Source code for Karana.KUtils.MultibodyTUI.view

from typing import TypeVar, Generic, Protocol, Self
from collections.abc import Iterable




class HasId(Protocol):
    """Structural type to require an id getter method"""



    def id(self) -> int: ...




# Generic type satisfying the HasId protocol
Value = TypeVar("Value", bound=HasId)




class View(Generic[Value]):
    """Container for exploring subsets of items of a given type

    At any time, the view has a current list of items (the 'selection').
    And, if the selection is nonempty, a single specific item from the
    selection (the 'current item').

    Key features:

    - Change to a different selection, maintaining the current item if
      it is a member of the new selection.
    - Mark the current item as a 'favorite' and list all favorites.
    - Take any number of steps forward or backward in the selection.

    """

    def __init__(self, name: str, init_values: Iterable[Value]):
        """View constructor

        Parameters
        ----------
        name: str
            Name of the view
        init_values: Iterable[Value]
            The initial selection

        """
        self._name = name
        self._values = list(init_values)
        self._index = 0
        self._favorites = {}



    def copy(self) -> Self:
        """Create a copy of this view

        Returns
        -------
        typing.Self
            A copy of this view

        """
        copy = View(self._name, self._values)
        copy._index = self._index
        copy._favorites = self._favorites
        return copy


    @property
    def current(self) -> Value | None:
        """The current item or None if the selection is empty"""
        if not self._values:
            return None
        return self._values[self._index]

    @property
    def selection(self) -> list[Value]:
        """The selection"""
        return self._values[:]

    @property
    def index(self) -> int:
        """The index of the current item in the selection list"""
        return self._index

    @property
    def name(self) -> str:
        """The name of the view"""
        return self._name



    def select(self, values: Iterable[Value], current: Value | None = None):
        """Change to a new selection

        Parameters
        ----------
        values: Iterable[Value]
            The new selection
        current: Value | None = None
            The prefered current item in the new selection, using the
            current item from the prior selection if None.

        """
        values = list(values)
        if not values:
            return
        if current is None:
            current = self.current
        if current is None:
            index = 0
        else:
            for index, candidate in enumerate(values):
                if candidate.id() == current.id():
                    break
            else:
                index = 0
        self._values = values
        self._index = index




    def is_favorite(self, value: Value) -> bool:
        """Whether the given item is a favorite

        Parameters
        ----------
        value: Value
            The item to check

        Returns
        -------
        bool
            Whether the given item is a favorite

        """
        return value.id() in self._favorites


    @property
    def on_favorite(self) -> bool:
        """Whether the current item is a favorite"""
        value = self.current
        if value is None:
            return False
        return self.is_favorite(value)

    @property
    def favorites(self) -> list[Value]:
        """The list of all favorite items"""
        return list(self._favorites.values())



    def toggle_favorite(self, value: Value | None = None):
        """Toggle the favorite status of an item

        Parameters
        ----------
        value: Value | None = None
            The item to toggle, or the current item if None

        """
        if value is None:
            value = self.current
        if value is None:
            return
        # Copy the favorites if we're going to modify it. Without
        # doing this copy, toggling a favorite in a copy of this
        # View would also affect the favorites of this View.
        # Instead, View.copy could copy the favorites dictionary,
        # but that would result in more overall favorites copies
        # getting created, so we do the copy here instead.
        favorites = self._favorites.copy()
        if value.id() in favorites:
            del favorites[value.id()]
        else:
            favorites[value.id()] = value
        self._favorites = favorites




    def next(self, step: int = 1):
        """Increment the current item index

        When the step size is greater than one, this has 'sticky'
        behavior around the endpoints of the selection, stopping early
        at both the end and beginning of the selection. This is more
        complex than the more obvious solution of using modulo, but will
        hopefully result in more intuitive behavior to the user.

        Parameters
        ----------
        step: int = 1
            The amount to increment the current item index

        """
        nval = len(self._values)
        if nval < 2:
            return
        i = self._index + step
        if i >= nval:
            # Make the point where we wrap around "sticky"
            if self._index < nval - 1:
                i = nval - 1
            else:
                i = 0
        self._index = i




    def prev(self, step: int = 1):
        """Decrement the current item index

        When the step size is greater than one, this has 'sticky'
        behavior around the endpoints of the selection, stopping early
        at both the beginning and end of the selection. This is more
        complex than the more obvious solution of using modulo, but will
        hopefully result in more intuitive behavior to the user.

        Parameters
        ----------
        step: int = 1
            The amount to decrement the current item index

        """
        nval = len(self._values)
        if nval < 2:
            return
        i = self._index - step
        if i < 0:
            # Make the point where we wrap around "sticky"
            if self._index > 0:
                i = 0
            else:
                i = nval - 1
        self._index = i




    def __bool__(self) -> bool:
        """Whether the view's selection is nonempty"""
        return bool(self._values)




    def __eq__(self, other: "View") -> bool:
        """Whether the views have identical state"""
        if self._index != other._index:
            return False
        if self._values != other._values:
            return False
        if self._favorites != other._favorites:
            return False
        return True




    def __len__(self) -> int:
        """Number of items in the view's selection"""
        return len(self._values)