"""Tests for the S-expression tree parser."""

from __future__ import annotations

import pytest

from freeroute.dsn.sexp import SExp, parse
from freeroute.dsn.tokenizer import DsnSyntaxError, Token


def test_parse_simple_head_and_values():
    tree = parse("(resolution um 10)")
    assert tree.head == "resolution"
    vals = tree.values()
    assert [v.text for v in vals] == ["um", "10"]


def test_nested_children():
    tree = parse("(structure (layer Top (type signal)) (layer Bot (type signal)))")
    assert tree.head == "structure"
    layers = tree.children("layer")
    assert len(layers) == 2
    assert isinstance(layers[0], SExp)
    assert layers[0].values()[0].text == "Top"
    type_scope = layers[0].child("type")
    assert type_scope is not None
    assert type_scope.values()[0].text == "signal"


def test_child_missing_returns_none():
    tree = parse("(a (b 1))")
    assert tree.child("nope") is None


def test_values_skips_nested_lists():
    tree = parse("(net NET_A (pins U1-1 R2-2))")
    assert [v.text for v in tree.values()] == ["NET_A"]
    pins = tree.child("pins")
    assert pins is not None
    assert [v.text for v in pins.values()] == ["U1-1", "R2-2"]


def test_leaf_items_are_tokens():
    tree = parse("(a 1 2)")
    assert all(isinstance(it, Token) for it in tree.items)


def test_unbalanced_raises():
    with pytest.raises(DsnSyntaxError):
        parse("(a (b )")


def test_trailing_token_raises():
    with pytest.raises(DsnSyntaxError):
        parse("(a) (b)")


def test_no_toplevel_list_raises():
    with pytest.raises(DsnSyntaxError):
        parse("just atoms no parens")