GSC winners and losers: the 28-day click swing, written to a Sheet

/**
 * GSC winners and losers
 * The SEM Dispatch Vault, semdispatch.com/vault
 *
 * Compares the last 28 days of Search Console clicks with the prior 28,
 * by query and by page, and writes Winners and Losers tabs to the bound Sheet.
 * Read-only: this script never changes the property or submits anything.
 */

var CONFIG = {
  // Your property, exactly as Search Console stores it.
  // Domain property:     "sc-domain:example.com"
  // URL-prefix property: "https://example.com/"
  SITE_URL: "sc-domain:example.com",

  // How many rows to keep per tab, per direction.
  ROW_LIMIT: 50
};

function main() {
  var recent = windowDates(0);   // last 28 days, ending 3 days ago
  var prior = windowDates(28);   // the 28 days before that

  buildTab("Winners and losers by query", "query", recent, prior);
  buildTab("Winners and losers by page", "page", recent, prior);
}

function windowDates(offsetDays) {
  var MS_DAY = 24 * 60 * 60 * 1000;
  // End 3 days back so the freshest, still-settling data is excluded.
  var end = new Date(Date.now() - (3 + offsetDays) * MS_DAY);
  var start = new Date(end.getTime() - 27 * MS_DAY);
  return { start: isoDate(start), end: isoDate(end) };
}

function isoDate(d) {
  return Utilities.formatDate(d, "UTC", "yyyy-MM-dd");
}

function buildTab(tabName, dimension, recent, prior) {
  var recentRows = queryClicks(dimension, recent);
  var priorRows = queryClicks(dimension, prior);

  var deltas = {};
  Object.keys(recentRows).forEach(function (key) {
    deltas[key] = (deltas[key] || 0) + recentRows[key];
  });
  Object.keys(priorRows).forEach(function (key) {
    deltas[key] = (deltas[key] || 0) - priorRows[key];
  });

  var rows = Object.keys(deltas).map(function (key) {
    return {
      key: key,
      now: recentRows[key] || 0,
      before: priorRows[key] || 0,
      change: deltas[key]
    };
  });

  var winners = rows
    .filter(function (r) { return r.change > 0; })
    .sort(function (a, b) { return b.change - a.change; })
    .slice(0, CONFIG.ROW_LIMIT);

  var losers = rows
    .filter(function (r) { return r.change < 0; })
    .sort(function (a, b) { return a.change - b.change; })
    .slice(0, CONFIG.ROW_LIMIT);

  writeTab(tabName, dimension, winners, losers);
}

function queryClicks(dimension, range) {
  var token = ScriptApp.getOAuthToken();
  var url = "https://www.googleapis.com/webmasters/v3/sites/" +
    encodeURIComponent(CONFIG.SITE_URL) + "/searchAnalytics/query";

  var payload = {
    startDate: range.start,
    endDate: range.end,
    dimensions: [dimension],
    rowLimit: 5000
  };

  var response = UrlFetchApp.fetch(url, {
    method: "post",
    contentType: "application/json",
    headers: { Authorization: "Bearer " + token },
    payload: JSON.stringify(payload),
    muteHttpExceptions: true
  });

  if (response.getResponseCode() !== 200) {
    throw new Error(
      "Search Console API said " + response.getResponseCode() +
      ": " + response.getContentText()
    );
  }

  var data = JSON.parse(response.getContentText());
  var out = {};
  (data.rows || []).forEach(function (row) {
    out[row.keys[0]] = row.clicks;
  });
  return out;
}

function writeTab(tabName, dimension, winners, losers) {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheetByName(tabName) || ss.insertSheet(tabName);
  sheet.clear();

  var header = [dimension, "Clicks now", "Clicks before", "Change"];
  var block = [];
  block.push(["WINNERS", "", "", ""]);
  block.push(header);
  winners.forEach(function (r) {
    block.push([r.key, r.now, r.before, "+" + r.change]);
  });
  block.push(["", "", "", ""]);
  block.push(["LOSERS", "", "", ""]);
  block.push(header);
  losers.forEach(function (r) {
    block.push([r.key, r.now, r.before, r.change]);
  });

  sheet.getRange(1, 1, block.length, 4).setValues(block);
}