content: /*
   * 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 com.itsaky.androidide.utils;
  
  import androidx.annotation.NonNull;
  import java.io.Reader;
  import java.io.Serializable;
  import java.util.Objects;
  
  /**
   * {@link Reader} implementation that can read from String, StringBuffer, StringBuilder or
   * CharBuffer.
   *
   * <p><strong>Note:</strong> Supports {@link #mark(int)} and {@link #reset()}.
   *
   * @since 1.4
   */
  public class CharSequenceReader extends Reader implements Serializable {
  
    private static final long serialVersionUID = 3724187752191401220L;
    private final CharSequence charSequence;
    /**
     * The start index in the character sequence, inclusive.
     *
     * <p>When de-serializing a CharSequenceReader that was serialized before this fields was added,
     * this field will be initialized to 0, which gives the same behavior as before: start reading
     * from the start.
     *
     * @see #start()
     * @since 2.7
     */
    private final int start;
    /**
     * The end index in the character sequence, exclusive.
     *
     * <p>When de-serializing a CharSequenceReader that was serialized before this fields was added,
     * this field will be initialized to {@code null}, which gives the same behavior as before: stop
     * reading at the CharSequence's length. If this field was an int instead, it would be initialized
     * to 0 when the CharSequenceReader is de-serialized, causing it to not return any characters at
     * all.
     *
     * @see #end()
     * @since 2.7
     */
    private final Integer end;
  
    private int idx;
    private int mark;
  
    /**
     * Constructs a new instance with the specified character sequence.
     *
     * @param charSequence The character sequence, may be {@code null}
     */
    public CharSequenceReader(final CharSequence charSequence) {
      this(charSequence, 0);
    }
  
    /**
     * Constructs a new instance with a portion of the specified character sequence.
     *
     * <p>The start index is not strictly enforced to be within the bounds of the character sequence.
     * This allows the character sequence to grow or shrink in size without risking any {@link
     * IndexOutOfBoundsException} to be thrown. Instead, if the character sequence grows smaller than
     * the start index, this instance will act as if all characters have been read.
     *
     * @param charSequence The character sequence, may be {@code null}
     * @param start The start index in the character sequence, inclusive
     * @throws IllegalArgumentException if the start index is negative
     * @since 2.7
     */
    public CharSequenceReader(final CharSequence charSequence, final int start) {
      this(charSequence, start, Integer.MAX_VALUE);
    }
  
    /**
     * Constructs a new instance with a portion of the specified character sequence.
     *
     * <p>The start and end indexes are not strictly enforced to be within the bounds of the character
     * sequence. This allows the character sequence to grow or shrink in size without risking any
     * {@link IndexOutOfBoundsException} to be thrown. Instead, if the character sequence grows
     * smaller than the start index, this instance will act as if all characters have been read; if
     * the character sequence grows smaller than the end, this instance will use the actual character
     * sequence length.
     *
     * @param charSequence The character sequence, may be {@code null}
     * @param start The start index in the character sequence, inclusive
     * @param end The end index in the character sequence, exclusive
     * @throws IllegalArgumentException if the start index is negative, or if the end index is smaller
     *     than the start index
     * @since 2.7
     */
    public CharSequenceReader(final CharSequence charSequence, final int start, final int end) {
      if (start < 0) {
        throw new IllegalArgumentException("Start index is less than zero: " + start);
      }
      if (end < start) {
        throw new IllegalArgumentException("End index is less than start " + start + ": " + end);
      }
      // Don't check the start and end indexes against the CharSequence,
      // to let it grow and shrink without breaking existing behavior.
  
      this.charSequence = charSequence != null ? charSequence : "";
      this.start = start;
      this.end = end;
  
      this.idx = start;
      this.mark = start;
    }
  
    /**
     * Return a String representation of the underlying character sequence.
     *
     * @return The contents of the character sequence
     */
    @NonNull
    @Override
    public String toString() {
      final CharSequence subSequence = charSequence.subSequence(start(), end());
      return subSequence.toString();
    }
    /** Close resets the file back to the start and removes any marked position. */
    @Override
    public void close() {
      idx = start;
      mark = start;
    }
  
    /**
     * Returns the index in the character sequence to start reading from, taking into account its
     * length.
     *
     * @return The start index in the character sequence (inclusive).
     */
    private int start() {
      return Math.min(charSequence.length(), start);
    }
    /**
     * Returns the index in the character sequence to end reading at, taking into account its length.
     *
     * @return The end index in the character sequence (exclusive).
     */
    private int end() {
      /*
       * end == null for de-serialized instances that were serialized before start and end were added.
       * Use Integer.MAX_VALUE to get the same behavior as before - use the entire CharSequence.
       */
      return Math.min(charSequence.length(), end == null ? Integer.MAX_VALUE : end);
    }
  
    /**
     * Mark the current position.
     *
     * @param readAheadLimit ignored
     */
    @Override
    public void mark(final int readAheadLimit) {
      mark = idx;
    }
  
    /**
     * Mark is supported (returns true).
     *
     * @return {@code true}
     */
    @Override
    public boolean markSupported() {
      return true;
    }
  
    /**
     * Read a single character.
     *
     * @return the next character from the character sequence or -1 if the end has been reached.
     */
    @Override
    public int read() {
      if (idx >= end()) {
        return -1;
      }
      return charSequence.charAt(idx++);
    }
  
    /**
     * Read the specified number of characters into the array.
     *
     * @param array The array to store the characters in
     * @param offset The starting position in the array to store
     * @param length The maximum number of characters to read
     * @return The number of characters read or -1 if there are no more
     */
    @Override
    public int read(final char[] array, final int offset, final int length) {
      if (idx >= end()) {
        return -1;
      }
      Objects.requireNonNull(array, "array");
      if (length < 0 || offset < 0 || offset + length > array.length) {
        throw new IndexOutOfBoundsException(
            "Array Size=" + array.length + ", offset=" + offset + ", length=" + length);
      }
  
      if (charSequence instanceof String) {
        final int count = Math.min(length, end() - idx);
        ((String) charSequence).getChars(idx, idx + count, array, offset);
        idx += count;
        return count;
      }
      if (charSequence instanceof StringBuilder) {
        final int count = Math.min(length, end() - idx);
        ((StringBuilder) charSequence).getChars(idx, idx + count, array, offset);
        idx += count;
        return count;
      }
      if (charSequence instanceof StringBuffer) {
        final int count = Math.min(length, end() - idx);
        ((StringBuffer) charSequence).getChars(idx, idx + count, array, offset);
        idx += count;
        return count;
      }
  
      int count = 0;
      for (int i = 0; i < length; i++) {
        final int c = read();
        if (c == -1) {
          return count;
        }
        array[offset + i] = (char) c;
        count++;
      }
      return count;
    }
  
    /**
     * Tells whether this stream is ready to be read.
     *
     * @return {@code true} if more characters from the character sequence are available, or {@code
     *     false} otherwise.
     */
    @Override
    public boolean ready() {
      return idx < end();
    }
  
    /**
     * Reset the reader to the last marked position (or the beginning if mark has not been called).
     */
    @Override
    public void reset() {
      idx = mark;
    }
  
    /**
     * Skip the specified number of characters.
     *
     * @param n The number of characters to skip
     * @return The actual number of characters skipped
     */
    @Override
    public long skip(final long n) {
      if (n < 0) {
        throw new IllegalArgumentException("Number of characters to skip is less than zero: " + n);
      }
      if (idx >= end()) {
        return 0;
      }
      final int dest = (int) Math.min(end(), idx + n);
      final int count = dest - idx;
      idx = dest;
      return count;
    }
  }
  