<?php

namespace App\Services;

/**
 * Chooses which channel delivers an OTP.
 *
 * OTP_PROVIDER=nabeh    -> Nabeh gateway
 * OTP_PROVIDER=whatsapp -> legacy self-hosted WhatsApp bots
 *
 * Callers pass the code, not a rendered message: Nabeh composes its own message
 * around the code, while the WhatsApp bots need finished text. Keeping that
 * difference here means call sites do not care which channel is active.
 *
 * With OTP_FALLBACK_ENABLED on, a failure is retried on the other channel
 * before the login is refused - losing OTP delivery locks out every user.
 */
class OtpSender
{
    public static function sendOtp(string $phone, string $otp): array
    {
        $provider = strtolower(trim((string)env('OTP_PROVIDER', 'whatsapp')));
        $fallback = strtolower((string)env('OTP_FALLBACK_ENABLED', 'true')) === 'true';

        $result = self::dispatch($provider, $phone, $otp);
        $result['provider'] = $provider;

        if ($result['success'] || !$fallback) {
            return $result;
        }

        $alternate = $provider === 'nabeh' ? 'whatsapp' : 'nabeh';
        error_log(sprintf(
            '[OTP] primary channel "%s" failed, falling back to "%s" | error=%s',
            $provider,
            $alternate,
            $result['error'] ?? substr((string)($result['raw_response'] ?? ''), 0, 200)
        ));

        $fallbackResult = self::dispatch($alternate, $phone, $otp);
        $fallbackResult['provider'] = $alternate;
        $fallbackResult['primary_error'] = $result['error'] ?? null;

        return $fallbackResult;
    }

    private static function dispatch(string $channel, string $phone, string $otp): array
    {
        if ($channel === 'nabeh') {
            return (new NabehOtpService())->sendOtp($phone, $otp);
        }

        $appName = (string)env('NABEH_APP_NAME', 'مُصادَق');
        $message = "رمز التحقق لتطبيق {$appName}:\n*{$otp}*\n\nصالح لمدة 5 دقائق.";

        return (new WhatsAppProxyService())->sendMessage($phone, $message);
    }
}