# Source code for cycler

    """
    Cycler
    ======

    Cycling through combinations of values, producing dictionaries.

    You can add cyclers::

        from cycler import cycler
        cc = (cycler(color=list('rgb')) +
              cycler(linestyle=['-', '--', '-.']))
        for d in cc:
            print(d)

    Results in::

        {'color': 'r', 'linestyle': '-'}
        {'color': 'g', 'linestyle': '--'}
        {'color': 'b', 'linestyle': '-.'}

    You can multiply cyclers::

        from cycler import cycler
        cc = (cycler(color=list('rgb')) *
              cycler(linestyle=['-', '--', '-.']))
        for d in cc:
            print(d)

    Results in::

        {'color': 'r', 'linestyle': '-'}
        {'color': 'r', 'linestyle': '--'}
        {'color': 'r', 'linestyle': '-.'}
        {'color': 'g', 'linestyle': '-'}
        {'color': 'g', 'linestyle': '--'}
        {'color': 'g', 'linestyle': '-.'}
        {'color': 'b', 'linestyle': '-'}
        {'color': 'b', 'linestyle': '--'}
        {'color': 'b', 'linestyle': '-.'}
    """

    from __future__ import annotations

    from collections.abc import Hashable, Iterable, Generator
    import copy
    from functools import reduce
    from itertools import product, cycle
    from operator import mul, add
    # Dict, List, Union required for runtime cast calls
    from typing import TypeVar, Generic, Callable, Union, Dict, List, Any, overload, cast

    __version__ = "0.12.1"

    K = TypeVar("K", bound=Hashable)
    L = TypeVar("L", bound=Hashable)
    V = TypeVar("V")
    U = TypeVar("U")

    def _process_keys(
        left: Cycler[K, V] | Iterable[dict[K, V]],
        right: Cycler[K, V] | Iterable[dict[K, V]] | None,
    ) -> set[K]:
        """
        Helper function to compose cycler keys.

        Parameters
        ----------
        left, right : iterable of dictionaries or None
            The cyclers to be composed.

        Returns
        -------
        keys : set
            The keys in the composition of the two cyclers.
        """
        l_peek: dict[K, V] = next(iter(left)) if left != [] else {}
        r_peek: dict[K, V] = next(iter(right)) if right is not None else {}
        l_key: set[K] = set(l_peek.keys())
        r_key: set[K] = set(r_peek.keys())
        if l_key & r_key:
            raise ValueError("Can not compose overlapping cycles")
        return l_key | r_key

    def concat(left: Cycler[K, V], right: Cycler[K, U]) -> Cycler[K, V | U]:
        r"""
        Concatenate `Cycler`\s, as if chained using `itertools.chain`.

        The keys must match exactly.

        Examples
        --------
        >>> num = cycler('a', range(3))
        >>> let = cycler('a', 'abc')
        >>> num.concat(let)
        cycler('a', [0, 1, 2, 'a', 'b', 'c'])

        Returns
        -------
        `Cycler`
            The concatenated cycler.
        """
        if left.keys != right.keys:
            raise ValueError(
                "Keys do not match:\n"
                "\tIntersection: {both!r}\n"
                "\tDisjoint: {just_one!r}".format(
                    both=left.keys & right.keys, just_one=left.keys ^ right.keys
                )
            )
        _l = cast(Dict[K, List[Union[V, U]]], left.by_key())
        _r = cast(Dict[K, List[Union[V, U]]], right.by_key())
        return reduce(add, (_cycler(k, _l[k] + _r[k]) for k in left.keys))

    class Cycler(Generic[K, V]):
        """
        Composable cycles.

        This class has compositions methods:

        ``+``
          for 'inner' products (zip)

        ``+=``
          in-place ``+``

        ``*``
          for outer products (`itertools.product`) and integer multiplication

        ``*=``
          in-place ``*``

        and supports basic slicing via ``[]``.

        Parameters
        ----------
        left, right : Cycler or None
            The 'left' and 'right' cyclers.
        op : func or None
            Function which composes the 'left' and 'right' cyclers.
        """

        def __call__(self):
            return cycle(self)

        def __init__(
            self,
            left: Cycler[K, V] | Iterable[dict[K, V]] | None,
            right: Cycler[K, V] | None = None,
            op: Any = None,
        ):
            """
            Semi-private init.

            Do not use this directly, use `cycler` function instead.
            """
            if isinstance(left, Cycler):
                self._left: Cycler[K, V] | list[dict[K, V]] = Cycler(
                    left._left, left._right, left._op
                )
            elif left is not None:
                # Need to copy the dictionary or else that will be a residual
                # mutable that could lead to strange errors
                self._left = [copy.copy(v) for v in left]
            else:
                self._left = []

            if isinstance(right, Cycler):
                self._right: Cycler[K, V] | None = Cycler(
                    right._left, right._right, right._op
                )
            else:
                self._right = None

            self._keys: set[K] = _process_keys(self._left, self._right)
            self._op: Any = op

        def __contains__(self, k):
            return k in self._keys

        @property
        def keys(self) -> set[K]:
            """The keys this Cycler knows about."""
            return set(self._keys)

        def change_key(self, old: K, new: K) -> None:
            """
            Change a key in this cycler to a new name.
            Modification is performed in-place.

            Does nothing if the old key is the same as the new key.
            Raises a ValueError if the new key is already a key.
            Raises a KeyError if the old key isn't a key.
            """
            if old == new:
                return
            if new in self._keys:
                raise ValueError(
                    f"Can't replace {old} with {new}, {new} is already a key"
                )
            if old not in self._keys:
                raise KeyError(
                    f"Can't replace {old} with {new}, {old} is not a key"
                )

            self._keys.remove(old)
            self._keys.add(new)

            if self._right is not None and old in self._right.keys:
                self._right.change_key(old, new)

            # self._left should always be non-None
            # if self._keys is non-empty.
            elif isinstance(self._left, Cycler):
                self._left.change_key(old, new)
            else:
                # It should be completely safe at this point to
                # assume that the old key can be found in each
                # iteration.
                self._left = [{new: entry[old]} for entry in self._left]

        @classmethod
        def _from_iter(cls, label: K, itr: Iterable[V]) -> Cycler[K, V]:
            """
            Class method to create 'base' Cycler objects
            that do not have a 'right' or 'op' and for which
            the 'left' object is not another Cycler.

            Parameters
            ----------
            label : hashable
                The property key.

            itr : iterable
                Finite length iterable of the property values.

            Returns
            -------
            `Cycler`
                New 'base' cycler.
            """
            ret: Cycler[K, V] = cls(None)
            ret._left = list({label: v} for v in itr)
            ret._keys = {label}
            return ret

        def __getitem__(self, key: slice) -> Cycler[K, V]:
            # TODO : maybe add numpy style fancy slicing
            if isinstance(key, slice):
                trans = self.by_key()
                return reduce(add, (_cycler(k, v[key]) for k, v in trans.items()))
            else:
                raise ValueError("Can only use slices with Cycler.__getitem__")

        def __iter__(self) -> Generator[dict[K, V], None, None]:
            if self._right is None:
                for left in self._left:
                    yield dict(left)
            else:
                if self._op is None:
                    raise TypeError(
                        "Operation cannot be None when both left and right are defined"
                    )
                for a, b in self._op(self._left, self._right):
                    out = {}
                    out.update(a)
                    out.update(b)
                    yield out

        def __add__(self, other: Cycler[L, U]) -> Cycler[K | L, V | U]:
            """
            Pair-wise combine two equal length cyclers (zip).

            Parameters
            ----------
            other : Cycler
            """
            if len(self) != len(other):
                raise ValueError(
                    f"Can only add equal length cycles, not {len(self)} and {len(other)}"
                )
            return Cycler(
                cast(Cycler[Union[K, L], Union[V, U]], self),
                cast(Cycler[Union[K, L], Union[V, U]], other),
                zip
            )

        @overload
        def __mul__(self, other: Cycler[L, U]) -> Cycler[K | L, V | U]:
            ...

        @overload
        def __mul__(self, other: int) -> Cycler[K, V]:
            ...

        def __mul__(self, other):
            """
            Outer product of two cyclers (`itertools.product`) or integer
            multiplication.

            Parameters
            ----------
            other : Cycler or int
            """
            if isinstance(other, Cycler):
                return Cycler(
                    cast(Cycler[Union[K, L], Union[V, U]], self),
                    cast(Cycler[Union[K, L], Union[V, U]], other),
                    product
                )
            elif isinstance(other, int):
                trans = self.by_key()
                return reduce(
                    add, (_cycler(k, v * other) for k, v in trans.items())
                )
            else:
                return NotImplemented

        @overload
        def __rmul__(self, other: Cycler[L, U]) -> Cycler[K | L, V | U]:
            ...

        @overload
        def __rmul__(self, other: int) -> Cycler[K, V]:
            ...

        def __rmul__(self, other):
            return self * other

        def __len__(self) -> int:
            op_dict: dict[Callable, Callable[[int, int], int]] = {zip: min, product: mul}
            if self._right is None:
                return len(self._left)
            l_len = len(self._left)
            r_len = len(self._right)
            return op_dict[self._op](l_len, r_len)

        # iadd and imul do not exapand the the type as the returns must be consistent with
        # self, thus they flag as inconsistent with add/mul
        def __iadd__(self, other: Cycler[K, V]) -> Cycler[K, V]:  # type: ignore[misc]
            """
            In-place pair-wise combine two equal length cyclers (zip).

            Parameters
            ----------
            other : Cycler
            """
            if not isinstance(other, Cycler):
                raise TypeError("Cannot += with a non-Cycler object")
            # True shallow copy of self is fine since this is in-place
            old_self = copy.copy(self)
            self._keys = _process_keys(old_self, other)
            self._left = old_self
            self._op = zip
            self._right = Cycler(other._left, other._right, other._op)
            return self

        def __imul__(self, other: Cycler[K, V] | int) -> Cycler[K, V]:  # type: ignore[misc]
            """
            In-place outer product of two cyclers (`itertools.product`).

            Parameters
            ----------
            other : Cycler
            """
            if not isinstance(other, Cycler):
                raise TypeError("Cannot *= with a non-Cycler object")
            # True shallow copy of self is fine since this is in-place
            old_self = copy.copy(self)
            self._keys = _process_keys(old_self, other)
            self._left = old_self
            self._op = product
            self._right = Cycler(other._left, other._right, other._op)
            return self

        def __eq__(self, other: object) -> bool:
            if not isinstance(other, Cycler):
                return False
            if len(self) != len(other):
                return False
            if self.keys ^ other.keys:
                return False
            return all(a == b for a, b in zip(self, other))

        __hash__ = None  # type: ignore

        def __repr__(self) -> str:
            op_map = {zip: "+", product: "*"}
            if self._right is None:
                lab = self.keys.pop()
                itr = list(v[lab] for v in self)
                return f"cycler({lab!r}, {itr!r})"
            else:
                op = op_map.get(self._op, "?")
                msg = "({left!r} {op} {right!r})"
                return msg.format(left=self._left, op=op, right=self._right)

        def _repr_html_(self) -> str:
            # an table showing the value of each key through a full cycle
            output = "<table>"
            sorted_keys = sorted(self.keys, key=repr)
            for key in sorted_keys:
                output += f"<th>{key!r}</th>"
            for d in iter(self):
                output += "<tr>"
                for k in sorted_keys:
                    output += f"<td>{d[k]!r}</td>"
                output += "</tr>"
            output += "</table>"
            return output

        def by_key(self) -> dict[K, list[V]]:
            """
            Values by key.

            This returns the transposed values of the cycler.  Iterating
            over a `Cycler` yields dicts with a single value for each key,
            this method returns a `dict` of `list` which are the values
            for the given key.

            The returned value can be used to create an equivalent `Cycler`
            using only `+`.

            Returns
            -------
            transpose : dict
                dict of lists of the values for each key.
            """

            # TODO : sort out if this is a bottle neck, if there is a better way
            # and if we care.

            keys = self.keys
            out: dict[K, list[V]] = {k: list() for k in keys}

            for d in self:
                for k in keys:
                    out[k].append(d[k])
            return out

        # for back compatibility
        _transpose = by_key

        def simplify(self) -> Cycler[K, V]:
            """
            Simplify the cycler into a sum (but no products) of cyclers.

            Returns
            -------
            simple : Cycler
            """
            # TODO: sort out if it is worth the effort to make sure this is
            # balanced.  Currently it is is
            # (((a + b) + c) + d) vs
            # ((a + b) + (c + d))
            # I would believe that there is some performance implications
            trans = self.by_key()
            return reduce(add, (_cycler(k, v) for k, v in trans.items()))

        concat = concat

    @overload
    def cycler(arg: Cycler[K, V]) -> Cycler[K, V]:
        ...

    @overload
    def cycler(**kwargs: Iterable[V]) -> Cycler[str, V]:
        ...

    @overload
    def cycler(label: K, itr: Iterable[V]) -> Cycler[K, V]:
        ...

    def cycler(*args, **kwargs):
        """
        Create a new `Cycler` object from a single positional argument,
        a pair of positional arguments, or the combination of keyword arguments.

        cycler(arg)
        cycler(label1=itr1[, label2=iter2[, ...]])
        cycler(label, itr)

        Form 1 simply copies a given `Cycler` object.

        Form 2 composes a `Cycler` as an inner product of the
        pairs of keyword arguments. In other words, all of the
        iterables are cycled simultaneously, as if through zip().

        Form 3 creates a `Cycler` from a label and an iterable.
        This is useful for when the label cannot be a keyword argument
        (e.g., an integer or a name that has a space in it).

        Parameters
        ----------
        arg : Cycler
            Copy constructor for Cycler (does a shallow copy of iterables).
        label : name
            The property key. In the 2-arg form of the function,
            the label can be any hashable object. In the keyword argument
            form of the function, it must be a valid python identifier.
        itr : iterable
            Finite length iterable of the property values.
            Can be a single-property `Cycler` that would
            be like a key change, but as a shallow copy.

        Returns
        -------
        cycler : Cycler
            New `Cycler` for the given property

        """
        if args and kwargs:
            raise TypeError(
                "cycler() can only accept positional OR keyword arguments -- not both."
            )

        if len(args) == 1:
            if not isinstance(args[0], Cycler):
                raise TypeError(
                    "If only one positional argument given, it must "
                    "be a Cycler instance."
                )
            return Cycler(args[0])
        elif len(args) == 2:
            return _cycler(*args)
        elif len(args) > 2:
            raise TypeError(
                "Only a single Cycler can be accepted as the lone "
                "positional argument. Use keyword arguments instead."
            )

        if kwargs:
            return reduce(add, (_cycler(k, v) for k, v in kwargs.items()))

        raise TypeError("Must have at least a positional OR keyword arguments")

    def _cycler(label: K, itr: Iterable[V]) -> Cycler[K, V]:
        """
        Create a new `Cycler` object from a property name and iterable of values.

        Parameters
        ----------
        label : hashable
            The property key.
        itr : iterable
            Finite length iterable of the property values.

        Returns
        -------
        cycler : Cycler
            New `Cycler` for the given property
        """
        if isinstance(itr, Cycler):
            keys = itr.keys
            if len(keys) != 1:
                msg = "Can not create Cycler from a multi-property Cycler"
                raise ValueError(msg)

            lab = keys.pop()
            # Doesn't need to be a new list because
            # _from_iter() will be creating that new list anyway.
            itr = (v[lab] for v in itr)

        return Cycler._from_iter(label, itr)