<?php
/**
 * gacBrokerClient -- class definition
 *
 * this is the class for declaring a brokerClient for use in testing, or within the framework when we need to publish
 * an event to another queue (that's not a logging event).
 *
 * This class simply abstracts the RabbitMQ processes so that you don't have to re-write all the RMQ code every
 * time you want to publish a message to the queues.
 *
 * IMPORTANT NOTE:
 * ---------------
 * Whenever you add a new queue to the pantheon, you'll need to update the constructor class, adding the queue name
 * to the $validQueues member, and to the switch-case statement that assigns the correct environment.
 *
 *
 * @author  mike@givingassistant.org
 * @version 1.0
 *
 * HISTORY:
 * ========
 * 06-15-17     mks     original coding
 * 02-08-17     mks     _INF-139: updated for migrations broker, PHPDoc variable casting for AMQP members
 * 07-31-18     mks     CORE-774:  PHP7.2 exception handling
 * 09-18-19     mks     DB-136: improved error messaging and exception handling
 *
 */

//use PhpAmqpLib\Connection\AMQPStreamConnection;
use PhpAmqpLib\Channel\AMQPChannel;
use PhpAmqpLib\Exception\AMQPRuntimeException;
use PhpAmqpLib\Exception\AMQPTimeoutException;
use PhpAmqpLib\Message\AMQPMessage;


class gacBrokerClient {
    private ?object $rabbitConnection = null;
    private ?AMQPChannel $rabbitChannel = null;
    private string $rabbitCallbackQueue;
    private ?string $rabbitResponse;
    private string $rabbitCorrelationID;
    private string $queueName;
    private array $validQueues;
    private gacErrorLogger $logger;
    private string $res = 'CLBR: ';
    public bool $status;

    /**
     * __construct() -- public method
     *
     * the constructor instantiates the class and establishes a connection to the RMQ broker.
     *
     * the constructor takes one input parameter:
     *
     * - queueName -- which queue does this instantiation wish to connect to
     *
     * as of this writing, there are two queuing services supported:  namaste and admin.  If more are added, then
     * they'll need to be defined (as constants) and the resource evaluation code updated.
     *
     * method returns a boolean indicating whether or not the resource management was successful and attempts to
     * provide diagnostics via logging, cli output, or via the status member variable.
     *
     * queue_declare arguments:
     * ------------------------
     * Queue Name: this is an arbitrary name, will be used to identify the queue
     * Passive: if set to true, the server will only check if the queue can be created, false will actually attempt to create the queue.
     * Durable: Typically, if the server stops or crashes, all queues and messages are lost... unless we declare the queue durable, in which case the queue will persist if the server is restarted.
     * Exclusive: If true, the queue can only be used by the connection that created it.
     * Autodelete: if true, the queue will be deleted once it has no messages and there are no subscribers connected
     *
     *
     * @author  mike@givingassistant.org
     * @version 1.0
     *
     * @param $_queueName
     * @param $_tag
     *
     * HISTORY:
     * ========
     * 06-15-17     mks     initial coding
     * 02-08-18     mks     _INF-139: support for the migration broker, fixed return statements, console log
     * 04-11-18     mks     _INF-188: warehousing broker support
     * 01-29-20     mks     DB-144: tercero support
     * 12-10-20     mks     DB-180: segundo cons broker support
     *
     */
    public function __construct(string $_queueName, $_tag = 'default')
    {
        register_shutdown_function(array($this, '__destruct'));
        $this->status = false;
        try {
            $this->logger = new gacErrorLogger();
        } catch (TypeError $t) {
            consoleLog($this->res, CON_ERROR, ERROR_TYPE_EXCEPTION . $t->getMessage());
        }
        $this->queueName = $_queueName;
        $this->validQueues = [
            BROKER_QUEUE_R,
            BROKER_QUEUE_W,
            BROKER_QUEUE_AI,
            BROKER_QUEUE_AO,
            BROKER_QUEUE_M,
            BROKER_QUEUE_WH,
            BROKER_QUEUE_U,
            BROKER_QUEUE_S,
            BROKER_QUEUE_C
        ];
        if (!in_array($this->queueName, $this->validQueues)) {
            $this->logger->warn(ERROR_INVALID_QUEUE_NAME . $this->queueName);
        } else {
            switch ($this->queueName) {
                case BROKER_QUEUE_R   :
                case BROKER_QUEUE_W   :
                case BROKER_QUEUE_M  :
                    $resource = RESOURCE_BROKER;
                break;

                case BROKER_QUEUE_AI :
                case BROKER_QUEUE_AO :
                    $resource = RESOURCE_ADMIN;
                break;

                case BROKER_QUEUE_WH :
                case BROKER_QUEUE_C  :
                    $resource = RESOURCE_SEGUNDO;
                break;

                case BROKER_QUEUE_U :
                case BROKER_QUEUE_S :
                    $resource = RESOURCE_TERCERO;
                break;

                default :
                    $msg = ERROR_RESOURCE_404 . $_queueName;
                    $this->logger->info($msg);
                    consoleLog($this->res, CON_SYSTEM, $msg);
                    return;
                break;
            }
            try {
                $this->rabbitConnection = gasResourceManager::fetchResource($resource);
                if (is_null($this->rabbitConnection)) return;
                $this->rabbitChannel = $this->rabbitConnection->channel();
                $label = uniqid('gacBrokerClient<' . $_tag . '>:');
                list($this->rabbitCallbackQueue, ,) = $this->rabbitChannel->queue_declare($label, false, false, false, true);  // was: f, f, f, t
                $this->rabbitChannel->basic_consume($this->rabbitCallbackQueue, '', false, false, false, false, array($this, BROKER_CLIENT_RESPONSE));
                $this->status = true;
            } catch (AMQPRuntimeException | AMQPTimeoutException | Throwable $t) {
                $hdr = basename(__METHOD__) . AT . __LINE__ . COLON;
                consoleLog($this->res, CON_ERROR, $hdr . ERROR_THROWABLE_EXCEPTION);
                consoleLog($this->res, CON_ERROR, $hdr . $t->getMessage());
            }
        }
        return;
    }


    /**
     * @noinspection PhpUnused
     * client_response -- public method
     *
     * this method checks to see if the current response, based on the correlation (request) ID, is the one it's
     * waiting for from the remote (vault) service.
     *
     * When it receives the awaited response, it stores the response into a member variable and exits.
     *
     *
     * @author  mikegivingassistant.org
     * @version 1.0
     * @param $_response - the class object created in the constructor
     *
     *
     * HISTORY:
     * ========
     * 06-15-17     mks     original coding
     * 09-18-19     mks     DB-136: exception wrapped this code
     *
     */
    public function client_response(AMQPMessage $_response)
    {
        try {
            if ($_response->get(BROKER_CORRELATION_ID) == $this->rabbitCorrelationID) {
                $this->rabbitResponse = $_response->body;
            }
        } catch (AMQPTimeoutException | AMQPRuntimeException | Throwable $t) {
            $hdr = basename(__METHOD__) . AT . __LINE__ . COLON;
            consoleLog($this->res, CON_ERROR, $hdr . ERROR_EXCEPTION);
            consoleLog($this->res, CON_ERROR, $hdr . $t->getMessage());
        }
    }


    /**
     * call() -- public method
     *
     * This method is invoked outside of the class and is the entry point for publishing a message request to the
     * broker.  It creates a new AMQP message and publishes it to the queue (defined in the constructor), and then
     * blocks-and-waits for a response from the remote (vault) service.
     *
     * Publishing a message is exception trapped and will generate a log message at the warn level if tripped.
     *
     * The "raw" response is returned directly to the calling client and will be processed at that level.
     *
     * @author  mike@givingassistant.org
     * @version 1.0
     *
     * @param $_data
     * @return null
     *
     * HISTORY:
     * ========
     * 06-15-17     mks     original coding
     * 05-31-18     mks     CORE-1011: update for new XML broker services configuration
     *
     */
    public function call($_data)
    {
        $this->rabbitResponse = null;
        $this->rabbitCorrelationID = uniqid();

        $rabbitMessage = new AMQPMessage((string)$_data, [BROKER_CORRELATION_ID => $this->rabbitCorrelationID, BROKER_REPLY_TO => $this->rabbitCallbackQueue]);
        try {
            $this->rabbitChannel->basic_publish($rabbitMessage, '', (gasConfig::$settings[CONFIG_BROKER_SERVICES][CONFIG_BROKER_QUEUE_TAG] . $this->queueName));
            while (!$this->rabbitResponse) {
                $this->rabbitChannel->wait();
            }
        } catch (AMQPTimeoutException | AMQPRuntimeException | Throwable $e) {
            $hdr = basename(__METHOD__) . AT . __LINE__ . COLON;
            $this->logger->fatal($hdr . ERROR_BROKER_EXCEPTION_TIMEOUT);
            $this->logger->fatal($hdr . $e->getMessage());
            consoleLog('_BTC: ', CON_ERROR, $hdr . $e->getMessage());
        }
        return ($this->rabbitResponse);
    }

    public function __destruct()
    {
        // As of PHP 5.3.10 destructors are not run on shutdown caused by fatal errors.
        //
        // destructor is registered shut-down function in constructor -- so any recovery
        // efforts should go in this method.
        try {
            if (!is_null($this->rabbitChannel))
                $this->rabbitChannel->close();
            if (!is_null($this->rabbitConnection))
                $this->rabbitConnection->close();
        } catch (Throwable $t) {
            $hdr = basename(__METHOD__) . AT . __LINE__ . COLON;
            consoleLog($this->res, CON_ERROR, $hdr . ERROR_THROWABLE_EXCEPTION);
            consoleLog($this->res, CON_ERROR, $hdr. $t->getMessage());
        }
    }
}