"""Tests for corner-rule line of effect and cover (los.py).

Geometry convention: a line is blocked when its relative interior touches a
blocking square (interior, border, or vertex); lines that merely start or end
on a blocking square's vertex do not count as passing through it.
"""

from __future__ import annotations

from pf1e_simulator.grid import Grid
from pf1e_simulator.los import (
    cover_bonus,
    has_cover,
    has_cover_cells,
    has_line_of_effect,
)
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_los_open_field() -> None:
    grid = make_grid(["...", "...", "..."])
    assert has_line_of_effect(grid, (0, 0), (2, 2)) is True


def test_los_same_square() -> None:
    grid = make_grid(["."])
    assert has_line_of_effect(grid, (0, 0), (0, 0)) is True


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


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


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


def test_los_blocked_past_wall_line() -> None:
    grid = make_grid(["...#.", "....."])
    assert has_line_of_effect(grid, (0, 0), (0, 4)) is False


def test_cover_open_field() -> None:
    grid = make_grid([".....", "....."])
    assert has_cover(grid, (0, 0), (0, 4), ranged=True) is False


def test_cover_pillar_between() -> None:
    grid = make_grid([".....", "..C..", "....."])
    assert has_cover(grid, (1, 0), (1, 4), ranged=True) is True


def test_no_cover_when_pillar_off_axis() -> None:
    grid = make_grid(["..C..", "....."])
    assert has_cover(grid, (1, 0), (1, 4), ranged=True) is False


def test_no_cover_adjacent_with_wall_behind_target() -> None:
    grid = make_grid(["..#"])
    assert has_cover(grid, (0, 0), (0, 1), ranged=True) is False


def test_cover_diagonal_past_wall_vertex() -> None:
    grid = make_grid([".#.", "#.."])
    assert has_cover(grid, (0, 0), (1, 1), ranged=True) is True


def test_cover_melee_adjacent_wall_vertex_grant_cover() -> None:
    grid = make_grid([".#.", "#.."])
    assert has_cover(grid, (0, 0), (1, 1), ranged=False) is True
    open_grid = make_grid(["...", "..."])
    assert has_cover(open_grid, (0, 0), (1, 1), ranged=False) is False


def test_cover_same_square_is_false() -> None:
    grid = make_grid(["."])
    assert has_cover(grid, (0, 0), (0, 0), ranged=True) is False


# ---------------------------------------------------------------------------
# Adjacent melee uses the SRD any-line rule (cover.md), not the ranged
# best-corner rule: "When making a melee attack against an adjacent target,
# your target has cover if any line from any corner of your square to the
# target's square goes through a wall."
# ---------------------------------------------------------------------------


def test_adjacent_melee_any_blocked_line_grants_cover() -> None:
    """Wall (0,1) blocks ONE corner line (0,1)->(2,1) of adjacent (1,0)->(1,1).

    The ranged best-corner rule finds attacker corner (1,2) with all four
    lines clear (no cover); the melee-adjacent any-line rule grants cover
    from the single grazing line. This is the divergence the fix closes.
    """
    grid = make_grid([".#", ".."])
    assert has_cover(grid, (1, 0), (1, 1), ranged=True) is False
    assert has_cover(grid, (1, 0), (1, 1), ranged=False) is True


def test_adjacent_melee_cover_bonus_grants_four() -> None:
    grid = make_grid([".#", ".."])
    assert cover_bonus(grid, (1, 0), (1, 1), ranged=False) == 4
    assert cover_bonus(grid, (1, 0), (1, 1), ranged=True) == 0


def test_adjacent_melee_worst_line_sets_level() -> None:
    """Pillar (1,1) grazes ONE line (1,2)->(2,2) of adjacent (2,0)->(2,1):
    the any-line rule takes the MAX over the sixteen corner lines, so the
    target keeps the +4 even though the attacker's best corner (0,3) sees
    every line clear (ranged level 0)."""
    grid = make_grid(["..", ".C", ".."])
    assert cover_bonus(grid, (2, 0), (2, 1), ranged=False) == 4
    assert cover_bonus(grid, (2, 0), (2, 1), ranged=True) == 0


def test_adjacent_melee_open_field_no_cover() -> None:
    grid = make_grid(["..", ".."])
    assert has_cover(grid, (0, 0), (0, 1), ranged=False) is False
    assert cover_bonus(grid, (0, 0), (0, 1), ranged=False) == 0


def test_nonadjacent_melee_keeps_ranged_best_corner_rule() -> None:
    """Reach attack at distance 2 (wall (0,1) off-axis): cover.md sends it
    to the ranged rule. Line (0,1)->(2,1) grazes the wall's border (the
    adjacent-melee rule would grant cover) but the attacker's top corner
    (0,2) sees every target corner clear -> no cover, exactly as ranged."""
    grid = make_grid([".#", ".."])
    assert has_cover(grid, (1, 0), (1, 2), ranged=True) is False
    assert has_cover(grid, (1, 0), (1, 2), ranged=False) is False


def test_adjacent_melee_multi_cell_attacker_picks_clear_pair() -> None:
    """2x1 attacker {(1,0),(1,1)} vs target (0,1): both squares touch it.
    Wall (0,2) blocks a line of the (1,1) pair (vertical x=2 along the
    wall's border) but the (1,0) pair sees every line clear - the attacker
    attacks through its clear square -> no cover (CRB "Big Creatures and
    Cover": the big creature picks its own square). Without the wall the
    same pair scan gives no cover either."""
    grid = make_grid(["..#", "..."])
    attacker = frozenset({(1, 0), (1, 1)})
    target = frozenset({(0, 1)})
    assert has_cover_cells(grid, attacker, target, ranged=False) is False
    assert has_cover_cells(grid, attacker, target, ranged=True) is False
    open_grid = make_grid(["...", "..."])
    assert has_cover_cells(open_grid, attacker, target, ranged=False) is False


def test_soft_cover_creature_between_grants_cover() -> None:
    """A creature between shooter and target grants cover on ranged attacks."""
    grid = make_grid([".....", ".....", "....."])
    occupied = frozenset({(1, 2)})
    assert has_cover(grid, (1, 0), (1, 4), ranged=True, occupied=occupied) is True


def test_soft_cover_melee_ignores_creatures() -> None:
    """Melee attacks ignore creatures for soft cover (CRB: ranged only)."""
    grid = make_grid([".....", ".....", "....."])
    occupied = frozenset({(1, 2)})
    assert has_cover(grid, (1, 0), (1, 4), ranged=False, occupied=occupied) is False


def test_soft_cover_creature_behind_target_ignored() -> None:
    """A creature behind the target does not grant cover."""
    grid = make_grid(["......", "......"])
    occupied = frozenset({(1, 5)})
    assert has_cover(grid, (1, 0), (1, 4), ranged=True, occupied=occupied) is False


def test_soft_cover_creature_off_axis_ignored() -> None:
    """A creature off the attack line does not grant cover."""
    grid = make_grid([".....", "....."])
    occupied = frozenset({(0, 2)})
    assert has_cover(grid, (1, 0), (1, 4), ranged=True, occupied=occupied) is False