"""S2.5 MAF version-guard — a TEST-TIME tripwire + a two-sided install pin.

The offline simulation depends on MAF's PRIVATE API (the ``_inner_get_response`` keyword-only
signature + ``_build_response_stream`` construction — see ``conftest`` / ``simulation``'s scripted
client). A major ``agent-framework-core`` bump could change those without notice. This is NOT a
runtime guard (an un-wired ``src`` helper would be green-but-dead); it is a test-time tripwire
against the installed distribution PLUS a two-sided pin in ``pyproject.toml`` (install-time).

Critical: the guard reads the DISTRIBUTION version via
``importlib.metadata.version("agent-framework-core")`` (verified ``1.9.0``), NOT
``agent_framework.__version__`` (verified ``0.0.0`` placeholder — reading that would make the guard
permanently RED / meaningless). Modelled on ``test_smoke``'s version-assert + ``test_portfolio``'s
grep-pin.
"""

from __future__ import annotations

import importlib.metadata
from pathlib import Path

import pytest

_DIST = "agent-framework-core"

#: F15 (2026-08-30): the floor lives in ONE place and the ``pyproject`` assert below DERIVES its
#: expected pin string from it. Two literals for one fact drift (the kø-(p) rule), and a drifted
#: floor is a guard that stops guarding without a local diff.
_MIN_MAJOR = 1
_MIN_MINOR = 18
_MIN_VERSION = f"{_MIN_MAJOR}.{_MIN_MINOR}.0"


def assert_supported_maf_version(version_str: str) -> None:
    """Raise ``ValueError`` when ``version_str`` is outside the supported ``>=1.18.0,<2`` range,
    naming the private-API premises to re-verify before a bump. Pure string parse — no import side
    effects, so a fake version can be passed directly (the RED-proof) without touching the real
    install."""
    parts = version_str.split(".")
    major = int(parts[0])
    minor = int(parts[1]) if len(parts) > 1 else 0
    if not (major == _MIN_MAJOR and minor >= _MIN_MINOR):
        raise ValueError(
            f"{_DIST} {version_str} is outside the supported range >={_MIN_VERSION},<2. Before "
            "bumping, re-verify the private-API premises the offline sim relies on: the "
            "_inner_get_response keyword-only signature (messages/options/stream) and the "
            "_build_response_stream construction. Update the pin in pyproject.toml once confirmed."
        )


def test_installed_maf_version_is_supported() -> None:
    """T-2.5d: the real installed distribution (verified 1.18.0) passes the guard — read from
    ``importlib.metadata.version``, NOT ``agent_framework.__version__`` (a 0.0.0 placeholder)."""
    assert_supported_maf_version(importlib.metadata.version(_DIST))


def test_guard_rejects_future_major() -> None:
    """T-2.5d: a future major (``2.0.0``) trips the guard with the actionable upgrade message —
    RED-proof without touching the real install."""
    with pytest.raises(ValueError, match="private-API premises"):
        assert_supported_maf_version("2.0.0")


def test_guard_rejects_too_old_minor() -> None:
    """T-2.5d / F15 / F16: every PREVIOUS floor now trips the guard — the pin is two-sided, and this
    is the arm that makes each lift measurable rather than asserted. ``1.15.0`` (the
    ``agent-framework-orchestrations`` 1.1.1 requirement ``core>=1.15.0``) and ``1.16.0`` (F15's
    floor) are rejected too, and so is ``1.17.0``, even though ``agent-framework-foundry`` 1.13.0
    and ``agent-framework-openai`` 1.14.3 only require ``core>=1.17.0``: a dependency's own floor is
    not our floor. 1.18.0 is the version whose private-API premises were actually re-verified
    (F16, docs/2026-09-12-f16-maf-1180.md)."""
    for stale in ("1.8.0", "1.9.0", "1.15.0", "1.16.0", "1.17.0"):
        with pytest.raises(ValueError, match="private-API premises"):
            assert_supported_maf_version(stale)


def test_pyproject_pins_agent_framework_core_below_2() -> None:
    """T-2.5d: ``pyproject.toml`` pins ``agent-framework-core>=1.18.0,<2`` — the install-time half of
    the guard (the test above is the test-time half). The expected string is DERIVED from
    ``_MIN_VERSION`` so the two halves cannot drift apart."""
    pyproject = (Path(__file__).resolve().parents[1] / "pyproject.toml").read_text(encoding="utf-8")
    assert f"agent-framework-core>={_MIN_VERSION},<2" in pyproject