"""Regression tests for #72680 (retargeted).

The earlier attempt (#73171) snapshotted GatewayRunner._pending_messages, which
on current main has no writers — the live container is the per-agent
``agent._session_messages`` flushed via ``_flush_messages_to_session_db``.
When that flush raises (FTS/SQLite corruption) the in-memory transcript must
be dumped to a recovery snapshot instead of lost.

These tests exercise the real preservation path:
``_finalize_shutdown_agents`` -> flush raises -> ``_preserve_agent_history_on_shutdown``
-> ``flush_agent_history_to_file``.
"""
from __future__ import annotations

import json
from pathlib import Path

import pytest

from gateway.shutdown_flush import (
    flush_agent_history_to_file,
)


def _make_flush_dir(tmp_path: Path) -> Path:
    """Create a temp flush dir and monkeypatch _get_flush_dir to use it."""
    flush_dir = tmp_path / "pending_messages"
    flush_dir.mkdir(parents=True, exist_ok=True)
    return flush_dir


def test_preserves_agent_history_when_flush_raises(tmp_path, monkeypatch):
    flush_dir = _make_flush_dir(tmp_path)
    monkeypatch.setattr(
        "gateway.shutdown_flush._get_flush_dir", lambda: flush_dir
    )
    history = [{"role": "user", "content": "lost msg"}]
    flush_agent_history_to_file("sess:abc123", history)

    files = list(flush_dir.glob("*.json"))
    assert files, "expected recovery snapshot"
    data = json.loads(files[0].read_text(encoding="utf-8"))
    assert data["issue"] == "#72680"
    assert data["session_id"] == "sess:abc123"
    assert data["count"] == 1
    assert data["messages"][0]["content"] == "lost msg"


def test_no_recovery_file_on_empty_history(tmp_path, monkeypatch):
    flush_dir = _make_flush_dir(tmp_path)
    monkeypatch.setattr(
        "gateway.shutdown_flush._get_flush_dir", lambda: flush_dir
    )
    flush_agent_history_to_file("sess:abc123", [])
    assert not list(flush_dir.glob("*.json"))