from __future__ import annotations

from typing import Any

# attempt the following imports only once,
# to be imported from itemadapter's submodules


_scrapy_item_classes: tuple
scrapy: Any

try:
    import scrapy
except ImportError:
    _scrapy_item_classes = ()
    scrapy = None
else:
    try:
        # handle deprecated base classes
        _base_item_cls = getattr(
            scrapy.item,
            "_BaseItem",
            scrapy.item.BaseItem,
        )
    except AttributeError:
        _scrapy_item_classes = (scrapy.item.Item,)
    else:
        _scrapy_item_classes = (scrapy.item.Item, _base_item_cls)

attr: Any
try:
    import attr
except ImportError:
    attr = None

pydantic_v1: Any = None
pydantic: Any = None

try:
    import pydantic
except ImportError:  # No pydantic
    pass
else:
    try:
        import pydantic.v1 as pydantic_v1
    except ImportError:  # Pydantic <1.10.17
        pydantic_v1 = pydantic
        pydantic = None
    else:  # Pydantic 1.10.17+
        if not hasattr(pydantic.BaseModel, "model_fields"):  # Pydantic <2
            pydantic_v1 = pydantic
            pydantic = None

try:
    from pydantic.v1.fields import Undefined as PydanticV1Undefined
    from pydantic_core import PydanticUndefined
except ImportError:  # < Pydantic 2.0
    try:
        from pydantic.fields import (  # type: ignore[attr-defined,no-redef]
            Undefined as PydanticUndefined,
        )
        from pydantic.fields import (  # type: ignore[attr-defined,no-redef]
            Undefined as PydanticV1Undefined,
        )
    except ImportError:
        PydanticUndefined = PydanticV1Undefined = None  # type: ignore[assignment]