from __future__ import annotations

import collections
from collections.abc import Iterable
import textwrap
from typing import Any
from typing import Callable
from typing import Dict
from typing import List
from typing import Mapping
from typing import Optional
from typing import overload
from typing import Sequence
from typing import Tuple
from typing import TypeVar
from typing import Union
import uuid
import warnings

from sqlalchemy.util import asbool  # noqa
from sqlalchemy.util import immutabledict  # noqa
from sqlalchemy.util import memoized_property  # noqa
from sqlalchemy.util import to_list  # noqa
from sqlalchemy.util import unique_list  # noqa

from .compat import inspect_getfullargspec


EMPTY_DICT: Mapping[Any, Any] = immutabledict()
_T = TypeVar("_T")


class _ModuleClsMeta(type):
    def __setattr__(cls, key: str, value: Callable) -> None:
        super().__setattr__(key, value)
        cls._update_module_proxies(key)  # type: ignore


class ModuleClsProxy(metaclass=_ModuleClsMeta):
    """Create module level proxy functions for the
    methods on a given class.

    The functions will have a compatible signature
    as the methods.

    """

    _setups: Dict[type, Tuple[set, list]] = collections.defaultdict(
        lambda: (set(), [])
    )

    @classmethod
    def _update_module_proxies(cls, name: str) -> None:
        attr_names, modules = cls._setups[cls]
        for globals_, locals_ in modules:
            cls._add_proxied_attribute(name, globals_, locals_, attr_names)

    def _install_proxy(self) -> None:
        attr_names, modules = self._setups[self.__class__]
        for globals_, locals_ in modules:
            globals_["_proxy"] = self
            for attr_name in attr_names:
                globals_[attr_name] = getattr(self, attr_name)

    def _remove_proxy(self) -> None:
        attr_names, modules = self._setups[self.__class__]
        for globals_, locals_ in modules:
            globals_["_proxy"] = None
            for attr_name in attr_names:
                del globals_[attr_name]

    @classmethod
    def create_module_class_proxy(cls, globals_, locals_):
        attr_names, modules = cls._setups[cls]
        modules.append((globals_, locals_))
        cls._setup_proxy(globals_, locals_, attr_names)

    @classmethod
    def _setup_proxy(cls, globals_, locals_, attr_names):
        for methname in dir(cls):
            cls._add_proxied_attribute(methname, globals_, locals_, attr_names)

    @classmethod
    def _add_proxied_attribute(cls, methname, globals_, locals_, attr_names):
        if not methname.startswith("_"):
            meth = getattr(cls, methname)
            if callable(meth):
                locals_[methname] = cls._create_method_proxy(
                    methname, globals_, locals_
                )
            else:
                attr_names.add(methname)

    @classmethod
    def _create_method_proxy(cls, name, globals_, locals_):
        fn = getattr(cls, name)

        def _name_error(name, from_):
            raise NameError(
                "Can't invoke function '%s', as the proxy object has "
                "not yet been "
                "established for the Alembic '%s' class.  "
                "Try placing this code inside a callable."
                % (name, cls.__name__)
            ) from from_

        globals_["_name_error"] = _name_error

        translations = getattr(fn, "_legacy_translations", [])
        if translations:
            spec = inspect_getfullargspec(fn)
            if spec[0] and spec[0][0] == "self":
                spec[0].pop(0)

            outer_args = inner_args = "*args, **kw"
            translate_str = "args, kw = _translate(%r, %r, %r, args, kw)" % (
                fn.__name__,
                tuple(spec),
                translations,
            )

            def translate(fn_name, spec, translations, args, kw):
                return_kw = {}
                return_args = []

                for oldname, newname in translations:
                    if oldname in kw:
                        warnings.warn(
                            "Argument %r is now named %r "
                            "for method %s()." % (oldname, newname, fn_name)
                        )
                        return_kw[newname] = kw.pop(oldname)
                return_kw.update(kw)

                args = list(args)
                if spec[3]:
                    pos_only = spec[0][: -len(spec[3])]
                else:
                    pos_only = spec[0]
                for arg in pos_only:
                    if arg not in return_kw:
                        try:
                            return_args.append(args.pop(0))
                        except IndexError:
                            raise TypeError(
                                "missing required positional argument: %s"
                                % arg
                            )
                return_args.extend(args)

                return return_args, return_kw

            globals_["_translate"] = translate
        else:
            outer_args = "*args, **kw"
            inner_args = "*args, **kw"
            translate_str = ""

        func_text = textwrap.dedent(
            """\
        def %(name)s(%(args)s):
            %(doc)r
            %(translate)s
            try:
                p = _proxy
            except NameError as ne:
                _name_error('%(name)s', ne)
            return _proxy.%(name)s(%(apply_kw)s)
            e
        """
            % {
                "name": name,
                "translate": translate_str,
                "args": outer_args,
                "apply_kw": inner_args,
                "doc": fn.__doc__,
            }
        )
        lcl = {}

        exec(func_text, globals_, lcl)
        return lcl[name]


def _with_legacy_names(translations):
    def decorate(fn):
        fn._legacy_translations = translations
        return fn

    return decorate


def rev_id() -> str:
    return uuid.uuid4().hex[-12:]


@overload
def to_tuple(x: Any, default: tuple) -> tuple:
    ...


@overload
def to_tuple(x: None, default: Optional[_T] = None) -> _T:
    ...


@overload
def to_tuple(x: Any, default: Optional[tuple] = None) -> tuple:
    ...


def to_tuple(x, default=None):
    if x is None:
        return default
    elif isinstance(x, str):
        return (x,)
    elif isinstance(x, Iterable):
        return tuple(x)
    else:
        return (x,)


def dedupe_tuple(tup: Tuple[str, ...]) -> Tuple[str, ...]:
    return tuple(unique_list(tup))


class Dispatcher:
    def __init__(self, uselist: bool = False) -> None:
        self._registry: Dict[tuple, Any] = {}
        self.uselist = uselist

    def dispatch_for(
        self, target: Any, qualifier: str = "default"
    ) -> Callable:
        def decorate(fn):
            if self.uselist:
                self._registry.setdefault((target, qualifier), []).append(fn)
            else:
                assert (target, qualifier) not in self._registry
                self._registry[(target, qualifier)] = fn
            return fn

        return decorate

    def dispatch(self, obj: Any, qualifier: str = "default") -> Any:

        if isinstance(obj, str):
            targets: Sequence = [obj]
        elif isinstance(obj, type):
            targets = obj.__mro__
        else:
            targets = type(obj).__mro__

        for spcls in targets:
            if qualifier != "default" and (spcls, qualifier) in self._registry:
                return self._fn_or_list(self._registry[(spcls, qualifier)])
            elif (spcls, "default") in self._registry:
                return self._fn_or_list(self._registry[(spcls, "default")])
        else:
            raise ValueError("no dispatch function for object: %s" % obj)

    def _fn_or_list(
        self, fn_or_list: Union[List[Callable], Callable]
    ) -> Callable:
        if self.uselist:

            def go(*arg, **kw):
                for fn in fn_or_list:
                    fn(*arg, **kw)

            return go
        else:
            return fn_or_list  # type: ignore

    def branch(self) -> Dispatcher:
        """Return a copy of this dispatcher that is independently
        writable."""

        d = Dispatcher()
        if self.uselist:
            d._registry.update(
                (k, [fn for fn in self._registry[k]]) for k in self._registry
            )
        else:
            d._registry.update(self._registry)
        return d


def not_none(value: Optional[_T]) -> _T:
    assert value is not None
    return value