from __future__ import annotations

import json
import unittest

from tests.conftest import append_ndjson, make_temp_paths, sample_events, write_ndjson
from event_watcher import EventWatcher


class EventWatcherTests(unittest.TestCase):
    def setUp(self) -> None:
        self.tempdir, self.paths = make_temp_paths()
        self.events = sample_events()

    def tearDown(self) -> None:
        self.tempdir.cleanup()

    def watcher(self) -> EventWatcher:
        return EventWatcher(self.paths.events_path, self.paths.cursor_path, poll_interval=0.1)

    def test_poll_empty_file(self) -> None:
        watcher = self.watcher()
        self.assertEqual(watcher.poll_once(), [])
        self.assertFalse(self.paths.cursor_path.exists())

    def test_poll_new_events(self) -> None:
        write_ndjson(self.paths.events_path, self.events[:3])

        polled = self.watcher().poll_once()

        self.assertEqual(polled, self.events[:3])

    def test_cursor_persistence(self) -> None:
        watcher = self.watcher()
        write_ndjson(self.paths.events_path, self.events[:3])

        first = watcher.poll_once()
        second = watcher.poll_once()

        self.assertEqual(first, self.events[:3])
        self.assertEqual(second, [])
        cursor = json.loads(self.paths.cursor_path.read_text(encoding="utf-8"))
        self.assertGreater(cursor["position"], 0)

    def test_cursor_survives_restart(self) -> None:
        write_ndjson(self.paths.events_path, self.events[:3])

        first_watcher = self.watcher()
        self.assertEqual(first_watcher.poll_once(), self.events[:3])

        second_watcher = self.watcher()
        self.assertEqual(second_watcher.poll_once(), [])

    def test_corrupt_line_skipped(self) -> None:
        self.paths.events_path.parent.mkdir(parents=True, exist_ok=True)
        with self.paths.events_path.open("w", encoding="utf-8") as handle:
            handle.write(json.dumps(self.events[0]) + "\n")
            handle.write("{not-json}\n")
            handle.write(json.dumps(self.events[1]) + "\n")

        polled = self.watcher().poll_once()

        self.assertEqual(polled, [self.events[0], self.events[1]])

    def test_callback_filtering(self) -> None:
        write_ndjson(self.paths.events_path, self.events)
        received: list[dict[str, object]] = []
        watcher = self.watcher()
        watcher.on(["task.completed"], received.append)

        watcher.poll_once()

        self.assertEqual(received, [self.events[2]])

    def test_callback_receives_events(self) -> None:
        write_ndjson(self.paths.events_path, self.events[:2])
        received: list[dict[str, object]] = []
        watcher = self.watcher()
        watcher.on([], received.append)

        polled = watcher.poll_once()

        self.assertEqual(received, self.events[:2])
        self.assertEqual(polled, self.events[:2])

    def test_file_grows_between_polls(self) -> None:
        watcher = self.watcher()
        write_ndjson(self.paths.events_path, self.events[:2])

        first = watcher.poll_once()
        append_ndjson(self.paths.events_path, self.events[2:5])
        second = watcher.poll_once()

        self.assertEqual(first, self.events[:2])
        self.assertEqual(second, self.events[2:5])


if __name__ == "__main__":
    unittest.main()