/*
 * 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
 *
 * 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 org.apache.logging.log4j.util;

import java.util.Iterator;
import java.util.Locale;
import java.util.Objects;

/**
 * Hive uses class with the same full name from log4j-api.
 * Added this class to avoid ClassNotFound errors from Hive.
 * <p>
 * This is a copy of the log4j-api 2.14.1 code with some minor tweaks to avoid dependency on other classes.
 *
 * See <a href="https://issues.apache.org/jira/browse/HIVE-23088">HIVE-23088</a> for the problem description.
 */
public final class Strings {

  /**
   * The empty string.
   */
  public static final String EMPTY = "";

  /**
   * OS-dependent line separator, defaults to {@code "\n"} if the system property {@code "line.separator"} cannot be
   * read. Apache Log4J 2.x code uses a PropertyUtil and may get a different result - but we don't want to copy all
   * that code to Drill.
   */
  public static final String LINE_SEPARATOR = System.lineSeparator();

  private static final char DQUOTE = '\"';
  private static final char QUOTE = '\'';

  /**
   * Returns a double quoted string.
   *
   * @param str a String
   * @return {@code "str"}
   */
  public static String dquote(final String str) {
    return DQUOTE + str + DQUOTE;
  }

  /**
   * Checks if a String is blank. A blank string is one that is either
   * {@code null}, empty, or all characters are {@link Character#isWhitespace(char)}.
   *
   * @param s the String to check, may be {@code null}
   * @return {@code true} if the String is {@code null}, empty, or or all characters are {@link Character#isWhitespace(char)}
   */
  public static boolean isBlank(final String s) {
    if (s == null || s.isEmpty()) {
      return true;
    }
    for (int i = 0; i < s.length(); i++) {
      char c = s.charAt(i);
      if (!Character.isWhitespace(c)) {
        return false;
      }
    }
    return true;
  }

  /**
   * <p>
   * Checks if a CharSequence is empty ("") or null.
   * </p>
   *
   * <pre>
   * Strings.isEmpty(null)      = true
   * Strings.isEmpty("")        = true
   * Strings.isEmpty(" ")       = false
   * Strings.isEmpty("bob")     = false
   * Strings.isEmpty("  bob  ") = false
   * </pre>
   *
   * <p>
   * NOTE: This method changed in Lang version 2.0. It no longer trims the CharSequence. That functionality is
   * available in isBlank().
   * </p>
   *
   * <p>
   * Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.isEmpty(CharSequence)
   * </p>
   *
   * @param cs the CharSequence to check, may be null
   * @return {@code true} if the CharSequence is empty or null
   */
  public static boolean isEmpty(final CharSequence cs) {
    return cs == null || cs.length() == 0;
  }

  /**
   * Checks if a String is not blank. The opposite of {@link #isBlank(String)}.
   *
   * @param s the String to check, may be {@code null}
   * @return {@code true} if the String is non-{@code null} and has content after being trimmed.
   */
  public static boolean isNotBlank(final String s) {
    return !isBlank(s);
  }

  /**
   * <p>
   * Checks if a CharSequence is not empty ("") and not null.
   * </p>
   *
   * <pre>
   * Strings.isNotEmpty(null)      = false
   * Strings.isNotEmpty("")        = false
   * Strings.isNotEmpty(" ")       = true
   * Strings.isNotEmpty("bob")     = true
   * Strings.isNotEmpty("  bob  ") = true
   * </pre>
   *
   * <p>
   * Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.isNotEmpty(CharSequence)
   * </p>
   *
   * @param cs the CharSequence to check, may be null
   * @return {@code true} if the CharSequence is not empty and not null
   */
  public static boolean isNotEmpty(final CharSequence cs) {
    return !isEmpty(cs);
  }

  /**
   * <p>Joins the elements of the provided {@code Iterable} into
   * a single String containing the provided elements.</p>
   *
   * <p>No delimiter is added before or after the list. Null objects or empty
   * strings within the iteration are represented by empty strings.</p>
   *
   * @param iterable  the {@code Iterable} providing the values to join together, may be null
   * @param separator  the separator character to use
   * @return the joined String, {@code null} if null iterator input
   */
  public static String join(final Iterable<?> iterable, final char separator) {
    if (iterable == null) {
      return null;
    }
    return join(iterable.iterator(), separator);
  }

  /**
   * <p>Joins the elements of the provided {@code Iterator} into
   * a single String containing the provided elements.</p>
   *
   * <p>No delimiter is added before or after the list. Null objects or empty
   * strings within the iteration are represented by empty strings.</p>
   *
   * @param iterator  the {@code Iterator} of values to join together, may be null
   * @param separator  the separator character to use
   * @return the joined String, {@code null} if null iterator input
   */
  public static String join(final Iterator<?> iterator, final char separator) {

    // handle null, zero and one elements before building a buffer
    if (iterator == null) {
      return null;
    }
    if (!iterator.hasNext()) {
      return EMPTY;
    }
    final Object first = iterator.next();
    if (!iterator.hasNext()) {
      return Objects.toString(first, EMPTY);
    }

    // two or more elements
    final StringBuilder buf = new StringBuilder(256); // Java default is 16, probably too small
    if (first != null) {
      buf.append(first);
    }

    while (iterator.hasNext()) {
      buf.append(separator);
      final Object obj = iterator.next();
      if (obj != null) {
        buf.append(obj);
      }
    }

    return buf.toString();
  }

  /**
   * <p>Gets the leftmost {@code len} characters of a String.</p>
   *
   * <p>If {@code len} characters are not available, or the
   * String is {@code null}, the String will be returned without
   * an exception. An empty String is returned if len is negative.</p>
   *
   * <pre>
   * StringUtils.left(null, *)    = null
   * StringUtils.left(*, -ve)     = ""
   * StringUtils.left("", *)      = ""
   * StringUtils.left("abc", 0)   = ""
   * StringUtils.left("abc", 2)   = "ab"
   * StringUtils.left("abc", 4)   = "abc"
   * </pre>
   *
   * <p>
   * Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.
   * </p>
   *
   * @param str  the String to get the leftmost characters from, may be null
   * @param len  the length of the required String
   * @return the leftmost characters, {@code null} if null String input
   */
  public static String left(final String str, final int len) {
    if (str == null) {
      return null;
    }
    if (len < 0) {
      return EMPTY;
    }
    if (str.length() <= len) {
      return str;
    }
    return str.substring(0, len);
  }

  /**
   * Returns a quoted string.
   *
   * @param str a String
   * @return {@code 'str'}
   */
  public static String quote(final String str) {
    return QUOTE + str + QUOTE;
  }

  /**
   * <p>
   * Removes control characters (char &lt;= 32) from both ends of this String returning {@code null} if the String is
   * empty ("") after the trim or if it is {@code null}.
   *
   * <p>
   * The String is trimmed using {@link String#trim()}. Trim removes start and end characters &lt;= 32.
   * </p>
   *
   * <pre>
   * Strings.trimToNull(null)          = null
   * Strings.trimToNull("")            = null
   * Strings.trimToNull("     ")       = null
   * Strings.trimToNull("abc")         = "abc"
   * Strings.trimToNull("    abc    ") = "abc"
   * </pre>
   *
   * <p>
   * Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.trimToNull(String)
   * </p>
   *
   * @param str the String to be trimmed, may be null
   * @return the trimmed String, {@code null} if only chars &lt;= 32, empty or null String input
   */
  public static String trimToNull(final String str) {
    final String ts = str == null ? null : str.trim();
    return isEmpty(ts) ? null : ts;
  }

  private Strings() {
    // empty
  }

  /**
   * Shorthand for {@code str.toUpperCase(Locale.ROOT);}
   * @param str The string to upper case.
   * @return a new string
   * @see String#toLowerCase(Locale)
   */
  public static String toRootUpperCase(final String str) {
    return str.toUpperCase(Locale.ROOT);
  }

  /**
   * Creates a new string repeating given {@code str} {@code count} times.
   * @param str input string
   * @param count the repetition count
   * @return the new string
   * @throws IllegalArgumentException if either {@code str} is null or {@code count} is negative
   */
  public static String repeat(final String str, final int count) {
    Objects.requireNonNull(str, "str");
    if (count < 0) {
      throw new IllegalArgumentException("count");
    }
    StringBuilder sb = new StringBuilder(str.length() * count);
    for (int index = 0; index < count; index++) {
      sb.append(str);
    }
    return sb.toString();
  }

}