<?php
/**
 * This file is part of escpos-php: PHP receipt printer library for use with
 * ESC/POS-compatible thermal and impact printers.
 *
 * Copyright (c) 2014-18 Michael Billington < michael.billington@gmail.com >,
 * incorporating modifications by others. See CONTRIBUTORS.md for a full list.
 *
 * This software is distributed under the terms of the MIT license. See LICENSE.md
 * for details.
 */

namespace Mike42\Escpos\PrintConnectors;

use Exception;

/**
 * PrintConnector for passing print data to a file.
 */
class FilePrintConnector implements PrintConnector
{
    /**
     * @var resource $fp
     *  The file pointer to send data to.
     */
    protected $fp;

    /**
     * Construct new connector, given a filename
     *
     * @param string $filename
     */
    public function __construct($filename)
    {
        $this -> fp = fopen($filename, "wb+");
        if ($this -> fp === false) {
            throw new Exception("Cannot initialise FilePrintConnector.");
        }
    }

    public function __destruct()
    {
        if ($this -> fp !== false) {
            trigger_error("Print connector was not finalized. Did you forget to close the printer?", E_USER_NOTICE);
        }
    }

    /**
     * Close file pointer
     */
    public function finalize()
    {
        if ($this -> fp !== false) {
            fclose($this -> fp);
            $this -> fp = false;
        }
    }
    
    /* (non-PHPdoc)
     * @see PrintConnector::read()
     */
    public function read($len)
    {
        if ($this -> fp === false) {
            throw new Exception("PrintConnector has been closed, cannot read input.");
        }
        return fread($this -> fp, $len);
    }
    
    /**
     * Write data to the file
     *
     * @param string $data
     */
    public function write($data)
    {
        if ($this -> fp === false) {
            throw new Exception("PrintConnector has been closed, cannot send output.");
        }
        fwrite($this -> fp, $data);
    }
}