<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Request;

/**
 * Auth for SuperAdmin → product (kill-switch / super settings):
 * 1) Authorization Bearer matching SUPERADMIN_REMOTE_TOKEN
 *    OR SUPERADMIN_SMS_SHARED_SECRET (CDN-safe; same secret as SMS)
 * 2) Optional: shared HMAC headers X-Abshode-* (may be stripped by CDN)
 */
class EnsureSuperAdminRemoteToken
{
    private const MAX_SKEW_SECONDS = 300;

    private const CANONICAL_PATH = '/api/super/settings';

    public function handle(Request $request, Closure $next)
    {
        if ($this->authByBearer($request)) {
            return $next($request);
        }

        if ($this->authByHmac($request)) {
            return $next($request);
        }

        $hasSecret = $this->sharedSecret() !== '';
        $hasToken = $this->bearerToken() !== '';
        if (! $hasSecret && ! $hasToken) {
            return response()->json([
                'message' => 'SUPERADMIN_SMS_SHARED_SECRET or SUPERADMIN_REMOTE_TOKEN is not configured',
            ], 503);
        }

        return response()->json(['message' => 'Unauthorized'], 401);
    }

    private function authByHmac(Request $request): bool
    {
        $secret = $this->sharedSecret();
        if ($secret === '') {
            return false;
        }

        $domainHeader = trim((string) $request->header('X-Abshode-Domain', ''));
        $tsRaw = trim((string) $request->header('X-Abshode-Timestamp', ''));
        $sigRaw = trim((string) $request->header('X-Abshode-Signature', ''));
        if ($domainHeader === '' || $tsRaw === '' || $sigRaw === '') {
            return false;
        }

        if (! ctype_digit($tsRaw)) {
            return false;
        }
        $timestamp = (int) $tsRaw;
        if (abs(time() - $timestamp) > self::MAX_SKEW_SECONDS) {
            return false;
        }

        $domain = $this->normalizeHost($domainHeader);
        if ($domain === '' || ! $this->domainAllowed($domain, $request)) {
            return false;
        }

        $method = strtoupper($request->getMethod());
        $payload = $timestamp.'.'.$method.'.'.self::CANONICAL_PATH.'.'.$domain;
        $expected = hash_hmac('sha256', $payload, $secret);

        return hash_equals(strtolower($expected), strtolower($sigRaw));
    }

    private function authByBearer(Request $request): bool
    {
        $auth = (string) $request->header('Authorization', '');
        if (! preg_match('/^\s*Bearer\s+(.+)\s*$/i', $auth, $m)) {
            return false;
        }

        $token = trim($m[1]);
        if ($token === '') {
            return false;
        }

        foreach ([$this->bearerToken(), $this->sharedSecret()] as $expected) {
            if ($expected !== '' && hash_equals($expected, $token)) {
                return true;
            }
        }

        return false;
    }

    private function domainAllowed(string $domain, Request $request): bool
    {
        $candidates = [
            $this->configuredDomain(),
            $this->normalizeHost((string) $request->getHost()),
        ];

        foreach ($candidates as $candidate) {
            if ($candidate !== '' && hash_equals($candidate, $domain)) {
                return true;
            }
        }

        return false;
    }

    private function sharedSecret(): string
    {
        return trim((string) config('services.superadmin.sms_shared_secret', ''));
    }

    private function bearerToken(): string
    {
        return trim((string) config('services.superadmin.remote_token', ''));
    }

    private function configuredDomain(): string
    {
        $override = trim((string) config('services.superadmin.sms_domain', ''));
        if ($override !== '') {
            return $this->normalizeHost($override);
        }

        $fromApp = parse_url((string) config('app.url'), PHP_URL_HOST);

        return $this->normalizeHost(is_string($fromApp) ? $fromApp : '');
    }

    private function normalizeHost(string $value): string
    {
        $host = strtolower(trim($value));
        $host = preg_replace('#^https?://#', '', $host) ?? $host;
        $host = explode('/', $host)[0] ?? $host;
        $host = explode(':', $host)[0] ?? $host;

        return trim($host);
    }
}