import contextlib
import functools
import inspect
import warnings


class MatplotlibDeprecationWarning(UserWarning):
    """
    A class for issuing deprecation warnings for Matplotlib users.

    In light of the fact that Python builtin DeprecationWarnings are ignored
    by default as of Python 2.7 (see link below), this class was put in to
    allow for the signaling of deprecation, but via UserWarnings which are not
    ignored by default.

    https://docs.python.org/dev/whatsnew/2.7.html#the-future-for-python-2-x
    """


mplDeprecation = MatplotlibDeprecationWarning
"""mplDeprecation is deprecated. Use MatplotlibDeprecationWarning instead."""


def _generate_deprecation_warning(
        since, message='', name='', alternative='', pending=False,
        obj_type='attribute', addendum='', *, removal=''):

    if removal == "":
        removal = {"2.2": "in 3.1", "3.0": "in 3.2", "3.1": "in 3.3"}.get(
            since, "two minor releases later")
    elif removal:
        if pending:
            raise ValueError(
                "A pending deprecation cannot have a scheduled removal")
        removal = "in {}".format(removal)

    if not message:
        message = (
            "\nThe %(name)s %(obj_type)s"
            + (" will be deprecated in a future version"
               if pending else
               (" was deprecated in Matplotlib %(since)s"
                + (" and will be removed %(removal)s"
                   if removal else
                   "")))
            + "."
            + (" Use %(alternative)s instead." if alternative else "")
            + (" %(addendum)s" if addendum else ""))

    warning_cls = (PendingDeprecationWarning if pending
                   else MatplotlibDeprecationWarning)

    return warning_cls(message % dict(
        func=name, name=name, obj_type=obj_type, since=since, removal=removal,
        alternative=alternative, addendum=addendum))


def warn_deprecated(
        since, *, message='', name='', alternative='', pending=False,
        obj_type='attribute', addendum='', removal=''):
    """
    Used to display deprecation in a standard way.

    Parameters
    ----------
    since : str
        The release at which this API became deprecated.

    message : str, optional
        Override the default deprecation message.  The format
        specifier `%(name)s` may be used for the name of the function,
        and `%(alternative)s` may be used in the deprecation message
        to insert the name of an alternative to the deprecated
        function.  `%(obj_type)s` may be used to insert a friendly name
        for the type of object being deprecated.

    name : str, optional
        The name of the deprecated object.

    alternative : str, optional
        An alternative API that the user may use in place of the deprecated
        API.  The deprecation warning will tell the user about this alternative
        if provided.

    pending : bool, optional
        If True, uses a PendingDeprecationWarning instead of a
        DeprecationWarning.  Cannot be used together with *removal*.

    obj_type : str, optional
        The object type being deprecated.

    addendum : str, optional
        Additional text appended directly to the final message.

    removal : str, optional
        The expected removal version.  With the default (an empty string), a
        removal version is automatically computed from *since*.  Set to other
        Falsy values to not schedule a removal date.  Cannot be used together
        with *pending*.

    Examples
    --------

        Basic example::

            # To warn of the deprecation of "matplotlib.name_of_module"
            warn_deprecated('1.4.0', name='matplotlib.name_of_module',
                            obj_type='module')
    """
    warning = _generate_deprecation_warning(
        since, message, name, alternative, pending, obj_type, addendum,
        removal=removal)
    from . import _warn_external
    _warn_external(warning)


def deprecated(since, *, message='', name='', alternative='', pending=False,
               obj_type=None, addendum='', removal=''):
    """
    Decorator to mark a function, a class, or a property as deprecated.

    When deprecating a classmethod, a staticmethod, or a property, the
    ``@deprecated`` decorator should go *under* the ``@classmethod``, etc.
    decorator (i.e., `deprecated` should directly decorate the underlying
    callable).

    Parameters
    ----------
    since : str
        The release at which this API became deprecated.  This is
        required.

    message : str, optional
        Override the default deprecation message.  The format
        specifier `%(name)s` may be used for the name of the object,
        and `%(alternative)s` may be used in the deprecation message
        to insert the name of an alternative to the deprecated
        object.

    name : str, optional
        The name of the deprecated object; if not provided the name
        is automatically determined from the passed in object,
        though this is useful in the case of renamed functions, where
        the new function is just assigned to the name of the
        deprecated function.  For example::

            def new_function():
                ...
            old_function = new_function

    alternative : str, optional
        An alternative API that the user may use in place of the deprecated
        API.  The deprecation warning will tell the user about this alternative
        if provided.

    pending : bool, optional
        If True, uses a PendingDeprecationWarning instead of a
        DeprecationWarning.  Cannot be used together with *removal*.

    obj_type : str, optional
        The object type being deprecated; by default, 'function' if decorating
        a function and 'class' if decorating a class.

    addendum : str, optional
        Additional text appended directly to the final message.

    removal : str, optional
        The expected removal version.  With the default (an empty string), a
        removal version is automatically computed from *since*.  Set to other
        Falsy values to not schedule a removal date.  Cannot be used together
        with *pending*.

    Examples
    --------

        Basic example::

            @deprecated('1.4.0')
            def the_function_to_deprecate():
                pass
    """

    def deprecate(obj, message=message, name=name, alternative=alternative,
                  pending=pending, obj_type=obj_type, addendum=addendum):

        if isinstance(obj, type):
            if obj_type is None:
                obj_type = "class"
            func = obj.__init__
            name = name or obj.__name__
            old_doc = obj.__doc__

            def finalize(wrapper, new_doc):
                try:
                    obj.__doc__ = new_doc
                except AttributeError:  # Can't set on some extension objects.
                    pass
                obj.__init__ = wrapper
                return obj

        elif isinstance(obj, property):
            obj_type = "attribute"
            func = None
            name = name or obj.fget.__name__
            old_doc = obj.__doc__

            class _deprecated_property(property):
                def __get__(self, instance, owner):
                    if instance is not None:
                        from . import _warn_external
                        _warn_external(warning)
                    return super().__get__(instance, owner)

                def __set__(self, instance, value):
                    if instance is not None:
                        from . import _warn_external
                        _warn_external(warning)
                    return super().__set__(instance, value)

                def __delete__(self, instance):
                    if instance is not None:
                        from . import _warn_external
                        _warn_external(warning)
                    return super().__delete__(instance)

            def finalize(_, new_doc):
                return _deprecated_property(
                    fget=obj.fget, fset=obj.fset, fdel=obj.fdel, doc=new_doc)

        else:
            if obj_type is None:
                obj_type = "function"
            func = obj
            name = name or obj.__name__
            old_doc = func.__doc__

            def finalize(wrapper, new_doc):
                wrapper = functools.wraps(func)(wrapper)
                wrapper.__doc__ = new_doc
                return wrapper

        warning = _generate_deprecation_warning(
            since, message, name, alternative, pending, obj_type, addendum,
            removal=removal)

        def wrapper(*args, **kwargs):
            from . import _warn_external
            _warn_external(warning)
            return func(*args, **kwargs)

        old_doc = inspect.cleandoc(old_doc or '').strip('\n')

        notes_header = '\nNotes\n-----'
        new_doc = (f"[*Deprecated*] {old_doc}\n"
                   f"{notes_header if notes_header not in old_doc else ''}\n"
                   f".. deprecated:: {since}\n"
                   f"   {message.strip()}")

        if not old_doc:
            # This is to prevent a spurious 'unexpected unindent' warning from
            # docutils when the original docstring was blank.
            new_doc += r'\ '

        return finalize(wrapper, new_doc)

    return deprecate


def _rename_parameter(since, old, new, func=None):
    """
    Decorator indicating that parameter *old* of *func* is renamed to *new*.

    The actual implementation of *func* should use *new*, not *old*.  If *old*
    is passed to *func*, a DeprecationWarning is emitted, and its value is
    used, even if *new* is also passed by keyword (this is to simplify pyplot
    wrapper functions, which always pass *new* explicitly to the Axes method).
    If *new* is also passed but positionally, a TypeError will be raised by the
    underlying function during argument binding.

    Examples
    --------

    ::
        @_rename_parameter("3.1", "bad_name", "good_name")
        def func(good_name): ...
    """

    if func is None:
        return functools.partial(_rename_parameter, since, old, new)

    signature = inspect.signature(func)
    assert old not in signature.parameters, (
        f"Matplotlib internal error: {old!r} cannot be a parameter for "
        f"{func.__name__}()")
    assert new in signature.parameters, (
        f"Matplotlib internal error: {new!r} must be a parameter for "
        f"{func.__name__}()")

    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        if old in kwargs:
            warn_deprecated(
                since, message=f"The {old!r} parameter of {func.__name__}() "
                f"has been renamed {new!r} since Matplotlib {since}; support "
                f"for the old name will be dropped %(removal)s.")
            kwargs[new] = kwargs.pop(old)
        return func(*args, **kwargs)

    # wrapper() must keep the same documented signature as func(): if we
    # instead made both *old* and *new* appear in wrapper()'s signature, they
    # would both show up in the pyplot function for an Axes method as well and
    # pyplot would explicitly pass both arguments to the Axes method.

    return wrapper


class _deprecated_parameter_class:
    def __repr__(self):
        return "<deprecated parameter>"


_deprecated_parameter = _deprecated_parameter_class()


def _delete_parameter(since, name, func=None):
    """
    Decorator indicating that parameter *name* of *func* is being deprecated.

    The actual implementation of *func* should keep the *name* parameter in its
    signature.

    Parameters that come after the deprecated parameter effectively become
    keyword-only (as they cannot be passed positionally without triggering the
    DeprecationWarning on the deprecated parameter), and should be marked as
    such after the deprecation period has passed and the deprecated parameter
    is removed.

    Examples
    --------

    ::
        @_delete_parameter("3.1", "unused")
        def func(used_arg, other_arg, unused, more_args): ...
    """

    if func is None:
        return functools.partial(_delete_parameter, since, name)

    signature = inspect.signature(func)
    assert name in signature.parameters, (
        f"Matplotlib internal error: {name!r} must be a parameter for "
        f"{func.__name__}()")
    func.__signature__ = signature.replace(parameters=[
        param.replace(default=_deprecated_parameter) if param.name == name
        else param
        for param in signature.parameters.values()])

    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        arguments = func.__signature__.bind(*args, **kwargs).arguments
        # We cannot just check `name not in arguments` because the pyplot
        # wrappers always pass all arguments explicitly.
        if name in arguments and arguments[name] != _deprecated_parameter:
            warn_deprecated(
                since, message=f"The {name!r} parameter of {func.__name__}() "
                f"is deprecated since Matplotlib {since} and will be removed "
                f"%(removal)s.  If any parameter follows {name!r}, they "
                f"should be pass as keyword, not positionally.")
        return func(*args, **kwargs)

    return wrapper


def _make_keyword_only(since, name, func=None):
    """
    Decorator indicating that passing parameter *name* (or any of the following
    ones) positionally to *func* is being deprecated.

    Note that this decorator **cannot** be applied to a function that has a
    pyplot-level wrapper, as the wrapper always pass all arguments by keyword.
    If it is used, users will see spurious DeprecationWarnings every time they
    call the pyplot wrapper.
    """

    if func is None:
        return functools.partial(_make_keyword_only, since, name)

    signature = inspect.signature(func)
    POK = inspect.Parameter.POSITIONAL_OR_KEYWORD
    KWO = inspect.Parameter.KEYWORD_ONLY
    assert (name in signature.parameters
            and signature.parameters[name].kind == POK), (
        f"Matplotlib internal error: {name!r} must be a positional-or-keyword "
        f"parameter for {func.__name__}()")
    names = [*signature.parameters]
    kwonly = [name for name in names[names.index(name):]
              if signature.parameters[name].kind == POK]
    func.__signature__ = signature.replace(parameters=[
        param.replace(kind=inspect.Parameter.KEYWORD_ONLY)
        if param.name in kwonly
        else param
        for param in signature.parameters.values()])

    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        bound = signature.bind(*args, **kwargs)
        if name in bound.arguments and name not in kwargs:
            warn_deprecated(
                since, message="Passing the %(name)s %(obj_type)s "
                "positionally is deprecated since Matplotlib %(since)s; the "
                "parameter will become keyword-only %(removal)s.",
                name=name, obj_type=f"parameter of {func.__name__}()")
        return func(*args, **kwargs)

    return wrapper


@contextlib.contextmanager
def _suppress_matplotlib_deprecation_warning():
    with warnings.catch_warnings():
        warnings.simplefilter("ignore", MatplotlibDeprecationWarning)
        yield
