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from typing import Optional

from pypaimon.pynative.common.row.key_value import KeyValue
from pypaimon.pynative.reader.core.record_iterator import RecordIterator
from pypaimon.pynative.reader.core.record_reader import RecordReader


class DropDeleteReader(RecordReader):
    """
    A RecordReader which drops KeyValue that does not meet RowKind. isAdd from the wrapped reader.
    """

    def __init__(self, wrapped_reader: RecordReader[KeyValue]):
        self.wrapped_reader = wrapped_reader

    def read_batch(self) -> Optional[RecordIterator]:
        batch = self.wrapped_reader.read_batch()
        if batch is None:
            return None

        return DropDeleteIterator(batch)

    def close(self) -> None:
        self.wrapped_reader.close()


class DropDeleteIterator(RecordIterator[KeyValue]):
    """
    An iterator that drops KeyValue that does not meet RowKind.
    """

    def __init__(self, batch: RecordIterator[KeyValue]):
        self.batch = batch

    def next(self) -> Optional[KeyValue]:
        while True:
            kv = self.batch.next()
            if kv is None:
                return None
            if kv.is_add():
                return kv

    def release_batch(self) -> None:
        self.batch.release_batch()