<?php
// sms-config.php - SMS Gateway Configuration and Helper Functions
require_once 'config.php';

class SMSManager {
    private $gateway;
    private $config;
    
    public function __construct() {
        // Configure your preferred SMS gateway here
        $this->gateway = 'msg91'; // Options: msg91, textlocal, twofactor, fast2sms
        
        // SMS Gateway configurations
        $this->config = [
            'msg91' => [
                'auth_key' => 'YOUR_MSG91_AUTH_KEY', // Replace with actual key
                'template_id' => 'YOUR_TEMPLATE_ID', // Replace with actual template ID
                'route' => '4', // Transactional route
                'country' => '91'
            ],
            'textlocal' => [
                'api_key' => 'YOUR_TEXTLOCAL_API_KEY',
                'username' => 'YOUR_TEXTLOCAL_USERNAME',
                'hash' => 'YOUR_TEXTLOCAL_HASH',
                'sender' => 'TXTLCL' // 6 characters or less
            ],
            'twofactor' => [
                'api_key' => '79d4feb6-d168-11ea-9fa5-0200cd936042' // Replace with your actual API key
            ],
            'fast2sms' => [
                'api_key' => 'YOUR_FAST2SMS_API_KEY',
                'route' => 'dlt', // DLT route for OTP
                'sender_id' => 'FSTSMS'
            ]
        ];
    }
    
    /**
     * Send OTP SMS
     */
    public function sendOTP($mobileNumber, $otpCode, $templateMessage = null) {
        // Clean mobile number
        $mobileNumber = preg_replace('/[^0-9]/', '', $mobileNumber);
        
        // Remove leading zero if present
        if (substr($mobileNumber, 0, 1) === '0') {
            $mobileNumber = substr($mobileNumber, 1);
        }
        
        // Default OTP message
        if (!$templateMessage) {
            $templateMessage = "Your Relevant Reflex verification code is: {$otpCode}. Valid for 10 minutes. Do not share this with anyone.";
        }
        
        switch ($this->gateway) {
            case 'msg91':
                return $this->sendViaMSG91($mobileNumber, $otpCode, $templateMessage);
            case 'textlocal':
                return $this->sendViaTextLocal($mobileNumber, $templateMessage);
            case 'twofactor':
                return $this->sendViaTwoFactor($mobileNumber, $otpCode);
            case 'fast2sms':
                return $this->sendViaFast2SMS($mobileNumber, $templateMessage);
            default:
                return $this->mockSend($mobileNumber, $otpCode); // For testing
        }
    }
    
    /**
     * MSG91 SMS Gateway
     */
    private function sendViaMSG91($mobileNumber, $otpCode, $message) {
        $config = $this->config['msg91'];
        
        $url = "https://api.msg91.com/api/v5/otp";
        
        $data = [
            'template_id' => $config['template_id'],
            'mobile' => $config['country'] . $mobileNumber,
            'authkey' => $config['auth_key'],
            'otp' => $otpCode,
            'extra_param' => json_encode(['otp' => $otpCode])
        ];
        
        return $this->makeAPICall($url, $data, 'POST');
    }
    
    /**
     * TextLocal SMS Gateway
     */
    private function sendViaTextLocal($mobileNumber, $message) {
        $config = $this->config['textlocal'];
        
        $url = "https://api.textlocal.in/send/";
        
        $data = [
            'apikey' => $config['api_key'],
            'numbers' => '91' . $mobileNumber,
            'message' => $message,
            'sender' => $config['sender']
        ];
        
        return $this->makeAPICall($url, $data, 'POST');
    }
    
    /**
     * 2Factor SMS Gateway
     */
    private function sendViaTwoFactor($mobileNumber, $otpCode) {
        $config = $this->config['twofactor'];
        
        // Use AUTOGEN3 for pre-approved template (works immediately)
        $url = "https://2factor.in/API/V1/{$config['api_key']}/SMS/91{$mobileNumber}/{$otpCode}/AUTOGEN3";
        
        return $this->makeAPICall($url, [], 'GET');
    }
    
    /**
     * Fast2SMS Gateway
     */
    private function sendViaFast2SMS($mobileNumber, $message) {
        $config = $this->config['fast2sms'];
        
        $url = "https://www.fast2sms.com/dev/bulkV2";
        
        $data = [
            'authorization' => $config['api_key'],
            'sender_id' => $config['sender_id'],
            'message' => $message,
            'route' => $config['route'],
            'numbers' => $mobileNumber
        ];
        
        $headers = [
            'authorization: ' . $config['api_key'],
            'Content-Type: application/json'
        ];
        
        return $this->makeAPICall($url, $data, 'POST', $headers);
    }
    
    /**
     * Mock SMS sending for testing
     */
    private function mockSend($mobileNumber, $otpCode) {
        logError('Mock SMS sent', [
            'mobile' => $mobileNumber,
            'otp' => $otpCode,
            'message' => 'OTP for testing: ' . $otpCode
        ]);
        
        return [
            'success' => true,
            'message' => 'SMS sent successfully (Mock)',
            'reference_id' => 'MOCK_' . time()
        ];
    }
    
    /**
     * Make API call to SMS gateway
     */
    private function makeAPICall($url, $data, $method = 'POST', $headers = []) {
        $ch = curl_init();
        
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_TIMEOUT, 30);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        
        if ($method === 'POST') {
            curl_setopt($ch, CURLOPT_POST, true);
            if (!empty($data)) {
                if (empty($headers) || !in_array('Content-Type: application/json', $headers)) {
                    curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($data));
                } else {
                    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
                }
            }
        }
        
        if (!empty($headers)) {
            curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
        }
        
        $response = curl_exec($ch);
        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        $error = curl_error($ch);
        curl_close($ch);
        
        if ($error) {
            logError('SMS API Error', ['error' => $error, 'url' => $url]);
            return [
                'success' => false,
                'message' => 'Network error: ' . $error
            ];
        }
        
        $decodedResponse = json_decode($response, true);
        
        logError('SMS API Response', [
            'url' => $url,
            'http_code' => $httpCode,
            'response' => $decodedResponse ?: $response
        ]);
        
        // Parse response based on gateway
        return $this->parseResponse($decodedResponse ?: $response, $httpCode);
    }
    
    /**
     * Parse SMS gateway response
     */
    private function parseResponse($response, $httpCode) {
        if ($httpCode >= 200 && $httpCode < 300) {
            return [
                'success' => true,
                'message' => 'SMS sent successfully',
                'response' => $response
            ];
        } else {
            return [
                'success' => false,
                'message' => 'SMS sending failed',
                'response' => $response
            ];
        }
    }
    
    /**
     * Get available SMS balance (if supported by gateway)
     */
    public function getBalance() {
        switch ($this->gateway) {
            case 'msg91':
                $config = $this->config['msg91'];
                $url = "https://api.msg91.com/api/balance.php?authkey={$config['auth_key']}&type=4";
                return $this->makeAPICall($url, [], 'GET');
            default:
                return ['success' => false, 'message' => 'Balance check not supported for this gateway'];
        }
    }
}

// Global SMS helper function
function sendOTPSMS($mobileNumber, $otpCode) {
    $smsManager = new SMSManager();
    return $smsManager->sendOTP($mobileNumber, $otpCode);
}

/* 
 * SETUP INSTRUCTIONS FOR SMS GATEWAYS
 * ===================================
 * 
 * 1. MSG91 Setup:
 *    - Sign up at https://msg91.com/
 *    - Get Auth Key from dashboard
 *    - Create OTP template and get Template ID
 *    - Update auth_key and template_id in config above
 * 
 * 2. TextLocal Setup:
 *    - Sign up at https://www.textlocal.in/
 *    - Get API Key from settings
 *    - Update api_key in config above
 * 
 * 3. 2Factor Setup:
 *    - Sign up at https://2factor.in/
 *    - Get API Key from dashboard
 *    - Update api_key in config above
 * 
 * 4. Fast2SMS Setup:
 *    - Sign up at https://www.fast2sms.com/
 *    - Get API Key from dashboard
 *    - Update api_key in config above
 * 
 * TESTING:
 * - Set gateway to 'mock' for testing without sending real SMS
 * - Check errors.log for SMS logs
 * 
 * USAGE IN YOUR CODE:
 * 
 * require_once 'sms-config.php';
 * 
 * $result = sendOTPSMS('9876543210', '123456');
 * if ($result['success']) {
 *     echo "SMS sent successfully";
 * } else {
 *     echo "Failed to send SMS: " . $result['message'];
 * }
 * 
 */

// Example DLT (Distributed Ledger Technology) approved template for India:
/*
 * Template: "Your verification code for Relevant Reflex is {#var#}. Valid for 10 minutes. Do not share this OTP with anyone."
 * 
 * Replace {#var#} with actual OTP in your template
 * Make sure to register this template with your SMS provider for DLT compliance
 */
?>