import math

import pytest

from engine.aim import apply_cone_deviation, snap_to_8way
from engine.camera import OrthoCamera


class FixedUniformRng:
    def __init__(self, value: float):
        self._value = value

    def uniform(self, _a, _b):
        return self._value


@pytest.mark.parametrize(
    "dx,dy,expected",
    [
        (5, 0, (1, 0)),
        (0, 5, (0, 1)),
        (-5, 0, (-1, 0)),
        (0, -5, (0, -1)),
        (5, 5, (1, 1)),
        (-5, 5, (-1, 1)),
        (-5, -5, (-1, -1)),
        (5, -5, (1, -1)),
        (0, 0, (0, 1)),
        (5, 0.1, (1, 0)),  # nearly east, snaps to east not northeast
    ],
)
def test_snap_to_8way(dx, dy, expected):
    assert snap_to_8way(dx, dy) == expected


def test_snap_to_8way_covers_full_circle():
    for degrees in range(0, 360, 5):
        radians = math.radians(degrees)
        dx, dy = math.cos(radians), math.sin(radians)
        dirx, diry = snap_to_8way(dx, dy)
        assert (dirx, diry) != (0, 0)
        assert abs(dirx) <= 1 and abs(diry) <= 1


def test_apply_cone_deviation_with_zero_cone_is_a_no_op():
    assert apply_cone_deviation(1, 0, 0.0, FixedUniformRng(50.0)) == (1, 0)


def test_apply_cone_deviation_with_zero_deviation_keeps_direction():
    assert apply_cone_deviation(1, 0, 30.0, FixedUniformRng(0.0)) == (1, 0)


def test_apply_cone_deviation_can_shift_to_an_adjacent_direction():
    # east (1,0) deviated by +40 degrees should snap to northeast (1,1) -> y-down world,
    # so a positive angle rotates toward (0,1)/south side
    result = apply_cone_deviation(1, 0, 90.0, FixedUniformRng(40.0))
    assert result != (1, 0)
    assert abs(result[0]) <= 1 and abs(result[1]) <= 1


def test_apply_cone_deviation_stays_within_grid_directions():
    rng = FixedUniformRng(179.0)
    for base_dx, base_dy in [(1, 0), (0, 1), (-1, 0), (0, -1)]:
        dirx, diry = apply_cone_deviation(base_dx, base_dy, 20.0, rng)
        assert (dirx, diry) != (0, 0)


def test_screen_to_world_center_of_viewport_is_camera_target():
    camera = OrthoCamera(viewport_w=800, viewport_h=600, tiles_visible_y=12.0)
    camera.set_target(5.0, 5.0)
    wx, wy = camera.screen_to_world(400, 300)
    assert wx == pytest.approx(5.0, abs=0.05)
    assert wy == pytest.approx(5.0, abs=0.05)


def test_screen_to_world_top_left_is_up_and_left_of_target():
    camera = OrthoCamera(viewport_w=800, viewport_h=600, tiles_visible_y=12.0)
    camera.set_target(5.0, 5.0)
    wx, wy = camera.screen_to_world(0, 0)
    assert wx < 5.0
    assert wy < 5.0


def test_screen_to_world_round_trips_with_scale_offset():
    camera = OrthoCamera(viewport_w=800, viewport_h=600, tiles_visible_y=12.0)
    camera.set_target(3.0, 7.0)
    (scale_x, scale_y), (offset_x, offset_y) = camera.scale_offset()

    wx, wy = camera.screen_to_world(200, 450)
    ndc_x = wx * scale_x + offset_x
    ndc_y = wy * scale_y + offset_y

    # (200,450) in an 800x600 viewport -> ndc (-0.5, -0.5) in the y-up NDC space
    assert ndc_x == pytest.approx(-0.5, abs=1e-6)
    assert ndc_y == pytest.approx(-0.5, abs=1e-6)