import neo4j, { Driver, Session } from "neo4j-driver";
import { readFileSync } from "node:fs";
import { resolve } from "node:path";

let driver: Driver | null = null;

function readPassword(): string {
  if (process.env.NEO4J_PASSWORD) return process.env.NEO4J_PASSWORD;
  const passwordFile = resolve(
    process.env.PLATFORM_ROOT ?? resolve(import.meta.dirname, "../../../.."),
    "config/.neo4j-password",
  );
  try {
    return readFileSync(passwordFile, "utf-8").trim();
  } catch {
    throw new Error(
      `Neo4j password not found. Expected at ${passwordFile} or in NEO4J_PASSWORD env var.`,
    );
  }
}

export function getDriver(): Driver {
  if (!driver) {
    const uri = process.env.NEO4J_URI;
    if (!uri) {
      throw new Error(
        "[property-data] NEO4J_URI unset — refusing to default to bolt://localhost:7687",
      );
    }
    const user = process.env.NEO4J_USER ?? "neo4j";
    const password = readPassword();
    console.error(`[property-data] resolved neo4j_uri=${uri}`);
    driver = neo4j.driver(uri, neo4j.auth.basic(user, password));
  }
  return driver;
}

export function getSession(): Session {
  return getDriver().session();
}

export async function closeDriver(): Promise<void> {
  if (driver) {
    await driver.close();
    driver = null;
  }
}