"""Audit-log smoke tests.

The audit log was rewritten to use an async queue + a background
writer thread after a synchronous-write implementation hung the GUI
on a hostile filesystem (Windows antivirus). These tests pin the
critical guarantees:

1. ``log_event`` returns in microseconds (non-blocking).
2. Events queued before ``flush_audit_log`` land on disk in the
   correct JSONL shape.
3. Backpressure: when the queue is full, oldest events are dropped
   and newest ones survive (most-recent-events-are-most-diagnostic).
4. The writer thread tolerates an unwritable target without
   crashing or hanging.
"""

from __future__ import annotations

import json
import time
from pathlib import Path

import pytest


@pytest.fixture
def isolated_audit(monkeypatch, tmp_path):
    """Redirect audit writes into ``tmp_path`` and reset module state
    so each test starts fresh."""
    monkeypatch.setenv("DATATOOLS_AUDIT_DIR", str(tmp_path))
    from src import audit
    audit.reset_for_tests()
    yield audit
    # Best-effort cleanup so a runaway writer thread doesn't keep
    # touching the tmp_path after the test exits.
    audit.flush_audit_log(timeout_s=0.5)
    audit.reset_for_tests()


def _read_all_events(audit_dir: Path) -> list[dict]:
    """Read every JSONL file in *audit_dir* and return parsed events."""
    out: list[dict] = []
    for f in sorted(audit_dir.glob("datatools-*.jsonl")):
        for line in f.read_text(encoding="utf-8").splitlines():
            if line.strip():
                out.append(json.loads(line))
    return out


class TestLogEventIsNonBlocking:
    def test_returns_in_under_one_millisecond(self, isolated_audit):
        """A pathological 1000-event burst should clear well under a
        second on the request path. The write happens off-thread."""
        audit = isolated_audit
        start = time.perf_counter()
        for i in range(1000):
            audit.log_event("test", f"event {i}", n=i)
        elapsed = time.perf_counter() - start
        # 1000 events × 1ms ceiling = 1.0s. In practice this should
        # be milliseconds total since put_nowait is microseconds.
        assert elapsed < 1.0, (
            f"log_event burst took {elapsed:.3f}s for 1000 events — "
            f"that's over 1ms per call. Async queue is regressing to "
            f"a sync write."
        )


class TestEventsLandOnDisk:
    def test_basic_round_trip(self, isolated_audit, tmp_path):
        audit = isolated_audit
        audit.log_event("upload", "Uploaded a.csv", filename="a.csv", bytes=42)
        audit.log_event("analyze", "Analyzed a.csv", findings=3)
        audit.flush_audit_log(timeout_s=2.0)

        events = _read_all_events(tmp_path)
        assert len(events) == 2
        kinds = [e["category"] for e in events]
        assert "upload" in kinds
        assert "analyze" in kinds

        upload = next(e for e in events if e["category"] == "upload")
        assert upload["filename"] == "a.csv"
        assert upload["bytes"] == 42
        assert "ts" in upload
        assert "session" in upload

    def test_session_start_renders(self, isolated_audit, tmp_path):
        audit = isolated_audit
        audit.log_session_start()
        audit.flush_audit_log(timeout_s=2.0)
        events = _read_all_events(tmp_path)
        assert any(
            e["category"] == "session" and "Session started" in e["message"]
            for e in events
        )

    def test_log_session_start_is_idempotent(self, isolated_audit, tmp_path):
        audit = isolated_audit
        for _ in range(5):
            audit.log_session_start()
        audit.flush_audit_log(timeout_s=2.0)
        events = _read_all_events(tmp_path)
        starts = [e for e in events if e["category"] == "session"]
        assert len(starts) == 1


class TestUnwritableTargetDoesntCrash:
    def test_pointing_at_a_nonexistent_parent_doesnt_hang(
        self, monkeypatch, tmp_path,
    ):
        # Point the audit dir at a path that DOES exist as a FILE,
        # so any mkdir there fails. The writer should swallow the
        # error and the GUI-facing producer should keep working.
        not_a_dir = tmp_path / "iam-a-file"
        not_a_dir.write_text("hi")
        monkeypatch.setenv("DATATOOLS_AUDIT_DIR", str(not_a_dir))
        from src import audit
        audit.reset_for_tests()
        try:
            start = time.perf_counter()
            audit.log_event("test", "should not crash")
            assert time.perf_counter() - start < 0.5
            audit.flush_audit_log(timeout_s=0.5)
        finally:
            audit.reset_for_tests()


class TestSerializationSafety:
    def test_non_json_extras_get_str_coerced(self, isolated_audit, tmp_path):
        audit = isolated_audit

        class Weird:
            def __repr__(self):
                return "<Weird>"

        audit.log_event("test", "carries a weird extra", obj=Weird())
        audit.flush_audit_log(timeout_s=2.0)

        events = _read_all_events(tmp_path)
        assert len(events) == 1
        assert events[0]["obj"] == "<Weird>"