"""Fixture-mode selection and per-test determinism for record/replay e2e runs.

``E2E_FIXTURE_MODE`` is live (the default; nothing changes), record, or replay.
This module owns everything mode-shaped that is independent of the provider
edge itself: parsing the raw env value, the collection-time gate that aborts a
run whose mode can never work (unknown value, or replay against a missing or
stale bundle), the pytest report-header lines, the running test's node id, and
the deterministic per-test marker that lets a replay run regenerate exactly
the requests the record run sent. The provider-edge server that records and
serves provider traffic lives in provider_edge.py (LIT-5745).
"""

from __future__ import annotations

import hashlib
import os
from collections.abc import Generator
from contextvars import ContextVar
from dataclasses import dataclass
from datetime import datetime
from pathlib import Path
from typing import Final, Literal, assert_never

import pytest
from fixture_bundle import (
    FreshBundle,
    StaleBundle,
    UnreadableBundle,
    check_freshness,
    format_age,
)
from fixture_profile import match_profile

type FixtureMode = Literal["live", "record", "replay"]

FIXTURE_MODES: Final[tuple[FixtureMode, ...]] = ("live", "record", "replay")

SESSION_TEST_KEY: Final = "session"


@dataclass(frozen=True, slots=True)
class InvalidFixtureMode:
    value: str


def parse_fixture_mode(raw: str) -> FixtureMode | InvalidFixtureMode:
    normalized = raw.strip().lower() or "live"
    match normalized:
        case "live" | "record" | "replay":
            return normalized
        case _:
            return InvalidFixtureMode(value=raw)


def current_test_key() -> str:
    """The pytest node id of the running test, from the PYTEST_CURRENT_TEST env
    var pytest maintains (``<nodeid> (setup|call|teardown)``); ``session`` for
    calls outside any test (e.g. session-finish cleanup)."""
    raw = os.environ.get("PYTEST_CURRENT_TEST", "")
    if not raw:
        return SESSION_TEST_KEY
    return raw.rsplit(" (", 1)[0]


REGISTRATION_OWNER: Final[ContextVar[str | None]] = ContextVar("registration_owner", default=None)


def registration_owner() -> str:
    """The pytest node that owns a deployment registered right now. While a
    fixture is being set up that is the node the fixture is scoped to: the module
    or class for a fixture its tests share, and ``session`` for a session- or
    package-scoped one, which every xdist worker sets up and no node can own.
    Anywhere else it is the running test."""
    owner = REGISTRATION_OWNER.get()
    return current_test_key() if owner is None else owner


@pytest.hookimpl(wrapper=True)
def pytest_fixture_setup(request: pytest.FixtureRequest) -> Generator[None, object, object]:
    node: Final = request.node  # pyright: ignore[reportUnknownMemberType, reportUnknownVariableType]  # pytest: untyped
    assert isinstance(node, pytest.Item | pytest.Collector)
    owner: Final = SESSION_TEST_KEY if request.scope in ("session", "package") else node.nodeid
    token: Final = REGISTRATION_OWNER.set(owner)
    try:
        return (yield)
    finally:
        REGISTRATION_OWNER.reset(token)


class ReplayMiss(AssertionError):
    """Replay had no recorded interaction for a provider call the proxy made.
    The suite drifted from the bundle (or the bundle from the suite): re-record."""


_marker_ordinals: Final[dict[str, int]] = {}


def deterministic_marker() -> str:
    """Stable stand-in for uuid-based unique markers in record and replay modes:
    the Nth marker of a test is a pure function of the test's node id and N, so a
    replay run regenerates exactly the model names, prompts, and tags the record
    run sent and every recorded provider interaction still matches its key."""
    test_key = current_test_key()
    ordinal = _marker_ordinals.get(test_key, 0)
    _marker_ordinals[test_key] = ordinal + 1
    return hashlib.sha1(f"{test_key}#{ordinal}".encode()).hexdigest()[:12]


def fixture_mode_collection_error(mode_raw: str, bundle_dir: Path, *, now: datetime) -> str | None:
    """Session-abort reason for a fixture-mode setup that can never work, or None.
    Called at collection time (conftest pytest_sessionstart) so a stale or missing
    bundle fails the whole run up front, naming the bundle age, instead of failing
    every test individually."""
    match_profile()
    mode = parse_fixture_mode(mode_raw)
    match mode:
        case InvalidFixtureMode(value=value):
            return f"E2E_FIXTURE_MODE={value!r} is not one of {', '.join(FIXTURE_MODES)}"
        case "live" | "record":
            return None
        case "replay":
            freshness = check_freshness(bundle_dir, now=now, profile=match_profile())
            match freshness:
                case FreshBundle():
                    return None
                case StaleBundle(recorded_at=recorded_at, age=age, limit=limit):
                    return (
                        f"fixture bundle at {bundle_dir} is stale: recorded {recorded_at.isoformat()}, "
                        f"age {format_age(age)} exceeds the {limit.days}-day limit; "
                        "re-record with E2E_FIXTURE_MODE=record"
                    )
                case UnreadableBundle(reason=reason):
                    return f"E2E_FIXTURE_MODE=replay cannot use bundle at {bundle_dir}: {reason}"
                case _:
                    assert_never(freshness)
        case _:
            assert_never(mode)


def fixture_report_lines(mode_raw: str, bundle_dir: Path, *, now: datetime) -> list[str]:
    """pytest report-header lines; empty in live mode so an unset
    E2E_FIXTURE_MODE keeps today's output byte-identical."""
    match_profile()
    mode = parse_fixture_mode(mode_raw)
    match mode:
        case InvalidFixtureMode() | "live":
            return []
        case "record":
            return [f"e2e fixture mode: record -> {bundle_dir}"]
        case "replay":
            freshness = check_freshness(bundle_dir, now=now, profile=match_profile())
            match freshness:
                case FreshBundle(manifest=manifest):
                    return [
                        f"e2e fixture mode: replay <- {bundle_dir} "
                        f"(recorded {manifest.recorded_at.isoformat()}, harness {manifest.harness_version})"
                    ]
                case StaleBundle() | UnreadableBundle():
                    return [f"e2e fixture mode: replay <- {bundle_dir}"]
                case _:
                    assert_never(freshness)
        case _:
            assert_never(mode)