"""Tests for 45-degree (diagonal) routing on the exact track.

The orthogonal exact router connects a 45-degree pin-to-pin net with a Manhattan
staircase (length ~ dx + dy). ``diagonal=True`` replaces it with a single
45-degree trace (length ~ hypot(dx, dy)) whose copper clearance is checked with
the exact integer octagon, not the coarse bounding box -- so it fits past an
obstacle that sits inside the diagonal's bounding box but clears the true thin
copper. ``diagonal_win.dsn`` places exactly such an obstacle, making the exact
clearance load-bearing rather than cosmetic.
"""

from __future__ import annotations

import math
from pathlib import Path

import pytest

from freeroute.board import build_board
from freeroute.dsn import parse_dsn
from freeroute.dsn.sexp import parse
from freeroute.geometry import IntBox, IntPoint, overlaps_2d, segment_octagon
from freeroute.route import route, route_dsn_board_exact

FIXTURES = Path(__file__).resolve().parent.parent / "dsn" / "fixtures"
DIAGONAL_WIN = FIXTURES / "diagonal_win.dsn"
SIMPLE = FIXTURES / "simple_2net.dsn"
CROSSING = FIXTURES / "crossing_2net.dsn"
KICAD = FIXTURES / "kicad_routable.dsn"


def _length(result):
    return sum(
        math.hypot(q.x - p.x, q.y - p.y)
        for _n, segs in result.result.wires.items()
        for _layer, pts in segs
        for p, q in zip(pts, pts[1:], strict=False)
    )


def _wire_key(result):
    return {
        n: [(layer, [(p.x, p.y) for p in pts]) for layer, pts in segs]
        for n, segs in result.result.wires.items()
    }


def _pins_by_net(fixture):
    board = build_board(parse_dsn(fixture.read_text()))
    out: dict[int, set[tuple[int, int]]] = {}
    for pin in board.get_pins():
        for net_no in pin.net_nos:
            out.setdefault(net_no, set()).add((pin.location.x, pin.location.y))
    return out


def _rule_clearance_board(fixture):
    from freeroute.route.pipeline import _rule_clearance_dsn

    dsn = parse_dsn(fixture.read_text())
    return round(_rule_clearance_dsn(dsn) * max(dsn.resolution.value, 1))


# --- the falsifiable length win ----------------------------------------------


def test_orthogonal_baseline_is_manhattan_length():
    """Orthogonal (diagonal off) connects the net with a Manhattan-length route --
    the staircase the exact grid produces for a 45-degree ratsnest."""
    dsn = parse_dsn(DIAGONAL_WIN.read_text())
    ortho, _, _ = route_dsn_board_exact(dsn)
    assert ortho.routed_net_numbers == {1}
    # pins are 80000 x 80000 DSN units apart -> Manhattan = 160000, scaled x10
    assert _length(ortho) == pytest.approx(1_600_000.0)


def test_diagonal_is_strictly_shorter_and_ideal():
    """Diagonal on connects the same net with a single 45-degree trace at the ideal
    hypotenuse length -- strictly shorter than the orthogonal staircase."""
    dsn = parse_dsn(DIAGONAL_WIN.read_text())
    ortho, _, _ = route_dsn_board_exact(dsn)
    diag, _, _ = route_dsn_board_exact(dsn, diagonal=True)
    assert diag.routed_net_numbers == {1}
    ideal = math.hypot(800_000, 800_000)  # board units
    assert _length(diag) == pytest.approx(ideal)
    assert _length(diag) < _length(ortho)
    # a real, sizeable win, not a rounding artifact
    assert _length(diag) / _length(ortho) < 0.72


def test_diagonal_route_is_a_single_45_degree_segment():
    dsn = parse_dsn(DIAGONAL_WIN.read_text())
    diag, _, _ = route_dsn_board_exact(dsn, diagonal=True)
    segs = diag.result.wires[1]
    assert len(segs) == 1
    _layer, pts = segs[0]
    assert len(pts) == 2
    (ax, ay), (bx, by) = (pts[0].x, pts[0].y), (pts[1].x, pts[1].y)
    assert abs(bx - ax) == abs(by - ay) != 0  # exactly 45 degrees


def test_diagonal_endpoints_stay_on_pads():
    dsn = parse_dsn(DIAGONAL_WIN.read_text())
    diag, _, _ = route_dsn_board_exact(dsn, diagonal=True)
    pins = _pins_by_net(DIAGONAL_WIN)
    for net_no, segments in diag.result.wires.items():
        pts = [(p.x, p.y) for _layer, run in segments for p in run]
        assert {pts[0], pts[-1]} == pins[net_no]


# --- DRC-clean, verified exactly and independently ---------------------------


def test_diagonal_is_drc_clean_via_tree():
    dsn = parse_dsn(DIAGONAL_WIN.read_text())
    clearance = _rule_clearance_board(DIAGONAL_WIN)
    diag, _, _ = route_dsn_board_exact(dsn, diagonal=True)
    assert diag.drc_clean
    assert diag.tree.has_violation(clearance) is None


def test_diagonal_is_drc_clean_independently_of_the_tree():
    """Reconstruct the 45-degree copper's clearance octagon from the emitted route
    and confirm it clears every different-net static copper (pads, the keepout) --
    a check that never consults the search tree the router verified against."""
    dsn = parse_dsn(DIAGONAL_WIN.read_text())
    board = build_board(dsn)
    clearance = _rule_clearance_board(DIAGONAL_WIN)
    half_width = 10_000  # trace_width 2000 * scale 10 / 2

    diag, _, _ = route_dsn_board_exact(dsn, diagonal=True)

    # different-net static copper: the keepout (net -1); pads share NET_A here
    obstacles = []
    for obstacle in board.get_obstacle_areas():
        for tile in obstacle.tiles:
            obstacles.append(tile.bounding_box())

    assert diag.result.wires  # sanity: the diagonal net was actually emitted
    conflicts = 0
    for _net_no, segments in diag.result.wires.items():
        for _layer, pts in segments:
            for p, q in zip(pts, pts[1:], strict=False):
                grown = segment_octagon(p, q, half_width + clearance)
                for box in obstacles:
                    if overlaps_2d(grown, box):
                        conflicts += 1
    assert conflicts == 0


def test_exact_clearance_is_load_bearing():
    """The keepout sits INSIDE the diagonal's bounding box (so the coarse bbox
    clearance the plain router uses would reject the diagonal) yet clears the exact
    octagon -- proving the octagon, not the box, is what lets the trace route."""
    a, b = IntPoint(200_000, -200_000), IntPoint(1_000_000, -1_000_000)
    half_width, clearance = 10_000, 20_000
    bbox = IntBox(a.x - half_width, b.y - half_width, b.x + half_width, a.y + half_width)
    keepout = IntBox(220_000, -980_000, 400_000, -800_000)
    assert not keepout.intersection(bbox).is_empty()  # inside the coarse cover
    assert not overlaps_2d(segment_octagon(a, b, half_width + clearance), keepout)  # clear exactly


def test_diagonal_is_deterministic():
    dsn = parse_dsn(DIAGONAL_WIN.read_text())
    a, _, _ = route_dsn_board_exact(dsn, diagonal=True)
    b, _, _ = route_dsn_board_exact(dsn, diagonal=True)
    assert _wire_key(a) == _wire_key(b)
    assert a.routed_net_numbers == b.routed_net_numbers


def test_diagonal_valid_ses():
    ses = route(DIAGONAL_WIN.read_text(), engine="exact", diagonal=True)
    top = parse(ses)
    assert top.head == "session"
    nets = top.child("routes").child("network_out").children("net")
    assert {n.values()[0].text for n in nets} == {"NET_A"}


# --- additive: diagonal off changes nothing on the orthogonal track ----------


@pytest.mark.parametrize("fixture", [DIAGONAL_WIN, SIMPLE, CROSSING, KICAD])
def test_diagonal_off_matches_orthogonal(fixture):
    dsn = parse_dsn(fixture.read_text())
    base, _, _ = route_dsn_board_exact(dsn)
    off, _, _ = route_dsn_board_exact(dsn, diagonal=False)
    assert _wire_key(base) == _wire_key(off)


@pytest.mark.parametrize("fixture", [SIMPLE, CROSSING, KICAD])
def test_diagonal_on_keeps_existing_fixtures_clean_and_connected(fixture):
    """Turning diagonal on never dirties the DRC or drops a net that orthogonal
    routed -- it only ever shortens."""
    dsn = parse_dsn(fixture.read_text())
    clearance = _rule_clearance_board(fixture)
    base, _, _ = route_dsn_board_exact(dsn)
    on, _, _ = route_dsn_board_exact(dsn, diagonal=True)
    assert on.drc_clean
    assert on.tree.has_violation(clearance) is None
    assert on.routed_net_numbers >= base.routed_net_numbers
    assert _length(on) <= _length(base) + 1e-6