// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (c) 2012-2014 Monty Program Ab
// Copyright (c) 2015-2021 MariaDB Corporation Ab

package org.mariadb.jdbc;

import java.io.*;
import java.sql.Blob;
import java.sql.SQLException;
import java.util.Arrays;

/** MariaDB Blob implementation */
public class MariaDbBlob implements Blob, Serializable {

  private static final long serialVersionUID = -4736603161284649490L;

  /** content */
  protected byte[] data;

  /** data offset */
  protected transient int offset;

  /** data length */
  protected transient int length;

  /** Creates an empty blob. */
  public MariaDbBlob() {
    data = new byte[0];
    offset = 0;
    length = 0;
  }

  /**
   * Creates a blob with content.
   *
   * @param bytes the content for the blob.
   */
  public MariaDbBlob(byte[] bytes) {
    if (bytes == null) {
      throw new IllegalArgumentException("byte array is null");
    }
    data = bytes;
    offset = 0;
    length = bytes.length;
  }

  /**
   * Creates a blob with content.
   *
   * @param bytes the content for the blob.
   * @param offset offset
   * @param length length
   */
  public MariaDbBlob(byte[] bytes, int offset, int length) {
    if (bytes == null) {
      throw new IllegalArgumentException("byte array is null");
    }
    data = bytes;
    this.offset = offset;
    this.length = Math.min(bytes.length - offset, length);
  }

  private MariaDbBlob(int offset, int length, byte[] bytes) {
    this.data = bytes;
    this.offset = offset;
    this.length = length;
  }

  /**
   * Return a new Blob from blob data
   *
   * @param bytes data
   * @param offset data offset
   * @param length data length
   * @return new Blob
   */
  public static MariaDbBlob safeMariaDbBlob(byte[] bytes, int offset, int length) {
    return new MariaDbBlob(offset, length, bytes);
  }

  /**
   * Returns the number of bytes in the <code>BLOB</code> value designated by this <code>Blob</code>
   * object.
   *
   * @return length of the <code>BLOB</code> in bytes
   */
  public long length() {
    return length;
  }

  /**
   * Retrieves all or part of the <code>BLOB</code> value that this <code>Blob</code> object
   * represents, as an array of bytes. This <code>byte</code> array contains up to <code>length
   * </code> consecutive bytes starting at position <code>pos</code>.
   *
   * @param pos the ordinal position of the first byte in the <code>BLOB</code> value to be
   *     extracted; the first byte is at position 1
   * @param length the number of consecutive bytes to be copied; the value for length must be 0 or
   *     greater
   * @return a byte array containing up to <code>length</code> consecutive bytes from the <code>BLOB
   *     </code> value designated by this <code>Blob</code> object, starting with the byte at
   *     position <code>pos</code>
   * @throws SQLException if there is an error accessing the <code>BLOB</code> value; if pos is less
   *     than 1 or length is less than 0
   * @see #setBytes
   * @since 1.2
   */
  public byte[] getBytes(final long pos, final int length) throws SQLException {
    if (pos < 1) {
      throw new SQLException(
          String.format("Out of range (position should be > 0, but is %s)", pos));
    }
    final int offset = this.offset + (int) (pos - 1);
    byte[] result = new byte[length];
    System.arraycopy(data, offset, result, 0, Math.min(this.length - (int) (pos - 1), length));
    return result;
  }

  /**
   * Retrieves the <code>BLOB</code> value designated by this <code>Blob</code> instance as a
   * stream.
   *
   * @return a stream containing the <code>BLOB</code> data
   * @throws SQLException if something went wrong
   * @see #setBinaryStream
   */
  public InputStream getBinaryStream() throws SQLException {
    return getBinaryStream(1, length);
  }

  /**
   * Returns an <code>InputStream</code> object that contains a partial <code>Blob</code> value,
   * starting with the byte specified by pos, which is length bytes in length.
   *
   * @param pos the offset to the first byte of the partial value to be retrieved. The first byte in
   *     the <code>Blob</code> is at position 1
   * @param length the length in bytes of the partial value to be retrieved
   * @return <code>InputStream</code> through which the partial <code>Blob</code> value can be read.
   * @throws SQLException if pos is less than 1 or if pos is greater than the number of bytes in the
   *     <code>Blob</code> or if pos + length is greater than the number of bytes in the <code>Blob
   *     </code>
   */
  public InputStream getBinaryStream(final long pos, final long length) throws SQLException {
    if (pos < 1) {
      throw new SQLException("Out of range (position should be > 0)");
    }
    if (pos - 1 > this.length) {
      throw new SQLException("Out of range (position > stream size)");
    }
    if (pos + length - 1 > this.length) {
      throw new SQLException("Out of range (position + length - 1 > streamSize)");
    }

    return new ByteArrayInputStream(data, this.offset + (int) pos - 1, (int) length);
  }

  /**
   * Retrieves the byte position at which the specified byte array <code>pattern</code> begins
   * within the <code>BLOB</code> value that this <code>Blob</code> object represents. The search
   * for <code>pattern</code> begins at position <code>start</code>.
   *
   * @param pattern the byte array for which to search
   * @param start the position at which to begin searching; the first position is 1
   * @return the position at which the pattern appears, else -1
   */
  public long position(final byte[] pattern, final long start) throws SQLException {
    if (pattern.length == 0) {
      return 0;
    }
    if (start < 1) {
      throw new SQLException(
          String.format("Out of range (position should be > 0, but is %s)", start));
    }
    if (start > this.length) {
      throw new SQLException("Out of range (start > stream size)");
    }

    outer:
    for (int i = (int) (offset + start - 1); i <= offset + this.length - pattern.length; i++) {
      for (int j = 0; j < pattern.length; j++) {
        if (data[i + j] != pattern[j]) {
          continue outer;
        }
      }
      return i + 1 - offset;
    }
    return -1;
  }

  /**
   * Retrieves the byte position in the <code>BLOB</code> value designated by this <code>Blob</code>
   * object at which <code>pattern</code> begins. The search begins at position <code>start</code>.
   *
   * @param pattern the <code>Blob</code> object designating the <code>BLOB</code> value for which
   *     to search
   * @param start the position in the <code>BLOB</code> value at which to begin searching; the first
   *     position is 1
   * @return the position at which the pattern begins, else -1
   */
  public long position(final Blob pattern, final long start) throws SQLException {
    byte[] blobBytes = pattern.getBytes(1, (int) pattern.length());
    return position(blobBytes, start);
  }

  /**
   * Writes the given array of bytes to the <code>BLOB</code> value that this <code>Blob</code>
   * object represents, starting at position <code>pos</code>, and returns the number of bytes
   * written. The array of bytes will overwrite the existing bytes in the <code>Blob</code> object
   * starting at the position <code>pos</code>. If the end of the <code>Blob</code> value is reached
   * while writing the array of bytes, then the length of the <code>Blob</code> value will be
   * increased to accommodate the extra bytes.
   *
   * @param pos the position in the <code>BLOB</code> object at which to start writing; the first
   *     position is 1
   * @param bytes the array of bytes to be written to the <code>BLOB</code> value that this <code>
   *     Blob</code> object represents
   * @return the number of bytes written
   * @see #getBytes
   */
  public int setBytes(final long pos, final byte[] bytes) throws SQLException {
    if (pos < 1) {
      throw new SQLException("pos should be > 0, first position is 1.");
    }

    final int arrayPos = (int) pos - 1;

    if (length > arrayPos + bytes.length) {

      System.arraycopy(bytes, 0, data, offset + arrayPos, bytes.length);

    } else {

      byte[] newContent = new byte[arrayPos + bytes.length];
      if (Math.min(arrayPos, length) > 0) {
        System.arraycopy(data, this.offset, newContent, 0, Math.min(arrayPos, length));
      }
      System.arraycopy(bytes, 0, newContent, arrayPos, bytes.length);
      data = newContent;
      length = arrayPos + bytes.length;
      offset = 0;
    }
    return bytes.length;
  }

  /**
   * Writes all or part of the given <code>byte</code> array to the <code>BLOB</code> value that
   * this <code>Blob</code> object represents and returns the number of bytes written. Writing
   * starts at position <code>pos</code> in the <code>BLOB</code> value; <code>len</code> bytes from
   * the given byte array are written. The array of bytes will overwrite the existing bytes in the
   * <code>Blob</code> object starting at the position <code>pos</code>. If the end of the <code>
   * Blob</code> value is reached while writing the array of bytes, then the length of the <code>
   * Blob</code> value will be increased to accommodate the extra bytes.
   *
   * <p><b>Note:</b> If the value specified for <code>pos</code> is greater than the length+1 of the
   * <code>BLOB</code> value then the behavior is undefined. Some JDBC drivers may throw a <code>
   * SQLException</code> while other drivers may support this operation.
   *
   * @param pos the position in the <code>BLOB</code> object at which to start writing; the first
   *     position is 1
   * @param bytes the array of bytes to be written to this <code>BLOB</code> object
   * @param offset the offset into the array <code>bytes</code> at which to start reading the bytes
   *     to be set
   * @param len the number of bytes to be written to the <code>BLOB</code> value from the array of
   *     bytes <code>bytes</code>
   * @return the number of bytes written
   * @throws SQLException if there is an error accessing the <code>BLOB</code> value or if pos is
   *     less than 1
   * @see #getBytes
   */
  public int setBytes(final long pos, final byte[] bytes, final int offset, final int len)
      throws SQLException {

    if (pos < 1) {
      throw new SQLException("pos should be > 0, first position is 1.");
    }

    final int arrayPos = (int) pos - 1;
    final int byteToWrite = Math.min(bytes.length - offset, len);

    if (length > arrayPos + byteToWrite) {

      System.arraycopy(bytes, offset, data, this.offset + arrayPos, byteToWrite);

    } else {

      byte[] newContent = new byte[arrayPos + byteToWrite];
      if (Math.min(arrayPos, length) > 0) {
        System.arraycopy(data, this.offset, newContent, 0, Math.min(arrayPos, length));
      }
      System.arraycopy(bytes, offset, newContent, arrayPos, byteToWrite);
      data = newContent;
      length = arrayPos + byteToWrite;
      this.offset = 0;
    }

    return byteToWrite;
  }

  /**
   * Retrieves a stream that can be used to write to the <code>BLOB</code> value that this <code>
   * Blob</code> object represents. The stream begins at position <code>pos</code>. The bytes
   * written to the stream will overwrite the existing bytes in the <code>Blob</code> object
   * starting at the position <code>pos</code>. If the end of the <code>Blob</code> value is reached
   * while writing to the stream, then the length of the <code>Blob</code> value will be increased
   * to accommodate the extra bytes.
   *
   * <p><b>Note:</b> If the value specified for <code>pos</code> is greater than the length+1 of the
   * <code>BLOB</code> value then the behavior is undefined. Some JDBC drivers may throw a <code>
   * SQLException</code> while other drivers may support this operation.
   *
   * @param pos the position in the <code>BLOB</code> value at which to start writing; the first
   *     position is 1
   * @return a <code>java.io.OutputStream</code> object to which data can be written
   * @throws SQLException if there is an error accessing the <code>BLOB</code> value or if pos is
   *     less than 1
   * @see #getBinaryStream
   * @since 1.4
   */
  public OutputStream setBinaryStream(final long pos) throws SQLException {
    if (pos < 1) {
      throw new SQLException("Invalid position in blob");
    }
    if (offset > 0) {
      byte[] tmp = new byte[length];
      System.arraycopy(data, offset, tmp, 0, length);
      data = tmp;
      offset = 0;
    }
    return new BlobOutputStream(this, (int) (pos - 1) + offset);
  }

  /**
   * Truncates the <code>BLOB</code> value that this <code>Blob</code> object represents to be
   * <code>len</code> bytes in length.
   *
   * @param len the length, in bytes, to which the <code>BLOB</code> value that this <code>Blob
   *     </code> object represents should be truncated
   */
  public void truncate(final long len) {
    if (len >= 0 && len < this.length) {
      this.length = (int) len;
    }
  }

  /**
   * This method frees the <code>Blob</code> object and releases the resources that it holds. The
   * object is invalid once the <code>free</code> method is called.
   *
   * <p>After <code>free</code> has been called, any attempt to invoke a method other than <code>
   * free</code> will result in a <code>SQLException</code> being thrown. If <code>free</code> is
   * called multiple times, the subsequent calls to <code>free</code> are treated as a no-op.
   */
  public void free() {
    this.data = new byte[0];
    this.offset = 0;
    this.length = 0;
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;

    MariaDbBlob that = (MariaDbBlob) o;

    if (length != that.length) return false;

    for (int i = 0; i < length; i++) {
      if (data[offset + i] != that.data[that.offset + i]) return false;
    }
    return true;
  }

  @Override
  public int hashCode() {
    int result = Arrays.hashCode(data);
    result = 31 * result + offset;
    result = 31 * result + length;
    return result;
  }

  static class BlobOutputStream extends OutputStream {

    private final MariaDbBlob blob;
    private int pos;

    public BlobOutputStream(MariaDbBlob blob, int pos) {
      this.blob = blob;
      this.pos = pos;
    }

    @Override
    public void write(int bit) {

      if (this.pos >= blob.length) {
        byte[] tmp = new byte[2 * blob.length + 1];
        System.arraycopy(blob.data, blob.offset, tmp, 0, blob.length);
        blob.data = tmp;
        pos -= blob.offset;
        blob.offset = 0;
        blob.length++;
      }
      blob.data[pos++] = (byte) bit;
    }

    @Override
    public void write(byte[] buf, int off, int len) throws IOException {
      if (off < 0) {
        throw new IOException("Invalid offset " + off);
      }
      if (len < 0) {
        throw new IOException("Invalid len " + len);
      }
      int realLen = Math.min(buf.length - off, len);
      if (pos + realLen >= blob.length) {
        int newLen = 2 * blob.length + realLen;
        byte[] tmp = new byte[newLen];
        System.arraycopy(blob.data, blob.offset, tmp, 0, blob.length);
        blob.data = tmp;
        pos -= blob.offset;
        blob.offset = 0;
        blob.length = pos + realLen;
      }
      System.arraycopy(buf, off, blob.data, pos, realLen);
      pos += realLen;
    }

    @Override
    public void write(byte[] buf) throws IOException {
      write(buf, 0, buf.length);
    }
  }
}