<?php
    namespace adapters;

    /**
     * Interface for phones adapters
     * Phone's adapters allow RaspiSMS to use a platform to communicate with a phone number.
     * Its an adapter between internal and external code, as an API, command line software, physical modem, etc.
     *
     * All Phone Adapters must implement this interface
     */
    class GammuAdapter implements AdapterInterface
    {
        /**
         * Classname of the adapter
         */
        public static function meta_classname() : string { return __CLASS__; }

        /**
         * Name of the adapter.
         * It should probably be the name of the service it adapt (e.g : Gammu SMSD, OVH SMS, SIM800L, etc.)
         */
        public static function meta_name() : string { return 'Gammu'; }

        /**
         * Description of the adapter.
         * A short description of the service the adapter implements.
         */
        public static function meta_description() : string { return 'Utilisation du logiciel Gammu qui doit être installé sur le serveur et configuré. Voir https://wammu.eu.'; }
        
        /**
         * Description of the datas expected by the adapter to help the user. (e.g : A list of expecteds Api credentials fields, with name and value)
         */
        public static function meta_datas_help() : string { return 'Fichier de configuration à fournir à Gammu pour utiliser ce modem.'; } 
        
        /**
         * List of entries we want in datas for the adapter
         * @return array : Every line is a field as an array with keys : name, title, description, required
         */
        public static function meta_datas_fields() : array
        {
            return [
                [
                    'name' => 'config_file',
                    'title' => 'Fichier de configuration',
                    'description' => 'Chemin vers le fichier de configuration que Gammu devra utilisé pour se connecter au téléphone.',
                    'required' => true,
                ],
                [
                    'name' => 'pin',
                    'title' => 'Code PIN',
                    'description' => 'Code PIN devant être utilisé pour activer la carte SIM (laisser vide pour ne pas utiliser de code PIN).',
                    'required' => false,
                ],
            ];
        }

        /**
         * Does the implemented service support flash smss
         */
        public static function meta_support_flash() : bool { return false ; }
        
        /**
         * Does the implemented service support status change
         */
        public static function meta_support_status_change() : bool { return true; }


        /**
         * Phone number using the adapter
         */
        private $number;

        /**
         * Datas used to configure interaction with the implemented service. (e.g : Api credentials, ports numbers, etc.).
         */
        private $datas;

        
        /**
         * Adapter constructor, called when instanciated by RaspiSMS
         * @param string $number : Phone number the adapter is used for
         * @param json string $datas : JSON string of the datas to configure interaction with the implemented service
         */
        public function __construct (string $number, string $datas)
        {
            $this->number = $number;
            $this->datas = json_decode($datas, true);
        }
    
    
        /**
         * Method called to send a SMS to a number
         * @param string $destination : Phone number to send the sms to
         * @param string $text : Text of the SMS to send
         * @param bool $flash : Is the SMS a Flash SMS
         * @return mixed : Uid of the sended message if send, False else
         */
        public function send (string $destination, string $text, bool $flash = false)
        {
            if (!$this->unlock_sim())
            {
                return false;
            }
            
            $command_parts = [
                'gammu',
                '--config',
                escapeshellarg($this->datas['config_file']),
                'sendsms',
                'TEXT',
                escapeshellarg($destination),
                '-text',
                escapeshellarg($text),
                '-validity',
                'MAX',
                '-autolen',
                mb_strlen($text),
            ];

            if ($flash)
            {
                $command_parts[] = '-flash';
            }

            $result = $this->exec_command($command_parts);
            if ($result['return'] != 0)
            {
                return false;
            }

            $find_ok = $this->search_for_string($result['output'], 'ok');
            if (!$find_ok)
            {
                return false;
            }

            $uid = false;
            foreach ($result['output'] as $line)
            {
                $matches = [];
                preg_match('#reference=([0-9]+)#u', $line, $matches);
                
                if ($matches[1] ?? false)
                {
                    $uid = $matches[1];
                    break;
                }
            }

            if ($uid === false)
            {
                return false;
            }

            return $uid;
        }


        /**
         * Method called to read SMSs of the number
         * @return array : Array of the sms reads
         */
        public function read () : array
        {
            if (!$this->unlock_sim())
            {
                return [];
            }
        }


        /**
         * Method called to verify if the adapter is working correctly
         * should be use for exemple to verify that credentials and number are both valid
         * @return boolean : False on error, true else
         */
        public function test () : bool
        {
            //Always return true as we cannot test because we would be needing a root account
            return true;
        }


        /**
         * Method called on reception of a status update notification for a SMS
         * @return mixed : False on error, else array ['uid' => uid of the sms, 'status' => New status of the sms ('unknown', 'delivered', 'failed')]
         */
        public static function status_change_callback ()
        {
            return false;
        }

    
        /**
         * Function to unlock pin 
         * @return bool : False on error, true else
         */
        private function unlock_sim () : bool
        {
            if (!$this->datas['pin'])
            {
                return true;
            }

            $command_parts = [
                'gammu',
                '--config',
                escapeshellarg($this->datas['config_file']),
                'entersecuritycode',
                'PIN',
                escapeshellarg($this->datas['pin']),
            ];

            $result = $this->exec_command($command_parts);


            //Check security status
            $command_parts = [
                'gammu',
                '--config',
                escapeshellarg($this->datas['config_file']),
                'getsecuritystatus',
            ];

            $result = $this->exec_command($command_parts);

            if ($result['return'] != 0)
            {
                return false;
            }

            return $this->search_for_string($result['output'], 'nothing');
        }


        /**
         * Function to execute a command and transmit it to Gammu
         * @param array $command_parts : Commands parts to be join with a space
         * @return array : ['return' => int:return code of command, 'output' => array:each raw is a line of the output]
         */
        private function exec_command (array $command_parts) : array
        {
            //Add redirect of error to stdout
            $command_parts[] = '2>&1';


            $command = implode(' ', $command_parts);
            
            $output = [];
            $return_var = null;
            exec($command, $output, $return_var);

            var_dump($output);

            return ['return' => (int) $return_var, 'output' => $output];
        }

    
        /**
         * Function to search a string in the output of an executer command
         * @param array $output : Text to search in where each raw is a line
         * @param string $search : Text to search for
         * @return bool : True if found, false else
         */
        private function search_for_string (array $output, string $search) : bool
        {
            $find = false;
            foreach ($output as $line)
            {
                $find = mb_stristr($line, $search);
                if ($find !== false)
                {
                    break;
                }
            }

            return (bool) $find;
        }


    }