import sys
import time
from collections import deque
import heapq
from dataclasses import dataclass


class Cell:
    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


class Maze:
    def __init__(self, width, height, cells, start=None, exit=None):
        self.width = width
        self.height = height
        self.cells = cells
        self.start = start
        self.exit = 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 get_neighbors(self, cell):
        neighbors = []
        for dx, dy in ((0, -1), (0, 1), (-1, 0), (1, 0)):
            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:
    @staticmethod
    def build_from_file(filename):
        with open(filename, 'r') as f:
            lines = [line.rstrip('\n') for line in f]
        if not lines:
            raise ValueError("Empty file")
        height = len(lines)
        width = max(len(line) for line in lines)
        cells = []
        start = None
        exit_cell = None
        for y, line in enumerate(lines):
            row = []
            for x in range(width):
                ch = line[x] if x < len(line) else ' '
                is_wall = (ch == '#')
                is_start = (ch == 'S')
                is_exit = (ch == 'E')
                if is_start:
                    start = Cell(x, y, False, True, False)
                    row.append(start)
                elif is_exit:
                    exit_cell = Cell(x, y, False, False, True)
                    row.append(exit_cell)
                else:
                    row.append(Cell(x, y, is_wall, False, False))
            cells.append(row)
        if start is None:
            raise ValueError("No start cell (S) found")
        if exit_cell is None:
            raise ValueError("No exit cell (E) found")
        return Maze(width, height, cells, start, exit_cell)


class PathFindingStrategy:
    def find_path(self, maze, start, exit):
        raise NotImplementedError


class BFSStrategy(PathFindingStrategy):
    def find_path(self, maze, start, exit):
        if start == exit:
            return [start], 1
        queue = deque([start])
        visited = {start}
        parent = {start: None}
        visited_count = 1
        while queue:
            current = queue.popleft()
            if current == exit:
                path = []
                while current:
                    path.append(current)
                    current = parent[current]
                path.reverse()
                return path, visited_count
            for neighbor in maze.get_neighbors(current):
                if neighbor not in visited:
                    visited.add(neighbor)
                    parent[neighbor] = current
                    queue.append(neighbor)
                    visited_count += 1
        return [], visited_count


class DFSStrategy(PathFindingStrategy):
    def find_path(self, maze, start, exit):
        if start == exit:
            return [start], 1
        stack = [start]
        visited = {start}
        parent = {start: None}
        visited_count = 1
        while stack:
            current = stack.pop()
            if current == exit:
                path = []
                while current:
                    path.append(current)
                    current = parent[current]
                path.reverse()
                return path, visited_count
            for neighbor in maze.get_neighbors(current):
                if neighbor not in visited:
                    visited.add(neighbor)
                    parent[neighbor] = current
                    stack.append(neighbor)
                    visited_count += 1
        return [], visited_count


class AStarStrategy(PathFindingStrategy):
    @staticmethod
    def manhattan(cell, target):
        return abs(cell.x - target.x) + abs(cell.y - target.y)

    def find_path(self, maze, start, exit):
        if start == exit:
            return [start], 1
        open_set = []
        counter = 0
        heapq.heappush(open_set, (0, counter, start))
        g_score = {start: 0}
        f_score = {start: self.manhattan(start, exit)}
        parent = {start: None}
        visited_count = 0
        visited = set()
        while open_set:
            _, _, current = heapq.heappop(open_set)
            if current in visited:
                continue
            visited.add(current)
            visited_count += 1
            if current == exit:
                path = []
                while current:
                    path.append(current)
                    current = parent[current]
                path.reverse()
                return path, visited_count
            for neighbor in maze.get_neighbors(current):
                tentative_g = g_score[current] + 1
                if neighbor not in g_score or tentative_g < g_score[neighbor]:
                    parent[neighbor] = current
                    g_score[neighbor] = tentative_g
                    f = tentative_g + self.manhattan(neighbor, exit)
                    f_score[neighbor] = f
                    counter += 1
                    heapq.heappush(open_set, (f, counter, neighbor))
        return [], visited_count


@dataclass
class SearchStats:
    time_ms: float
    visited_cells: int
    path_length: int


class MazeSolver:
    def __init__(self, maze, strategy=None):
        self.maze = maze
        self.strategy = strategy

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

    def solve(self):
        if self.strategy is None:
            raise ValueError("Strategy not set")
        start_time = time.perf_counter()
        path, visited = self.strategy.find_path(self.maze, self.maze.start, self.maze.exit)
        end_time = time.perf_counter()
        time_ms = (end_time - start_time) * 1000
        return path, SearchStats(time_ms, visited, len(path) if path else 0)


def print_maze(maze, path=None):
    path_set = set(path) if path else set()
    for y in range(maze.height):
        row = []
        for x in range(maze.width):
            cell = maze.get_cell(x, y)
            if cell in path_set and not cell.is_start and not cell.is_exit:
                row.append('*')
            elif cell.is_start:
                row.append('S')
            elif cell.is_exit:
                row.append('E')
            elif cell.is_wall:
                row.append('#')
            else:
                row.append(' ')
        print(''.join(row))


def main():
    if len(sys.argv) > 1:
        filename = sys.argv[1]
    else:
        filename = 'maze1.txt'

    try:
        maze = MazeBuilder.build_from_file(filename)
        print(f"Maze loaded ({maze.width}x{maze.height})")
        print("Select algorithm: (1) BFS, (2) DFS, (3) A*")
        choice = input("Choice: ").strip()
        if choice == '1':
            strategy = BFSStrategy()
        elif choice == '2':
            strategy = DFSStrategy()
        elif choice == '3':
            strategy = AStarStrategy()
        else:
            print("Invalid, using BFS")
            strategy = BFSStrategy()

        solver = MazeSolver(maze, strategy)
        path, stats = solver.solve()
        if path:
            print(f"Path found! Length: {len(path)}")
            print(f"Visited cells: {stats.visited_cells}")
            print(f"Time: {stats.time_ms:.4f} ms")
            print_maze(maze, path)
        else:
            print("No path found.")
            print(f"Visited cells: {stats.visited_cells}")
            print(f"Time: {stats.time_ms:.4f} ms")
    except Exception as e:
        print(f"Error: {e}")

if __name__ == '__main__':
    main()