"""
Copyright 2024, Zep Software, Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
"""

import logging
from datetime import datetime
from typing import Any

from falkordb import Graph as FalkorGraph  # type: ignore
from falkordb.asyncio import FalkorDB  # type: ignore

from graphiti_core.driver.driver import GraphDriver, GraphDriverSession
from graphiti_core.helpers import DEFAULT_DATABASE

logger = logging.getLogger(__name__)


class FalkorDriverSession(GraphDriverSession):
    def __init__(self, graph: FalkorGraph):
        self.graph = graph

    async def __aenter__(self):
        return self

    async def __aexit__(self, exc_type, exc, tb):
        # No cleanup needed for Falkor, but method must exist
        pass

    async def close(self):
        # No explicit close needed for FalkorDB, but method must exist
        pass

    async def execute_write(self, func, *args, **kwargs):
        # Directly await the provided async function with `self` as the transaction/session
        return await func(self, *args, **kwargs)

    async def run(self, query: str | list, **kwargs: Any) -> Any:
        # FalkorDB does not support argument for Label Set, so it's converted into an array of queries
        if isinstance(query, list):
            for cypher, params in query:
                params = convert_datetimes_to_strings(params)
                await self.graph.query(str(cypher), params)
        else:
            params = dict(kwargs)
            params = convert_datetimes_to_strings(params)
            await self.graph.query(str(query), params)
        # Assuming `graph.query` is async (ideal); otherwise, wrap in executor
        return None


class FalkorDriver(GraphDriver):
    provider: str = 'falkordb'

    def __init__(
        self,
        host: str = 'localhost',
        port: str = '6379',
        username: str | None = None,
        password: str | None = None,
        falkor_db: FalkorDB | None = None,
    ):
        """
        Initialize the FalkorDB driver.

        FalkorDB is a multi-tenant graph database.  
        To connect, provide the host and port.  
        The default parameters assume a local (on-premises) FalkorDB instance.
        """
        super().__init__()
        if falkor_db is not None:
            # If a FalkorDB instance is provided, use it directly
            self.client = falkor_db
        else:
            self.client = FalkorDB(host=host, port=port, username=username, password=password)

    def _get_graph(self, graph_name: str | None) -> FalkorGraph:
        # FalkorDB requires a non-None database name for multi-tenant graphs; the default is DEFAULT_DATABASE
        if graph_name is None:
            graph_name = DEFAULT_DATABASE
        return self.client.select_graph(graph_name)

    async def execute_query(self, cypher_query_, **kwargs: Any):
        graph_name = kwargs.pop('database_', DEFAULT_DATABASE)
        graph = self._get_graph(graph_name)

        # Convert datetime objects to ISO strings (FalkorDB does not support datetime objects directly)
        params = convert_datetimes_to_strings(dict(kwargs))

        try:
            result = await graph.query(cypher_query_, params)
        except Exception as e:
            if 'already indexed' in str(e):
                # check if index already exists
                logger.info(f'Index already exists: {e}')
                return None
            logger.error(f'Error executing FalkorDB query: {e}')
            raise

        # Convert the result header to a list of strings
        header = [h[1] for h in result.header]
        
        # Convert FalkorDB's result format (list of lists) to the format expected by Graphiti (list of dicts)
        records = []
        for row in result.result_set:
            record = {}
            for i, field_name in enumerate(header):
                if i < len(row):
                    record[field_name] = row[i]
                else:
                    # If there are more fields in header than values in row, set to None
                    record[field_name] = None
            records.append(record)
        
        return records, header, None

    def session(self, database: str | None) -> GraphDriverSession:
        return FalkorDriverSession(self._get_graph(database))

    async def close(self) -> None:
        """Close the driver connection."""
        if hasattr(self.client, 'aclose'):
            await self.client.aclose()
        elif hasattr(self.client.connection, 'aclose'):
            await self.client.connection.aclose()
        elif hasattr(self.client.connection, 'close'):
            await self.client.connection.close()

    async def delete_all_indexes(self, database_: str = DEFAULT_DATABASE) -> None:
        await self.execute_query(
            'CALL db.indexes() YIELD name DROP INDEX name',
            database_=database_,
        )


def convert_datetimes_to_strings(obj):
    if isinstance(obj, dict):
        return {k: convert_datetimes_to_strings(v) for k, v in obj.items()}
    elif isinstance(obj, list):
        return [convert_datetimes_to_strings(item) for item in obj]
    elif isinstance(obj, tuple):
        return tuple(convert_datetimes_to_strings(item) for item in obj)
    elif isinstance(obj, datetime):
        return obj.isoformat()
    else:
        return obj
