sysadmin reconstruct notification page (#4089)

* sysadmin reconstruct notification page

* [system admin] notifications: fixup & improvement

* [system admin] notifications: fixup for urls.py

frontend/src/components/dialog/sysadmin-dialog/sysadmin-add-sys-notification-dialog.js

@@ -0,0 +1,67 @@
+import React from 'react';
+import PropTypes from 'prop-types';
+import { Button, Modal, ModalHeader, ModalBody, ModalFooter, Form, FormGroup, Input } from 'reactstrap';
+import { gettext } from '../../../utils/constants';
+
+const propTypes = {
+  toggle: PropTypes.func.isRequired,
+  addNotification: PropTypes.func.isRequired
+};
+
+class SysAdminAddSysNotificationDialog extends React.Component {
+
+  constructor(props) {
+    super(props);
+    this.state = {
+      value: '',
+      isSubmitBtnActive: false
+    };
+  }
+
+  handleChange = (e) => {
+    const value = e.target.value;
+    if (!value.trim()) {
+      this.setState({isSubmitBtnActive: false});
+    } else {
+      this.setState({isSubmitBtnActive: true});
+    }
+
+    this.setState({value: value});
+  }
+
+  handleSubmit = () => {
+    this.toggle();
+    this.props.addNotification(this.state.value.trim());
+  }
+
+  toggle = () => {
+    this.props.toggle();
+  }
+
+  render() {
+    return (
+      <Modal isOpen={true} toggle={this.toggle}>
+        <ModalHeader toggle={this.toggle}>{gettext('Add new notification')}</ModalHeader>
+        <ModalBody>
+          <Form>
+            <FormGroup>
+              <Input
+                type="textarea"
+                value={this.state.value}
+                onChange={this.handleChange}
+              />
+            </FormGroup>
+          </Form>
+        </ModalBody>
+        <ModalFooter>
+          <Button color="secondary" onClick={this.toggle}>{gettext('Cancel')}</Button>
+          <Button color="primary" onClick={this.handleSubmit} disabled={!this.state.isSubmitBtnActive}>{gettext('Submit')}</Button>
+        </ModalFooter>
+      </Modal>
+    );
+  }
+}
+
+SysAdminAddSysNotificationDialog.propTypes = propTypes;
+
+export default SysAdminAddSysNotificationDialog;