"""Useful utility decorators. """

from typing import TypeVar
import sys
import types
import inspect
from functools import wraps, update_wrapper

from sympy.utilities.exceptions import sympy_deprecation_warning


T = TypeVar('T')
"""A generic type"""


def threaded_factory(func, use_add):
    """A factory for ``threaded`` decorators. """
    from sympy.core import sympify
    from sympy.matrices import MatrixBase
    from sympy.utilities.iterables import iterable

    @wraps(func)
    def threaded_func(expr, *args, **kwargs):
        if isinstance(expr, MatrixBase):
            return expr.applyfunc(lambda f: func(f, *args, **kwargs))
        elif iterable(expr):
            try:
                return expr.__class__([func(f, *args, **kwargs) for f in expr])
            except TypeError:
                return expr
        else:
            expr = sympify(expr)

            if use_add and expr.is_Add:
                return expr.__class__(*[ func(f, *args, **kwargs) for f in expr.args ])
            elif expr.is_Relational:
                return expr.__class__(func(expr.lhs, *args, **kwargs),
                                      func(expr.rhs, *args, **kwargs))
            else:
                return func(expr, *args, **kwargs)

    return threaded_func


def threaded(func):
    """Apply ``func`` to sub--elements of an object, including :class:`~.Add`.

    This decorator is intended to make it uniformly possible to apply a
    function to all elements of composite objects, e.g. matrices, lists, tuples
    and other iterable containers, or just expressions.

    This version of :func:`threaded` decorator allows threading over
    elements of :class:`~.Add` class. If this behavior is not desirable
    use :func:`xthreaded` decorator.

    Functions using this decorator must have the following signature::

      @threaded
      def function(expr, *args, **kwargs):

    """
    return threaded_factory(func, True)


def xthreaded(func):
    """Apply ``func`` to sub--elements of an object, excluding :class:`~.Add`.

    This decorator is intended to make it uniformly possible to apply a
    function to all elements of composite objects, e.g. matrices, lists, tuples
    and other iterable containers, or just expressions.

    This version of :func:`threaded` decorator disallows threading over
    elements of :class:`~.Add` class. If this behavior is not desirable
    use :func:`threaded` decorator.

    Functions using this decorator must have the following signature::

      @xthreaded
      def function(expr, *args, **kwargs):

    """
    return threaded_factory(func, False)


def conserve_mpmath_dps(func):
    """After the function finishes, resets the value of ``mpmath.mp.dps`` to
    the value it had before the function was run."""
    import mpmath

    def func_wrapper(*args, **kwargs):
        dps = mpmath.mp.dps
        try:
            return func(*args, **kwargs)
        finally:
            mpmath.mp.dps = dps

    func_wrapper = update_wrapper(func_wrapper, func)
    return func_wrapper


class no_attrs_in_subclass:
    """Don't 'inherit' certain attributes from a base class

    >>> from sympy.utilities.decorator import no_attrs_in_subclass

    >>> class A(object):
    ...     x = 'test'

    >>> A.x = no_attrs_in_subclass(A, A.x)

    >>> class B(A):
    ...     pass

    >>> hasattr(A, 'x')
    True
    >>> hasattr(B, 'x')
    False

    """
    def __init__(self, cls, f):
        self.cls = cls
        self.f = f

    def __get__(self, instance, owner=None):
        if owner == self.cls:
            if hasattr(self.f, '__get__'):
                return self.f.__get__(instance, owner)
            return self.f
        raise AttributeError


def doctest_depends_on(exe=None, modules=None, disable_viewers=None,
                       python_version=None, ground_types=None):
    """
    Adds metadata about the dependencies which need to be met for doctesting
    the docstrings of the decorated objects.

    ``exe`` should be a list of executables

    ``modules`` should be a list of modules

    ``disable_viewers`` should be a list of viewers for :func:`~sympy.printing.preview.preview` to disable

    ``python_version`` should be the minimum Python version required, as a tuple
    (like ``(3, 0)``)
    """
    dependencies = {}
    if exe is not None:
        dependencies['executables'] = exe
    if modules is not None:
        dependencies['modules'] = modules
    if disable_viewers is not None:
        dependencies['disable_viewers'] = disable_viewers
    if python_version is not None:
        dependencies['python_version'] = python_version
    if ground_types is not None:
        dependencies['ground_types'] = ground_types

    def skiptests():
        from sympy.testing.runtests import DependencyError, SymPyDocTests, PyTestReporter # lazy import
        r = PyTestReporter()
        t = SymPyDocTests(r, None)
        try:
            t._check_dependencies(**dependencies)
        except DependencyError:
            return True  # Skip doctests
        else:
            return False # Run doctests

    def depends_on_deco(fn):
        fn._doctest_depends_on = dependencies
        fn.__doctest_skip__ = skiptests

        if inspect.isclass(fn):
            fn._doctest_depdends_on = no_attrs_in_subclass(
                fn, fn._doctest_depends_on)
            fn.__doctest_skip__ = no_attrs_in_subclass(
                fn, fn.__doctest_skip__)
        return fn

    return depends_on_deco


def public(obj: T) -> T:
    """
    Append ``obj``'s name to global ``__all__`` variable (call site).

    By using this decorator on functions or classes you achieve the same goal
    as by filling ``__all__`` variables manually, you just do not have to repeat
    yourself (object's name). You also know if object is public at definition
    site, not at some random location (where ``__all__`` was set).

    Note that in multiple decorator setup (in almost all cases) ``@public``
    decorator must be applied before any other decorators, because it relies
    on the pointer to object's global namespace. If you apply other decorators
    first, ``@public`` may end up modifying the wrong namespace.

    Examples
    ========

    >>> from sympy.utilities.decorator import public

    >>> __all__ # noqa: F821
    Traceback (most recent call last):
    ...
    NameError: name '__all__' is not defined

    >>> @public
    ... def some_function():
    ...     pass

    >>> __all__ # noqa: F821
    ['some_function']

    """
    if isinstance(obj, types.FunctionType):
        ns = obj.__globals__
        name = obj.__name__
    elif isinstance(obj, (type(type), type)):
        ns = sys.modules[obj.__module__].__dict__
        name = obj.__name__
    else:
        raise TypeError("expected a function or a class, got %s" % obj)

    if "__all__" not in ns:
        ns["__all__"] = [name]
    else:
        ns["__all__"].append(name)

    return obj


def memoize_property(propfunc):
    """Property decorator that caches the value of potentially expensive
    ``propfunc`` after the first evaluation. The cached value is stored in
    the corresponding property name with an attached underscore."""
    attrname = '_' + propfunc.__name__
    sentinel = object()

    @wraps(propfunc)
    def accessor(self):
        val = getattr(self, attrname, sentinel)
        if val is sentinel:
            val = propfunc(self)
            setattr(self, attrname, val)
        return val

    return property(accessor)


def deprecated(message, *, deprecated_since_version,
               active_deprecations_target, stacklevel=3):
    '''
    Mark a function as deprecated.

    This decorator should be used if an entire function or class is
    deprecated. If only a certain functionality is deprecated, you should use
    :func:`~.warns_deprecated_sympy` directly. This decorator is just a
    convenience. There is no functional difference between using this
    decorator and calling ``warns_deprecated_sympy()`` at the top of the
    function.

    The decorator takes the same arguments as
    :func:`~.warns_deprecated_sympy`. See its
    documentation for details on what the keywords to this decorator do.

    See the :ref:`deprecation-policy` document for details on when and how
    things should be deprecated in SymPy.

    Examples
    ========

    >>> from sympy.utilities.decorator import deprecated
    >>> from sympy import simplify
    >>> @deprecated("""\
    ... The simplify_this(expr) function is deprecated. Use simplify(expr)
    ... instead.""", deprecated_since_version="1.1",
    ... active_deprecations_target='simplify-this-deprecation')
    ... def simplify_this(expr):
    ...     """
    ...     Simplify ``expr``.
    ...
    ...     .. deprecated:: 1.1
    ...
    ...        The ``simplify_this`` function is deprecated. Use :func:`simplify`
    ...        instead. See its documentation for more information. See
    ...        :ref:`simplify-this-deprecation` for details.
    ...
    ...     """
    ...     return simplify(expr)
    >>> from sympy.abc import x
    >>> simplify_this(x*(x + 1) - x**2) # doctest: +SKIP
    <stdin>:1: SymPyDeprecationWarning:
    <BLANKLINE>
    The simplify_this(expr) function is deprecated. Use simplify(expr)
    instead.
    <BLANKLINE>
    See https://docs.sympy.org/latest/explanation/active-deprecations.html#simplify-this-deprecation
    for details.
    <BLANKLINE>
    This has been deprecated since SymPy version 1.1. It
    will be removed in a future version of SymPy.
    <BLANKLINE>
      simplify_this(x)
    x

    See Also
    ========
    sympy.utilities.exceptions.SymPyDeprecationWarning
    sympy.utilities.exceptions.sympy_deprecation_warning
    sympy.utilities.exceptions.ignore_warnings
    sympy.testing.pytest.warns_deprecated_sympy

    '''
    decorator_kwargs = {"deprecated_since_version": deprecated_since_version,
               "active_deprecations_target": active_deprecations_target}
    def deprecated_decorator(wrapped):
        if hasattr(wrapped, '__mro__'):  # wrapped is actually a class
            class wrapper(wrapped):
                __doc__ = wrapped.__doc__
                __module__ = wrapped.__module__
                _sympy_deprecated_func = wrapped
                if '__new__' in wrapped.__dict__:
                    def __new__(cls, *args, **kwargs):
                        sympy_deprecation_warning(message, **decorator_kwargs, stacklevel=stacklevel)
                        return super().__new__(cls, *args, **kwargs)
                else:
                    def __init__(self, *args, **kwargs):
                        sympy_deprecation_warning(message, **decorator_kwargs, stacklevel=stacklevel)
                        super().__init__(*args, **kwargs)
            wrapper.__name__ = wrapped.__name__
        else:
            @wraps(wrapped)
            def wrapper(*args, **kwargs):
                sympy_deprecation_warning(message, **decorator_kwargs, stacklevel=stacklevel)
                return wrapped(*args, **kwargs)
            wrapper._sympy_deprecated_func = wrapped
        return wrapper
    return deprecated_decorator
