<?php
/**
 * Twilio API integration class
 */
class TWP_Twilio_API {
    
    private $account_sid;
    private $auth_token;
    private $phone_number;
    private $api_base = 'https://api.twilio.com/2010-04-01';
    
    /**
     * Constructor
     */
    public function __construct() {
        $this->account_sid = get_option('twp_twilio_account_sid');
        $this->auth_token = get_option('twp_twilio_auth_token');
        $this->phone_number = get_option('twp_twilio_phone_number');
    }
    
    /**
     * Make a phone call
     */
    public function make_call($to_number, $twiml_url, $status_callback = null, $from_number = null) {
        $url = $this->api_base . '/Accounts/' . $this->account_sid . '/Calls.json';
        
        $data = array(
            'To' => $to_number,
            'From' => $from_number ?: $this->phone_number,
            'Url' => $twiml_url
        );
        
        if ($status_callback) {
            $data['StatusCallback'] = $status_callback;
            $data['StatusCallbackEvent'] = array('initiated', 'ringing', 'answered', 'completed');
        }
        
        return $this->make_request('POST', $url, $data);
    }
    
    /**
     * Forward a call
     */
    public function forward_call($call_sid, $to_number) {
        $twiml = new SimpleXMLElement('<?xml version="1.0" encoding="UTF-8"?><Response></Response>');
        $dial = $twiml->addChild('Dial');
        $dial->addChild('Number', $to_number);
        
        return $this->update_call($call_sid, array(
            'Twiml' => $twiml->asXML()
        ));
    }
    
    /**
     * Update an active call
     */
    public function update_call($call_sid, $params) {
        $url = $this->api_base . '/Accounts/' . $this->account_sid . '/Calls/' . $call_sid . '.json';
        return $this->make_request('POST', $url, $params);
    }
    
    /**
     * Get call details
     */
    public function get_call($call_sid) {
        $url = $this->api_base . '/Accounts/' . $this->account_sid . '/Calls/' . $call_sid . '.json';
        return $this->make_request('GET', $url);
    }
    
    /**
     * Create TwiML for queue
     */
    public function create_queue_twiml($queue_name, $wait_url = null, $wait_message = null) {
        $twiml = new SimpleXMLElement('<?xml version="1.0" encoding="UTF-8"?><Response></Response>');
        
        if ($wait_message) {
            $say = $twiml->addChild('Say', $wait_message);
            $say->addAttribute('voice', 'alice');
        }
        
        $enqueue = $twiml->addChild('Enqueue', $queue_name);
        
        if ($wait_url) {
            $enqueue->addAttribute('waitUrl', $wait_url);
        }
        
        return $twiml->asXML();
    }
    
    /**
     * Create TwiML for IVR menu
     */
    public function create_ivr_twiml($message, $options = array()) {
        $twiml = new SimpleXMLElement('<?xml version="1.0" encoding="UTF-8"?><Response></Response>');
        
        $gather = $twiml->addChild('Gather');
        $gather->addAttribute('numDigits', '1');
        $gather->addAttribute('timeout', '10');
        
        if (!empty($options['action_url'])) {
            $gather->addAttribute('action', $options['action_url']);
        }
        
        $say = $gather->addChild('Say', $message);
        $say->addAttribute('voice', 'alice');
        
        // Fallback if no input
        if (!empty($options['no_input_message'])) {
            $say_fallback = $twiml->addChild('Say', $options['no_input_message']);
            $say_fallback->addAttribute('voice', 'alice');
        }
        
        return $twiml->asXML();
    }
    
    /**
     * Send SMS
     */
    public function send_sms($to_number, $message) {
        $url = $this->api_base . '/Accounts/' . $this->account_sid . '/Messages.json';
        
        $data = array(
            'To' => $to_number,
            'From' => $this->phone_number,
            'Body' => $message
        );
        
        return $this->make_request('POST', $url, $data);
    }
    
    /**
     * Get available phone numbers
     */
    public function get_phone_numbers() {
        $url = $this->api_base . '/Accounts/' . $this->account_sid . '/IncomingPhoneNumbers.json';
        return $this->make_request('GET', $url);
    }
    
    /**
     * Search for available phone numbers
     */
    public function search_available_numbers($country_code = 'US', $area_code = null, $contains = null, $limit = 20) {
        $url = $this->api_base . '/Accounts/' . $this->account_sid . '/AvailablePhoneNumbers/' . $country_code . '/Local.json';
        
        $params = array('Limit' => $limit);
        
        if ($area_code) {
            $params['AreaCode'] = $area_code;
        }
        
        if ($contains) {
            $params['Contains'] = $contains;
        }
        
        $url .= '?' . http_build_query($params);
        
        return $this->make_request('GET', $url);
    }
    
    /**
     * Purchase a phone number
     */
    public function purchase_phone_number($phone_number, $voice_url = null, $sms_url = null) {
        $url = $this->api_base . '/Accounts/' . $this->account_sid . '/IncomingPhoneNumbers.json';
        
        $data = array(
            'PhoneNumber' => $phone_number
        );
        
        if ($voice_url) {
            $data['VoiceUrl'] = $voice_url;
            $data['VoiceMethod'] = 'POST';
        }
        
        if ($sms_url) {
            $data['SmsUrl'] = $sms_url;
            $data['SmsMethod'] = 'POST';
        }
        
        return $this->make_request('POST', $url, $data);
    }
    
    /**
     * Release a phone number
     */
    public function release_phone_number($phone_number_sid) {
        $url = $this->api_base . '/Accounts/' . $this->account_sid . '/IncomingPhoneNumbers/' . $phone_number_sid . '.json';
        return $this->make_request('DELETE', $url);
    }
    
    /**
     * Configure phone number webhook
     */
    public function configure_phone_number($phone_sid, $voice_url, $sms_url = null) {
        $url = $this->api_base . '/Accounts/' . $this->account_sid . '/IncomingPhoneNumbers/' . $phone_sid . '.json';
        
        $data = array(
            'VoiceUrl' => $voice_url,
            'VoiceMethod' => 'POST'
        );
        
        if ($sms_url) {
            $data['SmsUrl'] = $sms_url;
            $data['SmsMethod'] = 'POST';
        }
        
        return $this->make_request('POST', $url, $data);
    }
    
    /**
     * Make API request
     */
    private function make_request($method, $url, $data = array()) {
        $args = array(
            'method' => $method,
            'headers' => array(
                'Authorization' => 'Basic ' . base64_encode($this->account_sid . ':' . $this->auth_token),
                'Content-Type' => 'application/x-www-form-urlencoded'
            ),
            'timeout' => 30
        );
        
        if ($method === 'POST' && !empty($data)) {
            $args['body'] = $data;
        }
        
        if ($method === 'GET') {
            $response = wp_remote_get($url, $args);
        } else {
            $response = wp_remote_post($url, $args);
        }
        
        if (is_wp_error($response)) {
            return array(
                'success' => false,
                'error' => $response->get_error_message()
            );
        }
        
        $body = wp_remote_retrieve_body($response);
        $decoded = json_decode($body, true);
        
        $status_code = wp_remote_retrieve_response_code($response);
        
        if ($status_code >= 200 && $status_code < 300) {
            return array(
                'success' => true,
                'data' => $decoded
            );
        } else {
            return array(
                'success' => false,
                'error' => isset($decoded['message']) ? $decoded['message'] : 'API request failed',
                'code' => $status_code
            );
        }
    }
    
    /**
     * Validate webhook signature
     */
    public function validate_webhook_signature($url, $params, $signature) {
        $data = $url;
        
        if (is_array($params) && !empty($params)) {
            ksort($params);
            foreach ($params as $key => $value) {
                $data .= $key . $value;
            }
        }
        
        $computed_signature = base64_encode(hash_hmac('sha1', $data, $this->auth_token, true));
        
        return hash_equals($signature, $computed_signature);
    }
}