const driver = require("../../graph_db");

function graphIdToNumber(value) {
  if (typeof value === "number") return value;
  if (value && typeof value.toNumber === "function") return value.toNumber();
  return Number(value);
}

function graphParams(userId) {
  return { db_id: Number(userId) };
}

async function getFriendIds(userId) {
  const { records } = await driver.executeQuery(
    "MATCH (me:Person {db_id: $db_id})-[:FRIENDS_WITH]-(f:Person) RETURN f.db_id AS id",
    graphParams(userId),
    { database: process.env.GRAPH_DB_NAME },
  );
  return new Set(records.map((record) => graphIdToNumber(record.get("id"))));
}

async function getFriendIdsAmong(userId, ids) {
  if (ids.length === 0) return new Set();
  const { records } = await driver.executeQuery(
    `MATCH (me:Person {db_id: $db_id})-[:FRIENDS_WITH]-(f:Person)
     WHERE f.db_id IN $ids
     RETURN f.db_id AS id`,
    { ...graphParams(userId), ids: ids.map(Number) },
    { database: process.env.GRAPH_DB_NAME },
  );
  return new Set(records.map((record) => graphIdToNumber(record.get("id"))));
}

async function areFriends(userId, otherId) {
  const friendIds = await getFriendIdsAmong(userId, [otherId]);
  return friendIds.has(Number(otherId));
}

module.exports = { getFriendIds, getFriendIdsAmong, areFriends, graphIdToNumber };