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from typing import Any, Optional

from pypaimon.read.reader.iface.record_iterator import RecordIterator
from pypaimon.read.reader.iface.record_reader import RecordReader
from pypaimon.table.row.internal_row import InternalRow
from pypaimon.table.row.key_value import KeyValue
from pypaimon.table.row.offset_row import OffsetRow


class KeyValueUnwrapRecordReader(RecordReader[InternalRow]):
    """
    A RecordReader that converts a KeyValue type record reader into an InternalRow type reader
    Corresponds to the KeyValueTableRead$1 in Java version.
    """

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

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

        return KeyValueUnwrapIterator(batch)

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


class KeyValueUnwrapIterator(RecordIterator[InternalRow]):
    """
    An Iterator that converts a KeyValue into an InternalRow
    """

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

    def next(self) -> Optional[Any]:
        kv = self.batch.next()
        if kv is None:
            return None

        row: OffsetRow = kv.value
        row.set_row_kind_byte(kv.value_row_kind_byte)
        return row