from __future__ import annotations

from engine.character import Character
from engine.map import MapEmbedding, rotated_size
from engine.world import World


def at_helm(character: Character, world: World) -> MapEmbedding | None:
    """Returns the embedding a character can steer, if they're standing on a helm tile of an
    embedded map (e.g. a ship's wheel) - None otherwise.
    """
    if character.position is None:
        return None
    map_ = world.maps[character.position.map_id]
    embedding = map_.parent_embedding
    if embedding is None:
        return None
    tile = map_.get_tile(character.position.x, character.position.y, character.position.z)
    room_def = world.registry.get_tile_layer_def("room", tile.layer_id("room"))
    if room_def is None or not room_def.is_helm:
        return None
    return embedding


def _footprint_is_clear(world: World, embedding: MapEmbedding, anchor: tuple[int, int, int], rotation: int) -> bool:
    parent = embedding.parent_map
    width, height = rotated_size(embedding.child_map.width, embedding.child_map.height, rotation)
    for ly in range(height):
        for lx in range(width):
            px, py, pz = anchor[0] + lx, anchor[1] + ly, anchor[2]
            if not parent.in_bounds(px, py, pz):
                return False
            if not parent.get_tile(px, py, pz).is_walkable(world.registry):
                return False
    return True


def try_steer_ship(character: Character, world: World, dx: int, dy: int, dz: int = 0) -> bool:
    """Moves the embedded map the character is helming by one step, if the destination footprint
    is clear in the parent map. Entities aboard need no updates - only the anchor changes.
    """
    embedding = at_helm(character, world)
    if embedding is None:
        return False
    new_anchor = (embedding.anchor[0] + dx, embedding.anchor[1] + dy, embedding.anchor[2] + dz)
    if not _footprint_is_clear(world, embedding, new_anchor, embedding.rotation):
        return False
    embedding.move_to(new_anchor)
    return True


def try_turn_ship(character: Character, world: World, quarter_turns: int) -> bool:
    """Turns the embedded map the character is helming, if the rotated footprint is clear."""
    embedding = at_helm(character, world)
    if embedding is None:
        return False
    new_rotation = (embedding.rotation + quarter_turns) % 4
    if not _footprint_is_clear(world, embedding, embedding.anchor, new_rotation):
        return False
    embedding.rotate_to(new_rotation)
    return True