"""Section-scoped and continuous object numbering."""

from collections import defaultdict


APPENDIX_LETTERS = "АБВГДЕЖИКЛМНПРСТУФХЦШЩЭЮЯ"  # without Ё З Й О Ч Ь Ы Ъ


class Numberer:
    """Assigns object numbers.

    * ``section`` (MIREA): ``1.1``, ``2.3`` or ``Б.1`` — counters reset per section/appendix.
    * ``continuous`` (PIS_custom): ``1``, ``2``, ``3`` — сквозная нумерация по всему документу.
    """

    def __init__(self, mode: str = "section"):
        if mode not in ("section", "continuous"):
            raise ValueError(f"Unknown numbering mode: {mode!r}")
        self._mode = mode
        self._section: int = 0
        self._appendix: str | None = None
        self._counters: dict[str, int] = defaultdict(int)
        self._labels: dict[tuple[str, str], str] = {}  # (category, unique_name) -> number string

    @property
    def mode(self) -> str:
        return self._mode

    @property
    def section(self) -> int:
        return self._section

    @property
    def appendix(self) -> str | None:
        return self._appendix

    def enter_section(self, section_number: int) -> None:
        """Start a numbered chapter (Heading 1 numbered)."""
        self._section = section_number
        self._appendix = None
        if self._mode != "continuous":
            self._counters.clear()

    def enter_appendix(self, letter: str) -> None:
        """Start an appendix (letter А, Б, …)."""
        self._appendix = letter
        if self._mode != "continuous":
            self._counters.clear()

    def next_number(self, category: str, unique_name: str | None = None) -> str:
        """Allocate next number for category; optionally bind a label."""
        self._counters[category] += 1
        n = self._counters[category]
        if self._mode == "continuous":
            number = str(n)
        elif self._appendix:
            number = f"{self._appendix}.{n}"
        elif self._section:
            number = f"{self._section}.{n}"
        else:
            number = str(n)
        if unique_name:
            self._labels[(category, unique_name)] = number
        return number

    def resolve(self, category: str, unique_name: str) -> str | None:
        return self._labels.get((category, unique_name))

    def register_label(self, category: str, unique_name: str, number: str) -> None:
        self._labels[(category, unique_name)] = number