import {
  createContext,
  useState,
  useContext,
  useEffect,
  useMemo,
  useCallback,
} from 'react';
import { useKeysContext } from './keys';
import { db } from '../db/initializeFirebase';
import {
  DID_OPEN_TABLES_EVENT_NAME,
  getSavedPOSTransactions,
  pointOfSaleEventEmitter,
  POS_EVENT_UPDATE,
  queuePOSTransactions,
} from '../app/functions/pos';
import { getTwoWeeksAgoDate } from '../app/functions/rotateAddressDateChecker';
import {
  collection,
  getDocs,
  onSnapshot,
  orderBy,
  query,
  startAfter,
  where,
} from '@react-native-firebase/firestore';
// Initiate context
const POSTransactionsContextManager = createContext(null);

const POSTransactionsProvider = ({ children }) => {
  const { publicKey, contactsPrivateKey } = useKeysContext();
  const [txList, setTxList] = useState([]);
  const [didOpenTable, setDidOpenTable] = useState(false);

  const updateTxListFunction = useCallback(async () => {
    const txs = await getSavedPOSTransactions();
    setTxList(txs || []);
    return txs || [];
  }, []);

  const groupedTxs = useMemo(() => {
    try {
      let totals = {};
      for (const tx of txList) {
        const serverName = tx.serverName?.toLowerCase()?.trim();
        let savedAccount = totals[serverName];
        if (!savedAccount) {
          totals[serverName] = {
            totalTipAmount: 0,
            txs: [],
            unpaidTxs: [],
            lastActivity: 0,
            totalUnpaidTxs: 0,
            totalPaidTxs: 0,
          };
        }
        savedAccount = totals[serverName];

        let newUnpaidTxArray = [...savedAccount.unpaidTxs];
        if (!tx.didPay) newUnpaidTxArray.push(tx);

        totals[serverName] = {
          totalTipAmount:
            savedAccount.totalTipAmount + (tx.didPay ? 0 : tx.tipAmountSats),
          txs: [tx, ...savedAccount.txs],
          unpaidTxs: newUnpaidTxArray,
          lastActivity:
            tx.timestamp > savedAccount.lastActivity
              ? tx.timestamp
              : savedAccount.lastActivity,
          totalUnpaidTxs:
            savedAccount.totalUnpaidTxs + (!tx.didPay ? tx.tipAmountSats : 0),
          totalPaidTxs:
            savedAccount.totalPaidTxs + (!!tx.didPay ? tx.tipAmountSats : 0),
        };
      }

      if (!Object.keys(totals).length) {
        return [];
      }

      return Object.entries(totals);
    } catch (err) {
      console.log('getting tip totals error', err);
      return [];
    }
  }, [txList]);

  useEffect(() => {
    if (!didOpenTable) return;
    if (!publicKey) return;
    console.log('running pos transactions listener...');
    const now = new Date().getTime();

    const transaction = query(
      collection(db, 'posTransactions'),
      where('storePubKey', '==', publicKey),
      orderBy('dateAdded'),
      startAfter(now),
    );

    const unsubscribe = onSnapshot(transaction, snapshot => {
      snapshot?.docChanges()?.forEach(change => {
        console.log('recived a new pos transaction', change.type);
        if (change.type === 'added') {
          const newTX = change.doc.data();
          queuePOSTransactions({
            transactionsList: [newTX],
            privateKey: contactsPrivateKey,
          });
        }
      });
    });

    return () => {
      console.log(`unsubscribing pos transactions listener...`, !!unsubscribe);
      if (unsubscribe) unsubscribe();
    };
  }, [publicKey, didOpenTable]);

  useEffect(() => {
    async function loadSavedTxs() {
      const txs = await updateTxListFunction();
      console.log('saved pos transactions', txs);
      const lastMessageTimestamp = txs.length
        ? txs[0]?.dbDateAdded
        : getTwoWeeksAgoDate();

      console.log('last pos transaction timestamp', txs[0]?.dbDateAdded);
      const transactionsRef = collection(db, 'posTransactions');

      const messagesQuery = query(
        transactionsRef,
        where('storePubKey', '==', publicKey),
        where('dateAdded', '>', lastMessageTimestamp),
      );

      const querySnapshot = await getDocs(messagesQuery);

      if (querySnapshot.empty) return;

      let messsageList = [];

      for (const doc of querySnapshot.docs) {
        const data = doc.data();
        messsageList.push(data);
      }
      console.log('loaded missed pos transactions', messsageList);
      queuePOSTransactions({
        transactionsList: messsageList,
        privateKey: contactsPrivateKey,
      });
    }
    if (!didOpenTable) return;
    if (!publicKey) return;
    loadSavedTxs();
  }, [publicKey, didOpenTable]);

  const handlePosTableOpen = useCallback(eventType => {
    if (eventType === 'opened') {
      setDidOpenTable(true);
    }
  }, []);
  useEffect(() => {
    // listens for events from the db and updates the state
    pointOfSaleEventEmitter.on(DID_OPEN_TABLES_EVENT_NAME, handlePosTableOpen);
    pointOfSaleEventEmitter.on(POS_EVENT_UPDATE, updateTxListFunction);
    return () => {
      pointOfSaleEventEmitter.removeAllListeners(POS_EVENT_UPDATE);
      pointOfSaleEventEmitter.removeAllListeners(DID_OPEN_TABLES_EVENT_NAME);
    };
  }, []);

  const contextValue = useMemo(
    () => ({
      groupedTxs,
    }),
    [groupedTxs],
  );

  return (
    <POSTransactionsContextManager.Provider value={contextValue}>
      {children}
    </POSTransactionsContextManager.Provider>
  );
};

function usePOSTransactions() {
  const context = useContext(POSTransactionsContextManager);
  if (!context) {
    throw new Error(
      'usePOSTransactions must be used within a POSTransactionsProvider',
    );
  }
  return context;
}

export {
  POSTransactionsContextManager,
  POSTransactionsProvider,
  usePOSTransactions,
};