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#  to you under the Apache License, Version 2.0 (the
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#
#    http://www.apache.org/licenses/LICENSE-2.0
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from typing import Optional

import pyarrow
from pyarrow import RecordBatch

from pypaimon.read.reader.iface.record_batch_reader import RecordBatchReader
from pypaimon.read.reader.iface.record_iterator import RecordIterator
from pypaimon.deletionvectors.deletion_vector import DeletionVector
from pypaimon.utils.roaring_bitmap import RoaringBitmap
from pypaimon.read.reader.iface.record_reader import RecordReader


class ApplyDeletionVectorReader(RecordBatchReader):
    """
    A RecordReader which applies DeletionVector to filter records.
    """

    def __init__(self, reader: RecordReader, deletion_vector: DeletionVector):
        """
        Initialize an ApplyDeletionVectorReader.

        Args:
            reader: The underlying record reader.
            deletion_vector: The deletion vector to apply.
        """
        self._reader = reader
        self._deletion_vector = deletion_vector

    def reader(self) -> RecordReader:
        return self._reader

    def deletion_vector(self) -> DeletionVector:
        return self._deletion_vector

    def read_arrow_batch(self) -> Optional[RecordBatch]:
        self._reader: RecordBatchReader
        arrow_batch = self._reader.read_arrow_batch()
        if arrow_batch is None:
            return None
        # Remove the deleted rows from the batch
        range_bitmap = RoaringBitmap()
        return_batch_pos = self._reader.return_batch_pos()
        range_bitmap.add_range(return_batch_pos - arrow_batch.num_rows, return_batch_pos - 1)
        intersection_bitmap = RoaringBitmap.remove_all(range_bitmap, self._deletion_vector.bit_map())
        added_row_list = [x - (return_batch_pos - arrow_batch.num_rows) for x in
                          list(intersection_bitmap)]
        return arrow_batch.take(pyarrow.array(added_row_list, type=pyarrow.int32()))

    def read_batch(self) -> Optional[RecordIterator]:
        """
        Reads one batch with deletion vector applied.

        Returns:
            A RecordIterator with deletion filtering, or None if no more data.
        """
        batch = self._reader.read_batch()

        if batch is None:
            return None

        return ApplyDeletionRecordIterator(batch, self._deletion_vector)

    def close(self):
        self._reader.close()


class ApplyDeletionRecordIterator(RecordIterator):
    """
    A RecordIterator that wraps another RecordIterator and applies a DeletionVector
    to filter out deleted records.
    """

    def __init__(self, iterator: RecordIterator, deletion_vector: DeletionVector):
        """
        Initialize an ApplyDeletionRecordIterator.

        Args:
            iterator: The underlying record iterator.
            deletion_vector: The deletion vector to apply for filtering.
        """
        self._iterator = iterator
        self._deletion_vector = deletion_vector

    def iterator(self) -> RecordIterator:
        return self._iterator

    def deletion_vector(self) -> DeletionVector:
        return self._deletion_vector

    def returned_position(self) -> int:
        return self._iterator.return_pos()

    def next(self) -> Optional[object]:
        """
        Gets the next non-deleted record from the iterator.

        This method skips over any records that are marked as deleted in the
        deletion vector, returning only non-deleted records.

        Returns:
            The next non-deleted record, or None if no more records exist.
        """
        while True:
            record = self._iterator.next()

            if record is None:
                return None

            # Check if the current position is deleted
            if not self._deletion_vector.is_deleted(self._iterator.return_pos()):
                return record
