const admin = require("firebase-admin");

module.exports = async (partyName) => {
  // DELETE MESSAGES
  const partyMessagesRef = admin
    .firestore()
    .collection("rooms")
    .doc(partyName)
    .collection("messages");
  const partyMessagesQuery = partyMessagesRef.orderBy("time").limit(200);
  deleteCollection(partyMessagesQuery);
  // DELETE USERS
  const partyUsersRef = admin
    .firestore()
    .collection("rooms")
    .doc(partyName)
    .collection("messages");
  const partyUsersQuery = partyUsersRef.orderBy("time").limit(200);
  deleteCollection(partyUsersQuery);
  // DELETE PARTY DOC
  admin.firestore().collection("rooms").doc(partyName).delete();
};

async function deleteCollection(query) {
  const db = admin.firestore();
  return new Promise((resolve, reject) => {
    deleteQueryBatch(db, query, resolve).catch(reject);
  });
}

async function deleteQueryBatch(db, query, resolve) {
  const snapshot = await query.get();
  const batchSize = snapshot.size;
  if (batchSize === 0) {
    resolve();
    return;
  }
  const batch = admin.firestore().batch();
  snapshot.docs.forEach((doc) => {
    batch.delete(doc.ref);
  });
  await batch.commit();
  process.nextTick(() => {
    deleteQueryBatch(db, query, resolve);
  });
}