import asyncio
import functools
import inspect
import typing as t

from flama import http, schemas, types

try:
    import forge
except Exception:  # pragma: no cover
    forge = None  # type: ignore

__all__ = ["LimitOffsetMixin", "LimitOffsetResponse"]


class LimitOffsetResponse(http.APIResponse):
    """
    Response paginated based on a limit of elements and an offset.

    First 10 elements:
        /resource?offset=0&limit=10
    Elements 20-30:
        /resource?offset=20&limit=10
    """

    default_limit = 10

    def __init__(
        self,
        schema: types.schema._T_Schema,
        offset: t.Optional[t.Union[int, str]] = None,
        limit: t.Optional[t.Union[int, str]] = None,
        count: t.Optional[bool] = True,
        **kwargs
    ):
        self.offset = int(offset) if offset is not None else 0
        self.limit = int(limit) if limit is not None else self.default_limit
        self.count = count
        super().__init__(schema=schema, **kwargs)

    def render(self, content: t.Sequence[t.Any]):
        init = self.offset
        end = self.offset + self.limit
        return super().render(
            {
                "meta": {"limit": self.limit, "offset": self.offset, "count": len(content) if self.count else None},
                "data": content[init:end],
            }
        )


class LimitOffsetMixin:
    def limit_offset(self, schema_name: str):
        """
        Decorator for adding pagination behavior to a view. That decorator produces a view based on limit-offset and
        it adds three query parameters to control the pagination: limit, offset and count. Offset has a default value of
        zero to start with the first element of the collection, limit default value is defined in
        :class:`LimitOffsetResponse` and count defines if the response will
        define the total number of elements.

        The output field is also modified by :class:`LimitOffsetSchema`,
        creating a new field based on it but using the old output field as the content of its data field.

        :param schema_name: Name used for output field.
        :return: Decorated view.
        """

        def _inner(func: t.Callable):
            assert forge is not None, "`python-forge` must be installed to use Paginator."

            resource_schema = schemas.Schema.from_type(inspect.signature(func).return_annotation).unique_schema
            paginated_schema_name = "LimitOffsetPaginated" + schema_name
            schema = schemas.Schema.build(
                paginated_schema_name,
                schema=schemas.schemas.LimitOffset,
                fields=[schemas.Field("data", resource_schema, multiple=True)],
            ).unique_schema

            forge_revision_list = (
                forge.copy(func),
                forge.insert(forge.arg("limit", default=None, type=t.Optional[int]), index=-1),
                forge.insert(forge.arg("offset", default=None, type=t.Optional[int]), index=-1),
                forge.insert(forge.arg("count", default=True, type=bool), index=-1),
                forge.delete("kwargs"),
                forge.returns(types.Schema[schema]),  # type: ignore[index,valid-type]
            )

            try:
                if asyncio.iscoroutinefunction(func):

                    @forge.compose(*forge_revision_list)
                    @functools.wraps(func)
                    async def decorator(
                        *args,
                        limit: t.Optional[int] = None,
                        offset: t.Optional[int] = None,
                        count: bool = True,
                        **kwargs
                    ):
                        return LimitOffsetResponse(
                            schema=schema, limit=limit, offset=offset, count=count, content=await func(*args, **kwargs)
                        )

                else:

                    @forge.compose(*forge_revision_list)
                    @functools.wraps(func)
                    def decorator(
                        *args,
                        limit: t.Optional[int] = None,
                        offset: t.Optional[int] = None,
                        count: bool = True,
                        **kwargs
                    ):
                        return LimitOffsetResponse(
                            schema=schema, limit=limit, offset=offset, count=count, content=func(*args, **kwargs)
                        )

            except ValueError as e:
                raise TypeError("Paginated views must define **kwargs param") from e
            else:
                self.schemas.update(  # type: ignore[attr-defined]
                    {schema_name: resource_schema, paginated_schema_name: schema}
                )

            return decorator

        return _inner
