<?php

declare(strict_types=1);

namespace App\Service;

use App\Entity\Groups\AccommodationBooking;
use App\Repository\Groups\AccommodationPriceRepository;

class AccommodationBookingBreakdownCalculator
{
    public function __construct(
        private readonly GroupsPriceCalculator $priceCalculator,
        private readonly AccommodationPriceRepository $priceRepo,
    ) {
    }

    /**
     * Returns the authoritative stored snapshot, falling back to current prices only for
     * bookings created before snapshot persistence was introduced, enriched with the
     * discount rows and the discounted total for rendering.
     *
     * @return array<string, mixed>|null null when no accommodation or dates are set
     */
    public function compute(AccommodationBooking $booking): ?array
    {
        $breakdown = $booking->getPriceBreakdown() ?? $this->computeCurrent($booking);

        if (null === $breakdown) {
            return null;
        }

        // Snapshots frozen before split-off periods existed (pricing version 1) read as a
        // booking without any, so templates only ever handle one shape.
        $breakdown += ['periods' => [], 'periodsTotal' => 0];

        return $this->withDiscounts($booking, $breakdown);
    }

    /**
     * Adds the discount rows and the price the customer actually pays. Derived on every read
     * and never persisted — refreshPriceSnapshot() stores the raw breakdown from
     * computeCurrent() — so the stored total and this one come out of the same code and
     * cannot drift apart.
     *
     * @param array<string, mixed> $breakdown
     *
     * @return array<string, mixed> the breakdown plus `discounts`, `discountSubtotal`,
     *                              `totalDiscountDetails` and `discountedTotal`
     */
    public function withDiscounts(AccommodationBooking $booking, array $breakdown): array
    {
        // The labels carry their own "Rabatt" prefix so that every row renders as plain
        // {label} {percent} %, while the freely named discount on the total below is a fixed
        // amount and renders as its label alone.
        $buckets = [
            ['Rabatt Unterkunft', $booking->getAccommodationDiscount(), (int) ($breakdown['basePrice'] ?? 0) + (int) ($breakdown['additionalPersonsPrice'] ?? 0)],
            ['Rabatt Verpflegung', $booking->getBoardServiceDiscount(), (int) ($breakdown['boardPrice'] ?? 0)],
            ['Rabatt Zusatzleistungen', $booking->getAdditionalServicesDiscount(), (int) ($breakdown['servicesPrice'] ?? 0)],
        ];

        $discounts = [];
        $discountSum = 0;

        foreach ($buckets as [$label, $percent, $base]) {
            $amount = self::discountAmount($base, $percent);

            // Nothing to show for a discount of 0 %, or one on a bucket this booking has no
            // price in — a "– 0,00 €" row only raises questions.
            if (0 === $amount) {
                continue;
            }

            $discountSum += $amount;
            $discounts[] = ['label' => $label, 'percent' => $percent, 'amount' => $amount];
        }

        // Deliberately not $booking->getTotalPrice(): refreshPriceSnapshot() calls this while
        // computing the new total, where the stored one is still the outdated value.
        $subtotal = (int) ($breakdown['total'] ?? 0) - $discountSum;

        // A fixed sum rather than a percentage, subtracted after the section discounts. Clamped to
        // what is left of the subtotal so that a discount larger than the price cannot produce a
        // negative total, the same guard BookingSummaryAssembler applies to vouchers.
        $totalDiscountAmount = min($booking->getTotalDiscountAmount() ?? 0, max(0, $subtotal));

        $breakdown['discounts'] = $discounts;
        $breakdown['totalDiscountDetails'] = 0 !== $totalDiscountAmount
            ? [
                'label' => (string) $booking->getTotalDiscountLabel(),
                'amount' => $totalDiscountAmount,
            ]
            : null;
        // Only worth a row when it sits between two sets of discounts — with no section discount
        // above it, a subtotal would merely restate the total one line up.
        $breakdown['discountSubtotal'] = 0 !== $totalDiscountAmount && [] !== $discounts ? $subtotal : null;
        $breakdown['discountedTotal'] = $subtotal - $totalDiscountAmount;

        return $breakdown;
    }

    private static function discountAmount(int $base, ?int $percent): int
    {
        return null !== $percent ? (int) round($base * $percent / 100) : 0;
    }

    /**
     * Calculates against the current catalog. Use only while creating or explicitly editing
     * a booking, or as a compatibility fallback for records created before price snapshots.
     *
     * The catalog prices the main period only; the split-off periods add their lines on top,
     * so `total` is the grand total the discounts are taken from. The price rows are loaded for
     * the whole stay, which the includedPax floor and the short-term surcharge are judged on.
     *
     * @return array<string, mixed>|null
     */
    public function computeCurrent(AccommodationBooking $booking): ?array
    {
        $accommodation = $booking->getAccommodation();
        $dateFrom = $booking->getDateFrom();
        $dateTo = $booking->getDateTo();

        if (null === $accommodation || null === $dateFrom || null === $dateTo) {
            return null;
        }

        $prices = $this->priceRepo->findByHotelCodeAndDateRange(
            $accommodation->getCalendarCode() ?? '',
            $dateFrom,
            $dateTo,
        );

        $breakdown = $this->priceCalculator->calculateFromSnapshots(
            $booking->getPaxCount(),
            $booking->getMinorsCount(),
            $booking->getMainNights(),
            $booking->getMainDateFrom() ?? $dateFrom,
            $booking->getMainDateTo() ?? $dateTo,
            $dateFrom,
            $booking->getNights(),
            $prices,
            $booking->getBoardServicePrice(),
            $booking->getAdditionalServices(),
            $accommodation->getCurrency(),
        );

        $periods = [];
        foreach (array_filter([$booking->getLeadingPeriod(), $booking->getTrailingPeriod()]) as $period) {
            $periods[] = [
                'position' => $period->getPosition()->value,
                'label' => $period->getLabel(),
                'dateFrom' => $period->getDateFrom()->format('Y-m-d'),
                'dateTo' => $period->getDateTo()->format('Y-m-d'),
                'nights' => $period->getNights(),
                'lines' => $period->getLines(),
                'total' => $period->getTotal(),
            ];
        }

        $periodsTotal = $booking->getPeriodsTotal();

        return [
            ...$breakdown,
            'periods' => $periods,
            'periodsTotal' => $periodsTotal,
            'total' => $breakdown['total'] + $periodsTotal,
        ];
    }
}