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<?php |
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declare(strict_types = 1); |
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namespace Kauri\Loan; |
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class PaymentsCalculator implements PaymentsCalculatorInterface |
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{ |
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/** |
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* @var PaymentAmountCalculatorInterface |
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*/ |
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private $paymentAmountCalculator; |
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/** |
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* @var InterestAmountCalculatorInterface |
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*/ |
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private $interestAmountCalculator; |
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/** |
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* PaymentsCalculator constructor. |
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* @param PaymentAmountCalculatorInterface $paymentAmountCalculator |
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* @param InterestAmountCalculatorInterface $interestAmountCalculator |
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*/ |
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public function __construct( |
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PaymentAmountCalculatorInterface $paymentAmountCalculator, |
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InterestAmountCalculatorInterface $interestAmountCalculator |
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) { |
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$this->paymentAmountCalculator = $paymentAmountCalculator; |
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$this->interestAmountCalculator = $interestAmountCalculator; |
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} |
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/** |
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* @param PaymentPeriodsInterface $paymentPeriods |
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* @param float $amountOfPrincipal |
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* @param float $yearlyInterestRate |
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* @param int $calculationMode |
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* @param float $futureValue |
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* @return array |
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*/ |
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public function calculatePayments( |
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PaymentPeriodsInterface $paymentPeriods, |
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float $amountOfPrincipal, |
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float $yearlyInterestRate, |
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int $calculationMode, |
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float $futureValue |
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): array { |
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$payments = array(); |
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$periodLengths = $this->getPeriodLengths($paymentPeriods, $calculationMode); |
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$paymentAmounts = $this->paymentAmountCalculator->getPaymentAmounts($periodLengths, $amountOfPrincipal, |
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$yearlyInterestRate, $futureValue); |
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$principalLeft = $amountOfPrincipal; |
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foreach ($paymentPeriods->getPeriods() as $period) { |
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/** |
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* Get payment amount |
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*/ |
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$paymentAmount = round($paymentAmounts[$period->getSequenceNo()], 2); |
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/** |
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* Get interest rate for period |
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*/ |
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$ratePerPeriod = $this->interestAmountCalculator->getPeriodInterestRate($yearlyInterestRate, |
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$period->getLength($calculationMode)); |
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/** |
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* Calculate interest part |
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*/ |
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$interest = round($this->interestAmountCalculator->getInterestAmount($principalLeft, $ratePerPeriod), 2); |
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/** |
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* Calculate principal part |
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*/ |
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if ($period->getSequenceNo() < $paymentPeriods->getNoOfPeriods()) { |
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$principal = $paymentAmount - $interest; |
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} else { |
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$principal = $principalLeft - $futureValue; |
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} |
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/** |
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* Calculate balance left |
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*/ |
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$principalLeft = $principalLeft - $principal; |
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/** |
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* Compose payment data |
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*/ |
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$paymentData = array( |
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'sequence_no' => $period->getSequenceNo(), |
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'payment' => $interest + $principal, |
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'principal' => $principal, |
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'interest' => $interest, |
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'principal_left' => $principalLeft, |
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'period' => $period |
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); |
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$payments[$period->getSequenceNo()] = $paymentData; |
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} |
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return $payments; |
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} |
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/** |
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* @param PaymentPeriodsInterface $paymentPeriods |
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* @param int $lengthMode |
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* @return array |
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*/ |
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private function getPeriodLengths(PaymentPeriodsInterface $paymentPeriods, int $lengthMode): array |
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{ |
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$lengths = array(); |
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/** @var PeriodInterface $period */ |
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foreach ($paymentPeriods->getPeriods() as $period) { |
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$lengths[$period->getSequenceNo()] = $period->getLength($lengthMode); |
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} |
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return $lengths; |
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} |
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} |
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kaurikk /
loan-payment-calculator
