<?php

declare(strict_types=1);

namespace App\Tests\Service;

use App\Entity\Groups\AccommodationPrice;
use App\Service\GroupsPriceCalculator;
use App\Service\PriceTimelineBuilder;
use PHPUnit\Framework\TestCase;

class GroupsPriceCalculatorTest extends TestCase
{
    private const int NIGHTS = 3;

    public function testFreeBoardDoesNotTriggerUndersubscriptionSurcharge(): void
    {
        $result = $this->calculate(30, 0);

        self::assertSame(0, $result['undersubscriptionSurcharge']);
        self::assertNull($result['undersubscriptionThreshold']);
        self::assertSame(0, $result['boardPrice']);
    }

    public function testNoBoardDoesNotTriggerUndersubscriptionSurcharge(): void
    {
        $result = $this->calculate(30, null);

        self::assertSame(0, $result['undersubscriptionSurcharge']);
        self::assertNull($result['undersubscriptionThreshold']);
        self::assertSame(0, $result['boardPrice']);
    }

    public function testPaidBoardBelow40TriggersTheLowerThresholdSurcharge(): void
    {
        $result = $this->calculate(30, 1500);

        self::assertSame(30 * 500 * self::NIGHTS, $result['undersubscriptionSurcharge']);
        self::assertSame(40, $result['undersubscriptionThreshold']);
        self::assertSame(1500 * 30 * self::NIGHTS, $result['boardPrice']);
    }

    public function testPaidBoardBelow50TriggersTheUpperThresholdSurcharge(): void
    {
        $result = $this->calculate(45, 1500);

        self::assertSame(45 * 250 * self::NIGHTS, $result['undersubscriptionSurcharge']);
        self::assertSame(50, $result['undersubscriptionThreshold']);
    }

    public function testTheShortTermSurchargeIsJudgedOnTheWholeStay(): void
    {
        // Three nights priced for the group, but one night split off a four-night stay: the
        // stay is not short-term, so the three nights must not pick up the 10 % surcharge.
        $price = $this->price('2026-06-01', '2026-08-31', 20);

        $split = $this->calculateMain('2026-07-02', '2026-07-05', '2026-07-01', 4, [$price]);
        $unsplit = $this->calculateMain('2026-07-02', '2026-07-05', '2026-07-02', 3, [$price]);

        self::assertSame(0, $split['shortTermSurcharge']);
        self::assertSame(3, $split['nights']);
        self::assertSame((int) round(($unsplit['basePrice'] + $unsplit['additionalPersonsPrice']) * 10 / 100), $unsplit['shortTermSurcharge']);
    }

    public function testTheShortTermSurchargeOfAShortStayIsChargedOnThePricedNightsOnly(): void
    {
        // A three-night stay with one night split off: 10 % on the two nights the group pays
        // for, not 20 % for a two-night stay and not on the split-off night's lines.
        $price = $this->price('2026-06-01', '2026-08-31', 20);

        $result = $this->calculateMain('2026-07-02', '2026-07-04', '2026-07-01', 3, [$price]);

        self::assertSame(2 * 100_00, $result['basePrice']);
        self::assertSame((int) round(($result['basePrice'] + $result['additionalPersonsPrice']) * 10 / 100), $result['shortTermSurcharge']);
    }

    public function testTheIncludedPaxFloorComesFromTheStaysFirstNight(): void
    {
        // The stay starts in a price period with a floor of 30; the main group arrives a day
        // later, in one with a floor of 50. Splitting the first night off must not raise the
        // floor the 20 people are billed at.
        $prices = [
            $this->price('2026-06-01', '2026-07-01', 30),
            $this->price('2026-07-02', '2026-08-31', 50),
        ];

        $result = $this->calculateMain('2026-07-02', '2026-07-08', '2026-07-01', 7, $prices, paxCount: 20, boardServicePrice: 1500);

        self::assertSame(30, $result['includedPax']);
        self::assertSame(30, $result['effectivePax']);
        self::assertSame(1500 * 30 * 6, $result['boardPrice']);
    }

    /**
     * @param list<AccommodationPrice> $prices
     *
     * @return array<string, mixed>
     */
    private function calculateMain(string $from, string $to, string $stayFrom, int $stayNights, array $prices, int $paxCount = 20, ?int $boardServicePrice = null): array
    {
        $dateFrom = new \DateTimeImmutable($from);
        $dateTo = new \DateTimeImmutable($to);

        return $this->calculator()->calculateFromSnapshots(
            $paxCount,
            0,
            $dateFrom->diff($dateTo)->days,
            $dateFrom,
            $dateTo,
            new \DateTimeImmutable($stayFrom),
            $stayNights,
            $prices,
            $boardServicePrice,
            [],
            'EUR',
        );
    }

    private function price(string $from, string $to, int $includedPax): AccommodationPrice
    {
        return (new AccommodationPrice())
            ->setDateFrom(new \DateTimeImmutable($from))
            ->setDateTo(new \DateTimeImmutable($to))
            ->setIncludedPax($includedPax)
            ->setPricePerNight(100_00)
            ->setPriceAdditionalPerson(10_00)
            ->setMinNights(1);
    }

    private function calculator(): GroupsPriceCalculator
    {
        return new GroupsPriceCalculator(new PriceTimelineBuilder(), [
            'runningCostsEur' => 0,
            'runningCostsChf' => 0,
            'undersubscription30Eur' => 5.0,
            'undersubscription30Chf' => 6.0,
            'undersubscription40Eur' => 2.5,
            'undersubscription40Chf' => 3.0,
        ]);
    }

    /**
     * @return array<string, mixed>
     */
    private function calculate(int $paxCount, ?int $boardServicePrice): array
    {
        $dateFrom = new \DateTimeImmutable('2026-07-01');
        $dateTo = $dateFrom->modify(sprintf('+%d days', self::NIGHTS));

        $price = (new AccommodationPrice())
            ->setDateFrom($dateFrom->modify('-1 month'))
            ->setDateTo($dateTo->modify('+1 month'))
            ->setIncludedPax(20)
            ->setPricePerNight(100_00)
            ->setPriceAdditionalPerson(10_00)
            ->setMinNights(1);

        return $this->calculator()->calculateFromSnapshots(
            $paxCount,
            0,
            self::NIGHTS,
            $dateFrom,
            $dateTo,
            $dateFrom,
            self::NIGHTS,
            [$price],
            $boardServicePrice,
            [],
            'EUR',
        );
    }
}