units.py

from __future__ import annotations

import random
from collections.abc import Callable, Generator, Iterable
from itertools import chain
from typing import TYPE_CHECKING, Any

from s2clientprotocol import raw_pb2
from sc2.ids.unit_typeid import UnitTypeId
from sc2.position import Point2
from sc2.unit import Unit

if TYPE_CHECKING:
    from sc2.bot_ai import BotAI


class Units(list[Unit]):
    """A collection of Unit objects. Makes it easy to select units by selectors."""

    @classmethod
    def from_proto(cls, units: list[raw_pb2.Unit], bot_object: BotAI) -> Units:
        return cls((Unit(raw_unit, bot_object=bot_object) for raw_unit in units), bot_object)

    def __init__(self, units: Iterable[Unit], bot_object: BotAI) -> None:
        """
        :param units:
        :param bot_object:
        """
        super().__init__(units)
        self._bot_object = bot_object

    def __call__(self, unit_types: UnitTypeId | Iterable[UnitTypeId]) -> Units:
        """Creates a new mutable Units object from Units or list object.

        :param unit_types:
        """
        return self.of_type(unit_types)

    def __iter__(self) -> Generator[Unit, None, None]:
        return (item for item in super().__iter__())

    def copy(self) -> Units:
        """Creates a new mutable Units object from Units or list object.

        :param units:
        """
        return Units(self, self._bot_object)

    def __or__(self, other: Units) -> Units:
        """
        :param other:
        """
        self_tags = {self_unit.tag for self_unit in self}
        return Units(
            chain(iter(self), (other_unit for other_unit in other if other_unit.tag not in self_tags)),
            self._bot_object,
        )

    def __add__(self, other: Units) -> Units:
        """
        :param other:
        """
        self_tags = {self_unit.tag for self_unit in self}
        return Units(
            chain(iter(self), (other_unit for other_unit in other if other_unit.tag not in self_tags)),
            self._bot_object,
        )

    def __and__(self, other: Units) -> Units:
        """
        :param other:
        """
        self_tags = {self_unit.tag for self_unit in self}
        return Units(
            (other_unit for other_unit in other if other_unit.tag in self_tags),
            self._bot_object,
        )

    def __sub__(self, other: Units) -> Units:
        """
        :param other:
        """
        other_tags = {other_unit.tag for other_unit in other}
        return Units(
            (self_unit for self_unit in self if self_unit.tag not in other_tags),
            self._bot_object,
        )

    def __hash__(self) -> int:
        return hash(unit.tag for unit in self)

    @property
    def amount(self) -> int:
        return len(self)

    @property
    def empty(self) -> bool:
        return not bool(self)

    @property
    def exists(self) -> bool:
        return bool(self)

    def find_by_tag(self, tag: int) -> Unit | None:
        """
        :param tag:
        """
        for unit in self:
            if unit.tag == tag:
                return unit
        return None

    def by_tag(self, tag: int) -> Unit:
        """
        :param tag:
        """
        unit = self.find_by_tag(tag)
        if unit is None:
            raise KeyError("Unit not found")
        return unit

    @property
    def first(self) -> Unit:
        assert self, "Units object is empty"
        return self[0]

    def take(self, n: int) -> Units:
        """
        :param n:
        """
        if n >= self.amount:
            return self
        return self.subgroup(self[:n])

    @property
    def random(self) -> Unit:
        assert self, "Units object is empty"
        return random.choice(self)

    def random_or(self, other: Any) -> Unit:
        return random.choice(self) if self else other

    def random_group_of(self, n: int) -> Units:
        """Returns self if n >= self.amount."""
        if n < 1:
            return Units([], self._bot_object)
        if n >= self.amount:
            return self
        return self.subgroup(random.sample(self, n))

    def in_attack_range_of(self, unit: Unit, bonus_distance: float = 0) -> Units:
        """Filters units that are in attack range of the given unit.
        This uses the unit and target unit.radius when calculating the distance, so it should be accurate.
        Caution: This may not work well for static structures (bunker, sieged tank, planetary fortress, photon cannon, spine and spore crawler) because it seems attack ranges differ for static / immovable units.

        Example::

            enemy_zerglings = self.enemy_units(UnitTypeId.ZERGLING)
            my_marine = next((unit for unit in self.units if unit.type_id == UnitTypeId.MARINE), None)
            if my_marine:
                all_zerglings_my_marine_can_attack = enemy_zerglings.in_attack_range_of(my_marine)

        Example::

            enemy_mutalisks = self.enemy_units(UnitTypeId.MUTALISK)
            my_marauder = next((unit for unit in self.units if unit.type_id == UnitTypeId.MARAUDER), None)
            if my_marauder:
                all_mutalisks_my_marauder_can_attack = enemy_mutaliskss.in_attack_range_of(my_marauder)
                # Is empty because mutalisk are flying and marauder cannot attack air

        :param unit:
        :param bonus_distance:
        """
        return self.filter(lambda x: unit.target_in_range(x, bonus_distance=bonus_distance))

    def closest_distance_to(self, position: Unit | Point2) -> float:
        """Returns the distance between the closest unit from this group to the target unit.

        Example::

            enemy_zerglings = self.enemy_units(UnitTypeId.ZERGLING)
            my_marine = next((unit for unit in self.units if unit.type_id == UnitTypeId.MARINE), None)
            if my_marine:
                closest_zergling_distance = enemy_zerglings.closest_distance_to(my_marine)
            # Contains the distance between the marine and the closest zergling

        :param position:
        """
        assert self, "Units object is empty"
        if isinstance(position, Unit):
            return min(self._bot_object._distance_squared_unit_to_unit(unit, position) for unit in self) ** 0.5
        return min(self._bot_object._distance_units_to_pos(self, position))

    def furthest_distance_to(self, position: Unit | Point2) -> float:
        """Returns the distance between the furthest unit from this group to the target unit


        Example::

            enemy_zerglings = self.enemy_units(UnitTypeId.ZERGLING)
            my_marine = next((unit for unit in self.units if unit.type_id == UnitTypeId.MARINE), None)
            if my_marine:
                furthest_zergling_distance = enemy_zerglings.furthest_distance_to(my_marine)
                # Contains the distance between the marine and the furthest away zergling

        :param position:
        """
        assert self, "Units object is empty"
        if isinstance(position, Unit):
            return max(self._bot_object._distance_squared_unit_to_unit(unit, position) for unit in self) ** 0.5
        return max(self._bot_object._distance_units_to_pos(self, position))

    def closest_to(self, position: Unit | Point2) -> Unit:
        """Returns the closest unit (from this Units object) to the target unit or position.

        Example::

            enemy_zerglings = self.enemy_units(UnitTypeId.ZERGLING)
            my_marine = next((unit for unit in self.units if unit.type_id == UnitTypeId.MARINE), None)
            if my_marine:
                closest_zergling = enemy_zerglings.closest_to(my_marine)
                # Contains the zergling that is closest to the target marine

        :param position:
        """
        assert self, "Units object is empty"
        if isinstance(position, Unit):
            return min(
                (unit1 for unit1 in self),
                key=lambda unit2: self._bot_object._distance_squared_unit_to_unit(unit2, position),
            )

        distances = self._bot_object._distance_units_to_pos(self, position)
        return min(((unit, dist) for unit, dist in zip(self, distances)), key=lambda my_tuple: my_tuple[1])[0]

    def furthest_to(self, position: Unit | Point2) -> Unit:
        """Returns the furhest unit (from this Units object) to the target unit or position.

        Example::

            enemy_zerglings = self.enemy_units(UnitTypeId.ZERGLING)
            my_marine = next((unit for unit in self.units if unit.type_id == UnitTypeId.MARINE), None)
            if my_marine:
                furthest_zergling = enemy_zerglings.furthest_to(my_marine)
                # Contains the zergling that is furthest away to the target marine

        :param position:
        """
        assert self, "Units object is empty"
        if isinstance(position, Unit):
            return max(
                (unit1 for unit1 in self),
                key=lambda unit2: self._bot_object._distance_squared_unit_to_unit(unit2, position),
            )
        distances = self._bot_object._distance_units_to_pos(self, position)
        return max(((unit, dist) for unit, dist in zip(self, distances)), key=lambda my_tuple: my_tuple[1])[0]

    def closer_than(self, distance: float, position: Unit | Point2) -> Units:
        """Returns all units (from this Units object) that are closer than 'distance' away from target unit or position.

        Example::

            enemy_zerglings = self.enemy_units(UnitTypeId.ZERGLING)
            my_marine = next((unit for unit in self.units if unit.type_id == UnitTypeId.MARINE), None)
            if my_marine:
                close_zerglings = enemy_zerglings.closer_than(3, my_marine)
                # Contains all zerglings that are distance 3 or less away from the marine (does not include unit radius in calculation)

        :param distance:
        :param position:
        """
        if not self:
            return self
        if isinstance(position, Unit):
            distance_squared = distance**2
            return self.subgroup(
                unit
                for unit in self
                if self._bot_object._distance_squared_unit_to_unit(unit, position) < distance_squared
            )
        distances = self._bot_object._distance_units_to_pos(self, position)
        return self.subgroup(unit for unit, dist in zip(self, distances) if dist < distance)

    def further_than(self, distance: float, position: Unit | Point2) -> Units:
        """Returns all units (from this Units object) that are further than 'distance' away from target unit or position.

        Example::

            enemy_zerglings = self.enemy_units(UnitTypeId.ZERGLING)
            my_marine = next((unit for unit in self.units if unit.type_id == UnitTypeId.MARINE), None)
            if my_marine:
                far_zerglings = enemy_zerglings.further_than(3, my_marine)
                # Contains all zerglings that are distance 3 or more away from the marine (does not include unit radius in calculation)

        :param distance:
        :param position:
        """
        if not self:
            return self
        if isinstance(position, Unit):
            distance_squared = distance**2
            return self.subgroup(
                unit
                for unit in self
                if distance_squared < self._bot_object._distance_squared_unit_to_unit(unit, position)
            )
        distances = self._bot_object._distance_units_to_pos(self, position)
        return self.subgroup(unit for unit, dist in zip(self, distances) if distance < dist)

    def in_distance_between(
        self, position: Unit | Point2 | tuple[float, float], distance1: float, distance2: float
    ) -> Units:
        """Returns units that are further than distance1 and closer than distance2 to unit or position.

        Example::

            enemy_zerglings = self.enemy_units(UnitTypeId.ZERGLING)
            my_marine = next((unit for unit in self.units if unit.type_id == UnitTypeId.MARINE), None)
            if my_marine:
                zerglings_filtered = enemy_zerglings.in_distance_between(my_marine, 3, 5)
                # Contains all zerglings that are between distance 3 and 5 away from the marine (does not include unit radius in calculation)

        :param position:
        :param distance1:
        :param distance2:
        """
        if not self:
            return self
        if isinstance(position, Unit):
            distance1_squared = distance1**2
            distance2_squared = distance2**2
            return self.subgroup(
                unit
                for unit in self
                if distance1_squared
                < self._bot_object._distance_squared_unit_to_unit(unit, position)
                < distance2_squared
            )
        distances = self._bot_object._distance_units_to_pos(self, position)
        return self.subgroup(unit for unit, dist in zip(self, distances) if distance1 < dist < distance2)

    def closest_n_units(self, position: Unit | Point2, n: int) -> Units:
        """Returns the n closest units in distance to position.

        Example::

            enemy_zerglings = self.enemy_units(UnitTypeId.ZERGLING)
            my_marine = next((unit for unit in self.units if unit.type_id == UnitTypeId.MARINE), None)
            if my_marine:
                zerglings_filtered = enemy_zerglings.closest_n_units(my_marine, 5)
                # Contains 5 zerglings that are the closest to the marine

        :param position:
        :param n:
        """
        if not self:
            return self
        return self.subgroup(self._list_sorted_by_distance_to(position)[:n])

    def furthest_n_units(self, position: Unit | Point2, n: int) -> Units:
        """Returns the n furhest units in distance to position.

        Example::

            enemy_zerglings = self.enemy_units(UnitTypeId.ZERGLING)
            my_marine = next((unit for unit in self.units if unit.type_id == UnitTypeId.MARINE), None)
            if my_marine:
                zerglings_filtered = enemy_zerglings.furthest_n_units(my_marine, 5)
                # Contains 5 zerglings that are the furthest to the marine

        :param position:
        :param n:
        """
        if not self:
            return self
        return self.subgroup(self._list_sorted_by_distance_to(position)[-n:])

    def in_distance_of_group(self, other_units: Units, distance: float) -> Units:
        """Returns units that are closer than distance from any unit in the other units object.

        :param other_units:
        :param distance:
        """
        assert other_units, "Other units object is empty"
        # Return self because there are no enemies
        if not self:
            return self
        distance_squared = distance**2
        if len(self) == 1:
            if any(
                self._bot_object._distance_squared_unit_to_unit(self[0], target) < distance_squared
                for target in other_units
            ):
                return self
            return self.subgroup([])

        return self.subgroup(
            self_unit
            for self_unit in self
            if any(
                self._bot_object._distance_squared_unit_to_unit(self_unit, other_unit) < distance_squared
                for other_unit in other_units
            )
        )

    def in_closest_distance_to_group(self, other_units: Units) -> Unit:
        """Returns unit in shortest distance from any unit in self to any unit in group.

        Loops over all units in self, then loops over all units in other_units and calculates the shortest distance. Returns the units that is closest to any unit of 'other_units'.

        :param other_units:
        """
        assert self, "Units object is empty"
        assert other_units, "Given units object is empty"
        return min(
            self,
            key=lambda self_unit: min(
                self._bot_object._distance_squared_unit_to_unit(self_unit, other_unit) for other_unit in other_units
            ),
        )

    def _list_sorted_closest_to_distance(self, position: Unit | Point2, distance: float) -> list[Unit]:
        """This function should be a bit faster than using units.sorted(key=lambda u: u.distance_to(position))

        :param position:
        :param distance:
        """
        if isinstance(position, Unit):
            return sorted(
                self,
                key=lambda unit: abs(self._bot_object._distance_squared_unit_to_unit(unit, position) - distance),
                reverse=True,
            )
        distances = self._bot_object._distance_units_to_pos(self, position)
        unit_dist_dict = {unit.tag: dist for unit, dist in zip(self, distances)}
        return sorted(self, key=lambda unit2: abs(unit_dist_dict[unit2.tag] - distance), reverse=True)

    def n_closest_to_distance(self, position: Point2, distance: float, n: int) -> Units:
        """Returns n units that are the closest to distance away.
        For example if the distance is set to 5 and you want 3 units, from units with distance [3, 4, 5, 6, 7] to position,
        the units with distance [4, 5, 6] will be returned

        :param position:
        :param distance:
        """
        return self.subgroup(self._list_sorted_closest_to_distance(position=position, distance=distance)[:n])

    def n_furthest_to_distance(self, position: Point2, distance: float, n: int) -> Units:
        """Inverse of the function 'n_closest_to_distance', returns the furthest units instead

        :param position:
        :param distance:
        """
        return self.subgroup(self._list_sorted_closest_to_distance(position=position, distance=distance)[-n:])

    def subgroup(self, units: Iterable[Unit]) -> Units:
        """Creates a new mutable Units object from Units or list object.

        :param units:
        """
        return Units(units, self._bot_object)

    def filter(self, pred: Callable[[Unit], Any]) -> Units:
        """Filters the current Units object and returns a new Units object.

        Example::

            from sc2.ids.unit_typeid import UnitTypeId
            my_marines = self.units.filter(lambda unit: unit.type_id == UnitTypeId.MARINE)

            completed_structures = self.structures.filter(lambda structure: structure.is_ready)

            queens_with_energy_to_inject = self.units.filter(lambda unit: unit.type_id == UnitTypeId.QUEEN and unit.energy >= 25)

            orbitals_with_energy_to_mule = self.structures.filter(lambda structure: structure.type_id == UnitTypeId.ORBITALCOMMAND and structure.energy >= 50)

            my_units_that_can_shoot_up = self.units.filter(lambda unit: unit.can_attack_air)

        See more unit properties in unit.py

        :param pred:
        """
        assert callable(pred), "Function is not callable"
        return self.subgroup(filter(pred, self))

    def sorted(self, key: Callable[[Unit], Any], reverse: bool = False) -> Units:
        return self.subgroup(sorted(self, key=key, reverse=reverse))

    def _list_sorted_by_distance_to(self, position: Unit | Point2, reverse: bool = False) -> list[Unit]:
        """This function should be a bit faster than using units.sorted(key=lambda u: u.distance_to(position))

        :param position:
        :param reverse:
        """
        if isinstance(position, Unit):
            return sorted(
                self, key=lambda unit: self._bot_object._distance_squared_unit_to_unit(unit, position), reverse=reverse
            )
        distances = self._bot_object._distance_units_to_pos(self, position)
        unit_dist_dict = {unit.tag: dist for unit, dist in zip(self, distances)}
        return sorted(self, key=lambda unit2: unit_dist_dict[unit2.tag], reverse=reverse)

    def sorted_by_distance_to(self, position: Unit | Point2, reverse: bool = False) -> Units:
        """This function should be a bit faster than using units.sorted(key=lambda u: u.distance_to(position))

        :param position:
        :param reverse:
        """
        return self.subgroup(self._list_sorted_by_distance_to(position, reverse=reverse))

    def tags_in(self, other: Iterable[int]) -> Units:
        """Filters all units that have their tags in the 'other' set/list/dict

        Example::

            my_inject_queens = self.units.tags_in(self.queen_tags_assigned_to_do_injects)

            # Do not use the following as it is slower because it first loops over all units to filter out if they are queens and loops over those again to check if their tags are in the list/set
            my_inject_queens_slow = self.units(QUEEN).tags_in(self.queen_tags_assigned_to_do_injects)

        :param other:
        """
        return self.filter(lambda unit: unit.tag in other)

    def tags_not_in(self, other: Iterable[int]) -> Units:
        """Filters all units that have their tags not in the 'other' set/list/dict

        Example::

            my_non_inject_queens = self.units.tags_not_in(self.queen_tags_assigned_to_do_injects)

            # Do not use the following as it is slower because it first loops over all units to filter out if they are queens and loops over those again to check if their tags are in the list/set
            my_non_inject_queens_slow = self.units(QUEEN).tags_not_in(self.queen_tags_assigned_to_do_injects)

        :param other:
        """
        return self.filter(lambda unit: unit.tag not in other)

    def of_type(self, other: UnitTypeId | Iterable[UnitTypeId]) -> Units:
        """Filters all units that are of a specific type

        Example::

            # Use a set instead of lists in the argument
            some_attack_units = self.units.of_type({ZERGLING, ROACH, HYDRALISK, BROODLORD})

        :param other:
        """
        if isinstance(other, UnitTypeId):
            other = {other}
        elif isinstance(other, list):
            other = set(other)
        return self.filter(lambda unit: unit.type_id in other)

    def exclude_type(self, other: UnitTypeId | Iterable[UnitTypeId]) -> Units:
        """Filters all units that are not of a specific type

        Example::

            # Use a set instead of lists in the argument
            ignore_units = self.enemy_units.exclude_type({LARVA, EGG, OVERLORD})

        :param other:
        """
        if isinstance(other, UnitTypeId):
            other = {other}
        elif isinstance(other, list):
            other = set(other)
        return self.filter(lambda unit: unit.type_id not in other)

    def same_tech(self, other: set[UnitTypeId]) -> Units:
        """Returns all structures that have the same base structure.

        Untested: This should return the equivalents for WarpPrism, Observer, Overseer, SupplyDepot and others

        Example::

            # All command centers, flying command centers, orbital commands, flying orbital commands, planetary fortress
            terran_townhalls = self.townhalls.same_tech(UnitTypeId.COMMANDCENTER)

            # All hatcheries, lairs and hives
            zerg_townhalls = self.townhalls.same_tech({UnitTypeId.HATCHERY})

            # All spires and greater spires
            spires = self.townhalls.same_tech({UnitTypeId.SPIRE})
            # The following returns the same
            spires = self.townhalls.same_tech({UnitTypeId.GREATERSPIRE})

            # This also works with multiple unit types
            zerg_townhalls_and_spires = self.structures.same_tech({UnitTypeId.HATCHERY, UnitTypeId.SPIRE})

        :param other:
        """
        assert isinstance(other, set), (
            "Please use a set as this filter function is already fairly slow. For example"
            + " 'self.units.same_tech({UnitTypeId.LAIR})'"
        )
        tech_alias_types: set[int] = {u.value for u in other}
        unit_data = self._bot_object.game_data.units
        for unit_type in other:
            for same in unit_data[unit_type.value]._proto.tech_alias:
                tech_alias_types.add(same)
        return self.filter(
            lambda unit: unit._proto.unit_type in tech_alias_types
            or any(same in tech_alias_types for same in unit._type_data._proto.tech_alias)
        )

    def same_unit(self, other: UnitTypeId | Iterable[UnitTypeId]) -> Units:
        """Returns all units that have the same base unit while being in different modes.

        Untested: This should return the equivalents for WarpPrism, Observer, Overseer, SupplyDepot and other units that have different modes but still act as the same unit

        Example::

            # All command centers on the ground and flying
            ccs = self.townhalls.same_unit(UnitTypeId.COMMANDCENTER)

            # All orbital commands on the ground and flying
            ocs = self.townhalls.same_unit(UnitTypeId.ORBITALCOMMAND)

            # All roaches and burrowed roaches
            roaches = self.units.same_unit(UnitTypeId.ROACH)
            # This is useful because roach has a different type id when burrowed
            burrowed_roaches = self.units(UnitTypeId.ROACHBURROWED)

        :param other:
        """
        if isinstance(other, UnitTypeId):
            other = {other}
        unit_alias_types: set[int] = {u.value for u in other}
        unit_data = self._bot_object.game_data.units
        for unit_type in other:
            unit_alias_types.add(unit_data[unit_type.value]._proto.unit_alias)
        unit_alias_types.discard(0)
        return self.filter(
            lambda unit: unit._proto.unit_type in unit_alias_types
            or unit._type_data._proto.unit_alias in unit_alias_types
        )

    @property
    def center(self) -> Point2:
        """Returns the central position of all units."""
        assert self, "Units object is empty"
        return Point2(
            (
                sum(unit._proto.pos.x for unit in self) / self.amount,
                sum(unit._proto.pos.y for unit in self) / self.amount,
            )
        )

    @property
    def selected(self) -> Units:
        """Returns all units that are selected by the human player."""
        return self.filter(lambda unit: unit.is_selected)

    @property
    def tags(self) -> set[int]:
        """Returns all unit tags as a set."""
        return {unit.tag for unit in self}

    @property
    def ready(self) -> Units:
        """Returns all structures that are ready (construction complete)."""
        return self.filter(lambda unit: unit.is_ready)

    @property
    def not_ready(self) -> Units:
        """Returns all structures that are not ready (construction not complete)."""
        return self.filter(lambda unit: not unit.is_ready)

    @property
    def idle(self) -> Units:
        """Returns all units or structures that are doing nothing (unit is standing still, structure is doing nothing)."""
        return self.filter(lambda unit: unit.is_idle)

    @property
    def owned(self) -> Units:
        """Deprecated: All your units."""
        return self.filter(lambda unit: unit.is_mine)

    @property
    def enemy(self) -> Units:
        """Deprecated: All enemy units."""
        return self.filter(lambda unit: unit.is_enemy)

    @property
    def flying(self) -> Units:
        """Returns all units that are flying."""
        return self.filter(lambda unit: unit.is_flying)

    @property
    def not_flying(self) -> Units:
        """Returns all units that not are flying."""
        return self.filter(lambda unit: not unit.is_flying)

    @property
    def structure(self) -> Units:
        """Deprecated: All structures."""
        return self.filter(lambda unit: unit.is_structure)

    @property
    def not_structure(self) -> Units:
        """Deprecated: All units that are not structures."""
        return self.filter(lambda unit: not unit.is_structure)

    @property
    def gathering(self) -> Units:
        """Returns all workers that are mining minerals or vespene (gather command)."""
        return self.filter(lambda unit: unit.is_gathering)

    @property
    def returning(self) -> Units:
        """Returns all workers that are carrying minerals or vespene and are returning to a townhall."""
        return self.filter(lambda unit: unit.is_returning)

    @property
    def collecting(self) -> Units:
        """Returns all workers that are mining or returning resources."""
        return self.filter(lambda unit: unit.is_collecting)

    @property
    def visible(self) -> Units:
        """Returns all units or structures that are visible.
        TODO: add proper description on which units are exactly visible (not snapshots?)"""
        return self.filter(lambda unit: unit.is_visible)

    @property
    def mineral_field(self) -> Units:
        """Returns all units that are mineral fields."""
        return self.filter(lambda unit: unit.is_mineral_field)

    @property
    def vespene_geyser(self) -> Units:
        """Returns all units that are vespene geysers."""
        return self.filter(lambda unit: unit.is_vespene_geyser)

    @property
    def prefer_idle(self) -> Units:
        """Sorts units based on if they are idle. Idle units come first."""
        return self.sorted(lambda unit: unit.is_idle, reverse=True)