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# Source code for astropy.cosmology._src.core

    # Licensed under a 3-clause BSD style license - see LICENSE.rst
    # Originally authored by Andrew Becker (becker@astro.washington.edu),
    # and modified by Neil Crighton (neilcrighton@gmail.com), Roban Kramer
    # (robanhk@gmail.com), and Nathaniel Starkman (n.starkman@mail.utoronto.ca).

    # Many of these adapted from Hogg 1999, astro-ph/9905116
    # and Linder 2003, PRL 90, 91301

    __all__ = ("Cosmology", "CosmologyError", "FlatCosmologyMixin")

    import inspect
    from abc import ABCMeta, abstractmethod
    from dataclasses import KW_ONLY, dataclass, replace
    from types import MappingProxyType
    from typing import Any, ClassVar, Literal, TypeVar, Union

    import numpy as np

    from astropy.io.registry import UnifiedReadWriteMethod
    from astropy.table import Table
    from astropy.utils.decorators import classproperty
    from astropy.utils.metadata import MetaData

    # isort: split
    from astropy.cosmology._src.parameter import (
        Parameter,
        ParametersAttribute,
        all_parameters,
    )
    from astropy.cosmology._src.typing import CosmoMeta, _CosmoT
    from astropy.cosmology.io import (
        CosmologyFromFormat,
        CosmologyRead,
        CosmologyToFormat,
        CosmologyWrite,
    )

    ##############################################################################
    # Parameters

    # typing
    # NOTE: private b/c RTD error
    _FlatCosmoT = TypeVar("_FlatCosmoT", bound="FlatCosmologyMixin")

    # dataclass transformation
    def _with_signature(cls: type["Cosmology"]) -> type["Cosmology"]:
        """Decorator to precompute the class' signature.

        This provides around a 20x speedup for future calls of ``inspect.signature(cls)``.
        `Cosmology` has a lot of I/O methods that use the signature, so this is a
        significant speedup for those methods.

        Note that CPython does not promise that this precomputation is a stable feature.
        If it is removed, the worst that will happen is that the signature will be
        computed on the fly, the speedup will be lost, and this decorator can be
        deprecated.
        """
        cls.__signature__ = None  # clear the signature cache
        cls.__signature__ = inspect.signature(cls)  # add the new signature to the class
        return cls

    def dataclass_decorator(cls: type["Cosmology"], /) -> type["Cosmology"]:
        """Decorator for the dataclass transform.

        Returns
        -------
        cls : type
            The `cls` transformed into a frozen `~dataclasses.dataclass`.
            The ``__eq__`` method is custom (``eq=False``).
            The signature is precomputed and added to the class.
        """
        return _with_signature(dataclass(frozen=True, repr=True, eq=False, init=True)(cls))

    ##############################################################################

    class CosmologyError(Exception):
        pass

    # TODO: replace with `field(converter=lambda x: None if x is None else str(x))` when
    #       the `converter` argument is available in `field` (py3.13, maybe?).
    #       See https://peps.python.org/pep-0712/
    @dataclass(frozen=True, slots=True)
    class _NameField:
        """Descriptor for the `Cosmology.name` field."""

        default: str | None = None

        def __get__(
            self, instance: Union["Cosmology", None], owner: type["Cosmology"] | None
        ) -> str:
            # Called from the class. `dataclass` uses this to create ``__init__``.
            if instance is None:
                return self.default
            # Called from the instance
            return instance._name

        def __set__(self, instance: "Cosmology", value: str | None) -> None:
            object.__setattr__(instance, "_name", (None if value is None else str(value)))

    @dataclass_decorator
    class Cosmology(metaclass=ABCMeta):
        """Base-class for all Cosmologies.

        Parameters
        ----------
        *args
            Arguments into the cosmology; used by subclasses, not this base class.
        name : str or None (optional, keyword-only)
            The name of the cosmology.
        meta : dict or None (optional, keyword-only)
            Metadata for the cosmology, e.g., a reference.
        **kwargs
            Arguments into the cosmology; used by subclasses, not this base class.

        Notes
        -----
        Class instances are static -- you cannot (and should not) change the
        values of the parameters.  That is, all of the above attributes
        (except meta) are read only.

        For details on how to create performant custom subclasses, see the
        documentation on :ref:`astropy-cosmology-fast-integrals`.

        Cosmology subclasses are automatically registered in a global registry
        and with various I/O methods. To turn off or change this registration,
        override the ``_register_cls`` classmethod in the subclass.
        """

        _: KW_ONLY
        name: _NameField = _NameField()
        """The name of the cosmology realization, e.g. 'Planck2018' or `None`."""

        meta: MetaData = MetaData()

        # Unified I/O object interchange methods
        from_format: ClassVar = UnifiedReadWriteMethod(CosmologyFromFormat)
        to_format: ClassVar = UnifiedReadWriteMethod(CosmologyToFormat)

        # Unified I/O read and write methods
        read: ClassVar = UnifiedReadWriteMethod(CosmologyRead)
        write: ClassVar = UnifiedReadWriteMethod(CosmologyWrite)

        # Parameters
        parameters = ParametersAttribute(attr_name="_parameters")
        """Immutable mapping of the Parameters.

        If accessed from the class, this returns a mapping of the Parameter
        objects themselves.  If accessed from an instance, this returns a
        mapping of the values of the Parameters.
        """

        _derived_parameters = ParametersAttribute(attr_name="_parameters_derived")
        """Immutable mapping of the derived Parameters.

        If accessed from the class, this returns a mapping of the Parameter
        objects themselves.  If accessed from an instance, this returns a
        mapping of the values of the Parameters.
        """

        _parameters: ClassVar = MappingProxyType[str, Parameter]({})
        _parameters_derived: ClassVar = MappingProxyType[str, Parameter]({})
        _parameters_all: ClassVar = frozenset[str]()

        __signature__: ClassVar[inspect.Signature | None] = None

        # ---------------------------------------------------------------

        def __init_subclass__(cls) -> None:
            super().__init_subclass__()

            # -------------------
            # Parameters

            all_params = all_parameters(cls)
            cls._parameters = MappingProxyType(
                {k: v for k, v in all_params.items() if not v.derived}
            )
            cls._derived_parameters = MappingProxyType(
                {k: v for k, v in all_params.items() if v.derived}
            )
            cls._parameters_all = frozenset(all_params)

            # -------------------
            # Registration

            if not inspect.isabstract(cls):  # skip abstract classes
                cls._register_cls()

        @classmethod
        def _register_cls(cls) -> None:
            # register class
            _COSMOLOGY_CLASSES[cls.__qualname__] = cls

            # register to YAML
            from astropy.cosmology._src.io.builtin.yaml import register_cosmology_yaml

            register_cosmology_yaml(cls)

        # ---------------------------------------------------------------

        def __post_init__(self) -> None:  # noqa: B027
            """Post-initialization, for subclasses to override if they need.

            This allows for subclasses to call ``super().__post_init__()`` without worrying
            about whether the parent class has a ``__post_init__`` method.
            """

        @property
        @abstractmethod
        def is_flat(self) -> bool:
            """Return bool; `True` if the cosmology is flat.

            This is abstract and must be defined in subclasses.
            """
            raise NotImplementedError("is_flat is not implemented")

        def clone(self, *, meta: CosmoMeta | None = None, **kwargs: Any) -> "Cosmology":
            """Returns a copy of this object with updated parameters, as specified.

            In general this returns an instance of the same class. For some classes (e.g.
            flat classes like `FlatLambdaCDM`) there are more options, which are documented
            in the relevant subclass.

            Parameters
            ----------
            meta : mapping or None (optional, keyword-only)
                Metadata that will update the current metadata.
            **kwargs
                Cosmology parameter (and name) modifications. If any parameter is
                changed and a new name is not given, the name will be set to "[old
                name] (modified)".

            Returns
            -------
            newcosmo : `~astropy.cosmology.Cosmology` subclass instance
                A new instance of this (or non-flat equivalent) class with updated
                parameters as specified. If no arguments are given, then a
                reference to this object is returned instead of a copy.

            Examples
            --------
            To make a copy of the ``Planck13`` cosmology with a different matter
            density (``Om0``), and a new name:

                >>> from astropy.cosmology import Planck13
                >>> Planck13.clone(name="Modified Planck 2013", Om0=0.35)
                FlatLambdaCDM(name='Modified Planck 2013', H0=<Quantity 67.77 km / (Mpc s)>,
                              Om0=0.35, ...

            If no name is specified, the new name will note the modification.

                >>> Planck13.clone(Om0=0.35).name
                'Planck13 (modified)'
            """
            # Quick return check, taking advantage of the Cosmology immutability.
            if meta is None and not kwargs:
                return self

            # There are changed parameter or metadata values.
            # The name needs to be changed accordingly, if it wasn't already.
            _modname = self.name + " (modified)"
            kwargs.setdefault("name", (_modname if self.name is not None else None))

            # mix new meta into existing, preferring the former.
            meta = meta if meta is not None else {}
            cloned = replace(self, meta=self.meta | meta, **kwargs)

            # Check if nothing has changed.
            # TODO! or should return self?
            if (cloned.name == _modname) and not meta and cloned.is_equivalent(self):
                object.__setattr__(cloned, "name", self.name)

            return cloned

        @classproperty
        def _init_has_kwargs(cls) -> bool:
            return (
                next(reversed(cls.__signature__.parameters.values())).kind
                == inspect.Parameter.VAR_KEYWORD
            )

        # ---------------------------------------------------------------
        # comparison methods

        def is_equivalent(
            self, other: Any, /, *, format: bool | None | str = False
        ) -> bool:
            r"""Check equivalence between Cosmologies.

            Two cosmologies may be equivalent even if not the same class.
            For example, an instance of ``LambdaCDM`` might have :math:`\Omega_0=1`
            and :math:`\Omega_k=0` and therefore be flat, like ``FlatLambdaCDM``.

            Parameters
            ----------
            other : `~astropy.cosmology.Cosmology` subclass instance, positional-only
                The object to which to compare.
            format : bool or None or str, optional keyword-only
                Whether to allow, before equivalence is checked, the object to be
                converted to a |Cosmology|. This allows, e.g. a |Table| to be
                equivalent to a Cosmology.
                `False` (default) will not allow conversion. `True` or `None` will,
                and will use the auto-identification to try to infer the correct
                format. A `str` is assumed to be the correct format to use when
                converting.
                ``format`` is broadcast to match the shape of ``other``.
                Note that the cosmology arguments are not broadcast against
                ``format``, so it cannot determine the output shape.

            Returns
            -------
            bool
                True if cosmologies are equivalent, False otherwise.

            Examples
            --------
            Two cosmologies may be equivalent even if not of the same class.
            In this examples the ``LambdaCDM`` has ``Ode0`` set to the same value
            calculated in ``FlatLambdaCDM``.

                >>> import astropy.units as u
                >>> from astropy.cosmology import LambdaCDM, FlatLambdaCDM
                >>> cosmo1 = LambdaCDM(70 * (u.km/u.s/u.Mpc), 0.3, 0.7)
                >>> cosmo2 = FlatLambdaCDM(70 * (u.km/u.s/u.Mpc), 0.3)
                >>> cosmo1.is_equivalent(cosmo2)
                True

            While in this example, the cosmologies are not equivalent.

                >>> cosmo3 = FlatLambdaCDM(70 * (u.km/u.s/u.Mpc), 0.3, Tcmb0=3 * u.K)
                >>> cosmo3.is_equivalent(cosmo2)
                False

            Also, using the keyword argument, the notion of equivalence is extended
            to any Python object that can be converted to a |Cosmology|.

                >>> from astropy.cosmology import Planck18
                >>> tbl = Planck18.to_format("astropy.table")
                >>> Planck18.is_equivalent(tbl, format=True)
                True

            The list of valid formats, e.g. the |Table| in this example, may be
            checked with ``Cosmology.from_format.list_formats()``.

            As can be seen in the list of formats, not all formats can be
            auto-identified by ``Cosmology.from_format.registry``. Objects of
            these kinds can still be checked for equivalence, but the correct
            format string must be used.

                >>> tbl = Planck18.to_format("yaml")
                >>> Planck18.is_equivalent(tbl, format="yaml")
                True
            """
            from astropy.cosmology._src.funcs import cosmology_equal

            try:
                return cosmology_equal(
                    self, other, format=(None, format), allow_equivalent=True
                )
            except Exception:
                # `is_equivalent` allows `other` to be any object and returns False
                # if `other` cannot be converted to a Cosmology, rather than
                # raising an Exception.
                return False

        def __equiv__(self, other: Any, /) -> bool:
            """Cosmology equivalence. Use ``.is_equivalent()`` for actual check!

            Parameters
            ----------
            other : Any, positional-only
                The object in which to compare.

            Returns
            -------
            bool or `NotImplemented`
                `NotImplemented` if ``other`` is from a different class.
                `True` if ``other`` is of the same class and has matching parameters
                and parameter values.
                `False` otherwise.
            """
            if other.__class__ is not self.__class__:
                return NotImplemented  # allows other.__equiv__

            # Check all parameters in 'other' match those in 'self' and 'other' has
            # no extra parameters (latter part should never happen b/c same class)
            # We do not use `self.parameters == other.parameters` because it does not work
            # for aggregating the truthiness of arrays, e.g. `m_nu`.
            return self._parameters_all == other._parameters_all and all(
                np.all(getattr(self, k) == getattr(other, k)) for k in self._parameters_all
            )

        def __eq__(self, other: Any, /) -> bool:
            """Check equality between Cosmologies.

            Checks the Parameters and immutable fields (i.e. not "meta").

            Parameters
            ----------
            other : `~astropy.cosmology.Cosmology` subclass instance, positional-only
                The object in which to compare.

            Returns
            -------
            bool
                `True` if Parameters and names are the same, `False` otherwise.
            """
            if other.__class__ is not self.__class__:
                return NotImplemented  # allows other.__eq__

            return (
                # non-Parameter checks: name
                self.name == other.name
                # check all parameters in 'other' match those in 'self' and 'other'
                # has no extra parameters (latter part should never happen b/c same
                # class). We do not use `self.parameters == other.parameters` because
                # it does not work for aggregating the truthiness of arrays, e.g. `m_nu`.
                # TODO! element-wise when there are array cosmologies
                and self._parameters_all == other._parameters_all
                and all(
                    np.all(getattr(self, k) == getattr(other, k))
                    for k in self._parameters_all
                )
            )

        # ---------------------------------------------------------------

        def __str__(self) -> str:
            """Return a string representation of the cosmology."""
            name_str = "" if self.name is None else f'name="{self.name}", '
            param_strs = (f"{k!s}={v!s}" for k, v in self.parameters.items())
            return f"{type(self).__name__}({name_str}{', '.join(param_strs)})"

        def __astropy_table__(self, cls: type[Table], copy: bool, **kwargs: Any) -> Table:
            """Return a `~astropy.table.Table` of type ``cls``.

            Parameters
            ----------
            cls : type
                Astropy ``Table`` class or subclass.
            copy : bool
                Ignored.
            **kwargs : dict, optional
                Additional keyword arguments. Passed to ``self.to_format()``.
                See ``Cosmology.to_format.help("astropy.table")`` for allowed kwargs.

            Returns
            -------
            `astropy.table.Table` or subclass instance
                Instance of type ``cls``.
            """
            return self.to_format("astropy.table", cls=cls, **kwargs)

    # Manipulate the dataclass fields for fields that are not created by `dataclass.fields`
    # and thus do not have a mechanism for setting "compare", "repr", etc.
    Cosmology.__dataclass_fields__["meta"].compare = False
    Cosmology.__dataclass_fields__["meta"].repr = False

    # registry of cosmology classes with {key=name : value=class}
    _COSMOLOGY_CLASSES: dict[str, type[Cosmology]] = {}

    @dataclass_decorator
    class FlatCosmologyMixin(metaclass=ABCMeta):
        """Mixin class for flat cosmologies.

        Do NOT instantiate directly. Note that all instances of
        ``FlatCosmologyMixin`` are flat, but not all flat cosmologies are
        instances of ``FlatCosmologyMixin``. As example, ``LambdaCDM`` **may**
        be flat (for the a specific set of parameter values), but
        ``FlatLambdaCDM`` **will** be flat.
        """

        _parameters: ClassVar[MappingProxyType[str, Parameter]]
        _parameters_derived: ClassVar[MappingProxyType[str, Parameter]]

        def __init_subclass__(cls: type[_FlatCosmoT]) -> None:  # noqa: PYI019
            super().__init_subclass__()

            # Determine the non-flat class.
            # This will raise a TypeError if the MRO is inconsistent.
            cls.__nonflatclass__  # noqa: B018

        # ===============================================================

        @classmethod  # TODO! make metaclass-method
        def _get_nonflat_cls(
            cls, kls: type[_CosmoT] | None = None
        ) -> type[Cosmology] | None:
            """Find the corresponding non-flat class.

            The class' bases are searched recursively.

            Parameters
            ----------
            kls : :class:`astropy.cosmology.Cosmology` class or None, optional
                If `None` (default) this class is searched instead of `kls`.

            Raises
            ------
            TypeError
                If more than one non-flat class is found at the same level of the
                inheritance. This is similar to the error normally raised by Python
                for an inconsistent method resolution order.

            Returns
            -------
            type
                A :class:`Cosmology` subclass this class inherits from that is not a
                :class:`FlatCosmologyMixin` subclass.
            """
            _kls = cls if kls is None else kls

            # Find non-flat classes
            nonflat: set[type[Cosmology]]
            nonflat = {
                b
                for b in _kls.__bases__
                if issubclass(b, Cosmology) and not issubclass(b, FlatCosmologyMixin)
            }

            if not nonflat:  # e.g. subclassing FlatLambdaCDM
                nonflat = {
                    k for b in _kls.__bases__ if (k := cls._get_nonflat_cls(b)) is not None
                }

            if len(nonflat) > 1:
                raise TypeError(
                    "cannot create a consistent non-flat class resolution order "
                    f"for {_kls} with bases {nonflat} at the same inheritance level."
                )
            if not nonflat:  # e.g. FlatFLRWMixin(FlatCosmologyMixin)
                return None

            return nonflat.pop()

        __nonflatclass__ = classproperty(
            _get_nonflat_cls, lazy=True, doc="Return the corresponding non-flat class."
        )

        # ===============================================================

        @property
        def is_flat(self) -> Literal[True]:
            """Return `True`, the cosmology is flat."""
            return True

        @property
        @abstractmethod
        def nonflat(self: _FlatCosmoT) -> _CosmoT:
            """Return the equivalent non-flat-class instance of this cosmology."""

        def clone(
            self,
            *,
            meta: CosmoMeta | None = None,
            to_nonflat: bool = False,
            **kwargs: Any,
        ) -> "Cosmology":
            """Returns a copy of this object with updated parameters, as specified.

            This cannot be used to change the type of the cosmology, except for
            changing to the non-flat version of this cosmology.

            Parameters
            ----------
            meta : mapping or None (optional, keyword-only)
                Metadata that will update the current metadata.
            to_nonflat : bool, optional keyword-only
                Whether to change to the non-flat version of this cosmology.
            **kwargs
                Cosmology parameter (and name) modifications. If any parameter is
                changed and a new name is not given, the name will be set to "[old
                name] (modified)".

            Returns
            -------
            newcosmo : `~astropy.cosmology.Cosmology` subclass instance
                A new instance of this (or non-flat equivalent) class with updated
                parameters as specified. If no arguments are given, then a
                reference to this object is returned instead of a copy.

            Examples
            --------
            To make a copy of the ``Planck13`` cosmology with a different matter
            density (``Om0``), and a new name:

                >>> from astropy.cosmology import Planck13
                >>> Planck13.clone(name="Modified Planck 2013", Om0=0.35)
                FlatLambdaCDM(name='Modified Planck 2013', H0=<Quantity 67.77 km / (Mpc s)>,
                              Om0=0.35, ...

            If no name is specified, the new name will note the modification.

                >>> Planck13.clone(Om0=0.35).name
                'Planck13 (modified)'

            The keyword 'to_nonflat' can be used to clone on the non-flat equivalent
            cosmology. For :class:`~astropy.cosmology.FLRW` cosmologies this means
            ``Ode0`` can be modified:

                >>> Planck13.clone(to_nonflat=True, Ode0=1)
                LambdaCDM(name='Planck13 (modified)', H0=<Quantity 67.77 km / (Mpc s)>,
                          Om0=0.30712, Ode0=1.0, ...
            """
            if to_nonflat:
                return self.nonflat.clone(meta=meta, **kwargs)
            return super().clone(meta=meta, **kwargs)

        # ===============================================================

        def __equiv__(self, other: Any, /) -> bool:
            """Flat-|Cosmology| equivalence.

            Use `astropy.cosmology.cosmology_equal` with
            ``allow_equivalent=True`` for actual checks!

            Parameters
            ----------
            other : Any, positional-only
                The object to which to compare for equivalence.

            Returns
            -------
            bool or `NotImplemented`
                `True` if ``other`` is of the same class / non-flat class (e.g.
                |FlatLambdaCDM| and |LambdaCDM|) has matching parameters and
                parameter values.
                `False` if ``other`` is of the same class but has different
                parameters.
                `NotImplemented` otherwise.
            """
            if isinstance(other, FlatCosmologyMixin):
                return super().__equiv__(other)  # super gets from Cosmology

            # check if `other` is the non-flat version of this class this makes the
            # assumption that any further subclass of a flat cosmo keeps the same
            # physics.
            if not issubclass(other.__class__, self.__nonflatclass__):
                return NotImplemented

            # Check if have equivalent parameters and all parameters in `other`
            # match those in `self`` and `other`` has no extra parameters.
            return (
                # no extra parameters
                self._parameters_all == other._parameters_all
                # equal
                and all(
                    np.all(getattr(self, k) == getattr(other, k)) for k in self.parameters
                )
                # flatness check
                and other.is_flat
            )