<?php

namespace Tests\Unit;

use App\Services\WithdrawalRefundCalculator;
use InvalidArgumentException;
use PHPUnit\Framework\TestCase;

final class WithdrawalRefundCalculatorTest extends TestCase
{
    private WithdrawalRefundCalculator $calculator;

    protected function setUp(): void
    {
        $this->calculator = new WithdrawalRefundCalculator();
    }

    public function testOneWeekRetainsIssuedBooksAndOneInstructionalWeek(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'valid_payment_cents' => 38000,
        ]));

        self::assertSame(210, $result['total_chargeable_days']);
        self::assertSame(7, $result['studied_calendar_days']);
        self::assertSame(1, $result['studied_weeks']);
        self::assertSame(5000, $result['issued_book_charge_cents']);
        self::assertSame(33000, $result['annual_instruction_cents']);
        self::assertSame(1100, $result['earned_tuition_cents']);
        self::assertSame(6100, $result['retained_charge_cents']);
        self::assertSame(31900, $result['new_refund_request_cents']);
        self::assertSame(0, $result['balance_due_cents']);
    }

    public function testPartialPaymentRefundsOnlyTheAmountAboveRetainedCharge(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'valid_payment_cents' => 10000,
        ]));

        self::assertSame(3900, $result['new_refund_request_cents']);
        self::assertSame(0, $result['balance_due_cents']);
    }

    public function testPartialPaymentBelowRetainedChargeProducesBalanceAndNoRefund(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'valid_payment_cents' => 5000,
        ]));

        self::assertSame(0, $result['new_refund_request_cents']);
        self::assertSame(1100, $result['balance_due_cents']);
    }

    public function testStartedSecondSevenDayPeriodChargesTwoWeeks(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'withdrawal_request_date' => '2026-08-08',
        ]));

        self::assertSame(8, $result['studied_calendar_days']);
        self::assertSame(2, $result['studied_weeks']);
        self::assertSame(2200, $result['earned_tuition_cents']);
        self::assertSame(7200, $result['retained_charge_cents']);
    }

    public function testCompletedPayoutAndReservationCannotBeRefundedAgain(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'valid_payment_cents' => 38000,
            'completed_payout_cents' => 10000,
            'open_reservation_cents' => 5000,
        ]));

        self::assertSame(21900, $result['refundable_credit_cents']);
        self::assertSame(16900, $result['new_refund_request_cents']);
    }

    public function testIssuedBooksCannotExceedInclusiveAnnualAllocation(): void
    {
        $this->expectException(InvalidArgumentException::class);
        $this->calculator->calculate($this->baseInput([
            'issued_book_charge_cents' => 38001,
        ]));
    }

    public function testBooksExcludedModeIsRejected(): void
    {
        $this->expectException(InvalidArgumentException::class);
        $this->calculator->calculate($this->baseInput([
            'annual_fee_includes_books' => false,
        ]));
    }

    public function testDayOneChargesOneStartedWeek(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'withdrawal_request_date' => '2026-08-01',
        ]));
        self::assertSame(1, $result['studied_calendar_days']);
        self::assertSame(1, $result['studied_weeks']);
    }

    public function testWithdrawalBeforeChargeStartChargesNoTuitionButRetainsBooks(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'enrollment_date' => '2026-08-10',
            'withdrawal_request_date' => '2026-08-09',
        ]));
        self::assertSame(0, $result['studied_calendar_days']);
        self::assertSame(0, $result['studied_weeks']);
        self::assertSame(5000, $result['retained_charge_cents']);
    }

    public function testLateEnrollmentBecomesChargeStart(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'enrollment_date' => '2026-08-20',
            'withdrawal_request_date' => '2026-08-26',
        ]));
        self::assertSame('2026-08-20', $result['charge_start_date']);
        self::assertSame(7, $result['studied_calendar_days']);
        self::assertSame(1, $result['studied_weeks']);
    }

    public function testEnrollmentBeforeSchoolStartsUsesSchoolStart(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'enrollment_date' => '2026-07-01',
            'withdrawal_request_date' => '2026-08-07',
        ]));
        self::assertSame('2026-08-01', $result['charge_start_date']);
        self::assertSame(1, $result['studied_weeks']);
    }

    public function testDurationCapsAtTotalInstructionalWeeks(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'withdrawal_request_date' => '2027-12-31',
            'valid_payment_cents' => 38000,
        ]));
        self::assertSame(210, $result['studied_calendar_days']);
        self::assertSame(30, $result['studied_weeks']);
        self::assertSame(38000, $result['retained_charge_cents']);
        self::assertSame(0, $result['new_refund_request_cents']);
    }

    public function testOtherChargesRemainPayable(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'valid_payment_cents' => 10000,
            'other_charge_cents' => 2000,
        ]));
        self::assertSame(8100, $result['retained_charge_cents']);
        self::assertSame(1900, $result['new_refund_request_cents']);
    }

    public function testProrationRoundsOnceInCents(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'annual_fee_allocation_cents' => 10000,
            'issued_book_charge_cents' => 0,
            'total_instructional_weeks' => 3,
            'withdrawal_request_date' => '2026-08-07',
        ]));
        self::assertSame(3333, $result['earned_tuition_cents']);
    }

    public function testZeroTotalInstructionalWeeksIsRejected(): void
    {
        $this->expectException(InvalidArgumentException::class);
        $this->calculator->calculate($this->baseInput(['total_instructional_weeks' => 0]));
    }

    public function testMalformedDateIsRejected(): void
    {
        $this->expectException(InvalidArgumentException::class);
        $this->calculator->calculate($this->baseInput(['withdrawal_request_date' => '2026-02-31']));
    }

    public function testNoSchoolCalendarDataCannotAffectPureCalculation(): void
    {
        $first = $this->calculator->calculate($this->baseInput());
        $second = $this->calculator->calculate($this->baseInput(['unrelated_no_school_dates' => ['2026-08-03']]));
        self::assertSame($first, $second);
    }

    public function testNoPaymentProducesNoRefundAndFullRetainedBalance(): void
    {
        $result = $this->calculator->calculate($this->baseInput());
        self::assertSame(0, $result['new_refund_request_cents']);
        self::assertSame(6100, $result['balance_due_cents']);
    }

    public function testPaymentEqualToRetainedChargeProducesNeitherRefundNorBalance(): void
    {
        $result = $this->calculator->calculate($this->baseInput(['valid_payment_cents' => 6100]));
        self::assertSame(0, $result['new_refund_request_cents']);
        self::assertSame(0, $result['balance_due_cents']);
    }

    public function testZeroIssuedBooksProratesTheEntireAnnualAllocation(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'issued_book_charge_cents' => 0,
            'valid_payment_cents' => 38000,
        ]));
        self::assertSame(0, $result['issued_book_charge_cents']);
        self::assertSame(1267, $result['earned_tuition_cents']);
        self::assertSame(36733, $result['new_refund_request_cents']);
    }

    public function testFinalWeekAlwaysClosesAtTheExactAnnualAllocation(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'withdrawal_request_date' => '2027-02-26',
            'valid_payment_cents' => 38000,
        ]));
        self::assertSame(30, $result['studied_weeks']);
        self::assertSame(33000, $result['earned_tuition_cents']);
        self::assertSame(38000, $result['retained_charge_cents']);
    }

    public function testOpenReservationCannotMakeARefundNegative(): void
    {
        $result = $this->calculator->calculate($this->baseInput([
            'valid_payment_cents' => 10000,
            'open_reservation_cents' => 999999,
        ]));
        self::assertSame(3900, $result['refundable_credit_cents']);
        self::assertSame(0, $result['new_refund_request_cents']);
    }

    /** @param array<string,mixed> $overrides */
    private function baseInput(array $overrides = []): array
    {
        return array_replace([
            'annual_fee_allocation_cents' => 38000,
            'issued_book_charge_cents' => 5000,
            'total_instructional_weeks' => 30,
            'school_year_start_date' => '2026-08-01',
            'enrollment_date' => '2026-08-01',
            'withdrawal_request_date' => '2026-08-07',
            'valid_payment_cents' => 0,
            'completed_payout_cents' => 0,
            'open_reservation_cents' => 0,
            'other_charge_cents' => 0,
            'annual_fee_includes_books' => true,
        ], $overrides);
    }
}