import json
import tempfile
import time
from pathlib import Path
from unittest import TestCase
from unittest.mock import patch
from station import operator_camera_view as preview


class PreviewCacheTest(TestCase):
    def tearDown(self):
        preview.watch(set(),set())
        preview._PREVIEW.clear();preview._META.clear()

    def test_switch_and_stale_worker_clear_frames(self):
        preview.watch({'left_color'},set())
        preview._PREVIEW['left_color']=(b'123',1,1)
        preview.watch({'right_color'},set())
        self.assertNotIn('left_color',preview.previews())
        with tempfile.TemporaryDirectory() as folder:
            preview._PREVIEW['right_color']=(b'123',1,1)
            payload={'frames':{},'exported_monotonic':time.monotonic()-10,'meta':{},'ages':{}}
            (Path(folder)/'meta.json').write_text(json.dumps(payload))
            with patch.object(preview,'_BRIDGE_DIR',Path(folder)):
                preview._ingest()
            self.assertEqual(preview.previews(),{})
            self.assertIn('未更新',preview.state()['error'])