calcserubi/assets/js/engine.js

/*
 * SERUBI cashback engine.
 * Faithful port of sheet "COB" and "CALCULATOR CASHBACK SERUBI" from
 * CALCULATOR CASHBACK SERUB KANTOR CABANG 22092026.xlsx. Cell references are
 * noted next to each step so the numbers can be audited against the workbook.
 * Works in the browser (window.SerubiEngine) and in Node (module.exports).
 */
(function (root, factory) {
  if (typeof module === 'object' && module.exports) module.exports = factory();
  else root.SerubiEngine = factory();
})(typeof self !== 'undefined' ? self : this, function () {
  'use strict';

  var PRODUCTS = [
    { key: 'giro', name: 'Giro Umum' },
    { key: 'simanja', name: 'Tabungan SIMANJA' },
    { key: 'simpeda', name: 'Tabungan SIMPEDA' }
  ];

  // Excel ROUNDDOWN(x, 0) works on 15 significant digits; mirror that so
  // values like 203424.99999999997 do not lose a rupiah.
  function rounddown(x) {
    var v = Number(x.toPrecision(15));
    return v < 0 ? Math.ceil(v) : Math.floor(v);
  }

  // Tiers are [{max: number|null, rate}], ascending; first tier with n <= max
  // wins, a null max means "di atas" (everything above the previous tier).
  function tierRate(tiers, n) {
    if (!tiers || !tiers.length) return 0;
    for (var i = 0; i < tiers.length; i++) {
      var t = tiers[i];
      if (t.max === null || t.max === undefined || n <= t.max) return Number(t.rate) || 0;
    }
    return 0;
  }

  // Cashback sharing: [{min, nasabah}] — highest min that n reaches wins (COB!I34:I35).
  function shareFor(params, n, tenor) {
    if ((params.cashbackTenors || []).indexOf(tenor) === -1) return { share: null, reason: 'tenor' };
    var tiers = (params.cashbackTiers || []).slice().sort(function (a, b) { return b.min - a.min; });
    for (var i = 0; i < tiers.length; i++) {
      if (n >= tiers[i].min) return { share: Number(tiers[i].nasabah), reason: null };
    }
    return { share: null, reason: 'nominal' };
  }

  function minCashbackNominal(params) {
    var mins = (params.cashbackTiers || []).map(function (t) { return t.min; });
    return mins.length ? Math.min.apply(null, mins) : 0;
  }

  function depositoRate(params, n, tenor) {
    if (n < params.settings.deposito_min) return 0;     // COB!K14: F4<1000000 -> 0
    return tierRate((params.depositoRates || {})[tenor], n);
  }

  function calculate(params, input) {
    var p = params.settings;
    var n = Math.max(0, Number(input.nominal) || 0);
    var t = Number(input.tenor) || 0;
    var customerType = input.customerType === 'badan' ? 'badan' : 'perorangan';
    var year = p.hari_setahun, month = p.hari_sebulan;

    // Pengelolaan dana (COB!F23:F38)
    var gwm = n * p.gwm;                                    // F24
    var kas = n * p.kas;                                    // F25
    var managed = n - (gwm + kas);                          // F26
    var puabBase = managed * p.porsi_puab;                  // F28
    var puabIncome = puabBase * p.puab * (month / year) * t; // F31 (A)
    var creditBase = managed * p.porsi_kredit;              // F34
    var creditIncome = creditBase * p.kredit * (t / 12);    // F36 (B)
    var income = puabIncome + creditIncome;                 // F38

    var sh = shareFor(params, n, t);
    var eligible = sh.share !== null;
    var share = eligible ? sh.share : 0;

    // Biaya & spread per produk (COB!H22:R37)
    var lps = Math.min(n, p.lps_batas) * p.premi_lps;       // J27 (charged once, not prorated)
    var ohc = puabIncome * p.ohc;                           // J26 / N25 / R25
    var products = {};
    PRODUCTS.forEach(function (prod) {
      var rate = tierRate((params.productRates || {})[prod.key], n);   // I24 / M24 / Q24
      var bunga = rounddown(((n * rate * month) / year) * t);          // J24 / N24 / R24
      var program = prod.key === 'simanja' ? p.biaya_program : 0;      // J25 (SIMANJA only)
      var cost = bunga + program + ohc + lps;                          // J28 / N27 / R27
      var spread = income - cost;                                      // J29 / N28 / R28
      var bungaTax = bunga * p.pajak_tabungan;                         // F7 / F10 / F13
      products[prod.key] = {
        key: prod.key, name: prod.name, rate: rate,
        bungaGross: bunga, bungaTax: bungaTax, bungaNet: bunga - bungaTax,
        program: program, ohc: ohc, lps: lps, cost: cost, spread: spread,
        cashbackGross: spread * share,                                 // J35 / N34 / R34
        costOfFund: managed > 0 ? (cost + spread * share) / managed : 0 // J30 / N29 / R29
      };
    });

    // Cashback = rata-rata 3 produk (COB!H7:H10)
    var gross = eligible ? (products.giro.cashbackGross + products.simanja.cashbackGross + products.simpeda.cashbackGross) / 3 : 0;
    var negative = gross < 0;
    if (negative) gross = 0;
    var taxRate = customerType === 'badan' ? p.pajak_cashback_badan : p.pajak_cashback_perorangan;
    var tax = gross * taxRate;                               // H9
    var net = gross - tax;                                   // H10
    var equiv = n > 0 && t > 0 ? (net / n) * (year / (month * t)) : 0; // CALC!D10

    // Deposito pembanding (COB!K14:L17)
    var dRate = depositoRate(params, n, t);
    var dGross = rounddown(((n * dRate * month) / year) * t);
    var dTax = dGross * p.pajak_deposito;
    var dNet = dGross - dTax;
    var deposito = { rate: dRate, gross: dGross, tax: dTax, net: dNet, monthly: t ? dNet / t : 0 };

    // Perbandingan (CALC!A10:F13)
    var comparison = PRODUCTS.map(function (prod) {
      var pr = products[prod.key];
      var total = pr.bungaNet + net;
      return {
        key: prod.key, name: prod.name, rate: pr.rate, bungaNet: pr.bungaNet,
        cashbackNet: net, total: total, totalRate: pr.rate + equiv, diff: total - dNet
      };
    });

    // Pinalti pencairan sebelum jatuh tempo (CALC!A17:B22)
    var penalty = {
      refund: net,
      tax: gross * taxRate,
      fee: net * p.pinalti,
      total: 0
    };
    penalty.total = penalty.refund + penalty.tax + penalty.fee;

    return {
      input: { nominal: n, tenor: t, customerType: customerType },
      eligible: eligible && !negative,
      reason: negative ? 'spread' : sh.reason,
      minNominal: minCashbackNominal(params),
      share: share, shareBank: eligible ? 1 - share : 0,
      fund: {
        gwm: gwm, kas: kas, managed: managed, puabBase: puabBase, puabIncome: puabIncome,
        creditBase: creditBase, creditIncome: creditIncome, income: income
      },
      products: products,
      cashback: { gross: gross, taxRate: taxRate, tax: tax, net: net, monthly: t ? net / t : 0, equiv: equiv },
      deposito: deposito,
      comparison: comparison,
      best: comparison.reduce(function (a, b) { return b.total > a.total ? b : a; }),
      penalty: penalty
    };
  }

  return {
    calculate: calculate, tierRate: tierRate, depositoRate: depositoRate,
    rounddown: rounddown, PRODUCTS: PRODUCTS
  };
});