"""Tests for the square grid: distance, step costs, corner rule, Dijkstra."""

from __future__ import annotations

from pf1e_simulator.grid import Grid
from pf1e_simulator.map import MapSpec, TerrainType


def make_grid(rows: list[str]) -> Grid:
    legend = {
        "#": TerrainType(type="wall", move_cost=None, blocks_los=True),
        ".": TerrainType(type="floor", move_cost=1),
        "T": TerrainType(type="rubble", move_cost=2),
        "C": TerrainType(type="pillar", move_cost=None, cover=True),
    }
    spec = MapSpec(name="test", terrain=tuple(rows), legend=legend)
    return Grid.from_spec(spec)


def test_distance_diagonal_table() -> None:
    grid = make_grid([".....", ".....", ".....", ".....", "....."])
    assert grid.distance((0, 0), (1, 1)) == 1
    assert grid.distance((0, 0), (2, 2)) == 3
    assert grid.distance((0, 0), (3, 2)) == 4
    assert grid.distance((0, 0), (0, 3)) == 3
    assert grid.distance((2, 1), (0, 0)) == 2


def test_step_cost_orthogonal_uses_entered_square() -> None:
    grid = make_grid([".T."])
    assert grid.step_cost((0, 0), (0, 1), 0) == 2
    assert grid.step_cost((0, 1), (0, 2), 0) == 1


def test_step_cost_diagonal_alternates() -> None:
    grid = make_grid(["...", "...", "..."])
    assert grid.step_cost((0, 0), (1, 1), 0) == 1
    assert grid.step_cost((1, 1), (2, 2), 1) == 2
    assert grid.step_cost((1, 1), (2, 2), 2) == 1


def test_step_cost_diagonal_into_difficult_is_flat_three() -> None:
    grid = make_grid(["..", ".T"])
    assert grid.step_cost((0, 0), (1, 1), 0) == 3
    assert grid.step_cost((0, 0), (1, 1), 1) == 3


def test_diagonal_forbidden_past_wall_corner() -> None:
    grid = make_grid([
        ".#.",
        ".#.",
        "...",
    ])
    assert grid.diagonal_allowed((2, 1), (1, 0)) is False
    assert grid.diagonal_allowed((2, 1), (1, 2)) is False


def test_diagonal_allowed_with_both_flanks_clear() -> None:
    grid = make_grid([
        ".#.",
        "...",
        "...",
    ])
    assert grid.diagonal_allowed((2, 1), (1, 0)) is True


def test_reachable_open_floor_costs() -> None:
    grid = make_grid([".....", ".....", ".....", ".....", "....."])
    reached = grid.reachable((0, 0), 10, frozenset())
    assert reached[(0, 0)] == 0
    assert reached[(1, 1)] == 1
    assert reached[(2, 2)] == 3
    assert reached[(3, 3)] == 4
    assert reached[(4, 4)] == 6
    assert reached[(0, 4)] == 4


def test_reachable_respects_budget() -> None:
    grid = make_grid([".....", ".....", ".....", ".....", "....."])
    reached = grid.reachable((0, 0), 2, frozenset())
    assert (1, 1) in reached
    assert (2, 2) not in reached


def test_reachable_diagonal_into_rubble_costs_three() -> None:
    grid = make_grid(["...", ".T.", "..."])
    reached = grid.reachable((0, 0), 6, frozenset())
    assert reached[(1, 1)] == 3


def test_reachable_through_rubble_cheaper_than_around() -> None:
    grid = make_grid(["...", ".T.", "..."])
    reached = grid.reachable((1, 0), 6, frozenset())
    assert reached[(1, 2)] == 3


def test_reachable_creatures_block_entry_not_diagonals() -> None:
    grid = make_grid(["...", "...", "..."])
    reached = grid.reachable((1, 1), 1, frozenset({(1, 0)}))
    assert (1, 0) not in reached
    assert reached[(0, 2)] == 1


def test_reachable_paths_around_creatures() -> None:
    grid = make_grid(["...", ".#.", "..."])
    reached = grid.reachable((1, 0), 6, frozenset())
    assert (1, 1) not in reached
    assert reached[(1, 2)] == 4


def test_reachable_cannot_enter_wall_squares() -> None:
    grid = make_grid(["..", ".C"])
    reached = grid.reachable((0, 0), 9, frozenset())
    assert (1, 1) not in reached


def test_reachable_unbounded_budget_covers_whole_map() -> None:
    grid = make_grid([".#.", "..."])
    reached = grid.reachable((0, 0), None, frozenset())
    assert reached == {(0, 0): 0, (1, 0): 1, (1, 1): 2, (1, 2): 3, (0, 2): 4}