derma/src/facebook-api.js

const { graphql_endpoint } = require('./constants');
const {
  map_event,
  get_past_events_from_page,
  get_upcoming_events_from_page,
  get_page_info,
  get_edges,
  sleep,
} = require('./logic');
const fetch = require('node-fetch');

const last = require('ramda/src/last');

const fetch_past_events = async (page_id, cursor = null) => {
  let doc_id;
  if (cursor === null) {
    doc_id = '3636086023161977';
  } else {
    doc_id = '3972530646159673';
  }

  const res = await do_events_request(page_id, doc_id, cursor);

  return get_past_events_from_page(res);
};

const get_past_events = async () => [];

const do_events_request = async (page_id, doc_id, cursor = null) => {
  const params = new URLSearchParams();

  let variables = {
    pageID: `${page_id}`,
    allowedStates: ['PUBLISHED', 'CANCELED'],
    cacheBreaker: 0,
  };

  if (cursor !== null) {
    variables = { ...variables, count: 20, cursor };
  }

  params.append('doc_id', doc_id);
  params.append('variables', JSON.stringify(variables));

  const fetch_options = {
    headers: {
      'Content-Type': 'application/x-www-form-urlencoded',
    },
    body: params,
    method: 'POST',
  };

  let res = null;

  try {
    res = await fetch(graphql_endpoint, fetch_options);
  } catch (e) {
    console.error(e);
    return null;
  }

  if (!res.ok) {
    return null;
  }

  try {
    res = await res.json();
  } catch (e) {
    console.error(e);
    return null;
  }

  return res;
};

const fetch_upcoming_events = async (page_id, cursor = null) => {
  let doc_id;
  if (cursor === null) {
    doc_id = '3636086023161977';
  } else {
    doc_id = '3911675102281316';
  }

  const res = await do_events_request(page_id, doc_id, cursor);

  return get_upcoming_events_from_page(res);
};

const get_upcoming_events = async (page_id) => {
  let next = true;
  let cursor;
  let edges = [];
  while (next) {
    const res = await fetch_upcoming_events(page_id, cursor);
    edges = [...edges, ...get_edges(res)];
    const { has_next_page } = get_page_info(res);
    next = has_next_page;
    cursor = last(edges).cursor;
    if (has_next_page === true) {
      await sleep(2);
    }
  }

  return edges;
};

const get_reoccuring_events = () => {};

const get_page_events = async (opt) => {
  let past_events = [];
  let upcoming_events = [];
  const { page_id } = opt;

  if (opt.get_past_events) {
    past_events = await get_past_events(page_id);
  }

  if (opt.get_upcoming_events) {
    upcoming_events = await get_upcoming_events(page_id);
  }

  const nodes = [...upcoming_events, ...past_events];

  return nodes.map(map_event);
};

module.exports = {
  get_page_events,
};