"""Logic tree and MPC versioning; changes require re-certification; historical preserved."""

from typing import Any


class VersionStore:
    """Immutable versioned store: logic trees and MPCs; historical read-only."""

    def __init__(self) -> None:
        self._versions: dict[str, list[tuple[int, Any]]] = {}  # id -> [(version, payload), ...]

    def put(self, id_key: str, version: int, payload: Any) -> None:
        """Store a new version; versions must be monotonic."""
        if id_key not in self._versions:
            self._versions[id_key] = []
        existing = self._versions[id_key]
        if existing and existing[-1][0] >= version:
            raise ValueError(f"Version must be greater than {existing[-1][0]}")
        existing.append((version, payload))

    def get(self, id_key: str, version: int | None = None) -> Any | None:
        """Return payload for id; optional version (latest if omitted)."""
        if id_key not in self._versions:
            return None
        versions = self._versions[id_key]
        if not versions:
            return None
        if version is None:
            return versions[-1][1]
        for v, payload in versions:
            if v == version:
                return payload
        return None

    def get_latest_version(self, id_key: str) -> int | None:
        """Return latest version number for id or None."""
        if id_key not in self._versions or not self._versions[id_key]:
            return None
        return self._versions[id_key][-1][0]

    def history(self, id_key: str) -> list[tuple[int, Any]]:
        """Return full version history (read-only)."""
        return list(self._versions.get(id_key, []))