"""The config schema-version stamp: raw reads of ``_config_version`` from config.yaml.

Split out of :mod:`hermes_cli.config` (code-health size ratchet); ``hermes_cli.config``
late-imports these and re-exports them, and :mod:`scripts.docker_config_migrate` reads the
raw stamp directly. ``_coerce_config_version`` stays module-private here.
"""

from __future__ import annotations

from typing import Optional, Tuple

from hermes_cli.config_defaults import DEFAULT_CONFIG


def _coerce_config_version(value) -> int:
    """Return a safe integer config version, treating invalid values as legacy."""
    if isinstance(value, bool):
        return 0
    try:
        version = int(value)
    except (TypeError, ValueError):
        return 0
    return max(version, 0)


def read_config_version_stamp(*, raise_on_parse_error: bool = False) -> tuple[Optional[int], int]:
    """Single raw read behind ``check_config_version()``: ``(stamp, latest_version)`` where
    *stamp* is ``None`` when config.yaml parsed but carries no ``_config_version`` key (a
    never-stamped current-schema file, not an ancient install — ``migrate_config()`` gives it only
    the legacy-key steps). A missing file, or malformed YAML under a tolerant caller, reads as
    ``latest`` exactly as ``check_config_version()`` always reported it."""
    from hermes_cli.config import InvalidUserConfigError, _warn_config_parse_failure, fast_safe_load, get_config_path

    latest = _coerce_config_version(DEFAULT_CONFIG.get("_config_version", 1)) or 1
    config_path = get_config_path()
    if not config_path.exists():
        return latest, latest

    try:
        with open(config_path, encoding="utf-8-sig") as f:
            config = fast_safe_load(f)
    except Exception as e:
        _warn_config_parse_failure(config_path, e)
        if raise_on_parse_error:
            raise InvalidUserConfigError(
                f"Cannot inspect {config_path}: config.yaml is not valid YAML ({e})"
            ) from e
        return latest, latest

    if config is None:
        config = {}  # empty file / bare document: valid first-run state
    if not isinstance(config, dict):
        # A list/scalar root parses fine but is just as unusable as broken YAML: save_config()
        # would refuse it later, after .env was already rewritten. Strict callers see it up front.
        if raise_on_parse_error:
            raise InvalidUserConfigError(
                f"Cannot inspect {config_path}: config.yaml top-level value must be "
                f"a mapping, got {type(config).__name__}"
            )
        config = {}
    if "_config_version" not in config:
        return None, latest
    return _coerce_config_version(config.get("_config_version")), latest


def check_config_version(*, raise_on_parse_error: bool = False) -> tuple[int, int]:
    """Return ``(current_version, latest_version)`` from the raw on-disk config.
    Reads the raw file rather than ``load_config()``: the deep-merge would make a file lacking
    ``_config_version`` inherit the latest version, hiding that the schema was never migrated.
    Invalid YAML gets a parse warning, not an automatic schema rewrite. Tolerant runtime status
    callers keep the historical latest/latest fallback for malformed YAML; mutation and explicit
    validation paths set ``raise_on_parse_error`` so a parse failure or a non-mapping root cannot
    be mistaken for an up-to-date config. A file with no version key reads as 0."""
    stamp, latest = read_config_version_stamp(raise_on_parse_error=raise_on_parse_error)
    return (0 if stamp is None else stamp), latest