"""Root sheet writer regression: hierarchical parent .kicad_sch."""

from tools.epro2.kicad._sexpr_reader import parse
from tools.epro2.kicad.root_sch_writer import ChildSheet, write_root_sheet


def _block(parsed, name):
    return [c for c in parsed if isinstance(c, list) and c and c[0] == name]


def test_root_emits_one_sheet_block_per_child():
    children = [
        ChildSheet("Overview.kicad_sch", "Overview", "uuid-1"),
        ChildSheet("MCU.kicad_sch", "MCU", "uuid-2"),
        ChildSheet("Codec.kicad_sch", "Codec", "uuid-3"),
    ]
    parsed = parse(write_root_sheet("CoreBoard", children))
    sheets = _block(parsed, "sheet")
    assert len(sheets) == 3
    # Each sheet block carries the assigned uuid + Sheetname + Sheetfile
    titles = []
    files = []
    uuids = []
    for sh in sheets:
        uuids.append(next(c for c in sh if isinstance(c, list) and c[0] == "uuid")[1])
        for c in sh:
            if isinstance(c, list) and c[0] == "property":
                if c[1] == "Sheetname":
                    titles.append(c[2])
                elif c[1] == "Sheetfile":
                    files.append(c[2])
    assert titles == ["Overview", "MCU", "Codec"]
    assert files == ["Overview.kicad_sch", "MCU.kicad_sch", "Codec.kicad_sch"]
    assert uuids == ["uuid-1", "uuid-2", "uuid-3"]


def test_root_assigns_sequential_page_numbers_starting_at_2():
    """Root itself is page 1 of the hierarchy; children start at page 2 so
    that a child's (sheet_instances (page "<n>")) lines up with the root's
    (instances ... (page "<n>"))."""
    children = [
        ChildSheet("a.kicad_sch", "A", "u-a"),
        ChildSheet("b.kicad_sch", "B", "u-b"),
    ]
    parsed = parse(write_root_sheet("Project", children))
    sheets = _block(parsed, "sheet")
    page_nums = []
    for sh in sheets:
        inst = next(c for c in sh if isinstance(c, list) and c[0] == "instances")
        proj = next(c for c in inst if isinstance(c, list) and c[0] == "project")
        path = next(c for c in proj if isinstance(c, list) and c[0] == "path")
        page = next(c for c in path if isinstance(c, list) and c[0] == "page")
        page_nums.append(page[1])
    assert page_nums == ["2", "3"]
    # And the root's own page is 1
    root_inst = _block(parsed, "sheet_instances")[0]
    root_path = next(c for c in root_inst if isinstance(c, list) and c[0] == "path")
    root_page = next(c for c in root_path if isinstance(c, list) and c[0] == "page")
    assert root_page[1] == "1"


def test_root_handles_zero_children():
    """Empty schematic: still emit a valid kicad_sch with no (sheet) blocks."""
    parsed = parse(write_root_sheet("Empty", []))
    assert parsed[0] == "kicad_sch"
    assert _block(parsed, "sheet") == []
    # sheet_instances still required (KiCad demands at least one path)
    assert _block(parsed, "sheet_instances")