# BSD 3-Clause License; see https://github.com/scikit-hep/awkward/blob/main/LICENSE

from __future__ import annotations

import awkward as ak
from awkward._dispatch import high_level_function
from awkward._layout import HighLevelContext
from awkward._nplikes.numpy_like import NumpyMetadata

__all__ = ("unzip",)

np = NumpyMetadata.instance()


@high_level_function()
def unzip(array, *, highlevel=True, behavior=None, attrs=None):
    """
    Args:
        array: Array-like data (anything #ak.to_layout recognizes).
        highlevel (bool): If True, return an #ak.Array; otherwise, return
            a low-level #ak.contents.Content subclass.
        behavior (None or dict): Custom #ak.behavior for the output array, if
            high-level.
        attrs (None or dict): Custom attributes for the output array, if
            high-level.

    If the `array` contains tuples or records, this operation splits them
    into a Python tuple of arrays, one for each field.

    If the `array` does not contain tuples or records, the single `array`
    is placed in a length 1 Python tuple.

    For example,

        >>> array = ak.Array([{"x": 1.1, "y": [1]},
        ...                   {"x": 2.2, "y": [2, 2]},
        ...                   {"x": 3.3, "y": [3, 3, 3]}])
        >>> x, y = ak.unzip(array)
        >>> x
        <Array [1.1, 2.2, 3.3] type='3 * float64'>
        >>> y
        <Array [[1], [2, 2], [3, 3, 3]] type='3 * var * int64'>
    """
    # Dispatch
    yield (array,)

    # Implementation
    return _impl(array, highlevel, behavior, attrs)


def _impl(array, highlevel, behavior, attrs):
    with HighLevelContext(behavior=behavior, attrs=attrs) as ctx:
        layout = ctx.unwrap(array, allow_record=True, primitive_policy="error")

    fields = ak.operations.fields(layout)

    def check_for_union(layout, **kwargs):
        if isinstance(layout, (ak.contents.RecordArray, ak.Record)):
            return layout  # don't descend into nested records

        elif layout.is_union:
            for content in layout.contents:
                if set(ak.operations.fields(content)) != set(fields):
                    raise ValueError(
                        "union of different sets of fields, cannot ak.unzip"
                    )

    ak._do.recursively_apply(layout, check_for_union, return_array=False)

    if len(fields) == 0:
        return (ctx.wrap(layout, highlevel=highlevel, allow_other=True),)
    else:
        return tuple(
            ctx.wrap(
                layout[n],
                highlevel=highlevel,
                allow_other=True,
            )
            for n in fields
        )
