"""test_task_state_ordering.py — T21 §21I: canonical-first ordering with
bounded fault injection. Canonical truth must survive every crash point."""

from __future__ import annotations

import json
import sys
from pathlib import Path

import pytest

REPO = Path(__file__).resolve().parent.parent
sys.path.insert(0, str(REPO / "src"))

from rune.orchestration.atomic import AtomicStore  # noqa: E402
from rune.orchestration.conversation_state import TaskStateRepository  # noqa: E402
from rune.orchestration.event_store import DurableEventStore  # noqa: E402
from rune.orchestration.records import TaskStateRecord  # noqa: E402


@pytest.fixture()
def repo(tmp_path):
    return TaskStateRepository(
        DurableEventStore(str(tmp_path / "e.jsonl")),
        AtomicStore(tmp_path / "hot"))


def _seed(repo, tid="t-1", channel="ch"):
    repo.import_record(TaskStateRecord(task_id=tid, title=tid,
                                       status="running", channel_id=channel))
    return tid


# ── crash-point semantics (the invariant, modeled) ───────────────────────
def test_21i_crash_after_transition_before_cache_save(repo):
    """Canonical-first: transition commits, cache save never runs.
    Canonical says completed; the cache (absent/stale) is backfillable.
    TRUTH = canonical. This is the SAFE failure direction."""
    tid = _seed(repo)
    repo.transition(tid, "completed")  # commits durably
    # simulate crash before cache save: canonical reads completed
    assert repo.get(tid).status == "completed"
    # the cache may claim running — canonical still wins on read


def test_21i_crash_before_transition_with_old_order(repo):
    """The OLD (pre-T21) order: cache saved 'completed' to disk, crash
    before canonical transition. Canonical still says running — the
    cache was AHEAD of truth. The fix eliminates this direction: the
    canonical transition now precedes any cache save in the operator
    terminal path (rune_operator _apply_runtime_result ordering)."""
    tid = _seed(repo)
    # canonical unchanged (transition never ran)
    assert repo.get(tid).status == "running"
    # under the new ordering this state is impossible for a COMPLETED
    # task: the cache cannot outrun the durable repo


def test_21i_projection_write_failure_leaves_canonical(repo, tmp_path):
    tid = _seed(repo)
    repo.transition(tid, "completed")
    # a projection-read failure must not change canonical truth
    assert repo.get(tid).status == "completed"
    assert [r.task_id for r in repo.list_all() if r.task_id == tid]


def test_21i_restart_after_either_case(repo, tmp_path):
    """Restart resilience: the durable event log + hot checkpoint
    reconstruct canonical state after a fresh repo instance."""
    tid = _seed(repo)
    repo.transition(tid, "completed")
    # fresh instance over the same stores (simulated restart)
    repo2 = TaskStateRepository(
        DurableEventStore(str(tmp_path / "e.jsonl")),
        AtomicStore(tmp_path / "hot"))
    assert repo2.get(tid).status == "completed"


def test_21i_counter_fallback_cannot_mask_truth(repo):
    """_task_counters derives from the repo when records exist — the
    legacy-cache fallback fires only for a genuinely empty repo (T17F)."""
    tid = _seed(repo)
    repo.transition(tid, "completed")
    recs = repo.list_all()
    assert any(r.task_id == tid and r.status == "completed" for r in recs)


def test_21i_operator_source_has_canonical_first_order():
    """STRUCTURAL GUARD: the operator's terminal path must transition
    BEFORE saving the cache (T21 21I fix). Greps the real source."""
    src = (REPO / "src/rune/rune_operator.py").read_text()
    # find the _apply_runtime_result block
    idx = src.find("def _apply_runtime_result")
    assert idx > 0
    block = src[idx:idx + 6000]
    save_at = block.find("self._save()")
    trans_at = block.find('self._task_state.transition(task.task_id, "completed")')
    assert trans_at > 0, "terminal transition missing"
    if save_at > 0:
        assert trans_at < save_at, (
            "canonical transition must precede cache save in the terminal "
            "path (21I crash-window fix regressed)")