"""Combo box for selecting a departure airfield."""
from typing import Iterable, Optional

from PySide2.QtCore import Signal
from PySide2.QtWidgets import QComboBox
from dcs.unittype import FlyingType

from game.dcs.aircrafttype import AircraftType
from game.inventory import GlobalAircraftInventory
from game.theater.controlpoint import ControlPoint


class QOriginAirfieldSelector(QComboBox):
    """A combo box for selecting a flight's departure airfield.

    The combo box will automatically be populated with all departure airfields
    that have unassigned inventory of the given aircraft type.
    """

    availability_changed = Signal(int)

    def __init__(
        self,
        global_inventory: GlobalAircraftInventory,
        origins: Iterable[ControlPoint],
        aircraft: Optional[AircraftType],
    ) -> None:
        super().__init__()
        self.global_inventory = global_inventory
        self.origins = list(origins)
        self.aircraft = aircraft
        self.rebuild_selector()
        self.currentIndexChanged.connect(self.index_changed)
        self.setSizeAdjustPolicy(self.AdjustToContents)

    def change_aircraft(self, aircraft: Optional[FlyingType]) -> None:
        if self.aircraft == aircraft:
            return
        self.aircraft = aircraft
        self.rebuild_selector()

    def rebuild_selector(self) -> None:
        self.clear()
        if self.aircraft is None:
            return
        for origin in self.origins:
            if not origin.can_operate(self.aircraft):
                continue

            inventory = self.global_inventory.for_control_point(origin)
            available = inventory.available(self.aircraft)
            if available:
                self.addItem(f"{origin.name} ({available} available)", origin)
        self.model().sort(0)

    @property
    def available(self) -> int:
        origin = self.currentData()
        if origin is None:
            return 0
        inventory = self.global_inventory.for_control_point(origin)
        return inventory.available(self.aircraft)

    def index_changed(self, index: int) -> None:
        origin = self.itemData(index)
        if origin is None:
            return
        inventory = self.global_inventory.for_control_point(origin)
        self.availability_changed.emit(inventory.available(self.aircraft))