// Copyright (c) 2019, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

package com.android.tools.r8.ir.desugar.backports;

import java.util.Iterator;

public final class StringMethods {

  public static String joinArray(CharSequence delimiter, CharSequence... elements) {
    if (delimiter == null) throw new NullPointerException("delimiter");
    StringBuilder builder = new StringBuilder();
    if (elements.length > 0) {
      builder.append(elements[0]);
      for (int i = 1; i < elements.length; i++) {
        builder.append(delimiter);
        builder.append(elements[i]);
      }
    }
    return builder.toString();
  }

  public static String joinIterable(CharSequence delimiter,
      Iterable<? extends CharSequence> elements) {
    if (delimiter == null) throw new NullPointerException("delimiter");
    StringBuilder builder = new StringBuilder();
    Iterator<? extends CharSequence> iterator = elements.iterator();
    if (iterator.hasNext()) {
      builder.append(iterator.next());
      while (iterator.hasNext()) {
        builder.append(delimiter);
        builder.append(iterator.next());
      }
    }
    return builder.toString();
  }

  public static String repeat(String receiver, int count) {
    if (count < 0) {
      throw new IllegalArgumentException("count is negative: " + count);
    }
    int length = receiver.length();
    if (count == 0 || length == 0) {
      return "";
    }
    if (count == 1) {
      return receiver;
    }
    // Condition `count * receiver.length() <= Integer.MAX_VALUE` must hold for the String to be
    // allocated.
    if (receiver.length() > Integer.MAX_VALUE / count) {
      throw new OutOfMemoryError(
          "Repeating "
              + receiver.length()
              + " bytes String "
              + count
              + " times will produce a String exceeding maximum size.");
    }
    StringBuilder builder = new StringBuilder(length * count);
    for (int i = 0; i < count; i++) {
      builder.append(receiver);
    }
    return builder.toString();
  }

  public static boolean isBlank(String receiver) {
    for (int i = 0, length = receiver.length(); i < length; ) {
      int codePoint = receiver.codePointAt(i);
      if (!Character.isWhitespace(codePoint)) {
        return false;
      }
      i += Character.charCount(codePoint);
    }
    return true;
  }

  public static String strip(String receiver) {
    int start = 0;
    int end = receiver.length();
    while (start < end) {
      int codePoint = receiver.codePointAt(start);
      if (!Character.isWhitespace(codePoint)) {
        break;
      }
      start += Character.charCount(codePoint);
    }
    while (end > start) {
      int codePoint = Character.codePointBefore(receiver, end);
      if (!Character.isWhitespace(codePoint)) {
        break;
      }
      end -= Character.charCount(codePoint);
    }
    return receiver.substring(start, end);
  }

  public static String stripLeading(String receiver) {
    int start = 0;
    int end = receiver.length();
    while (start < end) {
      int codePoint = receiver.codePointAt(start);
      if (!Character.isWhitespace(codePoint)) {
        break;
      }
      start += Character.charCount(codePoint);
    }
    return receiver.substring(start, end);
  }

  public static String stripTrailing(String receiver) {
    int end = receiver.length();
    while (end > 0) {
      int codePoint = Character.codePointBefore(receiver, end);
      if (!Character.isWhitespace(codePoint)) {
        break;
      }
      end -= Character.charCount(codePoint);
    }
    return receiver.substring(0, end);
  }
}