export default function ChatScreen()

in sample/src/screens/ChatScreen.js [20:137]
84 lines of code
6 McCabe index (conditional complexity)

export default function ChatScreen(props) {
  let { event } = props.route.params;
  const navigation = useNavigation();
  let [currentUser, setCurrentUser] = useState(null);
  const [messages, setMessages] = useState([]);
  const getChatsByEventQuery = `query GetEvent(
    $id: ID!
    $nextToken: String
    $limit: Int
  ) {
    getEvent(id: $id) {
      id
      chats (
        limit: $limit
        sortDirection: DESC
        nextToken: $nextToken
      ) {
        items  {
          id
          content
          createdAt
          user {
            id
            name
          }
        }
        nextToken
      }
    }
  }
  `;

  const onSend = (newMessages = []) => {
    setMessages(GiftedChat.append(messages, newMessages));
    createEventChat(event.id, currentUser.attributes.sub, newMessages[0].text);
  };

  const renderChat = () => {
    if (currentUser)
      return (
        <GiftedChat
          messages={messages}
          onSend={(newMessages) => onSend(newMessages)}
          user={{
            _id: currentUser.attributes.sub,
            name: currentUser.attributes.given_name
              ? `${currentUser.attributes.given_name} ${currentUser.attributes.family_name}`
              : currentUser.username,
          }}
          inverted={true}
          placeholder='Type a message...'
        />
      );
    return <Text>Loading...</Text>;
  };

  async function authUser() {
    const cognitoUser = await Auth.currentAuthenticatedUser();
    if (cognitoUser) {
      setCurrentUser(cognitoUser);
    }
  }

  useEffect(() => {
    const getChatsByEventId = async () => {
      const input = {
        id: event.id,
        nextToken: null,
        limit: 20,
      };

      try {
        const result = await API.graphql(
          graphqlOperation(getChatsByEventQuery, input)
        );
        const existingMessages = result.data.getEvent.chats.items;
        setMessages(
          existingMessages.map((item) => {
            return formatMessage(item);
          })
        );
      } catch (e) {
        console.log(e);
      }
    };

    getChatsByEventId();
  }, [setMessages]);

  useEffect(() => {
    authUser();
    const subscription = API.graphql(graphqlOperation(onCreateChat)).subscribe({
      next: (response) => {
        let newMessageFromResponse = response.value.data.onCreateChat;
        if (
          newMessageFromResponse.event.id === event.id &&
          newMessageFromResponse.user.id !== currentUser.attributes.sub
        ) {
          setMessages(
            GiftedChat.append(messages, formatMessage(newMessageFromResponse))
          );
        }
      },
      error: (error) => {
        console.error(error);
      },
    });

    return () => {
      subscription.unsubscribe();
    };
  }, [messages]);

  return (
    <Container>
      <Header>
        <Left>
          <Button transparent onPress={() => navigation.goBack()}>