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package org.scijava.io;

/**
 * A {@link ByteBank} is a self-growing buffer over arbitrary bytes.
 *
 * @author Gabriel Einsdorf
 * @author Curtis Rueden
 */
public interface ByteBank {

	/**
	 * @param pos the position to read from
	 * @return the byte at the given position
	 */
	public byte getByte(long pos);

	/**
	 * @param startPos the position in the buffer to start reading from
	 * @param bytes the byte array to read into
	 * @return the number of bytes read
	 */
	default int getBytes(long startPos, byte[] bytes) {
		return getBytes(startPos, bytes, 0, bytes.length);
	}

	/**
	 * @param startPos the position in the buffer to start reading from
	 * @param bytes the byte array to read into
	 * @param offset the offset in the bytes array
	 * @param length the number of elements to read into the bytes array
	 * @return number of bytes read
	 */
	int getBytes(long startPos, byte[] bytes, int offset, int length);

	/**
	 * Copies part of this buffer into a newly allocated byte array.
	 * 
	 * @param offset the initial position in the buffer
	 * @param len the number of bytes to copy
	 * @return The newly allocated byte array containing the data.
	 */
	default byte[] toByteArray(final long offset, final int len) {
		if (offset < 0 || len < 0 || offset + len > size()) {
			throw new IllegalArgumentException("Invalid range");
		}
		final byte[] bytes = new byte[len];
		getBytes(offset, bytes);
		return bytes;
	}

	/**
	 * Copies this entire buffer into a newly allocated byte array.
	 * 
	 * @return The newly allocated byte array containing the data.
	 */
	default byte[] toByteArray() {
		long max = size();
		if (max > Integer.MAX_VALUE) {
			throw new IllegalStateException(
				"Byte bank is too large to store into a single byte[]");
		}
		return toByteArray(0, (int) max);
	}

	/**
	 * Sets the bytes starting form the given position to the values form the
	 * provided array.
	 *
	 * @param startPos the position in the buffer to start writing from
	 * @param bytes the byte array to write
	 * @param offset the offset in the bytes array
	 * @param length the number of bytes to read
	 */
	void setBytes(long startPos, byte[] bytes, int offset, int length);

	/**
	 * Appends the given bytes to the buffer
	 *
	 * @param bytes the array containing the bytes to append to the buffer
	 * @param length the number of elements to append from the bytes array
	 */
	default void appendBytes(byte[] bytes, int length) {
		appendBytes(bytes, 0, length);
	}

	/**
	 * Appends the given bytes to the buffer
	 *
	 * @param bytes the array containing the bytes to append to the buffer
	 * @param offset the offset in the bytes array
	 * @param length the number of elements to append from the bytes array
	 */
	default void appendBytes(byte[] bytes, int offset, int length) {
		setBytes(size(), bytes, offset, length);
	}

	/**
	 * Check if we can read from the specified range
	 *
	 * @param start the start position of the range
	 * @param end the end position of the range
	 */
	default void checkReadPos(final long start, final long end) {
		basicRangeCheck(start, end);
		if (start > size()) {
			throw new IndexOutOfBoundsException("Requested position: " + start +
				" is outside the buffer: " + size());
		}
	}

	/**
	 * Check if we can write to the specified range
	 *
	 * @param start the start position of the range
	 * @param end the end position of the range
	 * @throws IndexOutOfBoundsException if
	 */
	default void checkWritePos(final long start, final long end) {
		if (start > size() + 1) { // we can't have holes in the buffer
			throw new IndexOutOfBoundsException("Requested start position: " + start +
				" would leave a hole in the buffer, largest legal position is: " +
				size());
		}
		if (end < start) {
			throw new IllegalArgumentException(
				"Invalid range, end is smaller than start!");
		}
		if (end > getMaxBufferSize()) {
			throw new IndexOutOfBoundsException("Requested position " + end +
				" is larger than the maximal buffer size: " + getMaxBufferSize());
		}
	}

	/**
	 * Ensures that the requested range satisfies basic sanity criteria.
	 *
	 * @param start the start of the range
	 * @param end the end of the range
	 */
	default void basicRangeCheck(final long start, final long end) {
		if (start > size()) {
			throw new IndexOutOfBoundsException("Requested position: " + start +
				" is outside the buffer: " + size());
		}
		if (end < start) {
			throw new IllegalArgumentException(
				"Invalid range, end is smaller than start!");
		}
	}

	/**
	 * Clears the buffer
	 */
	void clear();

	/**
	 * @return the offset which follows the last byte stored in this ByteBank
	 */
	long size();

	/**
	 * Sets the byte at the given position
	 *
	 * @param pos the position
	 * @param b the value to set
	 */
	void setByte(long pos, byte b);

	/**
	 * @return the maximal size of the buffer
	 */
	long getMaxBufferSize();

	/**
	 * @return True iff the buffer is read-only.
	 */
	default boolean isReadOnly() {
		return false;
	}
}