"""Tests for lines, emphasizing exact intersection.

Oracles hand-derived from ``geometry/planar/Line.java``.
"""

from __future__ import annotations

from freeroute.geometry import IntPoint, Line, RationalPoint, Side


def test_side_of_point():
    # Line.side_of reports where the *line* is relative to the point
    # (point.side_of(line).negate() in the source): a point above a +x line has
    # the line on its right.
    line = Line.from_coords(0, 0, 2, 0)  # along +x
    assert line.side_of(IntPoint(1, 1)) == Side.ON_THE_RIGHT
    assert line.side_of(IntPoint(1, -1)) == Side.ON_THE_LEFT
    assert line.side_of(IntPoint(5, 0)) == Side.COLLINEAR


def test_integral_intersection_fast_paths():
    # vertical x horizontal
    v = Line.from_coords(3, 0, 3, 9)
    h = Line.from_coords(0, 4, 9, 4)
    assert v.intersection(h) == IntPoint(3, 4)
    # horizontal x right-diagonal (y=x): y=4 -> (4,4)
    diag = Line.from_coords(0, 0, 5, 5)
    assert h.intersection(diag) == IntPoint(4, 4)


def test_general_integral_intersection():
    # y = x/2 and y = 1 -> x = 2
    a = Line.from_coords(0, 0, 2, 1)
    b = Line.from_coords(0, 1, 4, 1)
    assert a.intersection(b) == IntPoint(2, 1)


def test_rational_intersection_exact():
    # y = 2x/3 and y = 1 -> x = 1.5 -> RationalPoint (3,2,2)
    a = Line.from_coords(0, 0, 3, 2)
    b = Line.from_coords(0, 1, 5, 1)
    result = a.intersection(b)
    assert isinstance(result, RationalPoint)
    assert result == RationalPoint(3, 2, 2)
    assert not result.is_infinite()
    # float approximation agrees
    fp = result.to_float()
    assert abs(fp.x - 1.5) < 1e-9 and abs(fp.y - 1.0) < 1e-9


def test_parallel_intersection_is_infinite():
    a = Line.from_coords(0, 0, 1, 0)
    b = Line.from_coords(0, 5, 1, 5)
    result = a.intersection(b)
    assert result.is_infinite()
    assert a.is_parallel(b)


def test_intersection_exact_beyond_double_precision():
    # Two nearly-parallel steep lines crossing at a non-integer point far out.
    # Coordinates chosen so a double determinant would lose bits; int stays exact.
    a = Line.from_coords(0, 0, 1000000, 999999)
    b = Line.from_coords(0, 1, 1000000, 1000000)
    result = a.intersection(b)
    assert isinstance(result, RationalPoint)
    # Verify exactness: the intersection lies on both lines (exact side test).
    assert a.side_of(result) == Side.COLLINEAR
    assert b.side_of(result) == Side.COLLINEAR


def test_intersection_approx_matches_exact():
    a = Line.from_coords(0, 0, 3, 2)
    b = Line.from_coords(0, 1, 5, 1)
    approx = a.intersection_approx(b)
    assert abs(approx.x - 1.5) < 1e-9
    assert abs(approx.y - 1.0) < 1e-9


def test_translate_and_opposite():
    line = Line.from_coords(0, 0, 4, 0)
    assert line.opposite().direction().equals(line.direction()) is False
    from freeroute.geometry import IntVector

    moved = line.translate_by(IntVector(0, 5))
    assert moved.side_of(IntPoint(2, 5)) == Side.COLLINEAR


def test_perpendicular_and_parallel_predicates():
    horizontal = Line.from_coords(0, 0, 1, 0)
    vertical = Line.from_coords(0, 0, 0, 1)
    assert horizontal.is_perpendicular(vertical)
    assert not horizontal.is_parallel(vertical)
    assert horizontal.is_parallel(Line.from_coords(3, 7, 10, 7))


def test_line_equality_same_set_same_direction():
    a = Line.from_coords(0, 0, 2, 0)
    b = Line.from_coords(-5, 0, 9, 0)  # same line, same direction
    c = Line.from_coords(9, 0, -5, 0)  # same set, opposite direction
    assert a == b
    assert a != c
    assert a.is_equal_or_opposite(c)