<?php

namespace App\Support;

/** Text variants share one campaign identity and one set of financial rules. */
final class PromotionTranslations
{
    public const LANGUAGES = ['zh', 'en', 'vi'];
    public const FIELDS = ['title', 'content'];

    public static function all(array $activity): array
    {
        $stored = $activity['translations'] ?? null;
        if (is_string($stored)) $stored = json_decode($stored, true);
        if (!is_array($stored) || !$stored) {
            $lang = in_array($activity['lang'] ?? '', self::LANGUAGES, true) ? $activity['lang'] : 'zh';
            $stored = [$lang => array_intersect_key($activity, array_flip(self::FIELDS))];
        }
        $result = [];
        foreach (self::LANGUAGES as $lang) {
            foreach (self::FIELDS as $field) $result[$lang][$field] = (string) ($stored[$lang][$field] ?? '');
        }
        return $result;
    }

    public static function select(array $activity, string $lang): ?array
    {
        $text = self::all($activity)[$lang] ?? null;
        if (!$text || trim($text['title']) === '') return null;
        return ['lang' => $lang, 'title' => $text['title'],
            'content' => $text['content'] === '' ? null : $text['content']];
    }
}