#!/usr/bin/env python3
# Eryn Wells <eryn@erynwells.me>

import logging
from typing import Optional, TYPE_CHECKING
from .geometry import Direction

if TYPE_CHECKING:
    from .engine import Engine
    from .object import Entity

LOG = logging.getLogger('events')

class ActionResult:
    '''An object that represents the result of an Action.

    Attributes
    ----------
    success : bool
        True if the action succeeded
    done : bool
        True if the action is complete, and no follow-up action is needed.
    alternate : Action, optional
        An alternate action to perform if this action failed
    '''

    def __init__(self, success: bool, done: bool = True, alternate: Optional['Action'] = None):
        self.success = success
        self.done = done
        self.alternate = alternate

class Action:
    def perform(self, engine: 'Engine', entity: 'Entity') -> ActionResult:
        '''Perform this action.

        Parameters
        ----------
        engine : Engine
            The game engine
        entity : Entity
            The entity that this action is being performed on

        Returns
        -------
        ActionResult
            A result object reflecting how the action was handled, and what follow-up actions, if any, are needed to
            complete the action.
        '''
        raise NotImplementedError()

    def __repr__(self):
        return f'{self.__class__.__name__}()'

class ExitAction(Action):
    def perform(self, engine: 'Engine', entity: 'Entity') -> ActionResult:
        raise SystemExit()

class RegenerateRoomsAction(Action):
    def perform(self, engine: 'Engine', entity: 'Entity') -> ActionResult:
        return ActionResult(True)

class MovePlayerAction(Action):
    def __init__(self, direction: Direction):
        self.direction = direction

    def perform(self, engine: 'Engine', entity: 'Entity') -> None:
        new_player_position = entity.position + self.direction

        position_is_in_bounds = engine.map.tile_is_in_bounds(new_player_position)
        position_is_walkable = engine.map.tile_is_walkable(new_player_position)
        overlaps_another_entity = any(new_player_position == ent.position for ent in engine.entities if ent is not entity)

        if position_is_in_bounds and position_is_walkable and not overlaps_another_entity:
            LOG.info('Moving hero to %s (in_bounds:%s walkable:%s overlaps:%s)',
                     new_player_position,
                     position_is_in_bounds,
                     position_is_walkable,
                     overlaps_another_entity)
            entity.position = new_player_position