import * as React from 'react';
import { Link, useSearchParams } from 'react-router-dom';
import type { LinkProps } from 'react-router-dom';
import { useLazyQuery } from '@apollo/client';
import debounce from 'lodash/debounce';
import Box from '@mui/material/Box';
import Grid from '@mui/material/Grid';
import AddIcon from '@mui/icons-material/Add';
import CircularProgress from '@mui/material/CircularProgress';
import Divider from '@mui/material/Divider';
import Pagination from '@mui/material/Pagination';
import PaginationItem from '@mui/material/PaginationItem';
import type { IFlow } from '@automatisch/types';

import FlowRow from 'components/FlowRow';
import NoResultFound from 'components/NoResultFound';
import ConditionalIconButton from 'components/ConditionalIconButton';
import Container from 'components/Container';
import PageTitle from 'components/PageTitle';
import SearchInput from 'components/SearchInput';
import useFormatMessage from 'hooks/useFormatMessage'
import { GET_FLOWS } from 'graphql/queries/get-flows';
import * as URLS from 'config/urls';

const FLOW_PER_PAGE = 10;

const getLimitAndOffset = (page: number) => ({
  limit: FLOW_PER_PAGE,
  offset: (page - 1) * FLOW_PER_PAGE,
});

export default function Flows(): React.ReactElement {
  const formatMessage = useFormatMessage();
  const [searchParams, setSearchParams] = useSearchParams();
  const page = parseInt(searchParams.get('page') || '', 10) || 1;
  const [flowName, setFlowName] = React.useState('');
  const [loading, setLoading] = React.useState(false);
  const [getFlows, { data }] = useLazyQuery(GET_FLOWS, {
    onCompleted: () => { setLoading(false); },
  });

  const fetchData = React.useMemo(
    () => debounce((name) => getFlows(
      {
        variables: {
          ...getLimitAndOffset(page),
          name
        }
      }),
      300
    ),
    [page, getFlows]
  );

  React.useEffect(function fetchFlowsOnSearch() {
    setLoading(true);

    fetchData(flowName);
  }, [fetchData, flowName]);

  React.useEffect(function resetPageOnSearch() {
    // reset search params which only consists of `page`
    setSearchParams({})
  }, [flowName]);

  React.useEffect(function cancelDebounceOnUnmount() {
    return () => {
      fetchData.cancel();
    }
  }, []);

  const { pageInfo, edges } = data?.getFlows || {};

  const flows: IFlow[] = edges?.map(({ node }: { node: IFlow }) => node);
  const hasFlows = flows?.length;

  const onSearchChange = React.useCallback((event) => {
    setFlowName(event.target.value);
  }, []);

  const CreateFlowLink = React.useMemo(
    () =>
      React.forwardRef<HTMLAnchorElement, Omit<LinkProps, 'to'>>(function InlineLink(
        linkProps,
        ref,
      ) {
        return <Link ref={ref} to={URLS.CREATE_FLOW} {...linkProps} />;
      }),
    [],
  );

  return (
    <Box sx={{ py: 3 }}>
      <Container>
        <Grid container sx={{ mb: [0, 3] }} columnSpacing={1.5} rowSpacing={3}>
          <Grid container item xs sm alignItems="center" order={{ xs: 0 }}>
            <PageTitle>{formatMessage('flows.title')}</PageTitle>
          </Grid>

          <Grid item xs={12} sm="auto" order={{ xs: 2, sm: 1 }}>
            <SearchInput onChange={onSearchChange} />
          </Grid>

          <Grid container item xs="auto" sm="auto" alignItems="center" order={{ xs: 1, sm: 2 }}>
            <ConditionalIconButton
              type="submit"
              variant="contained"
              color="primary"
              size="large"
              component={CreateFlowLink}
              fullWidth
              icon={<AddIcon />}
              data-test="create-flow-button"
            >
              {formatMessage('flows.create')}
            </ConditionalIconButton>
          </Grid>
        </Grid>

        <Divider sx={{ mt: [2, 0], mb: 2 }} />

        {loading && <CircularProgress sx={{ display: 'block', margin: '20px auto' }} />}

        {!loading && flows?.map((flow) => (<FlowRow key={flow.id} flow={flow} />))}

        {!loading && !hasFlows && (<NoResultFound
          text={formatMessage('flows.noFlows')}
          to={URLS.CREATE_FLOW}
        />)}

        {!loading && pageInfo && pageInfo.totalPages > 1 && <Pagination
          sx={{ display: 'flex', justifyContent: 'center', mt: 3 }}
          page={pageInfo?.currentPage}
          count={pageInfo?.totalPages}
          onChange={(event, page) => setSearchParams({ page: page.toString() })}
          renderItem={(item) => (
            <PaginationItem
              component={Link}
              to={`${item.page === 1 ? '' : `?page=${item.page}`}`}
              {...item}
            />
          )}
        />}
      </Container>
    </Box>
  );
};