Filter rows with invalid emails from CSV file

Invalid email CSV filter

<?php

function filterRowsWithInvalidEmailsInCsv($fileName, $emailFieldIndex, $hasHeaderRow)
{
    if (($handle = fopen("{$fileName}.csv", "r")) !== FALSE) {
        $existingEmails = array();
        $count = 0;
        $filteredCsvFile = fopen("{$fileName}_filtered.csv", 'w');

        while (($data = fgetcsv($handle, 1000, ",")) !== FALSE) {
            if ($hasHeaderRow) {
                fputcsv($filteredCsvFile, $data);
                $hasHeaderRow = FALSE;
                continue;
            }
            $email = strtolower($data[$emailFieldIndex]);
            if (filter_var($email, FILTER_VALIDATE_EMAIL) &&
                !in_array($email, $existingEmails)) {
                $data[$emailFieldIndex] = $email;
                fputcsv($filteredCsvFile, $data);
                $existingEmails[] = $email;
                $count++;
            }
        }
        fclose($handle);
    }
}

parse_str(implode('&', array_slice($argv, 1)), $_GET);

if (strpos($argv[1], '.csv') === FALSE) {
    echo "\nInvalid arguments. Usage:\nphp -f {$argv[0]} CsvFileName [emailFieldIndex=... [hasHeaderRow=...]]\n\n";
    exit;
}

$fileName = substr($argv[1], 0, strpos($argv[1], '.csv'));
$emailFieldIndex = isset($_GET['emailFieldIndex']) ? $_GET['emailFieldIndex'] : 0;
$hasHeaderRow = isset($_GET['hasHeaderRow']) ? $_GET['hasHeaderRow'] : FALSE;

filterRowsWithInvalidEmailsInCsv($fileName, $emailFieldIndex, $hasHeaderRow);