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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * accompanied this code).
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package jdk.internal.net.http.qpack.readers;

import jdk.internal.net.http.http3.Http3Error;
import jdk.internal.net.http.qpack.DecodingCallback;
import jdk.internal.net.http.qpack.DynamicTable;
import jdk.internal.net.http.qpack.FieldSectionPrefix;
import jdk.internal.net.http.qpack.HeaderField;
import jdk.internal.net.http.qpack.QPACK;

import java.nio.ByteBuffer;
import java.util.concurrent.atomic.AtomicLong;

import static java.lang.String.format;
import static jdk.internal.net.http.qpack.QPACK.Logger.Level.NORMAL;

final class FieldLineIndexedReader extends FieldLineReader {
    private final IntegerReader integerReader;
    private final QPACK.Logger logger;

    public FieldLineIndexedReader(DynamicTable dynamicTable, long maxSectionSize,
                                  AtomicLong sectionSizeTracker, QPACK.Logger logger) {
        super(dynamicTable, maxSectionSize, sectionSizeTracker);
        this.logger = logger;
        integerReader = new IntegerReader(
                new ReaderError(Http3Error.QPACK_DECOMPRESSION_FAILED, false));
    }

    public void configure(int b) {
        integerReader.configure(6);
        fromStaticTable = (b & 0b0100_0000) != 0;
    }

    //              0   1   2   3   4   5   6   7
    //            +---+---+---+---+---+---+---+---+
    //            | 1 | T |     Index (6+)        |
    //            +---+---------------------------+
    //
    public boolean read(ByteBuffer input, FieldSectionPrefix prefix,
                        DecodingCallback action) {
        if (!integerReader.read(input)) {
            return false;
        }
        long intValue = integerReader.get();
        // "In a field line representation, a relative index of 0 refers to the
        //  entry with absolute index equal to Base - 1."
        long absoluteIndex = fromStaticTable ? intValue : prefix.base() - 1 - intValue;
        if (logger.isLoggable(NORMAL)) {
            logger.log(NORMAL, () -> format("%s index %s", fromStaticTable ? "Static" : "Dynamic",
                       absoluteIndex));
        }
        checkEntryIndex(absoluteIndex, prefix);
        HeaderField f = entryAtIndex(absoluteIndex);
        checkSectionSize(DynamicTable.headerSize(f));
        action.onIndexed(absoluteIndex, f.name(), f.value());
        reset();
        return true;
    }

    public void reset() {
        integerReader.reset();
    }
}