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


class Cell:
    def __init__(self, x, y):
        self._x = x
        self._y = y
        self._is_wall = False
        self._is_start = False
        self._is_exit = False
    
    @property
    def x(self):
        return self._x
    
    @property
    def y(self):
        return self._y
    
    @property
    def is_wall(self):
        return self._is_wall
    
    @is_wall.setter
    def is_wall(self, value):
        self._is_wall = value
    
    @property
    def is_start(self):
        return self._is_start
    
    @is_start.setter
    def is_start(self, value):
        self._is_start = value
    
    @property
    def is_exit(self):
        return self._is_exit
    
    @is_exit.setter
    def is_exit(self, value):
        self._is_exit = value
    
    def is_passable(self):
        return not self._is_wall


class Maze:
    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
    
    @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 get_cell(self, x, y):
        if 0 <= x < self._width and 0 <= y < self._height:
            return self._cells[y][x]
        return None
    
    def set_cell(self, x, y, cell_type):
        cell = self.get_cell(x, y)
        if cell is None:
            return
        
        if cell_type == 'wall':
            cell.is_wall = True
        elif cell_type == 'start':
            if self._start:
                self._start.is_start = False
            cell.is_start = True
            cell.is_wall = False
            self._start = cell
        elif cell_type == 'exit':
            if self._exit:
                self._exit.is_exit = False
            cell.is_exit = True
            cell.is_wall = False
            self._exit = cell
        elif cell_type == 'path':
            cell.is_wall = False
    
    def get_neighbors(self, cell):
        neighbors = []
        directions = [(0, -1), (0, 1), (-1, 0), (1, 0)]
        for dx, dy in directions:
            nx, ny = cell.x + dx, cell.y + dy
            neighbor = self.get_cell(nx, ny)
            if neighbor and neighbor.is_passable():
                neighbors.append(neighbor)
        return neighbors


class MazeBuilder:
    def build_from_file(self, filename):
        raise NotImplementedError("Need to realise in calss")


class TextFileMazeBuilder(MazeBuilder):
    def build_from_file(self, filename):
        with open(filename, 'r') 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
        start_en = 0
        exit_en = 0
        maze = Maze(width, height)

        for y, line in enumerate(lines):
            for x, ch in enumerate(line):
                if ch == "#":
                    maze.set_cell(x, y, "wall")
                elif ch == "S":
                    maze.set_cell(x, y, "start")
                    start_en += 1
                elif ch == "E":
                    maze.set_cell(x, y, "exit")
                    exit_en += 1
                else:
                    maze.set_cell(x, y, 'path')
        if start_en != 1 or exit_en != 1:
            raise ValueError(f"Labirint must have one S and one E. Found: S={start_en}, E={exit_en}")
        return maze


class PathFindingStrategy:
    def find_path(self, maze, start, exit_cell):
        raise NotImplementedError
    
    def _reconstruct_path(self, came_from, start, exit_cell):
        path = []
        current = exit_cell
        while current is not None:
            path.append(current)
            current = came_from.get(current)
        path.reverse()
        return path
    
    def get_visited_count(self):
        return getattr(self, '_visited_count', 0)


class BFSStrategy(PathFindingStrategy):
    def find_path(self, maze, start, exit_cell):
        queue = deque()
        queue.append(start)
        came_from = {start: None}
        visited = {start}
        
        while queue:
            current = queue.popleft()
            if current == exit_cell:
                self._visited_count = len(visited)
                return self._reconstruct_path(came_from, start, exit_cell)
            for neighbor in maze.get_neighbors(current):
                if neighbor not in visited:
                    visited.add(neighbor)
                    came_from[neighbor] = current
                    queue.append(neighbor)
        self._visited_count = len(visited)
        return []


class DFSStrategy(PathFindingStrategy):
    def find_path(self, maze, start, exit_cell):
        stack = [start]
        came_from = {start: None}
        visited = {start}
        
        while stack:
            current = stack.pop()
            if current == exit_cell:
                self._visited_count = len(visited)
                return self._reconstruct_path(came_from, start, exit_cell)
            for neighbor in maze.get_neighbors(current):
                if neighbor not in visited:
                    visited.add(neighbor)
                    came_from[neighbor] = current
                    stack.append(neighbor)
        self._visited_count = len(visited)
        return []


class AStarStrategy(PathFindingStrategy):
    def _heuristic(self, cell, exit_cell):
        return abs(cell.x - exit_cell.x) + abs(cell.y - exit_cell.y)
    
    def find_path(self, maze, start, exit_cell):
        heap = []
        counter = 0
        start_f = self._heuristic(start, exit_cell)
        heapq.heappush(heap, (start_f, counter, start))
        counter += 1
        
        came_from = {}
        g_score = {start: 0}
        f_score = {start: start_f}
        visited = set()
        
        while heap:
            current_f, _, current = heapq.heappop(heap)
            visited.add(current)
            
            if current == exit_cell:
                self._visited_count = len(visited)
                return self._reconstruct_path(came_from, start, exit_cell)
            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_cell)
                    f_score[neighbor] = new_f
                    heapq.heappush(heap, (new_f, counter, neighbor))
                    counter += 1
        self._visited_count = len(visited)
        return []


class SearchStats:
    def __init__(self, time_ms, visited_cells, path_length):
        self.time_ms = time_ms
        self.visited_cells = visited_cells
        self.path_length = path_length


class Observer:
    def update(self, event_type, data):
        raise NotImplementedError


class ConsoleView(Observer):
    def __init__(self, player=None):
        self._last_path = None
        self._player = player
    
    def update(self, event_type, data):
        if event_type == "maze_loaded":
            self.render_maze(data)
        elif event_type == "path_found":
            self._last_path = data
            self.render_path(data)
        elif event_type == "player_moved":
            self.render_maze_with_player(data)
    
    def render_maze(self, maze):
        os.system('cls' if os.name == 'nt' else 'clear')
        print("=" * (maze.width * 2 + 4))
        print("   LABIRINT")
        print("=" * (maze.width * 2 + 4))
        
        for y in range(maze.height):
            print("  ", end='')
            for x in range(maze.width):
                cell = maze.get_cell(x, y)
                if cell == maze.start:
                    print('S', end=' ')
                elif cell == maze.exit:
                    print('E', end=' ')
                elif cell.is_wall:
                    print('#', end=' ')
                else:
                    print('.', end=' ')
            print()
        print("=" * (maze.width * 2 + 4))
        print("  S - start  E - exit  # - wall  . - path")
    
    def render_maze_with_player(self, maze):
        os.system('cls' if os.name == 'nt' else 'clear')
        print("=" * (maze.width * 2 + 4))
        print("   LABIRINT (P - player)")
        print("=" * (maze.width * 2 + 4))
        
        for y in range(maze.height):
            print("  ", end='')
            for x in range(maze.width):
                cell = maze.get_cell(x, y)
                if self._player and cell == self._player.current:
                    print('P', end=' ')
                elif cell == maze.start:
                    print('S', end=' ')
                elif cell == maze.exit:
                    print('E', end=' ')
                elif cell.is_wall:
                    print('#', end=' ')
                else:
                    print('.', end=' ')
            print()
        print("=" * (maze.width * 2 + 4))
        print(f"  Player position: ({self._player.current.x}, {self._player.current.y})")
        print("  S - start  E - exit  # - wall  . - path  P - player")
    
    def render_path(self, path):
        if not path:
            print("\n  Path not found!")
            return
        print(f"\n  Path found! Length: {len(path)}")
    
    def render_player(self, player_cell):
        if self._player:
            self.render_maze_with_player(self._player._maze)


class Player:
    def __init__(self, start_cell, maze):
        self._current = start_cell
        self._previous = None
        self._maze = maze
    
    @property
    def current(self):
        return self._current
    
    def move_to(self, cell):
        if cell and cell.is_passable():
            self._previous = self._current
            self._current = cell
            return True
        return False
    
    def undo_move(self):
        if self._previous:
            self._current, self._previous = self._previous, None
            return True
        return False


class Command:
    def execute(self):
        raise NotImplementedError
    
    def undo(self):
        raise NotImplementedError


class MoveCommand(Command):
    def __init__(self, player, direction, maze):
        self._player = player
        self._direction = direction
        self._maze = maze
        self._executed = False
    
    def execute(self):
        dx, dy = self._direction
        new_x = self._player.current.x + dx
        new_y = self._player.current.y + dy
        target_cell = self._maze.get_cell(new_x, new_y)
        
        if target_cell and target_cell.is_passable():
            self._player.move_to(target_cell)
            self._executed = True
            return True
        return False
    
    def undo(self):
        if self._executed:
            self._player.undo_move()
            self._executed = False
            return True
        return False


class MazeSolver:
    def __init__(self, maze):
        self._maze = maze
        self._strategy = None
        self._observers = []
    
    def attach(self, observer):
        self._observers.append(observer)
    
    def notify(self, event_type, data):
        for observer in self._observers:
            observer.update(event_type, data)
    
    def set_strategy(self, strategy):
        self._strategy = strategy
    
    def solve(self):
        if self._strategy is None:
            return None
        
        start_time = time.perf_counter()
        path = self._strategy.find_path(self._maze, self._maze.start, self._maze.exit)
        end_time = time.perf_counter()
        time_ms = (end_time - start_time) * 1000
        
        self.notify("path_found", path)
        
        return SearchStats(time_ms, self._strategy.get_visited_count(), len(path))


def run_experiment(maze_file, strategy, runs=5):
    builder = TextFileMazeBuilder()
    maze = builder.build_from_file(maze_file)
    
    total_time = 0
    total_visited = 0
    total_length = 0
    
    for _ in range(runs):
        solver = MazeSolver(maze)
        solver.set_strategy(strategy)
        stats = solver.solve()
        if stats:
            total_time += stats.time_ms
            total_visited += stats.visited_cells
            total_length += stats.path_length
    
    return {
        'time_ms': total_time / runs,
        'visited_cells': total_visited / runs,
        'path_length': total_length / runs
    }


if __name__ == "__main__":
    if len(sys.argv) > 1 and sys.argv[1] == 'experiment':
        print("Running experiments...")
        sys.exit(0)
    
    builder = TextFileMazeBuilder()
    maze = builder.build_from_file("maze1.txt")
    
    player = Player(maze.start, maze)
    view = ConsoleView(player)
    view.render_maze(maze)
    
    solver = MazeSolver(maze)
    solver.attach(view)
    
    print("\n  CONTROLS:")
    print("  H (left)  J (down)  K (up)  L (right)")
    print("  U - undo    Q - quit")
    print("\n  AUTO SEARCH:")
    print("  B - BFS    D - DFS    A - A*")
    print("\n" + "=" * 50)
    
    command_stack = []
    
    while True:
        key = input("\n  Command > ").lower()
        
        if key == 'q':
            print("\n  Goodbye!")
            break
        elif key == 'b':
            solver.set_strategy(BFSStrategy())
            stats = solver.solve()
            print(f"\n  BFS: time={stats.time_ms:.3f}ms, visited={stats.visited_cells}, length={stats.path_length}")
        elif key == 'd':
            solver.set_strategy(DFSStrategy())
            stats = solver.solve()
            print(f"\n  DFS: time={stats.time_ms:.3f}ms, visited={stats.visited_cells}, length={stats.path_length}")
        elif key == 'a':
            solver.set_strategy(AStarStrategy())
            stats = solver.solve()
            print(f"\n  A*: time={stats.time_ms:.3f}ms, visited={stats.visited_cells}, length={stats.path_length}")
        elif key in ['h', 'j', 'k', 'l']:
            dirs = {'h': (-1, 0), 'l': (1, 0), 'k': (0, -1), 'j': (0, 1)}
            cmd = MoveCommand(player, dirs[key], maze)
            if cmd.execute():
                command_stack.append(cmd)
                view.render_maze_with_player(maze)
                if player.current == maze.exit:
                    print("\n  CONGRATULATIONS! YOU FOUND THE EXIT!")
                    print(f"  Total moves: {len(command_stack)}")
                    break
            else:
                print("\n  Cannot go there! It's a wall.")
        elif key == 'u':
            if command_stack:
                cmd = command_stack.pop()
                cmd.undo()
                view.render_maze_with_player(maze)
                print("\n  Undo last move")
            else:
                print("\n  Nothing to undo")
        else:
            print("\n  Unknown command. Use h,j,k,l to move, u to undo, q to quit")
    
    print("\n  Game over. Thanks for playing!")