import React, { useMemo, useState, useCallback } from 'react';
import { FormattedMessage } from 'react-intl';
import firstBy from 'thenby';
import { percentFilter } from 'lib/filters';
import DataTable from './DataTable';
import FilterButtons from 'components/common/FilterButtons';

const FILTER_REFERRERS = 0;
const FILTER_PAGES = 1;

export default function RealtimeViews({ websiteId, data, websites }) {
  const { pageviews } = data;
  const [filter, setFilter] = useState(FILTER_REFERRERS);
  const domains = useMemo(() => websites.map(({ domain }) => domain), [websites]);
  const getDomain = useCallback(
    id =>
      websites.length === 1
        ? websites[0]?.domain
        : websites.find(({ website_id }) => website_id === id)?.domain,
    [websites],
  );

  const buttons = [
    {
      label: <FormattedMessage id="metrics.referrers" defaultMessage="Referrers" />,
      value: FILTER_REFERRERS,
    },
    {
      label: <FormattedMessage id="metrics.pages" defaultMessage="Pages" />,
      value: FILTER_PAGES,
    },
  ];

  const renderLink = ({ x }) => {
    const domain = x.startsWith('/') ? getDomain(websiteId) : '';
    return (
      <a href={`//${domain}${x}`} target="_blank" rel="noreferrer noopener">
        {x}
      </a>
    );
  };

  const [referrers, pages] = useMemo(() => {
    if (pageviews) {
      const referrers = percentFilter(
        pageviews
          .reduce((arr, { referrer }) => {
            if (referrer?.startsWith('http')) {
              const hostname = new URL(referrer).hostname.replace(/^www\./, '');

              if (hostname && !domains.includes(hostname)) {
                const row = arr.find(({ x }) => x === hostname);

                if (!row) {
                  arr.push({ x: hostname, y: 1 });
                } else {
                  row.y += 1;
                }
              }
            }
            return arr;
          }, [])
          .sort(firstBy('y', -1)),
      );

      const pages = percentFilter(
        pageviews
          .reduce((arr, { url, website_id }) => {
            if (url?.startsWith('/')) {
              if (!websiteId && websites.length > 1) {
                url = `${getDomain(website_id)}${url}`;
              }
              const row = arr.find(({ x }) => x === url);

              if (!row) {
                arr.push({ x: url, y: 1 });
              } else {
                row.y += 1;
              }
            }
            return arr;
          }, [])
          .sort(firstBy('y', -1)),
      );

      return [referrers, pages];
    }
    return [];
  }, [pageviews]);

  return (
    <>
      <FilterButtons buttons={buttons} selected={filter} onClick={setFilter} />
      {filter === FILTER_REFERRERS && (
        <DataTable
          title={<FormattedMessage id="metrics.referrers" defaultMessage="Referrers" />}
          metric={<FormattedMessage id="metrics.views" defaultMessage="Views" />}
          renderLabel={renderLink}
          data={referrers}
        />
      )}
      {filter === FILTER_PAGES && (
        <DataTable
          title={<FormattedMessage id="metrics.pages" defaultMessage="Pages" />}
          metric={<FormattedMessage id="metrics.views" defaultMessage="Views" />}
          renderLabel={renderLink}
          data={pages}
        />
      )}
    </>
  );
}