Airbnb listing search in Google Sheets

/**
 * JEV_TOP10: find the 10 listings that best match a plain-language request, using TypeSafe Jev.
 *
 * Setup: Extensions > Apps Script, paste this file, save. Then Project Settings >
 * Script properties: add TYPESAFE_API_KEY with your TypeSafe key. No permission prompt.
 *
 * Usage: =JEV_TOP10(B1, Listings!A2:H1001)
 *   The listing columns must be: Name, Type, Price per night (R), Bedrooms, Guests, Rating,
 *   Description, Link.
 *
 * How it works, in 11 requests instead of one per listing:
 *   1. Shortlist: the listings are split into groups of 100. One request per group, all in
 *      parallel, asks a Choice question over the group's listing IDs. Jev returns a
 *      probability for every listing, and the 5 most likely go through.
 *   2. Score: one request holds the shortlisted listings in full, with one Score question
 *      per listing. The 10 best scores are returned, from 0 to 10.
 * Results are cached for six hours per request.
 */

const GROUP_SIZE = 100;
const SHORTLIST_PER_GROUP = 5;
const TOP = 10;
const SHORT_DESCRIPTION = 300;
const FULL_DESCRIPTION = 1500;
const LEVELS = [
  'Not a match at all',
  'Matches little of what was asked for',
  'Matches some of what was asked for',
  'Matches most of what was asked for',
  'Matches everything asked for',
];

/**
 * Returns the 10 listings that best match a request, with a 0-10 match score.
 *
 * @param {string} request What you're looking for, in plain language.
 * @param {Listings!A2:H1001} listings Name, Type, Price, Bedrooms, Guests, Rating, Description, Link.
 * @return Match, Name, Type, Price, Bedrooms, Guests, Rating, Link for the top 10.
 * @customfunction
 */
function JEV_TOP10(request, listings) {
  const key = PropertiesService.getScriptProperties().getProperty('TYPESAFE_API_KEY');
  if (!key) throw new Error('Add TYPESAFE_API_KEY under Project Settings > Script properties.');
  request = String(request || '').trim();
  if (!request) return [['Type what you are looking for in B1.']];

  const rows = listings.filter((r) => r[0] !== '');
  const cache = CacheService.getScriptCache();
  const cacheKey = digest(`${request}\n${rows.length}\n${rows.map((r) => r[7]).join('|')}`);
  const hit = cache.get(cacheKey);
  if (hit) return JSON.parse(hit);

  // Stage 1: one Choice over each group of 100 listing IDs, all groups in parallel.
  const groups = [];
  for (let start = 0; start < rows.length; start += GROUP_SIZE) {
    groups.push(rows.slice(start, start + GROUP_SIZE).map((_, j) => start + j));
  }
  const shortlistResponses = UrlFetchApp.fetchAll(groups.map((ids) => jevRequest(key, {
    state: ids.map((i) => line(i, rows[i], SHORT_DESCRIPTION)).join('\n'),
    questions: {
      best: {
        type: 'choice',
        instructions: `Which listing best matches what the guest is looking for: ${request}`,
        criteria: Object.fromEntries(ids.map((i) => [`L${i}`, null])),
      },
    },
  })));
  const shortlist = shortlistResponses.flatMap((res) => {
    const p = parse(res).answers.best.probabilities;
    return Object.keys(p).sort((a, b) => p[b] - p[a]).slice(0, SHORTLIST_PER_GROUP).map((id) => Number(id.slice(1)));
  });

  // Stage 2: score every shortlisted listing in one request.
  const scored = parse(UrlFetchApp.fetchAll([jevRequest(key, {
    state: shortlist.map((i) => line(i, rows[i], FULL_DESCRIPTION)).join('\n\n'),
    questions: Object.fromEntries(shortlist.map((i) => [`L${i}`, {
      type: 'score',
      instructions: `How well does listing [L${i}] match what the guest is looking for: ${request}`,
      criteria: LEVELS,
    }])),
  })])[0]).answers;

  const top = shortlist
    .map((i) => ({i, score: Math.round((scored[`L${i}`].score / (LEVELS.length - 1)) * 100) / 10}))
    .sort((a, b) => b.score - a.score)
    .slice(0, TOP)
    .map(({i, score}) => {
      const [name, type, price, beds, guests, rating, , link] = rows[i];
      return [score, name, type, price, beds, guests, rating, link];
    });
  cache.put(cacheKey, JSON.stringify(top), 6 * 60 * 60);
  return top;
}

function line(i, r, descriptionChars) {
  const [name, type, price, beds, guests, , description] = r;
  return `[L${i}] ${name} | ${type} | R${price}/night | ${beds || '?'} bedrooms | sleeps ${guests} | ${String(description).slice(0, descriptionChars)}`;
}

function jevRequest(key, body) {
  return {
    url: 'https://api.typesafe.ai/v1/systemone',
    method: 'post',
    contentType: 'application/json',
    headers: {Authorization: `Bearer ${key}`},
    muteHttpExceptions: true,
    payload: JSON.stringify(Object.assign({model: 'jev-latest'}, body)),
  };
}

function parse(res) {
  if (res.getResponseCode() !== 200) {
    throw new Error(`Jev returned HTTP ${res.getResponseCode()}: ${res.getContentText().slice(0, 200)}`);
  }
  return JSON.parse(res.getContentText());
}

function digest(text) {
  return Utilities.base64EncodeWebSafe(Utilities.computeDigest(Utilities.DigestAlgorithm.SHA_256, text));
}