[RN] Make the calendar the default tab when there are calendar entries fetched.

react/features/base/react/components/native/AbstractPagedList.js

     constructor(props: Props) {
         super(props);
 
-        // props.defaultPage may point to a non existing page if some of the
-        // pages are disabled.
-        const maxPageIndex
-            = props.pages.filter(page => page.component).length - 1;
-
         this.state = {
-            pageIndex: Math.max(0, Math.min(maxPageIndex, props.defaultPage))
+            pageIndex: this._validatePageIndex(props.defaultPage)
         };
     }
 
+    /**
+     * Implements React {@code Component}'s componentWillReceiveProps.
+     *
+     * @inheritdoc
+     */
+    componentWillReceiveProps(newProps: Props) {
+        const { defaultPage } = newProps;
+
+        if (defaultPage !== this.props.defaultPage) {
+            // Default page changed due to a redux update. This is likely to
+            // happen after APP_WILL_MOUNT. So we update the active tab.
+            this._platformSpecificPageSelect(defaultPage);
+        }
+    }
+
     /**
      * Renders the component.
      *
         );
     }
 
+    _platformSpecificPageSelect: number => void
+
+    /**
+     * Method to be overriden by the components implementing this abstract class
+     * to handle platform specific actions on page select.
+     *
+     * @protected
+     * @param {number} pageIndex - The selected page index.
+     * @returns {void}
+     */
+    _platformSpecificPageSelect(pageIndex) {
+        this._selectPage(pageIndex);
+    }
+
     _renderPagedList: boolean => React$Node;
 
     _selectPage: number => void;
      * @returns {void}
      */
     _selectPage(pageIndex: number) {
+        const validatedPageIndex = this._validatePageIndex(pageIndex);
+
         this.setState({
-            pageIndex
+            pageIndex: validatedPageIndex
         });
 
         // The page's Component may have a refresh(dispatch) function which we
         // invoke when the page is selected.
-        const selectedPage = this.props.pages[pageIndex];
+        const selectedPage = this.props.pages[validatedPageIndex];
 
         if (selectedPage && selectedPage.component) {
             const { refresh } = selectedPage.component;
             typeof refresh === 'function' && refresh(this.props.dispatch);
         }
     }
+
+    _validatePageIndex: number => number
+
+    /**
+     * Validates the requested page index and returns a safe value.
+     *
+     * @private
+     * @param {number} pageIndex - The requested page index.
+     * @returns {number}
+     */
+    _validatePageIndex(pageIndex) {
+        // pageIndex may point to a non existing page if some of the pages are
+        // disabled (their component property is undefined).
+        const maxPageIndex
+            = this.props.pages.filter(page => page.component).length - 1;
+
+        return Math.max(0, Math.min(maxPageIndex, pageIndex));
+    }
 }

react/features/base/react/components/native/PagedList.android.js

         }
     }
 
+    /**
+     * Platform specific actions to run on page select.
+     *
+     * @private
+     * @param {number} pageIndex - The selected page index.
+     * @returns {void}
+     */
+    _platformSpecificPageSelect(pageIndex) {
+        this._viewPager.setPage(pageIndex);
+        this._selectPage(pageIndex);
+    }
+
     /**
      * Renders a single page of the page list.
      *

react/features/calendar-sync/middleware.js

                     && store.dispatch(addKnownDomains(knownDomains));
             }
 
-            const result = next(action);
-
             _fetchCalendarEntries(store, false, false);
 
-            return result;
+            return next(action);
         }
 
         case REFRESH_CALENDAR: {

react/features/welcome/components/WelcomePageLists.js

 
 import React, { Component } from 'react';
 import { Platform } from 'react-native';
+import { connect } from 'react-redux';
 
 import { translate } from '../../base/i18n';
 import { PagedList } from '../../base/react';
 
 type Props = {
 
+    /**
+     * True if the calendar feature has fetched entries, false otherwise
+     */
+    _hasCalendarEntries: boolean,
+
     /**
      * Renders the lists disabled.
      */
      * @inheritdoc
      */
     render() {
-        const { disabled } = this.props;
+        const { disabled, _hasCalendarEntries } = this.props;
 
         return (
             <PagedList
-                defaultPage = { 0 }
+                defaultPage = { _hasCalendarEntries ? 1 : 0 }
                 disabled = { disabled }
                 pages = { this.pages } />
         );
     }
 }
 
-export default translate(WelcomePageLists);
+/**
+ * Maps (parts of) the redux state to the React {@code Component} props of
+ * {@code WelcomePageLists}.
+ *
+ * @param {Object} state - The redux state.
+ * @protected
+ * @returns {{
+ *     _hasCalendarEntries: boolean
+ * }}
+ */
+function _mapStateToProps(state: Object) {
+    const { events } = state['features/calendar-sync'];
+
+    return {
+        _hasCalendarEntries: Boolean(events && events.length)
+    };
+}
+
+export default translate(connect(_mapStateToProps)(WelcomePageLists));