simple program for playing Battleship

battleplayer.py

#!/usr/bin/env python3
from itertools import product
from battleserver import Board

if __name__ == '__main__':
    board = Board()
    for x, y in product(range(5), range(5)):
        action = x, y
        result = board(x, y)
        print(f'{action} → {result}')
        if not board:
            print('I won!')
            break

battleserver.py

#!/usr/bin/env python3
from random import choice
from sys import stdin, stderr

class Board:
    def __init__(self, ships={'carrier': 5, 'battleship': 3}, size=5):
        empty = {(x, y): None for x in range(size) for y in range(size)}
        self.ships = {}
        for name, size in ships.items():
            self.ships[name] = []

            while True:
                x, y = choice(list(empty))
                candidates = [
                    [(x, y)] + [(x, y - i) for i in range(1, size)],
                    [(x, y)] + [(x, y + i) for i in range(1, size)],
                    [(x, y)] + [(x - i, y) for i in range(1, size)],
                    [(x, y)] + [(x + i, y) for i in range(1, size)],
                ]
                candidates = [c for c in candidates
                              if all(pos in empty for pos in c)]
                if not candidates:
                    continue
                direction = choice(candidates)
                self.ships[name].extend(direction)
                for x, y in self.ships[name]:
                    del empty[x, y]
                break
        self.board = {(x, y): (name, pos) for name, pos in self.ships.items()
                                          for x, y in pos}

    def __call__(self, x, y):
        if (x, y) not in self.board:
            return 'miss'
        name, pos = self.board[x, y]
        if (x, y) not in pos:
            return 'miss'
        pos.remove((x, y))
        if not pos:
            del self.ships[name]
            return f'sunk {name}'
        return f'hit {name}'

    def __len__(self):
        return len(self.ships)

if __name__ == '__main__':
    board = Board()
    while True:
        try:
            action = next(stdin)
            if not action.strip():
                break
            x, y = action.split()
            x, y = int(x), int(y)
        except Exception as e:
            print(f'invalid action {action}', file=stderr)
            continue
        result = board(x, y)
        print(result)
        if not board:
            print('you win')
            break

Run python battleplayer.py. Output should look like:

(0, 0) → miss
(0, 1) → miss
(0, 2) → miss
(0, 3) → miss
(0, 4) → miss
(1, 0) → miss
(1, 1) → miss
(1, 2) → miss
(1, 3) → miss
(1, 4) → miss
(2, 0) → hit battleship
(2, 1) → hit battleship
(2, 2) → miss
(2, 3) → miss
(2, 4) → miss
(3, 0) → sunk battleship
(3, 1) → hit carrier
(3, 2) → hit carrier
(3, 3) → hit carrier
(3, 4) → miss
(4, 0) → miss
(4, 1) → miss
(4, 2) → hit carrier
(4, 3) → sunk carrier
I won!