"""Qt data models for game objects."""
from __future__ import annotations

import datetime
from typing import Any, Callable, Iterator, Optional, TypeVar

from PySide2.QtCore import (
    QAbstractListModel,
    QModelIndex,
    Qt,
    Signal,
)
from PySide2.QtGui import QIcon

from game.ato.airtaaskingorder import AirTaskingOrder
from game.ato.flight import Flight
from game.ato.flighttype import FlightType
from game.ato.package import Package
from game.game import Game
from game.sim.gameupdateevents import GameUpdateEvents
from game.squadrons.squadron import Pilot, Squadron
from game.theater.missiontarget import MissionTarget
from game.transfers import PendingTransfers, TransferOrder
from gen.flights.traveltime import TotEstimator
from qt_ui.simcontroller import SimController
from qt_ui.uiconstants import AIRCRAFT_ICONS


class DeletableChildModelManager:
    """Manages lifetimes for child models.

    Qt's data models don't have a good way of modeling related data aside from
    lists, tables, or trees of similar objects. We could build one monolithic
    GameModel that tracks all of the data in the game and use the parent/child
    relationships of that model to index down into the ATO, packages, flights,
    etc, but doing so is error prone because it requires us to manually manage
    that relationship tree and keep our own mappings from row/column into
    specific members.

    However, creating child models outside of the tree means that removing an
    item from the parent will not signal the child's deletion to any views, so
    we must track this explicitly.

    Any model which has child data types should use this class to track the
    deletion of child models. All child model types must define a signal named
    `deleted`. This signal will be emitted when the child model is being
    deleted. Any views displaying such data should subscribe to those events and
    update their display accordingly.
    """

    #: The type of data owned by models created by this class.
    DataType = TypeVar("DataType")

    #: The type of model managed by this class.
    ModelType = TypeVar("ModelType")

    ModelDict = dict[DataType, ModelType]

    def __init__(
        self,
        create_model: Callable[[DataType, GameModel], ModelType],
        game_model: GameModel,
    ) -> None:
        self.create_model = create_model
        self.game_model = game_model
        self.models: DeletableChildModelManager.ModelDict = {}

    def acquire(self, data: DataType) -> ModelType:
        """Returns a model for the given child data.

        If a model has already been created for the given data, it will be
        returned. The data type must be hashable.
        """
        if data in self.models:
            return self.models[data]
        model = self.create_model(data, self.game_model)
        self.models[data] = model
        return model

    def release(self, data: DataType) -> None:
        """Releases the model matching the given data, if one exists.

        If the given data has had a model created for it, that model will be
        deleted and its `deleted` signal will be emitted.
        """
        if data in self.models:
            model = self.models[data]
            del self.models[data]
            model.deleted.emit()

    def clear(self) -> None:
        """Deletes all managed models."""
        for data in list(self.models.keys()):
            self.release(data)


class NullListModel(QAbstractListModel):
    """Generic empty list model."""

    def rowCount(self, parent: QModelIndex = QModelIndex()) -> int:
        return 0

    def data(self, index: QModelIndex, role: int = Qt.DisplayRole) -> Any:
        return None


class PackageModel(QAbstractListModel):
    """The model for an ATO package."""

    FlightRole = Qt.UserRole

    #: Emitted when this package is being deleted from the ATO.
    deleted = Signal()

    tot_changed = Signal()

    def __init__(self, package: Package, game_model: GameModel) -> None:
        super().__init__()
        self.package = package
        self.game_model = game_model
        self.game_model.sim_controller.sim_update.connect(self.on_sim_update)

    def rowCount(self, parent: QModelIndex = QModelIndex()) -> int:
        return len(self.package.flights)

    def data(self, index: QModelIndex, role: int = Qt.DisplayRole) -> Any:
        if not index.isValid():
            return None
        flight = self.flight_at_index(index)
        if role == Qt.DisplayRole:
            return self.text_for_flight(flight)
        if role == Qt.DecorationRole:
            return self.icon_for_flight(flight)
        elif role == PackageModel.FlightRole:
            return flight
        return None

    def text_for_flight(self, flight: Flight) -> str:
        """Returns the text that should be displayed for the flight."""
        estimator = TotEstimator(self.package)
        delay = datetime.timedelta(
            seconds=int(estimator.mission_start_time(flight).total_seconds())
        )
        origin = flight.from_cp.name
        return f"{flight} from {origin} in {delay}"

    @staticmethod
    def icon_for_flight(flight: Flight) -> Optional[QIcon]:
        """Returns the icon that should be displayed for the flight."""
        name = flight.unit_type.dcs_id
        if name in AIRCRAFT_ICONS:
            return QIcon(AIRCRAFT_ICONS[name])
        return None

    def add_flight(self, flight: Flight) -> None:
        """Adds the given flight to the package."""
        self.beginInsertRows(QModelIndex(), self.rowCount(), self.rowCount())
        self.package.add_flight(flight)
        # update_tot is not called here because the new flight does not have a
        # flight plan yet. Will be called manually by the caller.
        self.endInsertRows()

    def delete_flight_at_index(self, index: QModelIndex) -> None:
        """Removes the flight at the given index from the package."""
        self.delete_flight(self.flight_at_index(index))

    def delete_flight(self, flight: Flight) -> None:
        """Removes the given flight from the package."""
        index = self.package.flights.index(flight)
        self.beginRemoveRows(QModelIndex(), index, index)
        if flight.cargo is not None:
            flight.cargo.transport = None
        flight.return_pilots_and_aircraft()
        self.package.remove_flight(flight)
        self.endRemoveRows()
        self.update_tot()

    def flight_at_index(self, index: QModelIndex) -> Flight:
        """Returns the flight located at the given index."""
        return self.package.flights[index.row()]

    def set_tot(self, tot: datetime.timedelta) -> None:
        self.package.time_over_target = tot
        self.update_tot()

    def set_asap(self, asap: bool) -> None:
        self.package.auto_asap = asap
        self.update_tot()

    def update_tot(self) -> None:
        if self.package.auto_asap:
            self.package.set_tot_asap()
        self.tot_changed.emit()
        # For some reason this is needed to make the UI update quickly.
        self.layoutChanged.emit()

    @property
    def mission_target(self) -> MissionTarget:
        """Returns the mission target of the package."""
        package = self.package
        target = package.target
        return target

    @property
    def description(self) -> str:
        """Returns the description of the package."""
        return self.package.package_description

    @property
    def flights(self) -> Iterator[Flight]:
        """Iterates over the flights in the package."""
        for flight in self.package.flights:
            yield flight

    def on_sim_update(self, _events: GameUpdateEvents) -> None:
        self.dataChanged.emit(self.index(0), self.index(self.rowCount()))


class AtoModel(QAbstractListModel):
    """The model for an AirTaskingOrder."""

    PackageRole = Qt.UserRole

    client_slots_changed = Signal()
    packages_changed = Signal()

    def __init__(self, game_model: GameModel, ato: AirTaskingOrder) -> None:
        super().__init__()
        self.game_model = game_model
        self.ato = ato
        self.package_models = DeletableChildModelManager(PackageModel, game_model)
        self.game_model.sim_controller.sim_update.connect(self.on_sim_update)

    @property
    def game(self) -> Optional[Game]:
        return self.game_model.game

    def rowCount(self, parent: QModelIndex = QModelIndex()) -> int:
        return len(self.ato.packages)

    def data(self, index: QModelIndex, role: int = Qt.DisplayRole) -> Any:
        if not index.isValid():
            return None
        package = self.ato.packages[index.row()]
        if role == Qt.DisplayRole:
            return f"{package.package_description} {package.target.name}"
        elif role == AtoModel.PackageRole:
            return package
        return None

    def add_package(self, package: Package) -> None:
        """Adds a package to the ATO."""
        self.beginInsertRows(QModelIndex(), self.rowCount(), self.rowCount())
        self.ato.add_package(package)
        self.endInsertRows()
        # noinspection PyUnresolvedReferences
        self.client_slots_changed.emit()
        self.on_packages_changed()

    def delete_package_at_index(self, index: QModelIndex) -> None:
        """Removes the package at the given index from the ATO."""
        self.delete_package(self.package_at_index(index))

    def delete_package(self, package: Package) -> None:
        """Removes the given package from the ATO."""
        self.package_models.release(package)
        index = self.ato.packages.index(package)
        self.beginRemoveRows(QModelIndex(), index, index)
        self.ato.remove_package(package)
        for flight in package.flights:
            flight.return_pilots_and_aircraft()
            if flight.cargo is not None:
                flight.cargo.transport = None
        self.endRemoveRows()
        # noinspection PyUnresolvedReferences
        self.client_slots_changed.emit()
        self.on_packages_changed()

    def on_packages_changed(self) -> None:
        if self.game is not None:
            self.game.compute_unculled_zones()
            self.packages_changed.emit()

    def package_at_index(self, index: QModelIndex) -> Package:
        """Returns the package at the given index."""
        return self.ato.packages[index.row()]

    def replace_from_game(self, player: bool) -> None:
        """Updates the ATO object to match the updated game object.

        If the game is None (as is the case when no game has been loaded), an
        empty ATO will be used.
        """
        self.beginResetModel()
        self.package_models.clear()
        if self.game is not None:
            if player:
                self.ato = self.game.blue.ato
            else:
                self.ato = self.game.red.ato
        else:
            self.ato = AirTaskingOrder()
        self.endResetModel()
        # noinspection PyUnresolvedReferences
        self.client_slots_changed.emit()

    def get_package_model(self, index: QModelIndex) -> PackageModel:
        """Returns a model for the package at the given index."""
        return self.package_models.acquire(self.package_at_index(index))

    def find_matching_package_model(self, package: Package) -> Optional[PackageModel]:
        for model in self.packages:
            if model.package == package:
                return model
        return None

    @property
    def packages(self) -> Iterator[PackageModel]:
        """Iterates over all the packages in the ATO."""
        for package in self.ato.packages:
            yield self.package_models.acquire(package)

    def on_sim_update(self, _events: GameUpdateEvents) -> None:
        self.dataChanged.emit(self.index(0), self.index(self.rowCount()))


class TransferModel(QAbstractListModel):
    """The model for a ground unit transfer."""

    TransferRole = Qt.UserRole

    def __init__(self, game_model: GameModel) -> None:
        super().__init__()
        self.game_model = game_model

    @property
    def transfers(self) -> PendingTransfers:
        return self.game_model.game.coalition_for(player=True).transfers

    def rowCount(self, parent: QModelIndex = QModelIndex()) -> int:
        return self.transfers.pending_transfer_count

    def data(self, index: QModelIndex, role: int = Qt.DisplayRole) -> Any:
        if not index.isValid():
            return None
        transfer = self.transfer_at_index(index)
        if role == Qt.DisplayRole:
            return self.text_for_transfer(transfer)
        if role == Qt.DecorationRole:
            return self.icon_for_transfer(transfer)
        elif role == TransferModel.TransferRole:
            return transfer
        return None

    @staticmethod
    def text_for_transfer(transfer: TransferOrder) -> str:
        """Returns the text that should be displayed for the transfer."""
        return str(transfer)

    @staticmethod
    def icon_for_transfer(_transfer: TransferOrder) -> Optional[QIcon]:
        """Returns the icon that should be displayed for the transfer."""
        return None

    def new_transfer(self, transfer: TransferOrder) -> None:
        """Updates the game with the new unit transfer."""
        self.beginInsertRows(QModelIndex(), self.rowCount(), self.rowCount())
        # TODO: Needs to regenerate base inventory tab.
        self.transfers.new_transfer(transfer)
        self.endInsertRows()

    def cancel_transfer_at_index(self, index: QModelIndex) -> None:
        """Cancels the planned unit transfer at the given index."""
        self.cancel_transfer(self.transfer_at_index(index))

    def cancel_transfer(self, transfer: TransferOrder) -> None:
        """Cancels the planned unit transfer at the given index."""
        index = self.transfers.index_of_transfer(transfer)
        self.beginRemoveRows(QModelIndex(), index, index)
        # TODO: Needs to regenerate base inventory tab.
        self.transfers.cancel_transfer(transfer)
        self.endRemoveRows()

    def transfer_at_index(self, index: QModelIndex) -> TransferOrder:
        """Returns the transfer located at the given index."""
        return self.transfers.transfer_at_index(index.row())


class AirWingModel(QAbstractListModel):
    """The model for an air wing."""

    SquadronRole = Qt.UserRole

    def __init__(self, game_model: GameModel, player: bool) -> None:
        super().__init__()
        self.game_model = game_model
        self.player = player

    def rowCount(self, parent: QModelIndex = QModelIndex()) -> int:
        return self.game_model.game.air_wing_for(self.player).size

    def data(self, index: QModelIndex, role: int = Qt.DisplayRole) -> Any:
        if not index.isValid():
            return None
        squadron = self.squadron_at_index(index)
        if role == Qt.DisplayRole:
            return self.text_for_squadron(squadron)
        if role == Qt.DecorationRole:
            return self.icon_for_squadron(squadron)
        elif role == AirWingModel.SquadronRole:
            return squadron
        return None

    @staticmethod
    def text_for_squadron(squadron: Squadron) -> str:
        """Returns the text that should be displayed for the squadron."""
        return str(squadron)

    @staticmethod
    def icon_for_squadron(squadron: Squadron) -> Optional[QIcon]:
        """Returns the icon that should be displayed for the squadron."""
        name = squadron.aircraft.dcs_id
        if name in AIRCRAFT_ICONS:
            return QIcon(AIRCRAFT_ICONS[name])
        return None

    def squadron_at_index(self, index: QModelIndex) -> Squadron:
        """Returns the squadron located at the given index."""
        return self.game_model.game.air_wing_for(self.player).squadron_at_index(
            index.row()
        )


class SquadronModel(QAbstractListModel):
    """The model for a squadron."""

    PilotRole = Qt.UserRole

    def __init__(self, squadron: Squadron) -> None:
        super().__init__()
        self.squadron = squadron

    def rowCount(self, parent: QModelIndex = QModelIndex()) -> int:
        return self.squadron.number_of_pilots_including_inactive

    def data(self, index: QModelIndex, role: int = Qt.DisplayRole) -> Any:
        if not index.isValid():
            return None
        pilot = self.pilot_at_index(index)
        if role == Qt.DisplayRole:
            return self.text_for_pilot(pilot)
        if role == Qt.DecorationRole:
            return self.icon_for_pilot(pilot)
        elif role == SquadronModel.PilotRole:
            return pilot
        return None

    @staticmethod
    def text_for_pilot(pilot: Pilot) -> str:
        """Returns the text that should be displayed for the pilot."""
        return pilot.name

    @staticmethod
    def icon_for_pilot(_pilot: Pilot) -> Optional[QIcon]:
        """Returns the icon that should be displayed for the pilot."""
        return None

    def pilot_at_index(self, index: QModelIndex) -> Pilot:
        """Returns the pilot located at the given index."""
        return self.squadron.pilot_at_index(index.row())

    def toggle_ai_state(self, index: QModelIndex) -> None:
        pilot = self.pilot_at_index(index)
        self.beginResetModel()
        pilot.player = not pilot.player
        self.endResetModel()

    def toggle_leave_state(self, index: QModelIndex) -> None:
        pilot = self.pilot_at_index(index)
        self.beginResetModel()
        if pilot.on_leave:
            self.squadron.return_from_leave(pilot)
        else:
            self.squadron.send_on_leave(pilot)
        self.endResetModel()

    def is_auto_assignable(self, task: FlightType) -> bool:
        return task in self.squadron.auto_assignable_mission_types

    def set_auto_assignable(self, task: FlightType, auto_assignable: bool) -> None:
        if auto_assignable:
            self.squadron.auto_assignable_mission_types.add(task)
        else:
            self.squadron.auto_assignable_mission_types.remove(task)


class GameModel:
    """A model for the Game object.

    This isn't a real Qt data model, but simplifies management of the game and
    its ATO objects.
    """

    def __init__(self, game: Optional[Game], sim_controller: SimController) -> None:
        self.game: Optional[Game] = game
        self.sim_controller = sim_controller
        self.transfer_model = TransferModel(self)
        self.blue_air_wing_model = AirWingModel(self, player=True)
        if self.game is None:
            self.ato_model = AtoModel(self, AirTaskingOrder())
            self.red_ato_model = AtoModel(self, AirTaskingOrder())
        else:
            self.ato_model = AtoModel(self, self.game.blue.ato)
            self.red_ato_model = AtoModel(self, self.game.red.ato)

    def ato_model_for(self, player: bool) -> AtoModel:
        if player:
            return self.ato_model
        return self.red_ato_model

    def set(self, game: Optional[Game]) -> None:
        """Updates the managed Game object.

        The argument will be None when no game has been loaded. In this state,
        much of the UI is still visible and needs to handle that behavior. To
        simplify that case, the AtoModel will model an empty ATO when no game is
        loaded.
        """
        self.game = game
        self.ato_model.replace_from_game(player=True)
        self.red_ato_model.replace_from_game(player=False)