216 lines
8.8 KiB
PHP
216 lines
8.8 KiB
PHP
<?php
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declare(strict_types=1);
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/*
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* SERUBI cashback engine, server side. Line-by-line port of assets/js/engine.js
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* (sheet "COB" and "CALCULATOR CASHBACK SERUBI" of the reference workbook), so
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* the public calculator gets results without receiving the bank's internal
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* parameters. Both engines are validated against tests/excel-fixtures.json.
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*/
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const ENGINE_PRODUCTS = ['giro' => 'Giro Umum', 'simanja' => 'Tabungan SIMANJA', 'simpeda' => 'Tabungan SIMPEDA'];
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/** Excel ROUNDDOWN(x, 0) on 15 significant digits (same as Number(x.toPrecision(15)) in JS). */
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function engine_rounddown(float $x): float
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{
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$v = (float)sprintf('%.14e', $x);
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return $v < 0 ? ceil($v) : floor($v);
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}
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/** Tiers [{max: float|null, rate}], ascending; first tier with n <= max wins, null max = "di atas". */
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function engine_tier_rate(?array $tiers, float $n): float
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{
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foreach ($tiers ?? [] as $t) {
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if (!isset($t['max']) || $n <= $t['max']) {
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return (float)($t['rate'] ?? 0);
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}
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}
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return 0.0;
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}
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/** Cashback sharing [{min, nasabah}]: highest min that n reaches wins (COB!I34:I35). */
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function engine_share(array $params, float $n, int $tenor): array
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{
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if (!in_array($tenor, $params['cashbackTenors'] ?? [], true)) {
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return ['share' => null, 'reason' => 'tenor'];
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}
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$tiers = $params['cashbackTiers'] ?? [];
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usort($tiers, fn($a, $b) => $b['min'] <=> $a['min']);
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foreach ($tiers as $t) {
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if ($n >= $t['min']) {
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return ['share' => (float)$t['nasabah'], 'reason' => null];
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}
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}
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return ['share' => null, 'reason' => 'nominal'];
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}
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function engine_min_cashback_nominal(array $params): float
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{
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$mins = array_column($params['cashbackTiers'] ?? [], 'min');
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return $mins ? (float)min($mins) : 0.0;
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}
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function engine_deposito_rate(array $params, float $n, int $tenor): float
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{
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if ($n < $params['settings']['deposito_min']) { // COB!K14: F4<1000000 -> 0
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return 0.0;
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}
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return engine_tier_rate($params['depositoRates'][$tenor] ?? null, $n);
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}
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function engine_calculate(array $params, float $nominal, int $tenor, string $customerType): array
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{
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$p = $params['settings'];
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$n = max(0.0, $nominal);
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$t = $tenor;
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$customerType = $customerType === 'badan' ? 'badan' : 'perorangan';
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$year = $p['hari_setahun'];
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$month = $p['hari_sebulan'];
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// Pengelolaan dana (COB!F23:F38)
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$gwm = $n * $p['gwm'];
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$kas = $n * $p['kas'];
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$managed = $n - ($gwm + $kas);
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$puabBase = $managed * $p['porsi_puab'];
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$puabIncome = $puabBase * $p['puab'] * ($month / $year) * $t;
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$creditBase = $managed * $p['porsi_kredit'];
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$creditIncome = $creditBase * $p['kredit'] * ($t / 12);
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$income = $puabIncome + $creditIncome;
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$sh = engine_share($params, $n, $t);
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$eligible = $sh['share'] !== null;
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$share = $eligible ? $sh['share'] : 0.0;
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// Biaya & spread per produk (COB!H22:R37)
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$lps = min($n, $p['lps_batas']) * $p['premi_lps'];
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$ohc = $puabIncome * $p['ohc'];
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$products = [];
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foreach (ENGINE_PRODUCTS as $key => $name) {
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$rate = engine_tier_rate($params['productRates'][$key] ?? null, $n);
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$bunga = engine_rounddown((($n * $rate * $month) / $year) * $t);
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$program = $key === 'simanja' ? $p['biaya_program'] : 0.0;
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$cost = $bunga + $program + $ohc + $lps;
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$spread = $income - $cost;
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$bungaTax = $bunga * $p['pajak_tabungan'];
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$products[$key] = [
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'key' => $key, 'name' => $name, 'rate' => $rate,
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'bungaGross' => $bunga, 'bungaTax' => $bungaTax, 'bungaNet' => $bunga - $bungaTax,
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'program' => $program, 'ohc' => $ohc, 'lps' => $lps, 'cost' => $cost, 'spread' => $spread,
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'cashbackGross' => $spread * $share,
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'costOfFund' => $managed > 0 ? ($cost + $spread * $share) / $managed : 0.0,
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];
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}
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// Cashback = rata-rata 3 produk (COB!H7:H10)
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$gross = $eligible ? ($products['giro']['cashbackGross'] + $products['simanja']['cashbackGross'] + $products['simpeda']['cashbackGross']) / 3 : 0.0;
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$negative = $gross < 0;
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if ($negative) {
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$gross = 0.0;
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}
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$taxRate = $customerType === 'badan' ? $p['pajak_cashback_badan'] : $p['pajak_cashback_perorangan'];
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$tax = $gross * $taxRate;
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$net = $gross - $tax;
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$equiv = $n > 0 && $t > 0 ? ($net / $n) * ($year / ($month * $t)) : 0.0;
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// Deposito pembanding (COB!K14:L17)
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$dRate = engine_deposito_rate($params, $n, $t);
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$dGross = engine_rounddown((($n * $dRate * $month) / $year) * $t);
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$dTax = $dGross * $p['pajak_deposito'];
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$dNet = $dGross - $dTax;
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$deposito = ['rate' => $dRate, 'gross' => $dGross, 'tax' => $dTax, 'net' => $dNet, 'monthly' => $t ? $dNet / $t : 0.0];
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// Perbandingan (CALC!A10:F13)
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$comparison = [];
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foreach (ENGINE_PRODUCTS as $key => $name) {
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$pr = $products[$key];
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$total = $pr['bungaNet'] + $net;
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$comparison[] = [
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'key' => $key, 'name' => $name, 'rate' => $pr['rate'], 'bungaNet' => $pr['bungaNet'],
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'cashbackNet' => $net, 'total' => $total, 'totalRate' => $pr['rate'] + $equiv, 'diff' => $total - $dNet,
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];
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}
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$best = array_reduce($comparison, fn($a, $b) => $a === null || $b['total'] > $a['total'] ? $b : $a);
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// Pinalti pencairan sebelum jatuh tempo (CALC!A17:B22)
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$penalty = ['refund' => $net, 'tax' => $gross * $taxRate, 'fee' => $net * $p['pinalti']];
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$penalty['total'] = $penalty['refund'] + $penalty['tax'] + $penalty['fee'];
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return [
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'input' => ['nominal' => $n, 'tenor' => $t, 'customerType' => $customerType],
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'eligible' => $eligible && !$negative,
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'reason' => $negative ? 'spread' : $sh['reason'],
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'minNominal' => engine_min_cashback_nominal($params),
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'share' => $share, 'shareBank' => $eligible ? 1 - $share : 0.0,
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'fund' => [
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'gwm' => $gwm, 'kas' => $kas, 'managed' => $managed, 'puabBase' => $puabBase, 'puabIncome' => $puabIncome,
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'creditBase' => $creditBase, 'creditIncome' => $creditIncome, 'income' => $income,
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],
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'products' => $products,
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'cashback' => ['gross' => $gross, 'taxRate' => $taxRate, 'tax' => $tax, 'net' => $net, 'monthly' => $t ? $net / $t : 0.0, 'equiv' => $equiv],
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'deposito' => $deposito,
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'comparison' => $comparison,
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'best' => $best,
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'penalty' => $penalty,
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];
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}
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/**
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* What a visitor without an admin session may see: the customer-facing result
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* only. Cost structure, spread, sharing tiers and the deposito comparison stay
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* on the server.
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*/
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function engine_public_result(array $r, array $params): array
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{
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return [
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'input' => $r['input'],
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'eligible' => $r['eligible'],
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'reason' => $r['reason'],
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'minNominal' => $r['minNominal'],
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'share' => $r['share'],
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'cashback' => $r['cashback'],
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'comparison' => array_map(fn($c) => array_diff_key($c, ['diff' => 1]), $r['comparison']),
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'penalty' => $r['penalty'] + ['rate' => $params['settings']['pinalti']],
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];
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}
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/**
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* Model for the public in-browser engine (assets/js/engine-public.js), so the
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* calculator answers instantly and offline. The bank's cost structure is folded
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* into one margin per tenor:
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*
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* pendapatan PUAB − OHC + pendapatan kredit = nominal × margin[tenor]
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* margin = (1 − GWM − kas) × (porsi PUAB × rate PUAB × hari sebulan/hari setahun × tenor × (1 − OHC)
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* + porsi kredit × bunga kredit × tenor/12)
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*
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* GWM, kas, porsi PUAB/kredit, rate PUAB, bunga kredit, OHC and the deposito
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* rates are not sent. Everything else is customer-facing (product rates, taxes,
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* penalty, LPS rules) or, like the sharing tiers, can be read off the results.
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*/
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function engine_client_model(array $params): array
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{
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$p = $params['settings'];
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$year = $p['hari_setahun'];
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$month = $p['hari_sebulan'];
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$margin = [];
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foreach ($params['tenors'] as $t) {
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$margin[(string)$t] = (1 - ($p['gwm'] + $p['kas']))
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* ($p['porsi_puab'] * $p['puab'] * ($month / $year) * $t * (1 - $p['ohc'])
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+ $p['porsi_kredit'] * $p['kredit'] * ($t / 12));
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}
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return [
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'tenors' => $params['tenors'],
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'cashbackTenors' => $params['cashbackTenors'],
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'minNominal' => engine_min_cashback_nominal($params),
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'days' => ['month' => $month, 'year' => $year],
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'margin' => $margin,
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'programAvg' => $p['biaya_program'] / 3, // SIMANJA programme fee, averaged over the 3 products
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'lps' => ['rate' => $p['premi_lps'], 'cap' => $p['lps_batas']],
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'productRates' => $params['productRates'],
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'cashbackTiers' => $params['cashbackTiers'],
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'tax' => ['bunga' => $p['pajak_tabungan'], 'perorangan' => $p['pajak_cashback_perorangan'], 'badan' => $p['pajak_cashback_badan']],
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'pinalti' => $p['pinalti'],
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'paramsAt' => $params['updatedAt'],
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'generatedAt' => date('c'),
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];
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}
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