save user queries in redis so that user can refresh the page and still come back to their latest task

crawler/redis_repository.py

@@ -0,0 +1,60 @@
+from datetime import timedelta
+from functools import lru_cache
+import json
+from string import Template
+from typing import Any
+from api.auth import User
+import redis
+from celery_app import app
+
+
+class RedisRepository:
+    redis_client: redis.Redis
+    tasks_key_template = Template("user:{user_id}/tasks")
+
+    def __init__(self):
+        redis_hostname = app.broker_connection().info()["hostname"]
+        redis_port = app.broker_connection().info()["port"]
+        self.redis_client = redis.Redis(
+            host=redis_hostname, port=redis_port, db=0, decode_responses=True
+        )  # decode_responses=True returns str, not bytes
+
+    @lru_cache(maxsize=None)
+    @staticmethod
+    def instance():
+        return RedisRepository()
+
+    def set_key(self, key: str, value, ttl: timedelta | None = None) -> None:
+        serialized_value = self.__serialize_value(value)
+        self.redis_client.set(key, serialized_value)
+
+        ttl = ttl or timedelta(hours=3)
+        self.redis_client.expire(key, ttl)
+
+    def get_key(self, key: str) -> Any | None:
+        serialized_value = self.redis_client.get(key)
+        if serialized_value is None:
+            return None
+        return self.__deserialize_value(serialized_value)
+
+    def add_task_for_user(self, user: User, task_id: str):
+        # Add the task ID to the Redis set for the user
+        current_tasks = (
+            self.get_key(self.tasks_key_template.substitute(user_id=user.email)) or []
+        )
+        self.set_key(
+            self.tasks_key_template.substitute(user_id=user.email),
+            [task_id] + current_tasks,
+        )
+
+    def get_tasks_for_user(self, user: User) -> list[str]:
+        # Get the task IDs from the Redis set for the user
+        return (
+            self.get_key(self.tasks_key_template.substitute(user_id=user.email)) or []
+        )
+
+    def __serialize_value(self, value: Any) -> str:
+        return json.dumps(value)
+
+    def __deserialize_value(self, value_str) -> Any:
+        return json.loads(value_str)