Improve AI targeting

battleship/engine/ai.py

@@ -6,52 +6,84 @@
 
 
 class TargetCaller:
-    def __init__(self, board: domain.Board) -> None:
+    def __init__(self, board: domain.Board, no_adjacent_ships: bool = False) -> None:
         self.board = board
-        self.next_targets: deque[domain.Cell] = deque()
+        self.no_adjacent_ships = no_adjacent_ships
+        self.next_targets: deque[domain.Coordinate] = deque()
+        self.excluded_cells: set[domain.Coordinate] = set()
 
     def call_out(self, *, count: int = 1) -> list[str]:
-        cells = self._get_targets(count)
-        return [cell.coordinate.to_human() for cell in cells]
+        targets = self._get_targets(count)
+        return [target.to_human() for target in targets]
 
     def provide_feedback(self, shots: Iterable[domain.Shot]) -> None:
         for shot in shots:
-            if shot.hit and not shot.ship.destroyed:  # type: ignore
-                cell = self.board.get_cell(shot.coordinate)
-
-                if cell is None:
-                    raise errors.CellOutOfRange(f"Cell at {shot.coordinate} doesn't exist.")
-
-                neighbors = self._find_neighbor_cells(cell)
-                self.next_targets.extend(neighbors)
-
-    def _get_targets(self, count: int) -> list[domain.Cell]:
-        targets: list[domain.Cell] = []
+            # If shot was a hit, we can learn something from it.
+            if shot.hit:
+                assert shot.ship, "Shot was a hit, but no ship present"
+
+                if shot.ship.destroyed and self.no_adjacent_ships:
+                    # If ship was destroyed and there's "No adjacent ships"
+                    # rule enabled, there's no point in firing cells
+                    # that surrounds the ship - it's impossible to place
+                    # another ship there.
+                    coordinates = self._find_cells_around_ship(shot.ship)
+                    self.excluded_cells.update(coordinates)
+                    self.next_targets.clear()
+                elif not shot.ship.destroyed:
+                    # If ship was hit, but not destroyed, keep on
+                    # firing cells around until it is destroyed.
+                    cells = self._target_ship(shot.coordinate)
+                    self.next_targets.extend(cells)
+
+    def _get_targets(self, count: int) -> list[domain.Coordinate]:
+        targets: list[domain.Coordinate] = []
 
         while len(self.next_targets) and len(targets) != count:
             next_target = self.next_targets.popleft()
             targets.append(next_target)
 
         if len(targets) != count:
-            random_targets = self._find_random_targets(count - len(targets))
+            random_targets = self._target_random_cells(count - len(targets))
             targets.extend(random_targets)
 
         return targets
 
-    def _find_random_targets(self, count: int) -> list[domain.Cell]:
-        candidates = [cell for cell in self.board.cells if not cell.is_shot]
+    def _target_random_cells(self, count: int) -> list[domain.Coordinate]:
+        candidates = [
+            cell.coordinate
+            for cell in self.board.cells
+            if not (cell.is_shot or cell.coordinate in self.excluded_cells)
+        ]
         return random.sample(candidates, k=min(len(candidates), count))
 
-    def _find_neighbor_cells(self, cell: domain.Cell) -> list[domain.Cell]:
+    def _target_ship(self, coordinate: domain.Coordinate) -> list[domain.Coordinate]:
         cells = []
 
-        for direction in list(domain.Direction):
-            candidate = self.board.get_adjacent_cell(cell, direction)  # type: ignore[arg-type]
-
-            if candidate is None or candidate.is_shot or candidate in self.next_targets:
+        for cell_ in self.board.get_adjacent_cells(coordinate, with_diagonals=False):
+            if (
+                cell_.is_shot
+                or cell_.coordinate in self.next_targets
+                or cell_.coordinate in self.excluded_cells
+            ):
                 continue
 
-            cells.append(candidate)
+            cells.append(cell_.coordinate)
+
+        return cells
+
+    def _find_cells_around_ship(self, ship: domain.Ship) -> list[domain.Coordinate]:
+        cells = []
+
+        for coordinate in ship.cells:
+            adjacent_cells = self.board.get_adjacent_cells(coordinate)
+            adjacent_coordinates = [
+                cell.coordinate
+                for cell in adjacent_cells
+                if not cell.is_shot and cell.coordinate not in ship.cells
+            ]
+
+            cells.extend(adjacent_coordinates)
 
         return cells
 
@@ -67,7 +99,11 @@ def __init__(self, board: domain.Board, ship_suite: rosters.Roster, no_adjacent_
     def place(self, ship_type: rosters.ShipType) -> list[domain.Coordinate]:
         ship_hp = self.ship_hp_map[ship_type]
         position: list[domain.Coordinate] = []
-        empty_cells = [cell for cell in self.board.cells if cell.ship is None]
+        empty_cells = [
+            cell.coordinate
+            for cell in self.board.cells
+            if not self.board.has_ship_at(cell.coordinate)
+        ]
         directions = list[domain.Direction](domain.Direction)
         random.shuffle(empty_cells)
         random.shuffle(directions)
@@ -79,16 +115,16 @@ def place(self, ship_type: rosters.ShipType) -> list[domain.Coordinate]:
                 # Try to found enough empty cells to place the ship in this direction.
                 for _ in range(ship_hp):
                     # Get the next cell in this direction.
-                    next_cell = self.board.get_adjacent_cell(start_cell, direction)
+                    next_cell = start_cell.next(direction)
 
                     # If there is no cell or the cell is taken,
                     # clear the progress and try another direction.
-                    if next_cell is None or next_cell.ship is not None:
+                    if not self.board.has_cell(next_cell) or self.board.has_ship_at(next_cell):
                         position.clear()
                         break
 
                     # Otherwise, save the coordinate.
-                    position.append(next_cell.coordinate)
+                    position.append(next_cell)
 
                     # If there is enough cells to place the ship, return the position.
                     if len(position) == ship_hp:

battleship/engine/domain.py

@@ -16,16 +16,26 @@
 ASCII_OFFSET = 64
 
 
+@enum.unique
 class Direction(StrEnum):
-    UP = "up"
-    DOWN = "down"
-    RIGHT = "right"
-    LEFT = "left"
+    UP = enum.auto()
+    DOWN = enum.auto()
+    RIGHT = enum.auto()
+    LEFT = enum.auto()
+
 
+@enum.unique
+class DiagonalDirection(StrEnum):
+    UP_RIGHT = enum.auto()
+    UP_LEFT = enum.auto()
+    DOWN_RIGHT = enum.auto()
+    DOWN_LEFT = enum.auto()
 
+
+@enum.unique
 class FiringOrder(StrEnum):
-    ALTERNATELY = "alternately"
-    UNTIL_MISS = "until_miss"
+    ALTERNATELY = enum.auto()
+    UNTIL_MISS = enum.auto()
 
 
 @dataclasses.dataclass
@@ -58,17 +68,16 @@ def __eq__(self, other: object) -> bool:
 
         raise NotImplementedError(f"Cannot compare Coordinate to {other.__class__.__name__}.")
 
-    def up(self) -> "Coordinate":
-        return Coordinate(self.x, self.y - 1)
+    def __hash__(self) -> int:
+        return hash((self.x, self.y))
 
-    def right(self) -> "Coordinate":
-        return Coordinate(self.x + 1, self.y)
-
-    def down(self) -> "Coordinate":
-        return Coordinate(self.x, self.y + 1)
+    def __repr__(self) -> str:
+        return f"Coordinate(x={self.x}, y={self.y}, human={self.to_human()})"
 
-    def left(self) -> "Coordinate":
-        return Coordinate(self.x - 1, self.y)
+    @classmethod
+    def from_human(cls, coordinate: str) -> "Coordinate":
+        col, row = parse_coordinate(coordinate)
+        return Coordinate(ord(col) - ASCII_OFFSET - 1, row - 1)
 
     @property
     def col(self) -> str:
@@ -78,14 +87,46 @@ def col(self) -> str:
     def row(self) -> int:
         return self.y + 1
 
-    @classmethod
-    def from_human(cls, coordinate: str) -> "Coordinate":
-        col, row = parse_coordinate(coordinate)
-        return Coordinate(ord(col) - ASCII_OFFSET - 1, row - 1)
-
     def to_human(self) -> str:
         return f"{self.col}{self.row}"
 
+    def up(self) -> "Coordinate":
+        return Coordinate(self.x, self.y - 1)
+
+    def right(self) -> "Coordinate":
+        return Coordinate(self.x + 1, self.y)
+
+    def down(self) -> "Coordinate":
+        return Coordinate(self.x, self.y + 1)
+
+    def left(self) -> "Coordinate":
+        return Coordinate(self.x - 1, self.y)
+
+    def next(self, direction: Direction | DiagonalDirection) -> "Coordinate":
+        match direction:
+            case Direction.UP:
+                return self.up()
+            case Direction.DOWN:
+                return self.down()
+            case Direction.RIGHT:
+                return self.right()
+            case Direction.LEFT:
+                return self.left()
+            case DiagonalDirection.UP_RIGHT:
+                up = self.up()
+                return up.right()
+            case DiagonalDirection.UP_LEFT:
+                up = self.up()
+                return up.left()
+            case DiagonalDirection.DOWN_RIGHT:
+                down = self.down()
+                return down.right()
+            case DiagonalDirection.DOWN_LEFT:
+                down = self.down()
+                return down.left()
+            case _:
+                raise ValueError(f"Invalid direction {direction}.")
+
 
 @dataclasses.dataclass
 class Cell:
@@ -164,50 +205,40 @@ def __repr__(self) -> str:
     def cells(self) -> list[Cell]:
         return [cell for row in self.grid for cell in row]
 
-    def get_adjacent_cell(self, cell: Cell, direction: Direction) -> Cell | None:
-        match direction:
-            case Direction.UP:
-                coordinate = cell.coordinate.up()
-            case Direction.DOWN:
-                coordinate = cell.coordinate.down()
-            case Direction.RIGHT:
-                coordinate = cell.coordinate.right()
-            case Direction.LEFT:
-                coordinate = cell.coordinate.left()
-            case _:
-                raise ValueError(f"Invalid direction {direction}.")
+    def has_cell(self, coordinate: Coordinate) -> bool:
+        return 0 <= coordinate.x < self.size and 0 <= coordinate.y < self.size
 
-        return self.get_cell(coordinate)
+    def has_ship_at(self, coordinate: Coordinate) -> bool:
+        return self.get_cell(coordinate).ship is not None
 
-    def get_cell(self, coordinate: Coordinate) -> Cell | None:
-        if not (0 <= coordinate.x < self.size and 0 <= coordinate.y < self.size):
-            return None
+    def get_adjacent_cells(self, coordinate: Coordinate, with_diagonals: bool = True) -> list[Cell]:
+        cells = []
 
-        return self.grid[coordinate.y][coordinate.x]
+        if with_diagonals:
+            directions = itertools.chain(Direction, DiagonalDirection)
+        else:
+            directions = itertools.chain(Direction)
 
-    def has_adjacent_ship(self, coordinate: Coordinate) -> bool:
-        cell = self.get_cell(coordinate)
+        for direction in directions:
+            try:
+                next_coordinate = coordinate.next(direction)  # type: ignore[arg-type]
+                adjacent_cell = self.get_cell(next_coordinate)
+            except errors.CellOutOfRange:
+                continue
+            else:
+                cells.append(adjacent_cell)
 
-        if not cell:
-            raise errors.CellOutOfRange(f"Cell at {coordinate=} does not exist.")
+        return cells
 
-        adjacent_coordinates = [
-            cell.coordinate.up(),
-            cell.coordinate.right(),
-            cell.coordinate.down(),
-            cell.coordinate.left(),
-        ]
-        diagonals = [
-            adjacent_coordinates[1].up(),
-            adjacent_coordinates[1].down(),
-            adjacent_coordinates[3].up(),
-            adjacent_coordinates[3].down(),
-        ]
-        adjacent_coordinates.extend(diagonals)
+    def get_cell(self, coordinate: Coordinate) -> Cell:
+        if not self.has_cell(coordinate):
+            raise errors.CellOutOfRange(f"Cell at {coordinate} doesn't exist.")
 
-        cells = [self.get_cell(coor) for coor in adjacent_coordinates]
+        return self.grid[coordinate.y][coordinate.x]
 
-        return any([cell is not None and cell.ship is not None for cell in cells])
+    def has_adjacent_ship(self, coordinate: Coordinate) -> bool:
+        adjacent_cells = self.get_adjacent_cells(coordinate)
+        return any([self.has_ship_at(cell.coordinate) for cell in adjacent_cells])
 
     def place_ship(
         self, coordinates: Collection[Coordinate], ship: Ship, no_adjacent_ships: bool = False
@@ -226,21 +257,13 @@ def place_ship(
 
         for coordinate in coordinates:
             cell = self.get_cell(coordinate)
-
-            if cell is None:
-                raise errors.CellOutOfRange(f"Cell at {coordinate} doesn't exist.")
-
             cell.set_ship(ship)
 
         self.ships.append(ship)
         ship.cells.extend(coordinates)
 
     def hit_cell(self, coordinate: Coordinate) -> Ship | None:
         cell = self.get_cell(coordinate)
-
-        if cell is None:
-            raise errors.CellOutOfRange(f"Cell at {coordinate} doesn't exist.")
-
         cell.hit()
         return cell.ship
 

battleship/tui/strategies.py

@@ -238,7 +238,9 @@ def __init__(self, game: domain.Game):
         self._enable_move_delay = not is_debug()
         self._human_player = game.player_a
         self._bot_player = game.player_b
-        self._target_caller = ai.TargetCaller(self._human_player.board)
+        self._target_caller = ai.TargetCaller(
+            self._human_player.board, self._game.no_adjacent_ships
+        )
         self._autoplacer = ai.Autoplacer(
             self._bot_player.board, self._game.roster, self._game.no_adjacent_ships
         )
@@ -319,14 +321,14 @@ def fire(self, position: Collection[str]) -> None:
     def cancel(self) -> None:
         pass
 
-    def _call_bot_target(self) -> Collection[str]:
+    def _call_bot_target(self) -> list[str]:
         if self._game.salvo_mode:
             count = self._bot_player.ships_alive
         else:
             count = 1
 
-        position = self._target_caller.call_out(count=count)
-        return position
+        targets = self._target_caller.call_out(count=count)
+        return targets
 
     def _spawn_bot_fleet(self) -> None:
         for item in self._game.roster: