/**
 * Why the customer app shows fewer products than the console does.
 *
 *   node scripts/appgap.mjs <tenantid> <locationid>
 *   npm run appgap 1135 1166
 *
 * Straight at Fiesta — no Hasura, no admin secret, nothing to configure. The
 * first version of this went at the database through Hasura, which was the
 * wrong instrument twice over: it needed a secret, it 404'd on an admin API
 * that is often disabled, and it answered a question about the DATABASE when
 * the question is about what the API returns. This calls the very endpoint the
 * app calls and compares it with what the console can see.
 *
 * ── The three filters ────────────────────────────────────────────────────────
 *
 * `getproductsbysubcategory` drops a product for one of three reasons, and none
 * of them is an error, logged or visible from either end:
 *
 *  A. `WHERE a.categoryid = 2` — not optional (`productRepository.go:865`).
 *     A product in another category cannot appear, whatever else is true.
 *
 *  B. `WHERE pl.locationid = ?` on a LEFT JOIN to `productlocations`. No row
 *     for this outlet means the join yields NULL and the WHERE drops it. Being
 *     in the catalogue is not the same as being on a shelf.
 *
 *  C. The grouping in `GetProductsBySubcategory` collects products under each
 *     real subcategory of category 2, then sweeps up `subcategoryid = 0` as
 *     "Uncategorized". A subcategoryid that is non-zero and NOT a subcategory
 *     of 2 matches neither and vanishes — present in the SQL, absent from the
 *     JSON.
 */

/**
 * Through the console's own host, not Fiesta directly.
 *
 * `app.nearledaily.com/fiesta/...` is the nginx proxy the deployed console
 * already uses, so this script exercises exactly the path the browser takes —
 * if the proxy is misconfigured this finds out, where hitting fiesta.nearle.app
 * would quietly work and prove nothing about production.
 *
 * Override with FIESTA_URL to point at the backend directly or at a dev server.
 */
const BASE = process.env.FIESTA_URL ?? 'https://app.nearledaily.com/fiesta';
const WEB = `${BASE}/live/api/v1/web`;
const MOB = `${BASE}/live/api/v1/mob`;

const [, , tenantArg, locationArg] = process.argv;
const tenantid = Number(tenantArg);
const locationid = Number(locationArg);

if (!tenantid || !locationid) {
  console.error('Usage: node scripts/appgap.mjs <tenantid> <locationid>');
  process.exit(1);
}

/** Fiesta answers under `details` in most places and `data` in a few. */
async function get(url, params) {
  const query = new URLSearchParams(
    Object.entries(params).filter(([, value]) => value !== undefined && value !== ''),
  );
  let response;
  try {
    response = await fetch(`${url}?${query}`, { headers: { Accept: 'application/json' } });
  } catch (cause) {
    console.error(`Could not reach ${BASE} — ${cause.message}`);
    process.exit(1);
  }
  const payload = await response.json().catch(() => null);
  if (!payload) {
    console.error(`Malformed response from ${url} (HTTP ${response.status})`);
    process.exit(1);
  }
  return payload.details ?? payload.data ?? null;
}

/**
 * Every product the tenant owns.
 *
 * `getallproducts` answers `[]models.Tenantproducts` — `{tenant, products}`
 * groups, not a flat list — and under `data` rather than `details`.
 */
async function allProducts() {
  const groups = await get(`${WEB}/products/getallproducts`, { tenantid });
  if (!Array.isArray(groups)) return [];
  return groups.flatMap((group) => group?.products ?? []);
}

/**
 * What is actually listed at this outlet.
 *
 * Paged, and the page size matters: the default is 50, so a shop with 200
 * products would look like one with 50 and every product past the first page
 * would be miscounted as "not listed". Walked until a short page comes back.
 */
async function locationProducts() {
  const rows = [];
  const pagesize = 200;
  for (let pageno = 1; pageno <= 50; pageno += 1) {
    const page = await get(`${WEB}/products/getlocationproducts`, {
      tenantid,
      locationid,
      pageno,
      pagesize,
    });
    const batch = Array.isArray(page) ? page : [];
    rows.push(...batch);
    if (batch.length < pagesize) break;
  }
  return rows;
}

/** Exactly what the app asks for, so the comparison is against reality. */
async function appView() {
  const payload = await get(`${MOB}/products/getproductsbysubcategory`, {
    categoryid: 2,
    tenantid,
    locationid,
  });
  const details = payload?.details ?? (Array.isArray(payload) ? payload : []);
  return Array.isArray(details) ? details : [];
}

const [products, listedRows, groups, subcategories] = await Promise.all([
  allProducts(),
  locationProducts(),
  appView(),
  get(`${WEB}/products/getproductsubcategories`, { tenantid, categoryid: 2 }),
]);

if (products.length === 0) {
  console.log(`Tenant ${tenantid} has no products at all — nothing for the app to show.`);
  process.exit(0);
}

const listed = new Set(listedRows.map((row) => row.productid));
/**
 * `subcatid`/`subcatname`, not `subcategoryid`/`subcategoryname`.
 *
 * This read the long names — the ones `getproductsubcategories` does NOT send —
 * so every entry was `undefined → undefined`, the map collapsed to a single
 * junk key, and check C below could never match. The footer duly announced
 * "(none returned)" for tenant 1147, whose category 2 has six subcategories.
 * A diagnostic that is confidently wrong is worse than one that is missing.
 */
const realSubs = new Map(
  (Array.isArray(subcategories) ? subcategories : []).map((row) => [row.subcatid, row.subcatname]),
);

const inApp = new Set();
for (const group of groups) {
  for (const product of group.products ?? []) inApp.add(product.productid);
}

const buckets = new Map();
const examples = new Map();

for (const product of products) {
  let reason;
  if (inApp.has(product.productid)) {
    reason = 'OK — the app shows this';
  } else if (product.categoryid !== 2) {
    reason = `A — categoryid is ${product.categoryid}, the app only asks for 2`;
  } else if (!listed.has(product.productid)) {
    reason = 'B — not listed at this outlet (no productlocations row)';
  } else if (product.subcategoryid !== 0 && !realSubs.has(product.subcategoryid)) {
    reason = `C — subcategoryid ${product.subcategoryid} is not a subcategory of 2, so it is dropped`;
  } else {
    // Everything checks out and it still is not there. Worth its own bucket
    // rather than being folded into one of the above: a wrong guess here would
    // send someone fixing data that is already correct.
    reason = '? — passes all three checks but the app still does not return it';
  }
  const key = reason.replace(/\d+/g, 'N');
  buckets.set(key, (buckets.get(key) ?? 0) + 1);
  if (!examples.has(key)) examples.set(key, { product, reason });
}

console.log(`Tenant ${tenantid}, outlet ${locationid}`);
console.log(`  ${products.length} products in the catalogue`);
console.log(`  ${listed.size} listed at this outlet`);
console.log(`  ${inApp.size} returned by the app's endpoint\n`);

for (const [key, count] of [...buckets.entries()].sort((a, b) => b[1] - a[1])) {
  const { product, reason } = examples.get(key);
  console.log(`  ${String(count).padStart(5)}  ${reason}`);
  console.log(
    `         e.g. "${product.productname}" — id ${product.productid}, category ${product.categoryid}, subcategory ${product.subcategoryid}`,
  );
}

console.log(
  `\nReal subcategories of category 2: ${[...realSubs.values()].join(', ') || '(none returned)'}`,
);