package jnpf.fileStorage.dms;

import javax.imageio.stream.ImageInputStreamImpl;
import java.io.IOException;
import java.util.Objects;

/** Seekable ImageIO input backed directly by the already-buffered source bytes. */
final class DmsByteArrayImageInputStream extends ImageInputStreamImpl {
    private final byte[] source;

    DmsByteArrayImageInputStream(byte[] source) {
        this.source = Objects.requireNonNull(source, "source");
    }

    @Override
    public int read() throws IOException {
        checkClosed();
        bitOffset = 0;
        if (streamPos >= source.length) {
            return -1;
        }
        return source[(int) streamPos++] & 0xFF;
    }

    @Override
    public int read(byte[] target, int offset, int length) throws IOException {
        checkClosed();
        Objects.checkFromIndexSize(offset, length, target.length);
        bitOffset = 0;
        if (length == 0) {
            return 0;
        }
        if (streamPos >= source.length) {
            return -1;
        }
        int count = (int) Math.min(length, source.length - streamPos);
        System.arraycopy(source, (int) streamPos, target, offset, count);
        streamPos += count;
        return count;
    }

    @Override
    public long length() {
        return source.length;
    }
}