/* @flow */
import { DEVICE, BLOCKCHAIN } from 'trezor-connect';
import { LOCATION_CHANGE } from 'connected-react-router';
import * as WALLET from 'actions/constants/wallet';
import * as CONNECT from 'actions/constants/TrezorConnect';

import * as WalletActions from 'actions/WalletActions';
import * as NotificationActions from 'actions/NotificationActions';
import * as LocalStorageActions from 'actions/LocalStorageActions';
import * as TrezorConnectActions from 'actions/TrezorConnectActions';
import * as SelectedAccountActions from 'actions/SelectedAccountActions';
import * as SendFormActions from 'actions/SendFormActions';
import * as DiscoveryActions from 'actions/DiscoveryActions';
import * as RouterActions from 'actions/RouterActions';

import type { Middleware, MiddlewareAPI, MiddlewareDispatch, Action } from 'flowtype';

/**
 * Middleware
 */
const WalletService: Middleware = (api: MiddlewareAPI) => (next: MiddlewareDispatch) => async (
    action: Action
): Promise<Action> => {
    const prevState = api.getState();
    // Application live cycle starts HERE!
    // when first LOCATION_CHANGE is called router does not have "location" set yet
    if (action.type === LOCATION_CHANGE && prevState.wallet.firstLocationChange) {
        // initialize wallet
        api.dispatch(WalletActions.init());
        // set initial url
        // TODO: validate if initial url is potentially correct
        // exclude landing page url
        const { pathname } = action.payload.location;
        const isValidPath = !api.dispatch(RouterActions.isLandingPageUrl(pathname, true));
        if (isValidPath) {
            api.dispatch({
                type: WALLET.SET_INITIAL_URL,
                pathname,
                state: {},
            });
        }
        // pass action and break process
        return next(action);
    }

    // pass action
    next(action);

    switch (action.type) {
        case WALLET.SET_FIRST_LOCATION_CHANGE:
            api.dispatch(LocalStorageActions.loadData());
            break;
        case WALLET.SET_SELECTED_DEVICE:
            // try to authorize device
            // api.dispatch(TrezorConnectActions.authorizeDevice());
            api.dispatch(TrezorConnectActions.requestWalletType());
            break;
        case DEVICE.CONNECT:
            api.dispatch(WalletActions.clearUnavailableDevicesData(prevState, action.payload));
            break;
        default: {
            break;
        }
    }

    // update common values ONLY if application is ready
    if (!api.getState().wallet.ready) return action;

    // check for "selectedDevice" change before any action
    const selectedDeviceDidChange = await api.dispatch(WalletActions.observe(prevState, action));

    // double verification needed
    // Corner case: LOCATION_CHANGE was called but pathname didn't changed (redirection from RouterService)
    const prevLocation = prevState.router.location;
    const currentLocation = api.getState().router.location;
    if (action.type === LOCATION_CHANGE && prevLocation.pathname !== currentLocation.pathname) {
        // watch for network change
        if (prevLocation.state.network !== currentLocation.state.network) {
            api.dispatch({
                type: CONNECT.NETWORK_CHANGED,
                payload: {
                    network: currentLocation.state.network,
                },
            });

            // try to stop currently running discovery on previous network
            api.dispatch(DiscoveryActions.stop());

            // try to start new discovery on new network
            api.dispatch(DiscoveryActions.restore());
        }

        // watch for account change
        if (
            prevLocation.state.network !== currentLocation.state.network ||
            prevLocation.state.account !== currentLocation.state.account
        ) {
            api.dispatch(SelectedAccountActions.dispose());
        }

        // clear notifications
        api.dispatch(NotificationActions.clear(prevLocation.state, currentLocation.state));
    }

    // if "selectedDevice" didn't change observe common values in SelectedAccountReducer
    if (!selectedDeviceDidChange) {
        if (!(await api.dispatch(SelectedAccountActions.observe(prevState, action)))) {
            // if "selectedAccount" didn't change observe send form props changes
            api.dispatch(SendFormActions.observe(prevState, action));
        }
    } else {
        // no changes in common values
        if (action.type === CONNECT.RECEIVE_WALLET_TYPE) {
            if (action.device.state) {
                // redirect to root view (Dashboard) if device was authenticated before
                api.dispatch(RouterActions.selectFirstAvailableDevice(true));
            }
            api.dispatch(TrezorConnectActions.authorizeDevice());
        }
        if (action.type === CONNECT.AUTH_DEVICE) {
            // selected device did changed
            // try to restore discovery after device authentication
            api.dispatch(DiscoveryActions.restore());
        }
    }

    // even if "selectedDevice" didn't change because it was updated on DEVICE.CHANGED before DEVICE.CONNECT action
    // try to restore discovery
    if (action.type === DEVICE.CONNECT) {
        api.dispatch(DiscoveryActions.restore());
    } else if (action.type === DEVICE.DISCONNECT) {
        api.dispatch(DiscoveryActions.stop());
    }

    // try to restore discovery on BLOCKCHAIN.CONNECT event
    // edge case when backend throws error during discovery
    if (action.type === BLOCKCHAIN.CONNECT) {
        api.dispatch(DiscoveryActions.restore());
    }

    return action;
};

export default WalletService;