<?php

namespace App\Services;

use App\Models\RateEntry;
use App\Models\CountryZone;
use App\Enums\ShipmentDirection;
use App\Enums\ShipmentType;

/**
 * PriceCalculatorService
 * ----------------------
 * 4-quadrant price calculator.
 *
 *  ┌──────────┬──────────────┬──────────────────┐
 *  │          │  DOCUMENT    │  NON-DOCUMENT    │
 *  ├──────────┼──────────────┼──────────────────┤
 *  │ Export   │ Export×Doc   │ Export×Parcel    │
 *  │ Import   │ Import×Doc   │ Import×Parcel    │
 *  └──────────┴──────────────┴──────────────────┘
 *
 * Currency flow:
 *   1. Look up AED rate for (direction, serviceType, weight, zone).
 *   2. Convert AED → IRR using ExchangeRateService at the current rate.
 *   3. Return IRR amount (plus optional AED reference).
 */
class PriceCalculatorService
{
    public function __construct(
        protected ExchangeRateService $exchangeRate,
    ) {}

    /**
     * Calculate the price for a shipment.
     *
     * @param string      $direction   'import' | 'export'
     * @param string      $serviceType 'document' | 'parcel'
     * @param float       $weightKg    actual shipment weight
     * @param string      $countryName destination country name (matched via country_zones)
     * @return array {
     *     @var float $aed         AED amount
     *     @var float $irr         IRR amount (rounded to nearest 1000)
     *     @var string $currency   Final currency code ('IRR')
     *     @var RateEntry|null $rate  the rate row that was used
     * }
     * @throws \RuntimeException  when no rate is found
     */
    public function calculate(
        string $direction,
        string $serviceType,
        float $weightKg,
        string $countryName,
    ): array {
        // 1. Look up zone for this country × service type
        $zone = CountryZone::lookupZone($countryName, $serviceType);
        if ($zone === null) {
            throw new \RuntimeException(
                "No zone mapping for country '{$countryName}' service type '{$serviceType}'"
            );
        }

        // 2. Look up the AED rate for this weight/zone
        $rateEntry = RateEntry::lookup($direction, $serviceType, $weightKg, $zone, 'AED');
        if (! $rateEntry) {
            throw new \RuntimeException(
                "No rate found for {$direction}×{$serviceType} weight={$weightKg}kg zone={$zone}"
            );
        }

        // 3. Convert AED → IRR using current exchange rate
        $aedAmount = (float) $rateEntry->rate;
        $irrAmount = $this->exchangeRate->convertToIrr($aedAmount, 'AED');
        $irrAmount = (int) round($irrAmount / 1000) * 1000; // round to nearest 1000 IRR

        return [
            'aed'       => $aedAmount,
            'irr'       => $irrAmount,
            'currency'  => 'IRR',
            'rate'      => $rateEntry,
        ];
    }

    /**
     * Convenience: calculate from a Shipment model.
     */
    public function calculateForShipment($shipment): array
    {
        $direction   = $shipment->direction === ShipmentDirection::Export->value
                       || $shipment->direction === 'export' ? 'export' : 'import';
        $serviceType = $shipment->type === ShipmentType::Document->value
                       || $shipment->type === 'document' ? 'document' : 'parcel';
        $weight      = (float) ($shipment->total_weight ?? $shipment->weight ?? 0);
        $country     = $shipment->toCountry?->name
                       ?? $shipment->receiver_country
                       ?? $shipment->destination_country;

        return $this->calculate($direction, $serviceType, $weight, $country);
    }
}