Projekt_Sztuczna_Inteligencja/searching_algorithms/bfs.py

from __future__ import annotations
from typing import List, Set

from project_constants import Direction, Action
from minefield import Minefield

# temporary goal for testing
GOAL = (2, 2)


class State:
    def __init__(self, row, column, direction: Direction):
        self.row = row
        self.column = column
        self.direction = direction

    # def __eq__(self, other):
    #     if not isinstance(other, State):
    #         # don't attempt to compare against unrelated types
    #         return NotImplemented
    #     return self.row == other.row and self.column == other.column and self.direction == other.direction


class Node:
    def __init__(self, state: State, parent: Node = None, action: Action = None):
        self.state = state
        self.parent = parent
        self.action = action

    # def __eq__(self, other):
    #     if not isinstance(other, Node):
    #         # don't attempt to compare against unrelated types
    #         return NotImplemented
    #     return self.state == other.state and self.parent == other.parent and self.action == other.action


def goal_test(state: State):
    if (state.row, state.column) == GOAL:
        return True
    return False


def get_successors(state: State, minefield: Minefield):
    successors = list()

    state_left = State(state.row, state.column, state.direction.previous())
    successors.append((Action.ROTATE_LEFT, state_left))

    state_right = State(state.row, state.column, state.direction.next())
    successors.append((Action.ROTATE_RIGHT, state_right))

    target = go(state.row, state.column, state.direction)

    if minefield.is_valid_move(target[0], target[1]):
        state_go = State(target[0], target[1], state.direction)
        successors.append((Action.GO, state_go))

    return successors


def graphsearch(initial_state: State, minefield: Minefield, fringe: List[Node] = None, explored: List[Node] = None):
    # fringe and explored initialization
    if fringe is None:
        fringe = list()
    if explored is None:
        explored = list()

    # root Node
    fringe.append(Node(initial_state))

    while True:
        # fringe empty -> solution not found
        if not len(fringe):
            return False

        # get first element from fringe
        element = fringe.pop(0)

        # if solution was found, prepare and return actions sequence
        if goal_test(element.state):
            actions_sequence = [element.action]
            parent = element.parent

            while parent is not None:
                # root's action will be None, don't add it
                if parent.action is not None:
                    actions_sequence.append(parent.action)
                parent = parent.parent

            actions_sequence.reverse()
            return actions_sequence

        # add current node to explored (prevents infinite cycles)
        explored.append(element)

        # loop through every possible next action
        for successor in get_successors(element.state, minefield):
            # either me or the pseudocode is dumb
            # somebody has to verify it
            fringe_states = [el.state for el in fringe]
            explored_states = [el.state for el in explored]

            # make sure not to fall into a cycle
            if successor[1] not in fringe_states and \
                    successor[1] not in explored_states:

                # create new Node and add it at the end of fringe
                new_node = Node(state=successor[1],
                                parent=element,
                                action=successor[0])
                fringe.append(new_node)


# TEMPORARY METHOD
def go(row, column, direction):
    target = tuple()

    if direction == Direction.RIGHT:
        target = row, column + 1
    elif direction == Direction.LEFT:
        target = row, column - 1
    elif direction == Direction.UP:
        target = row - 1, column
    elif direction == Direction.DOWN:
        target = row + 1, column

    return target