<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Cookie;

class SetLocale
{
    /** @var array<string> */
    private array $available = [
        'en','de','es','pt_BR','tr','pl',
        // prepared, not yet enabled in UI
        'fr','it','ru','uk','vi','id','zh_CN','ja','ko','sv','no','fi','nl',
    ];

    public function handle(Request $request, Closure $next)
    {
        $locale = $this->resolveLocale($request);

        // Apply
        app()->setLocale($locale);

        // Persist for guests as well (1 year)
        $request->session()->put('locale', $locale);
        Cookie::queue(cookie('locale', $locale, 60 * 24 * 365));

        // If logged in and preference changed, consider persisting upstream (no local DB writes)
        if ($user = $request->user()) {
            if (($user->preferred_locale ?? null) !== $locale) {
                // Defer persistence to external API; keep request-scoped preference only.
                // Optionally, emit an event or queue a task to sync.
            }
        }

        return $next($request);
    }

    private function resolveLocale(Request $request): string
    {
        // 1) explicit query param ?lang=xx
        $q = $request->query('lang');
        if ($q && $this->isAllowed($q)) return $this->normalize($q);

        // 2) user preference
        $u = $request->user();
        if ($u && $this->isAllowed($u->preferred_locale ?? null)) return $this->normalize($u->preferred_locale);

        // 3) session
        $s = $request->session()->get('locale');
        if ($this->isAllowed($s)) return $this->normalize((string) $s);

        // 4) cookie
        $c = $request->cookie('locale');
        if ($this->isAllowed($c)) return $this->normalize((string) $c);

        // 5) Accept-Language best effort
        $preferred = $request->getPreferredLanguage($this->available);
        if ($this->isAllowed($preferred)) return $this->normalize((string) $preferred);

        // 6) fallback
        return config('app.locale', 'en');
    }

    private function isAllowed($code): bool
    {
        if (!$code) return false;
        $norm = $this->normalize((string) $code);
        return in_array($norm, $this->available, true);
    }

    private function normalize(string $code): string
    {
        // Normalize e.g. pt-br → pt_BR, zh-cn → zh_CN; others lower-case
        $code = str_replace([' ', '-'], ['','_'], trim($code));
        if (strtolower($code) === 'pt_br') return 'pt_BR';
        if (strtolower($code) === 'zh_cn') return 'zh_CN';
        return strtolower($code);
    }
}