private int moveStartOffset()

in src/main/java/org/apache/rocketmq/dashboard/service/impl/MessageServiceImpl.java [470:530]
57 lines of code
14 McCabe index (conditional complexity)

    private int moveStartOffset(List<QueueOffsetInfo> queueOffsets, MessageQueryByPage query) {
        int size = queueOffsets.size();
        int next = 0;
        long offset = query.getPageNum() * query.getPageSize();
        if (offset == 0) {
            return next;
        }
        // sort by queueOffset size
        List<QueueOffsetInfo> orderQueue = queueOffsets
                .stream()
                .sorted((o1, o2) -> {
                    long size1 = o1.getEnd() - o1.getStart();
                    long size2 = o2.getEnd() - o2.getStart();
                    if (size1 < size2) {
                        return -1;
                    } else if (size1 > size2) {
                        return 1;
                    }
                    return 0;
                }).collect(Collectors.toList());

        // Take the smallest one each time
        for (int i = 0; i < size && offset >= (size - i); i++) {
            long minSize = orderQueue.get(i).getEnd() - orderQueue.get(i).getStartOffset();
            if (minSize == 0) {
                continue;
            }
            long reduce = minSize * (size - i);
            if (reduce <= offset) {
                offset -= reduce;
                for (int j = i; j < size; j++) {
                    orderQueue.get(j).incStartOffset(minSize);
                }
            } else {
                long addOffset = offset / (size - i);
                offset -= addOffset * (size - i);
                if (addOffset != 0) {
                    for (int j = i; j < size; j++) {
                        orderQueue.get(j).incStartOffset(addOffset);
                    }
                }
            }
        }
        for (QueueOffsetInfo info : orderQueue) {
            QueueOffsetInfo queueOffsetInfo = queueOffsets.get(info.getIdx());
            queueOffsetInfo.setStartOffset(info.getStartOffset());
            queueOffsetInfo.setEndOffset(info.getEndOffset());
        }

        for (QueueOffsetInfo info : queueOffsets) {
            if (offset == 0) {
                break;
            }
            next = (next + 1) % size;
            if (info.getStartOffset() < info.getEnd()) {
                info.incStartOffset();
                --offset;
            }
        }
        return next;
    }