<?php

namespace App\Services;

class RegisterLocationService
{
    private const SIGNUP_COUNTRY_TO_CSC_NAME = [
        'Antigua and Barbuda' => 'Antigua And Barbuda',
        'Eswatini' => 'Swaziland',
        'Guernsey' => 'Guernsey and Alderney',
        'Ivory Coast' => "Cote D'Ivoire (Ivory Coast)",
        'North Macedonia' => 'Macedonia',
        'Papua New Guinea' => 'Papua new Guinea',
        'Saint Kitts and Nevis' => 'Saint Kitts And Nevis',
        'Saint Vincent and the Grenadines' => 'Saint Vincent And The Grenadines',
        'Svalbard and Jan Mayen Islands' => 'Svalbard And Jan Mayen Islands',
        'Timor-Leste' => 'East Timor',
        'Trinidad and Tobago' => 'Trinidad And Tobago',
        'Turks and Caicos Islands' => 'Turks And Caicos Islands',
        'Wallis and Futuna Islands' => 'Wallis And Futuna Islands',
    ];

    private static $countries;
    private static $states;
    private static $cities;

    public function getCitiesForCountryState(string $countryName, string $stateName): array
    {
        $countryName = trim($countryName);
        $stateName = trim($stateName);
        if ($countryName === '' || $stateName === '') {
            return [];
        }

        $countryCode = $this->resolveCountryCode($countryName);
        if (!$countryCode) {
            return [];
        }

        $stateCode = $this->resolveStateCode($countryCode, $stateName);
        if (!$stateCode) {
            return [];
        }

        $names = [];
        foreach ($this->loadCities() as $row) {
            if (!is_array($row) || count($row) < 3) {
                continue;
            }
            if (($row[1] ?? '') === $countryCode && ($row[2] ?? '') === $stateCode) {
                $names[] = $row[0];
            }
        }

        $names = array_values(array_unique($names));
        sort($names, SORT_STRING);

        return $names;
    }

    private function resolveCountryCode(string $countryName): ?string
    {
        $lookup = self::SIGNUP_COUNTRY_TO_CSC_NAME[$countryName] ?? $countryName;

        foreach ($this->loadCountries() as $country) {
            if (!is_array($country)) {
                continue;
            }
            $name = $country['name'] ?? '';
            if ($name === $lookup || $name === $countryName) {
                return $country['isoCode'] ?? null;
            }
        }

        return null;
    }

    private function resolveStateCode(string $countryCode, string $stateName): ?string
    {
        foreach ($this->loadStates() as $state) {
            if (!is_array($state)) {
                continue;
            }
            if (($state['countryCode'] ?? '') === $countryCode && ($state['name'] ?? '') === $stateName) {
                return $state['isoCode'] ?? null;
            }
        }

        return null;
    }

    private function loadCountries(): array
    {
        if (self::$countries === null) {
            self::$countries = $this->readJson('country.json');
        }

        return self::$countries;
    }

    private function loadStates(): array
    {
        if (self::$states === null) {
            self::$states = $this->readJson('state.json');
        }

        return self::$states;
    }

    private function loadCities(): array
    {
        if (self::$cities === null) {
            self::$cities = $this->readJson('city.json');
        }

        return self::$cities;
    }

    private function readJson(string $filename): array
    {
        $path = storage_path('app/geo/' . $filename);
        if (!is_readable($path)) {
            return [];
        }

        $decoded = json_decode(file_get_contents($path), true);

        return is_array($decoded) ? $decoded : [];
    }
}