from pathlib import Path

import pytest

from engine.defs import DefRegistry
from engine.entity import Entity, EntityPosition
from engine.map import Map
from engine.tile import Tile, TileLayerInstance
from engine.world import World

DEFS_DIR = Path(__file__).resolve().parent.parent / "resources" / "defs"


@pytest.fixture()
def registry():
    return DefRegistry.load(DEFS_DIR)


def make_cliff_world(registry):
    """A 2x1 map: x=0 is a 3-level-tall column (floored at z=0,1,2), x=1 has floor only at
    z=0 - everything above that at x=1 is bare/unset (no flooring), simulating the "open air
    above a lower column" gap engine/worldgen/terrain.py leaves when no slope/cave connects a
    steep drop.
    """
    m = Map("cliff", 2, 1, 3)
    m.set_tile(0, 0, 0, Tile(flooring=TileLayerInstance("stone")))
    m.set_tile(0, 0, 1, Tile(flooring=TileLayerInstance("stone")))
    m.set_tile(0, 0, 2, Tile(flooring=TileLayerInstance("stone")))
    m.set_tile(1, 0, 0, Tile(flooring=TileLayerInstance("dirt")))
    # (1, 0, 1) and (1, 0, 2) left as bare Tile() - no flooring
    world = World(registry=registry)
    world.add_map(m)
    return world


def test_stepping_off_a_cliff_falls_straight_to_the_floor_below(registry):
    world = make_cliff_world(registry)
    walker = Entity(position=EntityPosition("cliff", 0, 0, 2))
    assert world.try_move(walker, 1, 0, 0) is True
    assert (walker.position.x, walker.position.y, walker.position.z) == (1, 0, 0)


def test_falling_skips_multiple_floorless_levels_to_the_first_real_floor(registry):
    world = make_cliff_world(registry)
    walker = Entity(position=EntityPosition("cliff", 0, 0, 1))
    assert world.try_move(walker, 1, 0, 0) is True
    assert walker.position.z == 0


def test_moving_between_two_floored_tiles_does_not_trigger_gravity(registry):
    m = Map("level", 2, 1, 1)
    m.set_tile(0, 0, 0, Tile(flooring=TileLayerInstance("dirt")))
    m.set_tile(1, 0, 0, Tile(flooring=TileLayerInstance("dirt")))
    world = World(registry=registry)
    world.add_map(m)
    walker = Entity(position=EntityPosition("level", 0, 0, 0))
    assert world.try_move(walker, 1, 0, 0) is True
    assert walker.position.z == 0


def test_gravity_also_applies_after_continuous_movement(registry):
    world = make_cliff_world(registry)
    walker = Entity(position=EntityPosition("cliff", 0.5, 0, 2))
    assert world.try_move_continuous(walker, 1, 0, 0, distance=1.0) is True
    assert walker.position.z == 0


def test_gravity_does_not_fire_on_a_single_level_map(registry):
    m = Map("flat", 2, 1, 1)
    m.set_tile(0, 0, 0, Tile(flooring=TileLayerInstance("dirt")))
    m.set_tile(1, 0, 0, Tile())  # bare, but nothing below z=0 to fall to
    world = World(registry=registry)
    world.add_map(m)
    walker = Entity(position=EntityPosition("flat", 0, 0, 0))
    assert world.try_move(walker, 1, 0, 0) is True
    assert (walker.position.x, walker.position.z) == (1, 0)  # stays put, no lower floor exists


def test_consume_fall_distance_reports_how_far_and_then_resets(registry):
    world = make_cliff_world(registry)
    walker = Entity(position=EntityPosition("cliff", 0, 0, 2))
    assert world.consume_fall_distance(walker.entity_id) == 0  # nothing yet
    world.try_move(walker, 1, 0, 0)
    assert world.consume_fall_distance(walker.entity_id) == 2  # dropped from z=2 to z=0
    assert world.consume_fall_distance(walker.entity_id) == 0  # one-shot, already consumed


def test_consume_fall_distance_is_zero_when_no_fall_happens(registry):
    m = Map("level", 2, 1, 1)
    m.set_tile(0, 0, 0, Tile(flooring=TileLayerInstance("dirt")))
    m.set_tile(1, 0, 0, Tile(flooring=TileLayerInstance("dirt")))
    world = World(registry=registry)
    world.add_map(m)
    walker = Entity(position=EntityPosition("level", 0, 0, 0))
    world.try_move(walker, 1, 0, 0)
    assert world.consume_fall_distance(walker.entity_id) == 0