5 files changed, 65 insertions, 21 deletions
diff --git a/app/app.js b/app/app.js
index c3d5acbcb8..f63a24733f 100644
--- a/app/app.js
+++ b/app/app.js
@@ -17,7 +17,7 @@ import mapBackendEventsToRouter from './lib/backend-routing';
 import type { LoginState, ConnectionState } from './enums';
 import type { TrayIconType } from './lib/tray-icon-manager';
 
-const initialState = {};
+const initialState = null;
 const memoryHistory = createMemoryHistory();
 const store = configureStore(initialState, memoryHistory);
 const backend = new Backend();
diff --git a/app/reducers/connect.js b/app/reducers/connect.js
index cf3dc35906..8ed4a564dc 100644
--- a/app/reducers/connect.js
+++ b/app/reducers/connect.js
@@ -1,7 +1,18 @@
+// @flow
 import { handleActions } from 'redux-actions';
 import actions from '../actions/connect';
 
-const initialState = {
+import type { ReduxAction } from '../store';
+import type { ConnectionState } from '../enums';
+
+export type ConnectReduxState = {
+  status: ConnectionState,
+  isOnline: boolean,
+  serverAddress: ?string,
+  clientIp: ?string
+};
+
+const initialState: ConnectReduxState = {
   status: 'disconnected',
   isOnline: true,
   serverAddress: null,
@@ -9,7 +20,7 @@ const initialState = {
 };
 
 export default handleActions({
-  [actions.connectionChange]: (state, action) => {
+  [actions.connectionChange.toString()]: (state: ConnectReduxState, action: ReduxAction<$Shape<ConnectReduxState>>) => {
     return { ...state, ...action.payload };
   }
 }, initialState);
diff --git a/app/reducers/settings.js b/app/reducers/settings.js
index 008930a6e0..2339d1fc3a 100644
--- a/app/reducers/settings.js
+++ b/app/reducers/settings.js
@@ -1,14 +1,22 @@
+// @flow
 import { handleActions } from 'redux-actions';
 import { defaultServer } from '../config';
 import actions from '../actions/settings';
 
-const initialState = {
+import type { ReduxAction } from '../store';
+
+export type SettingsReduxState = {
+  autoSecure: boolean,
+  preferredServer: string
+};
+
+const initialState: SettingsReduxState = {
   autoSecure: true,
   preferredServer: defaultServer
 };
 
 export default handleActions({
-  [actions.updateSettings]: (state, action) => {
+  [actions.updateSettings.toString()]: (state: SettingsReduxState, action: ReduxAction<$Shape<SettingsReduxState>>) => {
     return { ...state, ...action.payload };
   }
 }, initialState);
diff --git a/app/reducers/user.js b/app/reducers/user.js
index 1409c77a4e..47d9f97f5d 100644
--- a/app/reducers/user.js
+++ b/app/reducers/user.js
@@ -1,9 +1,24 @@
+// @flow
 import { handleActions } from 'redux-actions';
 import actions from '../actions/user';
 
-const initialState = {
+import type { ReduxAction } from '../store';
+import type { LoginState } from '../enums';
+import type { BackendError } from '../lib/backend';
+
+export type UserReduxState = {
+  account: ?string,
+  paidUntil: ?string, // ISO8601
+  location: Array<number>,
+  country: ?string,
+  city: ?string,
+  status: LoginState,
+  error: ?BackendError
+};
+
+const initialState: UserReduxState = {
   account: null,
-  paidUntil: null, // ISO8601
+  paidUntil: null,
   location: [0, 0],
   country: null,
   city: null,
@@ -12,7 +27,7 @@ const initialState = {
 };
 
 export default handleActions({
-  [actions.loginChange]: (state, action) => {
+  [actions.loginChange.toString()]: (state: UserReduxState, action: ReduxAction<$Shape<UserReduxState>>) => {
     return { ...state, ...action.payload };
   }
 }, initialState);
diff --git a/app/store.js b/app/store.js
index 6c48cbcde8..667f03b5a3 100644
--- a/app/store.js
+++ b/app/store.js
@@ -1,8 +1,8 @@
+// @flow
 import { createStore, applyMiddleware, combineReducers, compose } from 'redux';
 import { routerMiddleware, routerReducer, push, replace } from 'react-router-redux';
 import persistState from 'redux-localstorage';
 import thunk from 'redux-thunk';
-
 import user from './reducers/user';
 import connect from './reducers/connect';
 import settings from './reducers/settings';
@@ -10,18 +10,26 @@ import userActions from './actions/user';
 import connectActions from './actions/connect';
 import settingsActions from './actions/settings';
 
-/**
- * Configure redux store
- *
- * @export
- * @param {Object} initialState
- * @param {History} routerHistory
- * @returns {Redux.Store}
- */
-export default function configureStore(initialState, routerHistory) {
+import type { Store, Dispatch } from 'redux';
+import type { History } from 'history';
+import type { UserReduxState } from './reducers/user';
+import type { ConnectReduxState } from './reducers/connect';
+import type { SettingsReduxState } from './reducers/settings';
+
+export type ReduxState = {
+  user: UserReduxState,
+  connect: ConnectReduxState,
+  settings: SettingsReduxState
+};
+export type ReduxAction<T> = { type: string, payload: T };
+export type ReduxStore = Store<ReduxState, ReduxAction<*>>;
+export type ReduxGetStateFn = () => ReduxState;
+export type ReduxDispatchFn<T: *> = Dispatch<ReduxAction<T>>;
+
+export default function configureStore(initialState: ?ReduxState, routerHistory: History): ReduxStore {
   const router = routerMiddleware(routerHistory);
 
-  const actionCreators = {
+  const actionCreators: { string: Function } = {
     ...userActions,
     ...connectActions,
     ...settingsActions,
@@ -45,6 +53,8 @@ export default function configureStore(initialState, routerHistory) {
 
   const enhancer = composeEnhancers(applyMiddleware(...middlewares), persistState());
   const rootReducer = combineReducers(reducers);
-
-  return createStore(rootReducer, initialState, enhancer);
+  if(initialState) {
+    return createStore(rootReducer, initialState, enhancer);
+  }
+  return createStore(rootReducer, enhancer);
 }