DataGenerator.java

package com.firefly.codec.http2.encode;

import java.nio.ByteBuffer;
import java.util.LinkedList;
import java.util.List;

import com.firefly.codec.http2.frame.DataFrame;
import com.firefly.codec.http2.frame.Flags;
import com.firefly.codec.http2.frame.Frame;
import com.firefly.codec.http2.frame.FrameType;
import com.firefly.utils.io.BufferUtils;
import com.firefly.utils.lang.Pair;

public class DataGenerator {
	private final HeaderGenerator headerGenerator;

	public DataGenerator(HeaderGenerator headerGenerator) {
		this.headerGenerator = headerGenerator;
	}

	public Pair<Integer, List<ByteBuffer>> generate(DataFrame frame, int maxLength) {
		return generateData(frame.getStreamId(), frame.getData(), frame.isEndStream(), maxLength);
	}

	public Pair<Integer, List<ByteBuffer>> generateData(int streamId, ByteBuffer data, boolean last, int maxLength) {
		if (streamId < 0)
			throw new IllegalArgumentException("Invalid stream id: " + streamId);

		List<ByteBuffer> list = new LinkedList<>();

		if (streamId < 0)
			throw new IllegalArgumentException("Invalid stream id: " + streamId);

		int dataLength = data.remaining();
		int maxFrameSize = headerGenerator.getMaxFrameSize();
		int length = Math.min(dataLength, Math.min(maxFrameSize, maxLength));
		if (length == dataLength) {
			generateFrame(streamId, data, last, list);
		} else {
			int limit = data.limit();
			int newLimit = data.position() + length;
			data.limit(newLimit);
			ByteBuffer slice = data.slice();
			data.position(newLimit);
			data.limit(limit);
			generateFrame(streamId, slice, false, list);
		}
		return new Pair<>(length, list);
	}

	private void generateFrame(int streamId, ByteBuffer data, boolean last, List<ByteBuffer> list) {
		int length = data.remaining();

		int flags = Flags.NONE;
		if (last)
			flags |= Flags.END_STREAM;

		ByteBuffer header = headerGenerator.generate(FrameType.DATA, Frame.HEADER_LENGTH + length, length, flags,
				streamId);

		BufferUtils.flipToFlush(header, 0);
		list.add(header);

		if (data.remaining() > 0)
			list.add(data);
	}

}