This a print connector implementation to communicate the mike42/escpos-php package with the ablunier/escpos-print-api API

PrintServerApi.php

<?php

namespace Ablunier\Escpos\PrintConnectors\Connectors;

use Mike42\Escpos\PrintConnectors\PrintConnector;
use GuzzleHttp\Client;

/**
 * Class PrintServerApi
 */
class PrintServerApi implements PrintConnector
{
    /**
     * @var string
     */
    protected $stream;

    /**
     * @var Client
     */
    protected $httpClient;
    
    /**
     * @var string
     */
    protected $printerId;

    /**
     * @var string
     */
    protected $apiToken;

    /**
     * Construct new connector, given a filename
     *
     * @param string $host
     * @param string $printerId
     * @param string $apiToken
     */
    public function __construct($host, $printerId, $apiToken)
    {
        $this->httpClient = new Client(['base_uri' => $host]);
        $this->printerId = $printerId;
        $this->apiToken = $apiToken;

        $this->stream = '';
    }

    /**
     * Print connectors should cause a NOTICE if they are deconstructed
     * when they have not been finalized.
     */
    public function __destruct()
    {
        if (! empty($this->stream)) {
            trigger_error("Print connector was not finalized. Did you forget to close the printer?", E_USER_NOTICE);
        }
    }

    /**
     * Finish using this print connector (close file, socket, send
     * accumulated output, etc).
     */
    public function finalize()
    {
        $response = $this->httpClient->request('POST', 'printers/'.$this->printerId.'/print', [
            'query' => ['api_token' => $this->apiToken],
            'body'  => $this->stream
        ]);

        $this->stream = '';
    }

    /**
     * Read data from the printer.
     *
     * @param string $len Length of data to read.
     * @return string Data read from the printer, or false where reading is not possible.
     */
    public function read($len)
    {
        return $this->stream;
    }

    /**
     * Write data to the print connector.
     *
     * @param string $data The data to write
     */
    public function write($data)
    {
        $this->stream .= $data;
    }
}