Added logic to detect duplicated servers when importing a servers list

src/servers/helpers/DuplicatedServersModal.tsx

@@ -0,0 +1,38 @@
+import { FC, Fragment } from 'react';
+import { Button, Modal, ModalBody, ModalFooter, ModalHeader } from 'reactstrap';
+import { ServerData } from '../data';
+
+interface DuplicatedServersModalProps {
+  duplicatedServers: ServerData[];
+  isOpen: boolean;
+  onDiscard: () => void;
+  onSave: () => void;
+}
+
+export const DuplicatedServersModal: FC<DuplicatedServersModalProps> = (
+  { isOpen, duplicatedServers, onDiscard, onSave },
+) => {
+  const hasMultipleServers = duplicatedServers.length > 1;
+
+  return (
+    <Modal centered isOpen={isOpen}>
+      <ModalHeader>Duplicated server{hasMultipleServers && 's'}</ModalHeader>
+      <ModalBody>
+        <p>{hasMultipleServers ? 'The next servers already exist:' : 'There is already a server with:'}</p>
+        <ul>
+          {duplicatedServers.map(({ url, apiKey }, index) => !hasMultipleServers ? (
+            <Fragment key={index}>
+              <li>URL: <b>{url}</b></li>
+              <li>API key: <b>{apiKey}</b></li>
+            </Fragment>
+          ) : <li key={index}><b>{url}</b> - <b>{apiKey}</b></li>)}
+        </ul>
+        {hasMultipleServers ? 'Do you want to ignore duplicated servers?' : 'Do you want to save this server anyway?'}
+      </ModalBody>
+      <ModalFooter>
+        <Button color="link" onClick={onDiscard}>{hasMultipleServers ? 'Ignore duplicated' : 'Discard'}</Button>
+        <Button color="primary" onClick={onSave}>Save anyway</Button>
+      </ModalFooter>
+    </Modal>
+  );
+};