"""Tests for the multi-layer grid maze router and the DSN -> SES pipeline.

Fast tests assert the routing invariants (traces connect their pads, stay on
valid layers, stay in bounds, vias sit at real layer transitions, no same-layer
crossing between nets). Oracle-gated tests check connectivity parity against the
reference FreeRouting JAR.

Fixtures: ``simple_2net.dsn`` (single-layer routable) and ``crossing_2net.dsn``
(a full-width NET_A wall that NET_B must cross, forcing a via).
"""

from __future__ import annotations

from pathlib import Path
import sys

import pytest

from freeroute.board import build_board
from freeroute.dsn import parse_dsn
from freeroute.dsn.sexp import parse
from freeroute.route import route, route_dsn_board

sys.path.insert(0, str(Path(__file__).resolve().parent.parent))

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


def _network_out(ses_text: str):
    root = parse(ses_text)
    network = root.child("routes").child("network_out")
    return network.children("net")


def _net_scopes(ses_text: str):
    result = {}
    for net in _network_out(ses_text):
        name = net.values()[0].text
        result[name] = {"wires": net.children("wire"), "vias": net.children("via")}
    return result


def _wire_layer_and_coords(wire):
    path = wire.child("path")
    vals = [v.text for v in path.values()]
    nums = [float(v) for v in vals[2:]]
    coords = list(zip(nums[0::2], nums[1::2], strict=False))
    return vals[0], coords


def _orient(a, b, c):
    return (b[0] - a[0]) * (c[1] - a[1]) - (b[1] - a[1]) * (c[0] - a[0])


def _segments_properly_cross(p1, p2, p3, p4) -> bool:
    d1 = _orient(p3, p4, p1)
    d2 = _orient(p3, p4, p2)
    d3 = _orient(p1, p2, p3)
    d4 = _orient(p1, p2, p4)
    return ((d1 > 0) != (d2 > 0)) and ((d3 > 0) != (d4 > 0))


# --- single-layer / no-crossing case ----------------------------------------


def test_simple_board_routes_both_nets_without_vias():
    result, _, _ = route_dsn_board(parse_dsn(SIMPLE.read_text()))
    assert result.routed_net_numbers == {1, 2}
    assert result.via_count() == 0  # no crossing -> no layer change needed


def test_pipeline_emits_valid_ses_with_both_nets():
    ses = route(SIMPLE.read_text())
    assert parse(ses).head == "session"
    nets = _net_scopes(ses)
    assert set(nets) == {"NET_A", "NET_B"}
    assert all(n["wires"] for n in nets.values())


def test_simple_trace_endpoints_sit_on_the_net_pads():
    pads = {
        "NET_A": {(20000.0, -20000.0), (180000.0, -20000.0)},
        "NET_B": {(20000.0, -60000.0), (180000.0, -60000.0)},
    }
    for net_name, scope in _net_scopes(route(SIMPLE.read_text())).items():
        endpoints = set()
        for wire in scope["wires"]:
            _, coords = _wire_layer_and_coords(wire)
            endpoints.add(coords[0])
            endpoints.add(coords[-1])
        assert endpoints == pads[net_name]


# --- multi-layer crossing case ----------------------------------------------


def test_single_layer_cannot_route_the_crossing_board():
    result, _, _ = route_dsn_board(parse_dsn(CROSSING.read_text()), layers=[0])
    # NET_A is a full-width wall; on one layer NET_B cannot cross it
    assert len(result.routed_net_numbers) < 2
    assert result.via_count() == 0


def test_multilayer_routes_the_crossing_board_with_a_via():
    result, _, _ = route_dsn_board(parse_dsn(CROSSING.read_text()))
    assert result.routed_net_numbers == {1, 2}  # both nets connect
    assert result.via_count() >= 1  # the crossing net changes layers


def test_crossing_ses_contains_a_via():
    ses = route(CROSSING.read_text())
    nets = _net_scopes(ses)
    assert set(nets) == {"NET_A", "NET_B"}
    total_vias = sum(len(n["vias"]) for n in nets.values())
    assert total_vias >= 1


def test_vias_sit_at_real_layer_transitions():
    # every via location must be shared by two wire segments of the same net on
    # different layers (i.e. a genuine layer transition of that net's path).
    result, _, _ = route_dsn_board(parse_dsn(CROSSING.read_text()))
    for net_no, locations in result.vias.items():
        segments = result.wires.get(net_no, [])
        for via in locations:
            point = (via.x, via.y)
            layers_touching = {
                layer for layer, pts in segments if any((p.x, p.y) == point for p in pts)
            }
            assert len(layers_touching) >= 2, "via not at a layer transition"


def test_via_endpoints_come_from_the_net_pads_across_layers():
    # the crossing net's overall path still starts and ends on its two pads
    result, _, _ = route_dsn_board(parse_dsn(CROSSING.read_text()))
    board = build_board(parse_dsn(CROSSING.read_text()))
    pins_by_net: dict[int, set[tuple[int, int]]] = {}
    for pin in board.get_pins():
        for net_no in pin.net_nos:
            pins_by_net.setdefault(net_no, set()).add((pin.location.x, pin.location.y))
    for net_no, segments in result.wires.items():
        all_points = [(p.x, p.y) for _, pts in segments for p in pts]
        endpoints = {all_points[0], all_points[-1]}
        assert endpoints == pins_by_net[net_no]


# --- cross-net invariants ---------------------------------------------------


def test_no_two_nets_cross_on_the_same_layer():
    result, _, _ = route_dsn_board(parse_dsn(CROSSING.read_text()))
    per_layer: dict[int, list[tuple[int, list]]] = {}
    for net_no, segments in result.wires.items():
        for layer, pts in segments:
            coords = [(p.x, p.y) for p in pts]
            per_layer.setdefault(layer, []).append((net_no, coords))
    for entries in per_layer.values():
        for i in range(len(entries)):
            net_i, poly_i = entries[i]
            for j in range(i + 1, len(entries)):
                net_j, poly_j = entries[j]
                if net_i == net_j:
                    continue
                for a in range(len(poly_i) - 1):
                    for b in range(len(poly_j) - 1):
                        assert not _segments_properly_cross(
                            poly_i[a], poly_i[a + 1], poly_j[b], poly_j[b + 1]
                        ), "different nets cross on the same layer"


def test_traces_stay_within_the_board_outline():
    for path in (SIMPLE, CROSSING):
        ses = route(path.read_text())
        for scope in _net_scopes(ses).values():
            for wire in scope["wires"]:
                _, coords = _wire_layer_and_coords(wire)
                for x, y in coords:
                    assert 0 <= x <= 200000
                    assert -80000 <= y <= 0


def test_traces_stay_on_valid_layers():
    ses = route(CROSSING.read_text())
    for scope in _net_scopes(ses).values():
        for wire in scope["wires"]:
            layer, _ = _wire_layer_and_coords(wire)
            assert layer in {"Top", "Bottom"}


def test_router_does_not_crash_on_larger_board():
    result, _, _ = route_dsn_board(parse_dsn((FIXTURES / "kicad_routable.dsn").read_text()))
    assert isinstance(result.routed_net_numbers, set)


# --- oracle parity ----------------------------------------------------------


@pytest.mark.oracle
def test_connectivity_parity_on_crossing_board():
    from oracle import HAS_ORACLE, route_dsn, routed_net_set

    if not HAS_ORACLE:
        pytest.skip("FreeRouting oracle unavailable")
    our_nets = routed_net_set(route(CROSSING.read_text()))
    oracle_nets = routed_net_set(route_dsn(CROSSING, max_passes=3, timeout=300))
    assert oracle_nets, "oracle routed nothing on a routable board"
    assert oracle_nets <= our_nets  # freeroute connects every net the JAR does


@pytest.mark.oracle
def test_connectivity_parity_on_simple_board():
    from oracle import HAS_ORACLE, route_dsn, routed_net_set

    if not HAS_ORACLE:
        pytest.skip("FreeRouting oracle unavailable")
    our_nets = routed_net_set(route(SIMPLE.read_text()))
    oracle_nets = routed_net_set(route_dsn(SIMPLE, max_passes=3, timeout=300))
    assert oracle_nets, "oracle routed nothing on a routable board"
    assert oracle_nets <= our_nets