import warnings
from collections.abc import Mapping
from functools import wraps
from typing import TYPE_CHECKING, Any, Callable, Optional, TypeVar, Union, overload

from typing_extensions import deprecated

from .._internal import _config, _typing_extra
from ..alias_generators import to_pascal
from ..errors import PydanticUserError
from ..functional_validators import field_validator
from ..main import BaseModel, create_model
from ..warnings import PydanticDeprecatedSince20

if not TYPE_CHECKING:
    # See PyCharm issues https://youtrack.jetbrains.com/issue/PY-21915
    # and https://youtrack.jetbrains.com/issue/PY-51428
    DeprecationWarning = PydanticDeprecatedSince20

__all__ = ('validate_arguments',)

if TYPE_CHECKING:
    AnyCallable = Callable[..., Any]

    AnyCallableT = TypeVar('AnyCallableT', bound=AnyCallable)
    ConfigType = Union[None, type[Any], dict[str, Any]]


@overload
def validate_arguments(
    func: None = None, *, config: 'ConfigType' = None
) -> Callable[['AnyCallableT'], 'AnyCallableT']: ...


@overload
def validate_arguments(func: 'AnyCallableT') -> 'AnyCallableT': ...


@deprecated(
    'The `validate_arguments` method is deprecated; use `validate_call` instead.',
    category=None,
)
def validate_arguments(func: Optional['AnyCallableT'] = None, *, config: 'ConfigType' = None) -> Any:
    """Decorator to validate the arguments passed to a function."""
    warnings.warn(
        'The `validate_arguments` method is deprecated; use `validate_call` instead.',
        PydanticDeprecatedSince20,
        stacklevel=2,
    )

    def validate(_func: 'AnyCallable') -> 'AnyCallable':
        vd = ValidatedFunction(_func, config)

        @wraps(_func)
        def wrapper_function(*args: Any, **kwargs: Any) -> Any:
            return vd.call(*args, **kwargs)

        wrapper_function.vd = vd  # type: ignore
        wrapper_function.validate = vd.init_model_instance  # type: ignore
        wrapper_function.raw_function = vd.raw_function  # type: ignore
        wrapper_function.model = vd.model  # type: ignore
        return wrapper_function

    if func:
        return validate(func)
    else:
        return validate


ALT_V_ARGS = 'v__args'
ALT_V_KWARGS = 'v__kwargs'
V_POSITIONAL_ONLY_NAME = 'v__positional_only'
V_DUPLICATE_KWARGS = 'v__duplicate_kwargs'


class ValidatedFunction:
    def __init__(self, function: 'AnyCallable', config: 'ConfigType'):
        from inspect import Parameter, signature

        parameters: Mapping[str, Parameter] = signature(function).parameters

        if parameters.keys() & {ALT_V_ARGS, ALT_V_KWARGS, V_POSITIONAL_ONLY_NAME, V_DUPLICATE_KWARGS}:
            raise PydanticUserError(
                f'"{ALT_V_ARGS}", "{ALT_V_KWARGS}", "{V_POSITIONAL_ONLY_NAME}" and "{V_DUPLICATE_KWARGS}" '
                f'are not permitted as argument names when using the "{validate_arguments.__name__}" decorator',
                code=None,
            )

        self.raw_function = function
        self.arg_mapping: dict[int, str] = {}
        self.positional_only_args: set[str] = set()
        self.v_args_name = 'args'
        self.v_kwargs_name = 'kwargs'

        type_hints = _typing_extra.get_type_hints(function, include_extras=True)
        takes_args = False
        takes_kwargs = False
        fields: dict[str, tuple[Any, Any]] = {}
        for i, (name, p) in enumerate(parameters.items()):
            if p.annotation is p.empty:
                annotation = Any
            else:
                annotation = type_hints[name]

            default = ... if p.default is p.empty else p.default
            if p.kind == Parameter.POSITIONAL_ONLY:
                self.arg_mapping[i] = name
                fields[name] = annotation, default
                fields[V_POSITIONAL_ONLY_NAME] = list[str], None
                self.positional_only_args.add(name)
            elif p.kind == Parameter.POSITIONAL_OR_KEYWORD:
                self.arg_mapping[i] = name
                fields[name] = annotation, default
                fields[V_DUPLICATE_KWARGS] = list[str], None
            elif p.kind == Parameter.KEYWORD_ONLY:
                fields[name] = annotation, default
            elif p.kind == Parameter.VAR_POSITIONAL:
                self.v_args_name = name
                fields[name] = tuple[annotation, ...], None
                takes_args = True
            else:
                assert p.kind == Parameter.VAR_KEYWORD, p.kind
                self.v_kwargs_name = name
                fields[name] = dict[str, annotation], None
                takes_kwargs = True

        # these checks avoid a clash between "args" and a field with that name
        if not takes_args and self.v_args_name in fields:
            self.v_args_name = ALT_V_ARGS

        # same with "kwargs"
        if not takes_kwargs and self.v_kwargs_name in fields:
            self.v_kwargs_name = ALT_V_KWARGS

        if not takes_args:
            # we add the field so validation below can raise the correct exception
            fields[self.v_args_name] = list[Any], None

        if not takes_kwargs:
            # same with kwargs
            fields[self.v_kwargs_name] = dict[Any, Any], None

        self.create_model(fields, takes_args, takes_kwargs, config)

    def init_model_instance(self, *args: Any, **kwargs: Any) -> BaseModel:
        values = self.build_values(args, kwargs)
        return self.model(**values)

    def call(self, *args: Any, **kwargs: Any) -> Any:
        m = self.init_model_instance(*args, **kwargs)
        return self.execute(m)

    def build_values(self, args: tuple[Any, ...], kwargs: dict[str, Any]) -> dict[str, Any]:
        values: dict[str, Any] = {}
        if args:
            arg_iter = enumerate(args)
            while True:
                try:
                    i, a = next(arg_iter)
                except StopIteration:
                    break
                arg_name = self.arg_mapping.get(i)
                if arg_name is not None:
                    values[arg_name] = a
                else:
                    values[self.v_args_name] = [a] + [a for _, a in arg_iter]
                    break

        var_kwargs: dict[str, Any] = {}
        wrong_positional_args = []
        duplicate_kwargs = []
        fields_alias = [
            field.alias
            for name, field in self.model.__pydantic_fields__.items()
            if name not in (self.v_args_name, self.v_kwargs_name)
        ]
        non_var_fields = set(self.model.__pydantic_fields__) - {self.v_args_name, self.v_kwargs_name}
        for k, v in kwargs.items():
            if k in non_var_fields or k in fields_alias:
                if k in self.positional_only_args:
                    wrong_positional_args.append(k)
                if k in values:
                    duplicate_kwargs.append(k)
                values[k] = v
            else:
                var_kwargs[k] = v

        if var_kwargs:
            values[self.v_kwargs_name] = var_kwargs
        if wrong_positional_args:
            values[V_POSITIONAL_ONLY_NAME] = wrong_positional_args
        if duplicate_kwargs:
            values[V_DUPLICATE_KWARGS] = duplicate_kwargs
        return values

    def execute(self, m: BaseModel) -> Any:
        d = {
            k: v
            for k, v in m.__dict__.items()
            if k in m.__pydantic_fields_set__ or m.__pydantic_fields__[k].default_factory
        }
        var_kwargs = d.pop(self.v_kwargs_name, {})

        if self.v_args_name in d:
            args_: list[Any] = []
            in_kwargs = False
            kwargs = {}
            for name, value in d.items():
                if in_kwargs:
                    kwargs[name] = value
                elif name == self.v_args_name:
                    args_ += value
                    in_kwargs = True
                else:
                    args_.append(value)
            return self.raw_function(*args_, **kwargs, **var_kwargs)
        elif self.positional_only_args:
            args_ = []
            kwargs = {}
            for name, value in d.items():
                if name in self.positional_only_args:
                    args_.append(value)
                else:
                    kwargs[name] = value
            return self.raw_function(*args_, **kwargs, **var_kwargs)
        else:
            return self.raw_function(**d, **var_kwargs)

    def create_model(self, fields: dict[str, Any], takes_args: bool, takes_kwargs: bool, config: 'ConfigType') -> None:
        pos_args = len(self.arg_mapping)

        config_wrapper = _config.ConfigWrapper(config)

        if config_wrapper.alias_generator:
            raise PydanticUserError(
                'Setting the "alias_generator" property on custom Config for '
                '@validate_arguments is not yet supported, please remove.',
                code=None,
            )
        if config_wrapper.extra is None:
            config_wrapper.config_dict['extra'] = 'forbid'

        class DecoratorBaseModel(BaseModel):
            @field_validator(self.v_args_name, check_fields=False)
            @classmethod
            def check_args(cls, v: Optional[list[Any]]) -> Optional[list[Any]]:
                if takes_args or v is None:
                    return v

                raise TypeError(f'{pos_args} positional arguments expected but {pos_args + len(v)} given')

            @field_validator(self.v_kwargs_name, check_fields=False)
            @classmethod
            def check_kwargs(cls, v: Optional[dict[str, Any]]) -> Optional[dict[str, Any]]:
                if takes_kwargs or v is None:
                    return v

                plural = '' if len(v) == 1 else 's'
                keys = ', '.join(map(repr, v.keys()))
                raise TypeError(f'unexpected keyword argument{plural}: {keys}')

            @field_validator(V_POSITIONAL_ONLY_NAME, check_fields=False)
            @classmethod
            def check_positional_only(cls, v: Optional[list[str]]) -> None:
                if v is None:
                    return

                plural = '' if len(v) == 1 else 's'
                keys = ', '.join(map(repr, v))
                raise TypeError(f'positional-only argument{plural} passed as keyword argument{plural}: {keys}')

            @field_validator(V_DUPLICATE_KWARGS, check_fields=False)
            @classmethod
            def check_duplicate_kwargs(cls, v: Optional[list[str]]) -> None:
                if v is None:
                    return

                plural = '' if len(v) == 1 else 's'
                keys = ', '.join(map(repr, v))
                raise TypeError(f'multiple values for argument{plural}: {keys}')

            model_config = config_wrapper.config_dict

        self.model = create_model(to_pascal(self.raw_function.__name__), __base__=DecoratorBaseModel, **fields)
