"""Emit a minimal ``.kicad_pro`` so a sibling ``.kicad_sch`` + ``.kicad_pcb``
pair opens as one project in the KiCad GUI (double-click).

KiCad pairs files by basename: a directory containing
``EchoEar-CoreBoard.kicad_pro`` + ``EchoEar-CoreBoard.kicad_sch`` +
``EchoEar-CoreBoard.kicad_pcb`` is treated as one project, and opening the
.kicad_pro launches both editors with cross-navigation working. Without
this file each .kicad_sch / .kicad_pcb opens as a one-off and KiCad puts
up a "create project file?" dialog every time.

The .kicad_pro is JSON. KiCad will fill in defaults for anything missing
the next time the GUI opens it; we only emit the keys that meaningfully
identify the project (``meta``, ``sheets`` for hierarchy root binding,
empty stubs for ``board`` / ``schematic`` / ``net_settings`` so the
top-level keys exist in the form KiCad expects).
"""

from __future__ import annotations

import json


def write_kicad_pro(
    project_basename: str,
    *,
    root_sheet_uuid: str | None = None,
) -> str:
    """Render a JSON .kicad_pro string for one project.

    ``project_basename`` is the filename without extension — e.g.
    ``"EchoEar-CoreBoard"``. ``root_sheet_uuid`` is the uuid at the top of
    the sibling .kicad_sch's ``(uuid ...)`` form; KiCad uses it to bind
    the root sheet to the project's hierarchy. If omitted, KiCad
    generates one on first open (works but causes a "save changes?"
    prompt the first time).
    """
    sheets: list = []
    if root_sheet_uuid:
        sheets.append([root_sheet_uuid, ""])

    pro: dict = {
        "board": {
            "design_settings": {
                "defaults": {},
                "rules": {},
            },
            "layer_presets": [],
            "viewports": [],
        },
        "boards": [],
        "cvpcb": {"equivalence_files": []},
        "erc": {
            "erc_exclusions": [],
            "meta": {"version": 0},
            "pin_map": [],
            "rule_severities": {},
            "rule_severitieslegacy": {},
        },
        "libraries": {"pinned_footprint_libs": [], "pinned_symbol_libs": []},
        "meta": {
            "filename": f"{project_basename}.kicad_pro",
            "version": 1,
        },
        "net_settings": {
            "classes": [],
            "meta": {"version": 3},
            "net_colors": None,
            "netclass_assignments": None,
            "netclass_patterns": [],
        },
        "pcbnew": {
            "last_paths": {},
            "page_layout_descr_file": "",
        },
        "schematic": {
            "annotate_start_num": 0,
            "bom_export_filename": "",
            "bom_fmt_presets": [],
            "bom_fmt_settings": {},
            "bom_presets": [],
            "bom_settings": {},
            "drawing": {},
            "legacy_lib_dir": "",
            "legacy_lib_list": [],
            "meta": {"version": 1},
            "net_format_name": "",
            "page_layout_descr_file": "",
            "plot_directory": "",
            "spice_external_command": "spice \"%I\"",
            "subpart_first_id": 65,
            "subpart_id_separator": 0,
        },
        "sheets": sheets,
        "text_variables": {},
    }
    return json.dumps(pro, indent=2)