const parseCourseData_ = (courses) =>
  courses
    .filter(
      ({ is_paid, primary_category }) =>
        is_paid === false && ['Development', 'IT & Software'].includes(primary_category.title)
      // We are primarily interested in programming courses on Udemy
    )
    .map((e) => [
      `=IMAGE("${e.image_240x135}")`,
      `=HYPERLINK("https://www.udemy.com${e.url}";"${e.title}")`,
      e.visible_instructors.map(({ display_name }) => display_name).join(', '),
      e.num_subscribers,
      Math.round(e.avg_rating * 100) / 100,
      e.num_reviews,
      e.content_info_short,
      e.num_lectures,
      new Date(e.last_update_date),
    ]);

const listUdemyCoursesGoneFree = () => {
  // Put your Udemy credentials here
  const CLIENT_ID = '';
  const CLIENT_SECRET = '';

  const params = {
    page: 1,
    page_size: 100,
    is_paid: false,
    'fields[course]': '@all',
  };

  const query = Object.entries(params)
    .map(([key, value]) => `${key}=${encodeURIComponent(value)}`)
    .join('&');

  const apiUrl = `https://www.udemy.com/api-2.0/courses/?${query}`;
  const bearer = Utilities.base64Encode(`${CLIENT_ID}:${CLIENT_SECRET}`);
  const options = {
    muteHttpExceptions: true,
    headers: {
      Authorization: `Basic ${bearer}`,
    },
  };

  const courses = [];

  do {
    const response = UrlFetchApp.fetch(apiUrl, options);
    const { results = [], next } = JSON.parse(response);
    courses.push(...parseCourseData_(results));
    url = next;
  } while (url && courses.length < 500);

  const ss = SpreadsheetApp.getActiveSpreadsheet();
  const [sheet] = ss.getSheets();
  sheet.getRange(2, 1, sheet.getLastRow(), sheet.getLastColumn()).clearContent();
  sheet.getRange(2, 1, courses.length, courses[0].length).setValues(courses);
};