import sys
from collections import deque
import heapq
import time
import os

class Cell:
    """клетка лабиринта"""
    def __init__(self, x, y, is_wall=False, is_start=False, is_exit=False):
        self.x = x
        self.y = y
        self.is_wall = is_wall
        self.is_start = is_start
        self.is_exit = is_exit
    
    def is_passable(self):
        return not self.is_wall
    
    def __repr__(self):
        return f"Cell({self.x}, {self.y})"


class Maze:
    """лабиринт"""
    def __init__(self, width, height):
        self.width = width
        self.height = height
        self.cells = [[Cell(x, y) for x in range(width)] for y in range(height)]
        self.start = None
        self.exit = None
    
    def get_cell(self, x, y):
        if 0 <= x < self.width and 0 <= y < self.height:
            return self.cells[y][x]
        return None
    
    def get_neighbors(self, cell):
        neighbors = []
        directions = [(-1, 0), (1, 0), (0, -1), (0, 1)]
        for dx, dy in directions:
            neighbor = self.get_cell(cell.x + dx, cell.y + dy)
            if neighbor and neighbor.is_passable():
                neighbors.append(neighbor)
        return neighbors
    
    def set_start(self, x, y):
        cell = self.get_cell(x, y)
        if cell:
            cell.is_start = True
            self.start = cell
    
    def set_exit(self, x, y):
        cell = self.get_cell(x, y)
        if cell:
            cell.is_exit = True
            self.exit = cell



class MazeBuilder:
    """интерфейс строителя лабиринта"""
    
    def buildFromFile(self, filename):
        raise NotImplementedError


class TextFileMazeBuilder(MazeBuilder):
    """загрузка лабиринта из текстового файла"""
    
    def buildFromFile(self, filename):
        with open(filename, 'r', encoding='utf-8') as f:
            lines = [line.rstrip('\n') for line in f.readlines()]
        
        height = len(lines)
        width = max(len(line) for line in lines) if height > 0 else 0
        
        for i in range(height):
            if len(lines[i]) < width:
                lines[i] = lines[i] + ' ' * (width - len(lines[i]))
        
        maze = Maze(width, height)
        start_count = 0
        exit_count = 0
        
        for y, line in enumerate(lines):
            for x, ch in enumerate(line):
                if ch == '#':
                    maze.get_cell(x, y).is_wall = True
                elif ch == 'S':
                    maze.set_start(x, y)
                    start_count += 1
                elif ch == 'E':
                    maze.set_exit(x, y)
                    exit_count += 1
                else:
                    maze.get_cell(x, y).is_wall = False
        
        if start_count != 1 or exit_count != 1:
            raise ValueError(f"Ошибка: S={start_count}, E={exit_count} (нужно по одному)")
        
        return maze
    
class SearchStats:
    """статистика поиска"""
    def __init__(self, time_ms=0, visited_cells=0, path_length=0):
        self.time_ms = time_ms
        self.visited_cells = visited_cells
        self.path_length = path_length
    
    def __str__(self):
        return f"Время: {self.time_ms:.2f} мс, Посещено: {self.visited_cells}, Длина пути: {self.path_length}"


class PathFindingStrategy:
    """интерфейс стратегии поиска пути"""
    
    def findPath(self, maze, start, exit):
        raise NotImplementedError
    
    def get_name(self):
        raise NotImplementedError


class BFSStrategy(PathFindingStrategy):
    """BFS - гарантирует кратчайший путь"""
    
    def get_name(self):
        return "BFS (Поиск в ширину)"
    
    def findPath(self, maze, start, exit):
        from collections import deque
        
        if not start or not exit:
            return [], 0
        
        queue = deque([(start, [start])])
        visited = {start}
        
        while queue:
            current, path = queue.popleft()
            
            if current == exit:
                return path, len(visited)
            
            for neighbor in maze.get_neighbors(current):
                if neighbor not in visited:
                    visited.add(neighbor)
                    queue.append((neighbor, path + [neighbor]))
        
        return [], len(visited)


class DFSStrategy(PathFindingStrategy):
    """DFS - быстрый, но не обязательно кратчайший"""
    
    def get_name(self):
        return "DFS (Поиск в глубину)"
    
    def findPath(self, maze, start, exit):
        if not start or not exit:
            return [], 0
        
        stack = [(start, [start])]
        visited = {start}
        
        while stack:
            current, path = stack.pop()
            
            if current == exit:
                return path, len(visited)
            
            for neighbor in maze.get_neighbors(current):
                if neighbor not in visited:
                    visited.add(neighbor)
                    stack.append((neighbor, path + [neighbor]))
        
        return [], len(visited)


class AStarStrategy(PathFindingStrategy):
    """алгоритм A Star - оптимальный и быстрый с эвристикой"""
    
    def get_name(self):
        return "A Star"
    
    def _heuristic(self, a, b):
        return abs(a.x - b.x) + abs(a.y - b.y)
    
    def findPath(self, maze, start, exit):
        if not start or not exit:
            return [], 0
        
        import heapq
        
        heap = []
        counter = 0
        start_f = self._heuristic(start, exit)
        heapq.heappush(heap, (start_f, counter, start))
        
        came_from = {}
        g_score = {start: 0}
        f_score = {start: start_f}
        visited = set()
        visited.add(start)
        
        while heap:
            current_f, _, current = heapq.heappop(heap)
            
            if current == exit:
                path = []
                while current in came_from:
                    path.append(current)
                    current = came_from[current]
                path.append(start)
                path.reverse()
                return path, len(visited)
            
            if current_f > f_score.get(current, float('inf')):
                continue
            
            for neighbor in maze.get_neighbors(current):
                tentative_g = g_score[current] + 1
                
                if tentative_g < g_score.get(neighbor, float('inf')):
                    came_from[neighbor] = current
                    g_score[neighbor] = tentative_g
                    new_f = tentative_g + self._heuristic(neighbor, exit)
                    f_score[neighbor] = new_f
                    counter += 1
                    heapq.heappush(heap, (new_f, counter, neighbor))
                    visited.add(neighbor)
        
        return [], len(visited)


class DijkstraStrategy(PathFindingStrategy):
    """алгоритм Дейкстры"""
    
    def get_name(self):
        return "Дейкстра (Dijkstra)"
    
    def findPath(self, maze, start, exit):
        if not start or not exit:
            return [], 0
        
        import heapq
        
        heap = []
        counter = 0
        heapq.heappush(heap, (0, counter, start))
        
        distances = {start: 0}
        came_from = {}
        visited = set()
        visited.add(start)
        
        while heap:
            current_dist, _, current = heapq.heappop(heap)
            
            if current == exit:
                path = []
                while current in came_from:
                    path.append(current)
                    current = came_from[current]
                path.append(start)
                path.reverse()
                return path, len(visited)
            
            if current_dist > distances.get(current, float('inf')):
                continue
            
            for neighbor in maze.get_neighbors(current):
                new_dist = current_dist + 1
                
                if new_dist < distances.get(neighbor, float('inf')):
                    distances[neighbor] = new_dist
                    came_from[neighbor] = current
                    counter += 1
                    heapq.heappush(heap, (new_dist, counter, neighbor))
                    visited.add(neighbor)
        
        return [], len(visited)
    


class MazeSolver:
    """решатель лабиринта - оркестратор, использующий стратегию"""
    
    def __init__(self, maze):
        self.maze = maze
        self._strategy = None
    
    def setStrategy(self, strategy):
        """динамическая смена стратегии поиска"""
        self._strategy = strategy
        print(f"  Стратегия изменена на: {strategy.get_name()}")
    
    def solve(self):
        """
        решение лабиринта с использованием текущей стратегии.
        возвращает SearchStats (время, посещённые клетки, длина пути)
        """
        if self._strategy is None:
            raise ValueError("Стратегия не установлена. Используйте setStrategy()")
        
        
        start_time = time.perf_counter()
        
      
        path, visited = self._strategy.findPath(self.maze, self.maze.start, self.maze.exit)
        
        
        end_time = time.perf_counter()
        time_ms = (end_time - start_time) * 1000
        
        
        stats = SearchStats(
            time_ms=time_ms,
            visited_cells=visited,
            path_length=len(path) if path else 0
        )
        
        return path, stats
    
# ==================== ЭТАП 5: НАБЛЮДАТЕЛЬ (OBSERVER) ====================

class Observer:
    """Интерфейс наблюдателя"""
    
    def update(self, event, data):
        raise NotImplementedError


class ConsoleDisplay(Observer):
    """Консольная визуализация - наблюдатель"""
    
    def __init__(self):
        self._last_path = None
        self._last_maze = None
    
    def update(self, event, data):
        if event == "maze_loaded":
            self._draw_maze(data)
        elif event == "path_found":
            self._last_path = data
            self._show_path(data)
        elif event == "player_moved":
            self._draw_maze_with_player(data)
    
    def _draw_maze(self, maze):
        """Отрисовка лабиринта"""
        os.system('cls' if os.name == 'nt' else 'clear')
        print("=" * (maze.width * 2 + 4))
        print("ЛАБИРИНТ")
        print("=" * (maze.width * 2 + 4))
        
        for y in range(maze.height):
            line = ""
            for x in range(maze.width):
                cell = maze.get_cell(x, y)
                if cell == maze.start:
                    line += "S "
                elif cell == maze.exit:
                    line += "E "
                elif cell.is_wall:
                    line += "# "
                else:
                    line += ". "
            print(line)
        
        print("=" * (maze.width * 2 + 4))
        print("S - старт   E - выход   # - стена   . - проход")
    
    def _draw_maze_with_player(self, game_state):
        """Отрисовка лабиринта с игроком"""
        maze = game_state['maze']
        player = game_state['player']
        
        os.system('cls' if os.name == 'nt' else 'clear')
        print("=" * (maze.width * 2 + 4))
        print("ЛАБИРИНТ (P - игрок)")
        print("=" * (maze.width * 2 + 4))
        
        for y in range(maze.height):
            line = ""
            for x in range(maze.width):
                cell = maze.get_cell(x, y)
                if player and cell == player.get_position():
                    line += "P "
                elif cell == maze.start:
                    line += "S "
                elif cell == maze.exit:
                    line += "E "
                elif cell.is_wall:
                    line += "# "
                else:
                    line += ". "
            print(line)
        
        print("=" * (maze.width * 2 + 4))
        if player:
            pos = player.get_position()
            print(f"Игрок: ({pos.x}, {pos.y})")
        print("S - старт   E - выход   # - стена   . - проход   P - игрок")
    
    def _show_path(self, path):
        """Показ информации о найденном пути"""
        if not path:
            print("\n  Путь не найден!")
            return
        print(f"\n  Путь найден! Длина: {len(path)} клеток")


# ==================== ЭТАП 5: КОМАНДА (COMMAND) ====================

class Command:
    """Интерфейс команды"""
    
    def execute(self):
        raise NotImplementedError
    
    def undo(self):
        raise NotImplementedError


class MoveCommand(Command):
    """Команда перемещения игрока"""
    
    def __init__(self, player, direction, maze):
        self._player = player
        self._dx, self._dy = direction
        self._maze = maze
        self._executed = False
        self._prev_position = None
    
    def execute(self):
        """Выполнение перемещения"""
        if self._executed:
            return False
        
        pos = self._player.get_position()
        new_x = pos.x + self._dx
        new_y = pos.y + self._dy
        target = self._maze.get_cell(new_x, new_y)
        
        if target and target.is_passable():
            self._prev_position = pos
            self._player.set_position(target)
            self._executed = True
            return True
        return False
    
    def undo(self):
        """Отмена перемещения"""
        if not self._executed or self._prev_position is None:
            return False
        
        self._player.set_position(self._prev_position)
        self._executed = False
        return True
    
    def get_name(self):
        dir_names = {(-1, 0): "ВЛЕВО", (1, 0): "ВПРАВО", (0, -1): "ВВЕРХ", (0, 1): "ВНИЗ"}
        return f"Перемещение {dir_names.get((self._dx, self._dy), 'НЕИЗВЕСТНО')}"


class CommandInvoker:
    """Инвокер команд (история для undo/redo)"""
    
    def __init__(self):
        self._history = []
        self._redo_stack = []
    
    def execute(self, command):
        """Выполнение команды с сохранением в истории"""
        if command.execute():
            self._history.append(command)
            self._redo_stack.clear()
            return True
        return False
    
    def undo(self):
        """Отмена последней команды"""
        if not self._history:
            return False
        
        command = self._history.pop()
        if command.undo():
            self._redo_stack.append(command)
            return True
        return False
    
    def redo(self):
        """Повтор отменённой команды"""
        if not self._redo_stack:
            return False
        
        command = self._redo_stack.pop()
        if command.execute():
            self._history.append(command)
            return True
        return False
    
    def get_history_size(self):
        return len(self._history)


# ==================== ЭТАП 5: ИГРОК ====================

class Player:
    """Игрок, перемещающийся по лабиринту"""
    
    def __init__(self, start_cell):
        self._position = start_cell
        self._start = start_cell
    
    def get_position(self):
        return self._position
    
    def set_position(self, cell):
        self._position = cell
    
    def reset(self):
        self._position = self._start
    
    def is_at_exit(self, maze):
        return self._position == maze.exit
    
    def get_steps_count(self, invoker):
        return invoker.get_history_size()



class GameController:
    """контроллер, объединяющий все компоненты"""
    
    def __init__(self, maze):
        self.maze = maze
        self.player = Player(maze.start)
        self.solver = MazeSolver(maze)
        self.invoker = CommandInvoker()
        self.view = ConsoleDisplay()
    
    def run(self):
        """запуск интерактивного режима"""
        self.view.update("maze_loaded", self.maze)
        
        print("УПРАВЛЕНИЕ:")
        print("  H/J/K/L или ←/↓/↑/→ - движение")
        print("  U - отменить ход")
        print("  R - повторить ход")
        print("  B - BFS поиск пути")
        print("  D - DFS поиск пути")
        print("  A - A* поиск пути")
        print("  P - показать путь")
        print("  Q - выход")
        
        path = None
        last_strategy_name = ""
        
        while True:
            cmd = input("\nКоманда > ").lower()
            
            if cmd == 'q':
                print("До свидания!")
                break
            
            elif cmd in ['h', 'j', 'k', 'l']:
                dir_map = {'h': (-1, 0), 'l': (1, 0), 'k': (0, -1), 'j': (0, 1)}
                command = MoveCommand(self.player, dir_map[cmd], self.maze)
                
                if self.invoker.execute(command):
                    self.view.update("player_moved", {
                        'maze': self.maze,
                        'player': self.player
                    })
                    
                    if self.player.is_at_exit(self.maze):
                        print(f"\n  *** ПОБЕДА! ВЫХОД ДОСТИГНУТ за {self.player.get_steps_count(self.invoker)} шагов! ***")
                        break
                else:
                    print("  Стена! Нельзя пройти.")
            
            elif cmd == 'u':
                if self.invoker.undo():
                    self.view.update("player_moved", {
                        'maze': self.maze,
                        'player': self.player
                    })
                    print("  Отменено")
                else:
                    print("  Нечего отменять")
            
            elif cmd == 'r':
                if self.invoker.redo():
                    self.view.update("player_moved", {
                        'maze': self.maze,
                        'player': self.player
                    })
                    print("  Повторено")
                else:
                    print("  Нечего повторять")
            
            elif cmd == 'b':
                self.solver.setStrategy(BFSStrategy())
                start_time = time.perf_counter()
                path, stats = self.solver.solve()
                self.view.update("path_found", path)
                print(f"  BFS: {stats}")
                last_strategy_name = "BFS"
            
            elif cmd == 'd':
                self.solver.setStrategy(DFSStrategy())
                path, stats = self.solver.solve()
                self.view.update("path_found", path)
                print(f"  DFS: {stats}")
                last_strategy_name = "DFS"
            
            elif cmd == 'a':
                self.solver.setStrategy(AStarStrategy())
                path, stats = self.solver.solve()
                self.view.update("path_found", path)
                print(f"  A*: {stats}")
                last_strategy_name = "A*"
            
            elif cmd == 'p':
                if path:
                    self._show_path_on_maze(path)
                else:
                    print("  Сначала найдите путь (B, D или A)")
            
            else:
                print("  Неизвестная команда")
    
    def _show_path_on_maze(self, path):
        """показать путь на лабиринте"""
        os.system('cls' if os.name == 'nt' else 'clear')
        print("=" * (self.maze.width * 2 + 4))
        print("ЛАБИРИНТ С ПУТЁМ (* - путь)")
        print("=" * (self.maze.width * 2 + 4))
        
        path_set = set(path)
        
        for y in range(self.maze.height):
            line = ""
            for x in range(self.maze.width):
                cell = self.maze.get_cell(x, y)
                if cell == self.player.get_position():
                    line += "P "
                elif cell == self.maze.start:
                    line += "S "
                elif cell == self.maze.exit:
                    line += "E "
                elif cell in path_set and cell.is_passable():
                    line += "* "
                elif cell.is_wall:
                    line += "# "
                else:
                    line += ". "
            print(line)
        
        print("=" * (self.maze.width * 2 + 4))
        print("S - старт   E - выход   # - стена   . - проход   * - путь   P - игрок")
        input("\nНажмите Enter для продолжения...")
        self.view.update("player_moved", {
            'maze': self.maze,
            'player': self.player
        })