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package com.firefly.codec.http2.encode;

import com.firefly.codec.http2.frame.Flags;
import com.firefly.codec.http2.frame.Frame;
import com.firefly.codec.http2.frame.FrameType;
import com.firefly.codec.http2.frame.SettingsFrame;
import com.firefly.utils.io.BufferUtils;

import java.nio.ByteBuffer;
import java.util.Collections;
import java.util.List;
import java.util.Map;

public class SettingsGenerator extends FrameGenerator {
    public SettingsGenerator(HeaderGenerator headerGenerator) {
        super(headerGenerator);
    }

    @Override
    public List generate(Frame frame) {
        SettingsFrame settingsFrame = (SettingsFrame) frame;
        return Collections.singletonList(generateSettings(settingsFrame.getSettings(), settingsFrame.isReply()));
    }

    public ByteBuffer generateSettings(Map settings, boolean reply) {
        // Two bytes for the identifier, four bytes for the value.
        int entryLength = 2 + 4;
        int length = entryLength * settings.size();
        if (length > getMaxFrameSize())
            throw new IllegalArgumentException("Invalid settings, too big");

        ByteBuffer header = generateHeader(FrameType.SETTINGS, length, reply ? Flags.ACK : Flags.NONE, 0);

        for (Map.Entry entry : settings.entrySet()) {
            header.putShort(entry.getKey().shortValue());
            header.putInt(entry.getValue());
        }

        BufferUtils.flipToFlush(header, 0);
        return header;
    }
}