# genesis/graphdb.py
from __future__ import annotations

import os
from typing import Dict, List

from neo4j import GraphDatabase

NEO4J_URI = os.getenv("NEO4J_URI")
NEO4J_USER = os.getenv("NEO4J_USER")
NEO4J_PASSWORD = os.getenv("NEO4J_PASSWORD")


def _require_config():
    if not (NEO4J_URI and NEO4J_USER and NEO4J_PASSWORD):
        raise RuntimeError(
            "Neo4j not configured. Set NEO4J_URI, NEO4J_USER, NEO4J_PASSWORD in Space Secrets."
        )


async def write_topic_and_papers(topic: str, citations: List[Dict[str, str]]) -> Dict[str, int]:
    """
    Create/merge a Topic node and Paper nodes, and connect them with MENTIONS edges.
    Schema:
      (t:Topic {id})-[:MENTIONS]->(p:Paper {url})  with p.title set/updated.
    Returns: {"nodes": <int>, "rels": <int>}
    """
    _require_config()
    driver = GraphDatabase.driver(NEO4J_URI, auth=(NEO4J_USER, NEO4J_PASSWORD))

    nodes = 0
    rels = 0
    try:
        with driver.session() as sess:
            # Topic
            sess.run(
                "MERGE (t:Topic {id:$id}) SET t.title=$title",
                id=(topic or "Topic")[:200],
                title=(topic or "Topic")[:500],
            )
            nodes += 1

            # Papers + edges
            for c in citations or []:
                title = (c.get("title") or "citation")[:500]
                url = (c.get("url") or "")[:1000]
                if not url and not title:
                    continue

                sess.run(
                    """
                    MERGE (p:Paper {url:$url})
                    ON CREATE SET p.title=$title
                    ON MATCH SET  p.title = coalesce(p.title, $title)
                    WITH p
                    MATCH (t:Topic {id:$topic})
                    MERGE (t)-[:MENTIONS]->(p)
                    """,
                    url=url,
                    title=title,
                    topic=(topic or "Topic")[:200],
                )
                nodes += 1
                rels += 1

        return {"nodes": nodes, "rels": rels}
    finally:
        driver.close()


# Optional helper for debugging connectivity in a notebook/Space shell
def verify_connection() -> str:
    _require_config()
    driver = GraphDatabase.driver(NEO4J_URI, auth=(NEO4J_USER, NEO4J_PASSWORD))
    try:
        with driver.session() as sess:
            res = sess.run("RETURN 1 AS ok").single()
            assert res and res["ok"] == 1
        return "Neo4j connection OK."
    finally:
        driver.close()