<?php

declare(strict_types=1);

namespace App\BusProNet\Utility;

use Psr\Log\LoggerInterface;

/**
 * Maps BusPro's `hotel/land` token onto a lowercase ISO 3166-1 alpha-2 code.
 *
 * BusPro has no country vocabulary: the field is free text that has accumulated three
 * conventions side by side — ISO-2 (`CH`, `NL`), the European vehicle registration codes
 * (`D`, `A`, `F`, `S`, `FL`) and ISO-3 (`AUT`, `PRT`, `HRV`), with the same country often
 * under several tokens. The table below is therefore part of the API contract rather than
 * a derivation: consumers render a flag from it, and a wrong entry mislabels a destination
 * silently, which is worse than no flag at all. An unknown token maps to null — never to a
 * guess, never to an empty string.
 */
class CountryCodeMapper
{
    /**
     * Keys are upper-cased tokens, values lowercase ISO-2.
     *
     * Entries worth their explanation:
     * - `IR` is Ireland, not Iran. Every row carrying it is Dublin or Carlow.
     * - `SLO` is Slovakia here, not Slovenia: its only row is a Slovak company, and
     *   Slovenia already arrives under its own `SI`.
     * - `S`, `N`, `FL` are vehicle codes (Sweden, Norway, Liechtenstein), consistent with
     *   the `D`/`A`/`F`/`I`/`E`/`B` in the same column.
     * - `UK` is the colloquial form of the ISO `GB`.
     *
     * @var array<string, string>
     */
    private const MAP = [
        'A' => 'at',
        'AT' => 'at',
        'AUT' => 'at',
        'B' => 'be',
        'CA' => 'ca',
        'CH' => 'ch',
        'CZ' => 'cz',
        'D' => 'de',
        'DEU' => 'de',
        'DK' => 'dk',
        'E' => 'es',
        'ES' => 'es',
        'F' => 'fr',
        'FI' => 'fi',
        'FL' => 'li',
        'FR' => 'fr',
        'GR' => 'gr',
        'GRE' => 'gr',
        'HR' => 'hr',
        'HRV' => 'hr',
        'HU' => 'hu',
        'I' => 'it',
        'IL' => 'il',
        'IR' => 'ie',
        'IS' => 'is',
        'IT' => 'it',
        'LT' => 'lt',
        'LV' => 'lv',
        'MT' => 'mt',
        'N' => 'no',
        'NL' => 'nl',
        'PL' => 'pl',
        'PRT' => 'pt',
        'PT' => 'pt',
        'RUS' => 'ru',
        'S' => 'se',
        'SI' => 'si',
        'SLO' => 'sk',
        'UK' => 'gb',
        'USA' => 'us',
        'ZA' => 'za',
    ];

    /**
     * Tokens already reported in this process, so a master data file full of the same
     * unknown token produces one log line rather than one per hotel.
     *
     * @var array<string, true>
     */
    private array $reported = [];

    public function __construct(
        private readonly LoggerInterface $logger,
    ) {
    }

    /**
     * @param string|null $token the raw `hotel/land` value
     *
     * @return string|null lowercase ISO-2, or null when absent, empty or unmappable
     */
    public function map(?string $token): ?string
    {
        if (null === $token) {
            return null;
        }

        $normalized = strtoupper(trim($token));

        if ('' === $normalized) {
            return null;
        }

        if (isset(self::MAP[$normalized])) {
            return self::MAP[$normalized];
        }

        if (false === isset($this->reported[$normalized])) {
            $this->reported[$normalized] = true;
            $this->logger->warning('Unmapped BusPro country token', ['token' => $token]);
        }

        return null;
    }
}