import sys
import os
from collections import deque

class Tile:
    def __init__(self, x, y):
        self._x = x
        self._y = y
        self._wall = False
        self._entry = False
        self._goal = False

    @property
    def x(self): return self._x
    @property
    def y(self): return self._y
    @property
    def is_wall(self): return self._wall
    @is_wall.setter
    def is_wall(self, value): self._wall = value
    @property
    def is_entry(self): return self._entry
    @is_entry.setter
    def is_entry(self, value): self._entry = value
    @property
    def is_goal(self): return self._goal
    @is_goal.setter
    def is_goal(self, value): self._goal = value
    def can_walk(self): return not self._wall


class Labyrinth:
    def __init__(self, width, height):
        self._width = width
        self._height = height
        self._grid = [[Tile(x, y) for x in range(width)] for y in range(height)]
        self._start = None
        self._exit = None

    @property
    def width(self): return self._width
    @property
    def height(self): return self._height
    @property
    def start(self): return self._start
    @property
    def exit(self): return self._exit

    def tile_at(self, x, y):
        if 0 <= x < self._width and 0 <= y < self._height:
            return self._grid[y][x]
        return None

    def configure_tile(self, x, y, kind):
        tile = self.tile_at(x, y)
        if tile is None: return
        if kind == 'wall':
            tile.is_wall = True
        elif kind == 'entry':
            if self._start: self._start.is_entry = False
            tile.is_entry = True
            tile.is_wall = False
            self._start = tile
        elif kind == 'goal':
            if self._exit: self._exit.is_goal = False
            tile.is_goal = True
            tile.is_wall = False
            self._exit = tile
        elif kind == 'floor':
            tile.is_wall = False

    def neighbours(self, tile):
        res = []
        for dx, dy in ((0,-1),(0,1),(-1,0),(1,0)):
            nb = self.tile_at(tile.x+dx, tile.y+dy)
            if nb and nb.can_walk():
                res.append(nb)
        return res


class LabyrinthBuilder:
    def build(self, filename): raise NotImplementedError

class TextLabyrinthBuilder(LabyrinthBuilder):
    def build(self, filename):
        with open(filename, 'r', encoding='utf-8') as f:
            lines = [line.rstrip('\n') for line in f]
        h = len(lines)
        w = max(len(l) for l in lines) if h else 0
        entries = exits = 0
        lab = Labyrinth(w, h)
        for y, row in enumerate(lines):
            for x, ch in enumerate(row):
                if ch == '#':
                    lab.configure_tile(x, y, 'wall')
                elif ch == 'S':
                    lab.configure_tile(x, y, 'entry')
                    entries += 1
                elif ch == 'E':
                    lab.configure_tile(x, y, 'goal')
                    exits += 1
                else:
                    lab.configure_tile(x, y, 'floor')
        if entries != 1 or exits != 1:
            raise ValueError(f"Некорректный лабиринт: найдено S={entries}, E={exits}")
        return lab


class Pathfinder:
    def find_path(self, lab, start, goal): raise NotImplementedError

    def _build_path(self, predecessors, start, goal):
        path = []
        cur = goal
        while cur is not None:
            path.append(cur)
            cur = predecessors.get(cur)
        path.reverse()
        return path

    @property
    def visited_count(self):
        return getattr(self, '_visited', 0)


class BFS_Pathfinder(Pathfinder):
    def find_path(self, lab, start, goal):
        q = deque([start])
        preds = {start: None}
        seen = {start}
        while q:
            cur = q.popleft()
            if cur == goal:
                self._visited = len(seen)
                return self._build_path(preds, start, goal)
            for nb in lab.neighbours(cur):
                if nb not in seen:
                    seen.add(nb)
                    preds[nb] = cur
                    q.append(nb)
        self._visited = len(seen)
        return []


class DFS_Pathfinder(Pathfinder):
    def find_path(self, lab, start, goal):
        stack = [start]
        preds = {start: None}
        seen = {start}
        while stack:
            cur = stack.pop()
            if cur == goal:
                self._visited = len(seen)
                return self._build_path(preds, start, goal)
            for nb in lab.neighbours(cur):
                if nb not in seen:
                    seen.add(nb)
                    preds[nb] = cur
                    stack.append(nb)
        self._visited = len(seen)
        return []


class LabyrinthSolver:
    def __init__(self, lab):
        self._lab = lab
        self._strategy = None

    def set_strategy(self, strategy):
        self._strategy = strategy

    def solve(self):
        if self._strategy is None:
            return None
        path = self._strategy.find_path(self._lab, self._lab.start, self._lab.exit)
        return path


def show_labyrinth(lab):
    os.system('cls' if os.name == 'nt' else 'clear')
    print('=' * (lab.width * 2 + 4))
    print('   ЛАБИРИНТ')
    print('=' * (lab.width * 2 + 4))
    for y in range(lab.height):
        print('  ', end='')
        for x in range(lab.width):
            t = lab.tile_at(x, y)
            if t == lab.start: print('S', end=' ')
            elif t == lab.exit: print('E', end=' ')
            elif t.is_wall: print('#', end=' ')
            else: print('.', end=' ')
        print()
    print('=' * (lab.width * 2 + 4))
    print('  S – вход   E – выход   # – стена   . – пол')


if __name__ == '__main__':
    maze_file = sys.argv[1] if len(sys.argv) > 1 else 'maze1.txt'
    builder = TextLabyrinthBuilder()
    labyrinth = builder.build(maze_file)
    show_labyrinth(labyrinth)

    solver = LabyrinthSolver(labyrinth)
    print("\nВыберите алгоритм: 1 – BFS, 2 – DFS")
    choice = input("> ").strip()
    if choice == '1':
        solver.set_strategy(BFS_Pathfinder())
        print("Запущен BFS...")
    elif choice == '2':
        solver.set_strategy(DFS_Pathfinder())
        print("Запущен DFS...")
    else:
        print("Неверный выбор, выход.")
        sys.exit(0)

    path = solver.solve()
    if path:
        print(f"Путь найден! Длина: {len(path)} клеток")
        print(f"Посещено клеток: {solver._strategy.visited_count}")
    else:
        print("Путь не найден!")