Support multiple integration managers behind a labs flag

Fixes https://github.com/vector-im/riot-web/issues/10622
Implements [MSC1957](https://github.com/matrix-org/matrix-doc/pull/1957)

Design is not final.

src/components/views/dialogs/TabbedIntegrationManagerDialog.js

@@ -0,0 +1,172 @@
+/*
+Copyright 2019 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import React from 'react';
+import PropTypes from 'prop-types';
+import {IntegrationManagers} from "../../../integrations/IntegrationManagers";
+import {Room} from "matrix-js-sdk";
+import sdk from '../../../index';
+import {dialogTermsInteractionCallback, TermsNotSignedError} from "../../../Terms";
+import classNames from 'classnames';
+import ScalarMessaging from "../../../ScalarMessaging";
+
+export default class TabbedIntegrationManagerDialog extends React.Component {
+    static propTypes = {
+        /**
+         * Called with:
+         *     * success {bool} True if the user accepted any douments, false if cancelled
+         *     * agreedUrls {string[]} List of agreed URLs
+         */
+        onFinished: PropTypes.func.isRequired,
+
+        /**
+         * Optional room where the integration manager should be open to
+         */
+        room: PropTypes.instanceOf(Room),
+
+        /**
+         * Optional screen to open on the integration manager
+         */
+        screen: PropTypes.string,
+
+        /**
+         * Optional integration ID to open in the integration manager
+         */
+        integrationId: PropTypes.string,
+    };
+
+    constructor(props) {
+        super(props);
+
+        this.state = {
+            managers: IntegrationManagers.sharedInstance().getOrderedManagers(),
+            busy: true,
+            currentIndex: 0,
+            currentConnected: false,
+            currentLoading: true,
+            currentScalarClient: null,
+        };
+    }
+
+    componentDidMount(): void {
+        this.openManager(0, true);
+    }
+
+    openManager = async (i: number, force = false) => {
+        if (i === this.state.currentIndex && !force) return;
+
+        const manager = this.state.managers[i];
+        const client = manager.getScalarClient();
+        this.setState({
+            busy: true,
+            currentIndex: i,
+            currentLoading: true,
+            currentConnected: false,
+            currentScalarClient: client,
+        });
+
+        ScalarMessaging.setOpenManagerUrl(manager.uiUrl);
+
+        client.setTermsInteractionCallback((policyInfo, agreedUrls) => {
+            // To avoid visual glitching of two modals stacking briefly, we customise the
+            // terms dialog sizing when it will appear for the integrations manager so that
+            // it gets the same basic size as the IM's own modal.
+            return dialogTermsInteractionCallback(
+                policyInfo, agreedUrls, 'mx_TermsDialog_forIntegrationsManager',
+            );
+        });
+
+        try {
+            await client.connect();
+            if (!client.hasCredentials()) {
+                this.setState({
+                    busy: false,
+                    currentLoading: false,
+                    currentConnected: false,
+                });
+            } else {
+                this.setState({
+                    busy: false,
+                    currentLoading: false,
+                    currentConnected: true,
+                });
+            }
+        } catch (e) {
+            if (e instanceof TermsNotSignedError) {
+                return;
+            }
+
+            console.error(e);
+            this.setState({
+                busy: false,
+                currentLoading: false,
+                currentConnected: false,
+            });
+        }
+    };
+
+    _renderTabs() {
+        const AccessibleButton = sdk.getComponent("views.elements.AccessibleButton");
+        return this.state.managers.map((m, i) => {
+            const classes = classNames({
+                'mx_TabbedIntegrationManagerDialog_tab': true,
+                'mx_TabbedIntegrationManagerDialog_currentTab': this.state.currentIndex === i,
+            });
+            return (
+                <AccessibleButton
+                    className={classes}
+                    onClick={() => this.openManager(i)}
+                    key={`tab_${i}`}
+                    disabled={this.state.busy}
+                >
+                    {m.name}
+                </AccessibleButton>
+            );
+        })
+    }
+
+    _renderTab() {
+        const IntegrationsManager = sdk.getComponent("views.settings.IntegrationsManager");
+        let uiUrl = null;
+        if (this.state.currentScalarClient) {
+            uiUrl = this.state.currentScalarClient.getScalarInterfaceUrlForRoom(
+                this.props.room,
+                this.props.screen,
+                this.props.integrationId,
+            );
+        }
+        return <IntegrationsManager
+            configured={true}
+            loading={this.state.currentLoading}
+            connected={this.state.currentConnected}
+            url={uiUrl}
+            onFinished={() => {/* no-op */}}
+        />;
+    }
+
+    render() {
+        return (
+            <div className='mx_TabbedIntegrationManagerDialog_container'>
+                <div className='mx_TabbedIntegrationManagerDialog_tabs'>
+                    {this._renderTabs()}
+                </div>
+                <div className='mx_TabbedIntegrationManagerDialog_currentManager'>
+                    {this._renderTab()}
+                </div>
+            </div>
+        )
+    }
+}