import json
import time
from datetime import timedelta
from unittest.mock import patch

from django.test import override_settings
from django.utils import timezone
from rest_framework.test import APITestCase

from apps.notifications.api import views
from apps.notifications.services import store as services
from apps.notifications.services import RedisNotificationStore
from apps.notifications.tests.fakes import FakePubSub, FakeRedis
from apps.users.models import User


class NotificationViewTests(APITestCase):
    @classmethod
    def setUpTestData(cls):
        cls.user = User.objects.create_user(mobile="09121111111", password="secret123")
        cls.second_user = User.objects.create_user(
            mobile="09122222222",
            password="secret123",
        )

    def setUp(self):
        self.fake_redis = FakeRedis()
        self.original_redis_client = services.redis_client
        services.redis_client = self.fake_redis

    def tearDown(self):
        services.redis_client = self.original_redis_client

    @staticmethod
    def _read_sse_chunks(response, count):
        iterator = iter(response.streaming_content)
        chunks = []
        for _ in range(count):
            chunk = next(iterator)
            if isinstance(chunk, bytes):
                chunk = chunk.decode("utf-8")
            chunks.append(chunk)
        response.close()
        return chunks

    @staticmethod
    def _parse_sse_data(chunk):
        for line in chunk.splitlines():
            if line.startswith("data: "):
                return json.loads(line.removeprefix("data: "))
        raise AssertionError("SSE payload did not include data")

    def test_stream_token_endpoint_returns_short_lived_token(self):
        self.client.force_authenticate(user=self.user)

        response = self.client.post("/api/notifications/stream-token/")

        self.assertEqual(response.status_code, 200)
        self.assertTrue(response.data["token"])
        self.assertGreater(response.data["expires_in"], 0)

    def test_stream_endpoint_rejects_missing_and_expired_token(self):
        missing = self.client.get("/api/notifications/stream/")
        self.assertEqual(missing.status_code, 401)

        with override_settings(NOTIFICATION_STREAM_TOKEN_LIFETIME_SECONDS=1):
            token = views._issue_stream_token_for_user(str(self.user.id))
            time.sleep(1.1)
            expired = self.client.get(f"/api/notifications/stream/?token={token}")

        self.assertEqual(expired.status_code, 401)

    def test_stream_endpoint_sends_only_current_users_notifications(self):
        RedisNotificationStore.add(str(self.user.id), {"title": "For current user"})
        RedisNotificationStore.add(str(self.second_user.id), {"title": "For another user"})
        pubsub = FakePubSub()

        with patch.object(
            RedisNotificationStore,
            "get_pubsub",
            classmethod(lambda cls: pubsub),
        ):
            token = views._issue_stream_token_for_user(str(self.user.id))
            response = self.client.get(
                f"/api/notifications/stream/?token={token}",
                HTTP_ACCEPT="text/event-stream",
            )
            retry_line, connected_chunk = self._read_sse_chunks(response, 2)

        self.assertEqual(response.status_code, 200)
        self.assertTrue(retry_line.startswith("retry:"))
        connected = self._parse_sse_data(connected_chunk)
        self.assertEqual(connected["unread_count"], 1)
        self.assertEqual(
            [item["title"] for item in connected["notifications"]],
            ["For current user"],
        )

    def test_stream_endpoint_emits_heartbeat(self):
        pubsub = FakePubSub()
        first_now = timezone.now()
        tick_values = iter(
            [
                first_now,
                first_now,
                first_now + timedelta(seconds=2),
                first_now + timedelta(seconds=2),
                first_now + timedelta(seconds=2),
                first_now + timedelta(seconds=2),
            ]
        )
        last_tick = first_now + timedelta(seconds=2)

        def fake_now():
            return next(tick_values, last_tick)

        with override_settings(NOTIFICATION_SSE_HEARTBEAT_SECONDS=1):
            with patch.object(
                RedisNotificationStore,
                "get_pubsub",
                classmethod(lambda cls: pubsub),
            ):
                with patch.object(views.timezone, "now", side_effect=fake_now):
                    view = views.NotificationStreamView()
                    stream = view._build_stream(str(self.user.id))
                    chunks = [next(stream) for _ in range(4)]
                    stream.close()

        self.assertIn("event: ping", chunks[3])

    def test_notification_list_and_seen_endpoints_work(self):
        notification = RedisNotificationStore.add(
            str(self.user.id),
            {"title": "Deploy succeeded", "type": "deploy"},
        )
        self.client.force_authenticate(user=self.user)

        list_response = self.client.get("/api/notifications/list/?type=deploy")
        self.assertEqual(list_response.status_code, 200)
        self.assertEqual(list_response.data["count"], 1)
        self.assertEqual(list_response.data["unread_count"], 1)
        self.assertEqual(
            list_response.data["notifications"][0]["title"],
            "Deploy succeeded",
        )

        seen_response = self.client.post(
            "/api/notifications/seen/",
            {"id": notification["id"]},
            format="json",
        )
        self.assertEqual(seen_response.status_code, 200)
        self.assertTrue(seen_response.data["marked_read"])
        self.assertTrue(seen_response.data["notification"]["is_seen"])

    def test_notification_delete_endpoint_removes_notification(self):
        notification = RedisNotificationStore.add(
            str(self.user.id),
            {"title": "Delete me", "type": "deploy"},
        )
        self.client.force_authenticate(user=self.user)

        response = self.client.delete(f"/api/notifications/{notification['id']}/")

        self.assertEqual(response.status_code, 200)
        self.assertTrue(response.data["deleted"])
        self.assertEqual(response.data["notification_id"], notification["id"])
        self.assertIsNone(RedisNotificationStore.get(str(self.user.id), notification["id"]))