Outputs file to small parts as keeping original file data format

PHP File Splitter (Keeps original file format)

<?php

class splitFile{
	
	private $fileName;
	private $filecontents;
	private $fileLen;
	private $PIN;
	private $partSize;

	function __construct($fileName, $outputFileName, $pin, $partsize) {

		$this->fileName = $fileName;
		$this->outputFileName = $outputFileName;
		$this->PIN = $pin;
		$this->partSize = ceil($partsize);
		$this->filecontents = file_get_contents($this->fileName);
		$this->fileLen = mb_strlen($this->filecontents);

	}

	function split(){

		$fileContents = $this->filecontents;
		$PINlen = mb_strlen( $this->PIN );
		$len = $this->fileLen / $this->partSize;
		$past = 0;

		for($i=1; $i < $len; $i++){

			$splitpos = mb_strpos($fileContents, $this->PIN, $i * $this->partSize);
			if( $i == floor($len) ){
				$part = mb_substr($fileContents, $past + $PINlen );
			}else{
				if($i != 1){ $marginS = $PINlen; $marginE = 0; }else{  $marginS = 0; $marginE = $PINlen; }
				$part = mb_substr($fileContents, $past + $marginS, $splitpos - $past + $marginE );
			}

			$past = $splitpos;//get previous last as current start offset
			file_put_contents($this->outputFileName . $i . '.csv', $part);

		}

		return $this->outputResult();

	}

	function outputResult(){

		$output  = 'Completed!';		
		$output .= '<br>';
		$output .= 'Master file size (MB):'. round($this->fileLen/(1024*1024), 1);
		$output .= '<br>';
		$output .= 'Total part qty: ' . floor($this->fileLen / $this->partSize);
		$output .= '<br>';
		$output .= 'Part files average size(MB): ' . round($this->partSize/(1024*1024), 2);
		
		return Array('output' => $output, 'parts' => floor($this->fileLen / $this->partSize));
	}
}



?>

// example for splitting SQL file: part size 1MB / 5
$splitter = new splitFile('sampleSQL.txt', ');', (1024*1024) / 5 );
$splitter->split();