// Copyright 2015, 2016 Parity Technologies (UK) Ltd.
// This file is part of Parity.

// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity.  If not, see <http://www.gnu.org/licenses/>.

import Contracts from '~/contracts';
import subscribeToEvent from '~/util/subscribe-to-event';

import registryABI from '~/contracts/abi/registry.json';

import { setReverse, startCachingReverses } from './actions';

export default class RegistryMiddleware {
  toMiddleware () {
    return (store) => {
      const api = Contracts.get()._api;
      let contract, confirmedEvents, removedEvents, interval;

      let addressesToCheck = {};

      const onLog = (log) => {
        switch (log.event) {
          case 'ReverseConfirmed':
            addressesToCheck[log.params.reverse.value] = true;

            break;
          case 'ReverseRemoved':
            delete addressesToCheck[log.params.reverse.value];

            break;
        }
      };

      const checkReverses = () => {
        Object
          .keys(addressesToCheck)
          .forEach((address) => {
            contract
              .instance
              .reverse
              .call({}, [ address ])
              .then((reverse) => store.dispatch(setReverse(address, reverse)));
          });

        addressesToCheck = {};
      };

      return (next) => (action) => {
        switch (action.type) {
          case 'initAll':
            next(action);
            store.dispatch(startCachingReverses());

            break;
          case 'startCachingReverses':
            const { registry } = Contracts.get();

            registry.getInstance()
              .then((instance) => api.newContract(registryABI, instance.address))
              .then((_contract) => {
                contract = _contract;

                confirmedEvents = subscribeToEvent(_contract, 'ReverseConfirmed');
                confirmedEvents.on('log', onLog);

                removedEvents = subscribeToEvent(_contract, 'ReverseRemoved');
                removedEvents.on('log', onLog);

                interval = setInterval(checkReverses, 2000);
              })
              .catch((err) => {
                console.error('Failed to start caching reverses:', err);
                throw err;
              });

            break;
          case 'stopCachingReverses':
            if (confirmedEvents) {
              confirmedEvents.unsubscribe();
            }
            if (removedEvents) {
              removedEvents.unsubscribe();
            }
            if (interval) {
              clearInterval(interval);
            }

            break;
          default:
            next(action);
        }
      };
    };
  }
};