public int read()

in httpcore5/src/main/java/org/apache/hc/core5/http/impl/nio/ChunkDecoder.java [185:270]
76 lines of code
21 McCabe index (conditional complexity)

    public int read(final ByteBuffer dst) throws IOException {
        Args.notNull(dst, "Byte buffer");
        if (this.state == State.COMPLETED) {
            return -1;
        }

        int totalRead = 0;
        while (this.state != State.COMPLETED) {

            if (!this.buffer.hasData() || this.chunkSize == -1L) {
                final int bytesRead = fillBufferFromChannel();
                if (bytesRead == -1) {
                    this.endOfStream = true;
                }
            }

            switch (this.state) {
            case READ_CONTENT:

                if (this.chunkSize == -1L) {
                    readChunkHead();
                    if (this.chunkSize == -1L) {
                        // Unable to read a chunk head
                        return totalRead;
                    }
                    if (this.chunkSize == 0L) {
                        // Last chunk. Read footers
                        this.chunkSize = -1L;
                        this.state = State.READ_FOOTERS;
                        break;
                    }
                }
                final long maxLen = this.chunkSize - this.pos;
                final int len = this.buffer.read(dst, (int) Math.min(maxLen, Integer.MAX_VALUE));
                if (len > 0) {
                    this.pos += len;
                    totalRead += len;
                } else {
                    if (!this.buffer.hasData() && this.endOfStream) {
                        this.state = State.COMPLETED;
                        setCompleted();
                        throw new TruncatedChunkException(
                                        "Truncated chunk (expected size: %d; actual size: %d)",
                                        chunkSize, pos);
                    }
                }

                if (this.pos == this.chunkSize) {
                    // At the end of the chunk
                    this.chunkSize = -1L;
                    this.pos = 0L;
                    this.endOfChunk = true;
                    break;
                }
                return totalRead;
            case READ_FOOTERS:
                if (this.lineBuf == null) {
                    this.lineBuf = new CharArrayBuffer(32);
                } else {
                    this.lineBuf.clear();
                }
                if (!this.buffer.readLine(this.lineBuf, this.endOfStream)) {
                    // Unable to read a footer
                    if (this.endOfStream) {
                        this.state = State.COMPLETED;
                        setCompleted();
                    }
                    return totalRead;
                }
                if (this.lineBuf.length() > 0) {
                    final int maxHeaderCount = this.http1Config.getMaxHeaderCount();
                    if (maxHeaderCount > 0 && trailerBufs.size() >= maxHeaderCount) {
                        throw new MessageConstraintException("Maximum header count exceeded");
                    }
                    parseHeader();
                } else {
                    this.state = State.COMPLETED;
                    setCompleted();
                    processFooters();
                }
                break;
            }

        }
        return totalRead;
    }