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'])

    def test_unchanged_shared_frame_is_not_copied_again(self):
        from types import SimpleNamespace
        preview.watch({'left_color'},set())
        header=bytearray(preview._SHM_HEAD.size)
        preview._SHM_HEAD.pack_into(header,0,2,1280,720,1280*720*3)
        with tempfile.TemporaryDirectory() as folder:
            payload={'frames':{'left_color':{'name':'owned_test','store':'left_color','kind':'rgb'}},
                     'meta':{},'ages':{'left_color':0},'exported_monotonic':time.monotonic()}
            (Path(folder)/'meta.json').write_text(json.dumps(payload))
            with patch.object(preview,'_BRIDGE_DIR',Path(folder)), \
                 patch.object(preview,'_SHM_SEQ',{'owned_test':2}), \
                 patch.object(preview,'_attach',return_value=SimpleNamespace(buf=header)), \
                 patch.object(preview,'_shm_read',side_effect=AssertionError('unchanged frame copied')):
                preview._ingest()

    def test_full_hd_is_preserved_and_larger_frames_fit_transport(self):
        import numpy as np
        image=np.zeros((1080,1920,3),np.uint8)
        self.assertEqual(preview.rgb_preview(image,bgr=False).shape,image.shape)
        portrait=preview.rgb_preview(np.zeros((1280,720,3),np.uint8),bgr=False)
        self.assertLessEqual(portrait.shape[0],1080)
        self.assertLessEqual(portrait.nbytes,preview._SHM_MAX)

    def test_refresh_worker_exit_does_not_kill_preview(self):
        import os,sys,subprocess,threading
        real_popen=subprocess.Popen
        spawning=[]
        def popen(argv,**kwargs):
            spawning.append(threading.current_thread().name)
            command=[sys.executable,'-m','station.child_process',str(os.getpid()),
                     sys.executable,'-c','import time;time.sleep(20)']
            proc=real_popen(command,**kwargs)
            time.sleep(.2)  # Allow the child to install its parent-death watch.
            return proc
        with patch.object(preview,'stream_targets',return_value=[{'id':'fake','label':'fake'}]), \
             patch.object(preview.subprocess,'Popen',side_effect=popen), \
             patch.object(preview,'_poll_loop',side_effect=lambda:preview._STOP.wait(5)):
            worker=threading.Thread(target=preview.start,name='short-refresh-worker')
            worker.start();worker.join(3)
            try:
                self.assertFalse(worker.is_alive())
                self.assertEqual(spawning,['cam-poll'])
                time.sleep(.3)
                self.assertIsNone(preview._BRIDGE.poll())
            finally:preview.stop()