import os
from dataclasses import dataclass

from neo4j import GraphDatabase


@dataclass(frozen=True)
class Neo4jSettings:
    uri: str
    user: str
    password: str
    database: str


def get_neo4j_settings() -> Neo4jSettings:
    password = os.getenv("NEO4J_PASSWORD")

    if not password:
        raise RuntimeError(
            "NEO4J_PASSWORD is not configured."
        )

    return Neo4jSettings(
        uri=os.getenv(
            "NEO4J_URI",
            "bolt://localhost:7687",
        ),
        user=os.getenv(
            "NEO4J_USER",
            "neo4j",
        ),
        password=password,
        database=os.getenv(
            "NEO4J_DATABASE",
            "neo4j",
        ),
    )


def create_neo4j_driver(
    settings: Neo4jSettings | None = None,
):
    resolved = settings or get_neo4j_settings()

    return GraphDatabase.driver(
        resolved.uri,
        auth=(
            resolved.user,
            resolved.password,
        ),
    )


def verify_neo4j_connection() -> Neo4jSettings:
    settings = get_neo4j_settings()

    with create_neo4j_driver(settings) as driver:
        driver.verify_connectivity()

        with driver.session(
            database=settings.database
        ) as session:
            record = session.run(
                "RETURN 1 AS value"
            ).single()

            if (
                record is None
                or record["value"] != 1
            ):
                raise RuntimeError(
                    "Neo4j connectivity check failed."
                )

    return settings