils.containsAllWords("abc def", "def", "abc") = true
     * </pre>
     *
     * @param word The CharSequence to check, may be null.
     * @param words The array of String words to search for, may be null.
     * @return {@code true} if all search words are found, {@code false} otherwise.
     */
    public static boolean containsAllWords(final CharSequence word, final CharSequence... words) {
        if (StringUtils.isEmpty(word) || ArrayUtils.isEmpty(words)) {
            return false;
        }
        for (final CharSequence w : words) {
            if (StringUtils.isBlank(w)) {
                return false;
            }
            final Pattern p = Pattern.compile(".*\\b" + Pattern.quote(w.toString()) + "\\b.*", Pattern.DOTALL);
            if (!p.matcher(word).matches()) {
                return false;
            }
        }
        return true;
    }

    /**
     * Given the array of delimiters supplied; returns a function determining whether a character code point is a delimiter.
     * The function provides O(1) lookup time.
     * Whitespace is defined by {@link Character#isWhitespace(char)} and is used as the defaultvalue if delimiters is null.
     *
     * @param delimiters The set of characters to determine delimiters, null means whitespace.
     * @return A Predicate<Integer> taking a code point value as an argument and returning true if a delimiter.
     */
    private static Predicate<Integer> generateIsDelimiterFunction(final char[] delimiters) {
        final Predicate<Integer> isDelimiter;
        if (delimiters == null || delimiters.length == 0) {
            isDelimiter = delimiters == null ? Character::isWhitespace : c -> false;
        } else {
            final Set<Integer> delimiterSet = new HashSet<>();
            for (int index = 0; index < delimiters.length; index++) {
                delimiterSet.add(Character.codePointAt(delimiters, index));
            }
            isDelimiter = delimiterSet::contains;
        }
        return isDelimiter;
    }

    /**
     * Extracts the initial characters from each word in the String.
     * <p>
     * All first characters after whitespace are returned as a new string. Their case is not changed.
     * </p>
     * <p>
     * Whitespace is defined by {@link Character#isWhitespace(char)}. A {@code null} input String returns {@code null}.
     * </p>
     *
     * <pre>
     * WordUtils.initials(null)             = null
     * WordUtils.initials("")               = ""
     * WordUtils.initials("Ben John Lee")   = "BJL"
     * WordUtils.initials("Ben J.Lee")      = "BJ"
     * </pre>
     *
     * @param str The String to get initials from, may be null.
     * @return A new String of initial letters, or {@code null} if null String input.
     * @see #initials(String,char[])
     */
    public static String initials(final String str) {
        return initials(str, null);
    }

    /**
     * Extracts the initial characters from each word in the String.
     * <p>
     * All first characters after the defined delimiters are returned as a new string. Their case is not changed.
     * </p>
     * <p>
     * If the delimiters array is null, then Whitespace is used. Whitespace is defined by {@link Character#isWhitespace(char)}. A {@code null} input String
     * returns {@code null}. An empty delimiter array returns an empty String.
     * </p>
     *
     * <pre>
     * WordUtils.initials(null, *)                = null
     * WordUtils.initials("", *)                  = ""
     * WordUtils.initials("Ben John Lee", null)   = "BJL"
     * WordUtils.initials("Ben J.Lee", null)      = "BJ"
     * WordUtils.initials("Ben J.Lee", [' ','.']) = "BJL"
     * WordUtils.initials(*, new char[0])         = ""
     * </pre>
     *
     * @param str        The String to get initials from, may be null.
     * @param delimiters The Set of characters to determine words, null means whitespace.
     * @return String of initial characters, or {@code null} if null String input.
     * @see #initials(String)
     */
    public static String initials(final String str, final char... delimiters) {
        if (StringUtils.isEmpty(str)) {
            return str;
        }
        if (delimiters != null && delimiters.length == 0) {
            return StringUtils.EMPTY;
        }
        final Predicate<Integer> isDelimiter = generateIsDelimiterFunction(delimiters);
        final int strLen = str.length();
        final int[] newCodePoints = new int[strLen / 2 + 1];
        int count = 0;
        boolean lastWasGap = true;
        for (int i = 0; i < strLen;) {
            final int codePoint = str.codePointAt(i);
            if (isDelimiter.test(codePoint)) {
                lastWasGap = true;
            } else if (lastWasGap) {
                newCodePoints[count++] = codePoint;
                lastWasGap = false;
            }
            i += Character.charCount(codePoint);
        }
        return new String(newCodePoints, 0, count);
    }

    /**
     * Is the character a delimiter.
     *
     * @param ch         The character to check.
     * @param delimiters The delimiters.
     * @return true if it is a delimiter.
     * @deprecated as of 1.2 and will be removed in 2.0.
     */
    @Deprecated
    public static boolean isDelimiter(final char ch, final char[] delimiters) {
        if (delimiters == null) {
            return Character.isWhitespace(ch);
        }
        for (final char delimiter : delimiters) {
            if (ch == delimiter) {
                return true;
            }
        }
        return false;
    }

    /**
     * Is the codePoint a delimiter.
     *
     * @param codePoint  The codePint to check.
     * @param delimiters The delimiters.
     * @return true if it is a delimiter.
     * @deprecated as of 1.2 and will be removed in 2.0.
     */
    @Deprecated
    public static boolean isDelimiter(final int codePoint, final char[] delimiters) {
        if (delimiters == null) {
            return Character.isWhitespace(codePoint);
        }
        for (int index = 0; index < delimiters.length; index++) {
            final int delimiterCodePoint = Character.codePointAt(delimiters, index);
            if (delimiterCodePoint == codePoint) {
                return true;
            }
        }
        return false;
    }

    /**
     * Swaps the case of a String using a word based algorithm.
     * <ul>
     * <li>Upper case character converts to Lower case</li>
     * <li>Title case character converts to Lower case</li>
     * <li>Lower case character after Whitespace or at start converts to Title case</li>
     * <li>Other Lower case character converts to Upper case</li>
     * </ul>
     * <p>
     * Whitespace is defined by {@link Character#isWhitespace(char)}. A {@code null} input String returns {@code null}.
     * </p>
     *
     * <pre>
     * StringUtils.swapCase(null)                 = null
     * StringUtils.swapCase("")                   = ""
     * StringUtils.swapCase("The dog has a BONE") = "tHE DOG HAS A bone"
     * </pre>
     *
     * @param str The String to swap case, may be null.
     * @return The changed String, or {@code null} if null String input.
     */
    public static String swapCase(final String str) {
        if (StringUtils.isEmpty(str)) {
            return str;
        }
        final int strLen = str.length();
        final int[] newCodePoints = new int[strLen];
        int outOffset = 0;
        boolean whitespace = true;
        for (int index = 0; index < strLen;) {
            final int oldCodepoint = str.codePointAt(index);
            final int newCodePoint;
            if (Character.isUpperCase(oldCodepoint) || Character.isTitleCase(oldCodepoint)) {
                newCodePoint = Character.toLowerCase(oldCodepoint);
                whitespace = false;
            } else if (Character.isLowerCase(oldCodepoint)) {
                if (whitespace) {
                    newCodePoint = Character.toTitleCase(oldCodepoint);
                    whitespace = false;
                } else {
                    newCodePoint = Character.toUpperCase(oldCodepoint);
                }
            } else {
                whitespace = Character.isWhitespace(oldCodepoint);
                newCodePoint = oldCodepoint;
            }
            newCodePoints[outOffset++] = newCodePoint;
            index += Character.charCount(newCodePoint);
        }
        return new String(newCodePoints, 0, outOffset);
    }

    /**
     * Uncapitalizes all the whitespace separated words in a String. Only the first character of each word is changed.
     * <p>
     * Whitespace is defined by {@link Character#isWhitespace(char)}. A {@code null} input String returns {@code null}.
     * </p>
     *
     * <pre>
     * WordUtils.uncapitalize(null)        = null
     * WordUtils.uncapitalize("")          = ""
     * WordUtils.uncapitalize("I Am FINE") = "i am fINE"
     * </pre>
     *
     * @param str The String to uncapitalize, may be null.
     * @return A new uncapitalized String, or {@code null} if null String input.
     * @see #capitalize(String)
     */
    public static String uncapitalize(final String str) {
        return uncapitalize(str, null);
    }

    /**
     * Uncapitalizes all the whitespace separated words in a String. Only the first character of each word is changed.
     * <p>
     * The delimiters represent a set of characters understood to separate words. The first string character and the first non-delimiter character after a
     * delimiter will be uncapitalized.
     * </p>
     * <p>
     * Whitespace is defined by {@link Character#isWhitespace(char)}. A {@code null} input String returns {@code null}.
     * </p>
     *
     * <pre>
     * WordUtils.uncapitalize(null, *)            = null
     * WordUtils.uncapitalize("", *)              = ""
     * WordUtils.uncapitalize(*, null)            = *
     * WordUtils.uncapitalize(*, new char[0])     = *
     * WordUtils.uncapitalize("I AM.FINE", {'.'}) = "i AM.fINE"
     * WordUtils.uncapitalize("I am fine", new char[]{}) = "i am fine"
     * </pre>
     *
     * @param str        The String to uncapitalize, may be null.
     * @param delimiters set of characters to determine uncapitalization, null means whitespace.
     * @return uncapitalized String, or {@code null} if null String input.
     * @see #capitalize(String)
     */
    public static String uncapitalize(final String str, final char... delimiters) {
        return applyWordCaseTransform(str, delimiters, Character::toLowerCase);
    }

    /**
     * Wraps a single line of text, identifying words by {@code ' '}.
     *
     * <p>New lines will be separated by the system property line separator.
     * Very long words, such as URLs will <em>not</em> be wrapped.</p>
     *
     * <p>Leading spaces on a new line are stripped.
     * Trailing spaces are not stripped.</p>
     *
     * <table border="1">
     *  <caption>Examples</caption>
     *  <tr>
     *   <th>input</th>
     *   <th>wrapLength</th>
     *   <th>result</th>
     *  </tr>
     *  <tr>
     *   <td>null</td>
     *   <td>*</td>
     *   <td>null</td>
     *  </tr>
     *  <tr>
     *   <td>""</td>
     *   <td>*</td>
     *   <td>""</td>
     *  </tr>
     *  <tr>
     *   <td>"Here is one line of text that is going to be wrapped after 20 columns."</td>
     *   <td>20</td>
     *   <td>"Here is one line of\ntext that is going\nto be wrapped after\n20 columns."</td>
     *  </tr>
     *  <tr>
     *   <td>"Click here to jump to the commons website - https://commons.apache.org"</td>
     *   <td>20</td>
     *   <td>"Click here to jump\nto the commons\nwebsite -\nhttps://commons.apache.org"</td>
     *  </tr>
     *  <tr>
     *   <td>"Click here, https://commons.apache.org, to jump to the commons website"</td>
     *   <td>20</td>
     *   <td>"Click here,\nhttps://commons.apache.org,\nto jump to the\ncommons website"</td>
     *  </tr>
     * </table>
     *
     * (assuming that '\n' is the systems line separator)
     *
     * @param str  The String to be word wrapped, may be null.
     * @param wrapLength  The column to wrap the words at, less than 1 is treated as 1.
     * @return A line with newlines inserted, {@code null} if null input.
     */
    public static String wrap(final String str, final int wrapLength) {
        return wrap(str, wrapLength, null, false);
    }

    /**
     * Wraps a single line of text, identifying words by {@code ' '}.
     *
     * <p>Leading spaces on a new line are stripped.
     * Trailing spaces are not stripped.</p>
     *
     * <table border="1">
     *  <caption>Examples</caption>
     *  <tr>
     *   <th>input</th>
     *   <th>wrapLength</th>
     *   <th>newLineString</th>
     *   <th>wrapLongWords</th>
     *   <th>result</th>
     *  </tr>
     *  <tr>
     *   <td>null</td>
     *   <td>*</td>
     *   <td>*</td>
     *   <td>true/false</td>
     *   <td>null</td>
     *  </tr>
     *  <tr>
     *   <td>""</td>
     *   <td>*</td>
     *   <td>*</td>
     *   <td>true/false</td>
     *   <td>""</td>
     *  </tr>
     *  <tr>
     *   <td>"Here is one line of text that is going to be wrapped after 20 columns."</td>
     *   <td>20</td>
     *   <td>"\n"</td>
     *   <td>true/false</td>
     *   <td>"Here is one line of\ntext that is going\nto be wrapped after\n20 columns."</td>
     *  </tr>
     *  <tr>
     *   <td>"Here is one line of text that is going to be wrapped after 20 columns."</td>
     *   <td>20</td>
     *   <td>"&lt;br /&gt;"</td>
     *   <td>true/false</td>
     *   <td>"Here is one line of&lt;br /&gt;text that is going&lt;
     *   br /&gt;to be wrapped after&lt;br /&gt;20 columns."</td>
     *  </tr>
     *  <tr>
     *   <td>"Here is one line of text that is going to be wrapped after 20 columns."</td>
     *   <td>20</td>
     *   <td>null</td>
     *   <td>true/false</td>
     *   <td>"Here is one line of" + systemNewLine + "text that is going"
     *   + systemNewLine + "to be wrapped after" + systemNewLine + "20 columns."</td>
     *  </tr>
     *  <tr>
     *   <td>"Click here to jump to the commons website - https://commons.apache.org"</td>
     *   <td>20</td>
     *   <td>"\n"</td>
     *   <td>false</td>
     *   <td>"Click here to jump\nto the commons\nwebsite -\nhttps://commons.apache.org"</td>
     *  </tr>
     *  <tr>
     *   <td>"Click here to jump to the commons website - https://commons.apache.org"</td>
     *   <td>20</td>
     *   <td>"\n"</td>
     *   <td>true</td>
     *   <td>"Click here to jump\nto the commons\nwebsite -\nhttps://commons.apach\ne.org"</td>
     *  </tr>
     * </table>
     *
     * @param str  The String to be word wrapped, may be null.
     * @param wrapLength  The column to wrap the words at, less than 1 is treated as 1.
     * @param newLineStr  The string to insert for a new line, {@code null} uses the system property line separator.
     * @param wrapLongWords  true if long words (such as URLs) should be wrapped.
     * @return A line with newlines inserted, {@code null} if null input.
     */
    public static String wrap(final String str, final int wrapLength, final String newLineStr, final boolean wrapLongWords) {
        return wrap(str, wrapLength, newLineStr, wrapLongWords, " ");
    }

    /**
     * Wraps a single line of text, identifying words by {@code wrapOn}.
     *
     * <p>Leading spaces on a new line are stripped.
     * Trailing spaces are not stripped.</p>
     *
     * <table border="1">
     *  <caption>Examples</caption>
     *  <tr>
     *   <th>input</th>
     *   <th>wrapLength</th>
     *   <th>newLineString</th>
     *   <th>wrapLongWords</th>
     *   <th>wrapOn</th>
     *   <th>result</th>
     *  </tr>
     *  <tr>
     *   <td>null</td>
     *   <td>*</td>
     *   <td>*</td>
     *   <td>true/false</td>
     *   <td>*</td>
     *   <td>null</td>
     *  </tr>
     *  <tr>
     *   <td>""</td>
     *   <td>*</td>
     *   <td>*</td>
     *   <td>true/false</td>
     *   <td>*</td>
     *   <td>""</td>
     *  </tr>
     *  <tr>
     *   <td>"Here is one line of text that is going to be wrapped after 20 columns."</td>
     *   <td>20</td>
     *   <td>"\n"</td>
     *   <td>true/false</td>
     *   <td>" "</td>
     *   <td>"Here is one line of\ntext that is going\nto be wrapped after\n20 columns."</td>
     *  </tr>
     *  <tr>
     *   <td>"Here is one line of text that is going to be wrapped after 20 columns."</td>
     *   <td>20</td>
     *   <td>"&lt;br /&gt;"</td>
     *   <td>true/false</td>
     *   <td>" "</td>
     *   <td>"Here is one line of&lt;br /&gt;text that is going&lt;br /&gt;
     *   to be wrapped after&lt;br /&gt;20 columns."</td>
     *  </tr>
     *  <tr>
     *   <td>"Here is one line of text that is going to be wrapped after 20 columns."</td>
     *   <td>20</td>
     *   <td>null</td>
     *   <td>true/false</td>
     *   <td>" "</td>
     *   <td>"Here is one line of" + systemNewLine + "text that is going"
     *   + systemNewLine + "to be wrapped after" + systemNewLine + "20 columns."</td>
     *  </tr>
     *  <tr>
     *   <td>"Click here to jump to the commons website - https://commons.apache.org"</td>
     *   <td>20</td>
     *   <td>"\n"</td>
     *   <td>false</td>
     *   <td>" "</td>
     *   <td>"Click here to jump\nto the commons\nwebsite -\nhttps://commons.apache.org"</td>
     *  </tr>
     *  <tr>
     *   <td>"Click here to jump to the commons website - https://commons.apache.org"</td>
     *   <td>20</td>
     *   <td>"\n"</td>
     *   <td>true</td>
     *   <td>" "</td>
     *   <td>"Click here to jump\nto the commons\nwebsite -\nhttps://commons.apach\ne.org"</td>
     *  </tr>
     *  <tr>
     *   <td>"flammable/inflammable"</td>
     *   <td>20</td>
     *   <td>"\n"</td>
     *   <td>true</td>
     *   <td>"/"</td>
     *   <td>"flammable\ninflammable"</td>
     *  </tr>
     * </table>
     *
     * @param str  The String to be word wrapped, may be null.
     * @param wrapLength  The column to wrap the words at, less than 1 is treated as 1.
     * @param newLineStr  The string to insert for a new line, {@code null} uses the system property line separator.
     * @param wrapLongWords  true if long words (such as URLs) should be wrapped.
     * @param wrapOn Regex expression to be used as a breakable characters, if blank string is provided a space character will be used.
     * @return A line with newlines inserted, {@code null} if null input.
     */
    public static String wrap(final String str, int wrapLength, String newLineStr, final boolean wrapLongWords, String wrapOn) {
        if (str == null) {
            return null;
        }
        if (newLineStr == null) {
            newLineStr = System.lineSeparator();
        }
        if (wrapLength < 1) {
            wrapLength = 1;
        }
        if (StringUtils.isBlank(wrapOn)) {
            wrapOn = " ";
        }
        final Pattern patternToWrapOn = Pattern.compile(wrapOn);
        final int inputLineLength = str.length();
        int offset = 0;
        final StringBuilder wrappedLine = new StringBuilder(inputLineLength + 32);
        int matcherSize = -1;
        while (offset < inputLineLength) {
            int spaceToWrapAt = -1;
            Matcher matcher = patternToWrapOn
                    .matcher(str.substring(offset, Math.min((int) Math.min(Integer.MAX_VALUE, offset + wrapLength + 1L), inputLineLength)));
            if (matcher.find()) {
                if (matcher.start() == 0) {
                    matcherSize = matcher.end();
                    if (matcherSize != 0) {
                        offset += matcher.end();
                        continue;
                    }
                    offset += 1;
                }
                spaceToWrapAt = matcher.start() + offset;
            }
            // only last line without leading spaces is left
            if (inputLineLength - offset <= wrapLength) {
                break;
            }
            while (matcher.find()) {
                spaceToWrapAt = matcher.start() + offset;
            }
            if (spaceToWrapAt >= offset) {
                // normal case
                wrappedLine.append(str, offset, spaceToWrapAt);
                wrappedLine.append(newLineStr);
                offset = spaceToWrapAt + 1;
            } else // really long word or URL
            if (wrapLongWords) {
                if (matcherSize == 0) {
                    offset--;
                }
                // wrap really long word one line at a time, but keep a surrogate pair whole
                int wrapAt = wrapLength + offset;
                if (Character.isHighSurrogate(str.charAt(wrapAt - 1)) && Character.isLowSurrogate(str.charAt(wrapAt))) {
                    wrapAt++;
                }
                wrappedLine.append(str, offset, wrapAt);
                wrappedLine.append(newLineStr);
                offset = wrapAt;
                matcherSize = -1;
            } else {
                // do not wrap really long word, just extend beyond limit
                matcher = patternToWrapOn.matcher(str.substring(offset + wrapLength));
                if (matcher.find()) {
                    matcherSize = matcher.end() - matcher.start();
                    spaceToWrapAt = matcher.start() + offset + wrapLength;
                }
                if (spaceToWrapAt >= 0) {
                    if (matcherSize == 0 && offset != 0) {
                        offset--;
                    }
                    wrappedLine.append(str, offset, spaceToWrapAt);
                    wrappedLine.append(newLineStr);
                    offset = spaceToWrapAt + 1;
                } else {
                    if (matcherSize == 0 && offset != 0) {
                        offset--;
                    }
                    wrappedLine.append(str, offset, str.length());
                    offset = inputLineLength;
                    matcherSize = -1;
                }
            }
        }
        if (matcherSize == 0 && offset < inputLineLength) {
            offset--;
        }
        // Whatever is left in line is short enough to just pass through
        wrappedLine.append(str, offset, str.length());
        return wrappedLine.toString();
    }

    /**
     * {@code WordUtils} instances should NOT be constructed in standard programming. Instead, the class should be used as
     * {@code WordUtils.wrap("foo bar", 20);}.
     * <p>
     * This constructor is public to permit tools that require a JavaBean instance to operate.
     * </p>
     */
    public WordUtils() {
    }
 }