"""Mission stack of behaviors to be executed by the drone."""

from __future__ import annotations

# Copyright 2024 Universidad Politécnica de Madrid
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# modification, are permitted provided that the following conditions are met:
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#      documentation and/or other materials provided with the distribution.
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#      contributors may be used to endorse or promote products derived from
#      this software without specific prior written permission.
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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__authors__ = 'Pedro Arias Pérez'
__copyright__ = 'Copyright (c) 2024 Universidad Politécnica de Madrid'
__license__ = 'BSD-3-Clause'

from collections import deque
from typing import Deque, TYPE_CHECKING

if TYPE_CHECKING:
    from as2_python_api.mission_interpreter.mission import MissionItem


class MissionStack:
    """Mission stack."""

    def __init__(self, mission_stack: list = None) -> None:
        mission_stack = [] if mission_stack is None else mission_stack

        self.__pending: Deque[MissionItem] = deque(mission_stack)  # FIFO
        self.__done: Deque[MissionItem] = deque()  # LIFO
        self.__current: MissionItem = None

    def __str__(self) -> 'MissionItem':
        current = 'None' if self.current is None else self.current
        return current.json() + str(self.pending)

    def next_item(self) -> 'MissionItem':
        """Get next item in the stack."""
        if self.__current is not None:
            self.__done.append(self.__current)

        if len(self.pending) > 0:
            self.__current = self.__pending.popleft()
        else:
            self.__current = None
        return self.__current

    def previous_item(self) -> 'MissionItem':
        """Get previous item in the stack."""
        if self.__current is not None:
            self.__pending.appendleft(self.__current)
            self.__current = None

        if self.last_done is not None:
            self.__current = self.__done.pop()
        return self.__current

    def add(self, item: 'MissionItem' | list['MissionItem']):
        """Add item(s) to the end of the stack."""
        if not isinstance(item, list):
            item = [item]
        self.__pending.extend(item)

    def insert(self, item: 'MissionItem' | list['MissionItem']):
        """Insert item(s) to the beggining of the stack."""
        if not isinstance(item, list):
            item = [item]
        item.reverse()  # Insert in reverse order
        self.__pending.extendleft(item)

    def modify(self, idx: int, item: 'MissionItem') -> bool:
        """Modify item at index."""
        if idx < len(self.__done):
            print('Cannot modify done items.')
            return False
        if idx >= len(self.__done) + len(self.__pending) + 1:
            print('Index out of range.')
            return False
        idx = idx - len(self.__done) - 1
        valid: bool = self.__pending[idx].modify(item)
        return valid

    @property
    def current_idx(self) -> int:
        return len(self.__done)

    @property
    def last_done(self):
        """Get last done item."""
        if len(self.__done) == 0:
            return None
        return self.__done[0]

    @property
    def pending(self) -> list['MissionItem']:
        """Get pending items."""
        return list(self.__pending)

    @property
    def done(self) -> list['MissionItem']:
        """Get done items."""
        return list(self.__done)

    @property
    def current(self) -> 'MissionItem':
        """Get current item."""
        if self.__current is None:
            return None
        return self.__current
