import importlib
import json
from contextlib import contextmanager
from typing import Optional

import redis

from regiojet_search import settings
from regiojet_search.encoders import SearchResultJSONEncoder
from regiojet_search.models import City, Result
from regiojet_search.settings import CACHE_BACKEND, CACHE_SURNAME


@contextmanager
def get_redis_connection(host: str, port: int, db: int):
    connection = redis.Redis(host=host, port=port, db=db)
    yield connection
    connection.close()


class RedisCache:
    def __init__(self, host: str = settings.CACHE_HOST, port: int = settings.CACHE_PORT, db: int = settings.CACHE_DB):
        self.host = host
        self.port = port
        self.db = db

    def get(self, key: str) -> Optional[list[dict]]:
        with get_redis_connection(self.host, self.port, self.db) as redis_connection:
            cached_value = redis_connection.get(f"{CACHE_SURNAME}:{key}")

        try:
            return json.loads(cached_value)
        except Exception:  # noqa cache get is not that important, so make it fail-operational
            return None

    def set(self, key: str, value: list[City | Result]) -> None:
        with get_redis_connection(self.host, self.port, self.db) as redis_connection:
            redis_connection.set(f"{CACHE_SURNAME}:{key}", json.dumps(value, cls=SearchResultJSONEncoder))


class DummyCache:
    def __init__(self, host: str = settings.CACHE_HOST, port: int = settings.CACHE_PORT, db: int = settings.CACHE_DB):
        self.host = host
        self.port = port
        self.db = db

    def get(self, key: str) -> Optional[list[dict]]:
        return None

    def set(self, key: str, value: list[City | Result]) -> None:
        return None


def load_cache():
    cache_backend_module = ".".join(CACHE_BACKEND.split(".")[:-1])
    cache_backend_name = CACHE_BACKEND.split(".")[-1]
    cache_class = getattr(importlib.import_module(cache_backend_module), cache_backend_name)
    return cache_class()


cache = load_cache()