import datetime
import logging
from datetime import datetime
from typing import Optional, List

from pymongo import MongoClient
from pymongo.errors import ConfigurationError

from llama_stack.providers.utils.kvstore import KVStore, MongoDBKVStoreConfig

log = logging.getLogger(__name__)


class MongoDBKVStoreImpl(KVStore):
    def __init__(self, config: MongoDBKVStoreConfig):
        self.config = config
        self.conn = None
        self.collection = None

    async def initialize(self) -> None:
        try:
            conn_creds = {
                "host": self.config.host,
                "port": self.config.port,
                "username": self.config.user,
                "password": self.config.password,
            }
            conn_creds = {k: v for k, v in conn_creds if v is not None}

            try:
                self.conn = MongoClient(**conn_creds)
                self.collection = self.conn[self.config.db]
            except (ConnectionError, ConfigurationError) as e:
                raise Exception(f"Failed to connect to MongoDB: {e}")
        except Exception as e:
            log.exception("Could not connect to MongoDB database server")
            raise RuntimeError("Could not connect to MongoDB database server") from e

    def _namespaced_key(self, key: str) -> str:
        if not self.config.namespace:
            return key
        return f"{self.config.namespace}:{key}"

    async def set(
            self, key: str, value: str, expiration: Optional[datetime] = None
    ) -> None:
        key = self._namespaced_key(key)
        update_query = {
            "$set": {
                "value": value,
                "expiration": expiration
            }
        }
        self.collection.update_one(
            {"key": key},
            update_query,
            upsert=True
        )

    async def get(self, key: str) -> Optional[str]:
        key = self._namespaced_key(key)
        query = {
            "key": key,
            "$or": [
                {"expiration": {"$exists": False}},
                {"expiration": {"$gt": datetime.now(datetime.UTC)}},
            ],
        }
        result = self.collection.find_one(query, {"value": 1, "_id": 0})
        return result["value"] if result else None

    async def delete(self, key: str) -> None:
        key = self._namespaced_key(key)
        self.collection.delete_one({"key": key})

    async def range(self, start_key: str, end_key: str) -> List[str]:
        start_key = self._namespaced_key(start_key)
        end_key = self._namespaced_key(end_key)
        query = {
            "key": {"$gte": start_key, "$lt": end_key},
            "$or": [
                {"expiration": {"$exists": False}},
                {"expiration": {"$gt": datetime.now(datetime.UTC)}},
            ],
        }
        cursor = self.collection.find(query, {"value": 1, "_id": 0}).sort("key", 1)
        return [doc["value"] for doc in cursor]