'use strict';

const { createHash } = require('crypto');

function normalizeText(value, maxLength = 1000) {
  return String(value ?? '').trim().slice(0, maxLength);
}

function buildAlibaba1688SkuKey(sku, position) {
  const specs = (Array.isArray(sku?.specs) ? sku.specs : [])
    .map(item => `${normalizeText(item?.name, 120)}=${normalizeText(item?.value, 500)}`)
    .filter(value => value !== '=')
    .join('|');
  return `${Number(sku?.index) || position + 1}:${specs || normalizeText(sku?.name, 500)}`;
}

function buildAlibaba1688SkuFingerprint(skus) {
  const keys = (Array.isArray(skus) ? skus : [])
    .map((sku, index) => buildAlibaba1688SkuKey(sku, index));
  return createHash('sha256').update(JSON.stringify(keys), 'utf8').digest('hex');
}

module.exports = {
  buildAlibaba1688SkuKey,
  buildAlibaba1688SkuFingerprint,
};