csv_download.php

<?php

class Example
{
    public function handle()
    {
        $this->sendHeader('test.csv');
        $this->sendData(['foo', 'bar', 'foobar'], [
            ['a', 'b', 'c'],
            ['d', 'e', 'f'],
            ['h i', 'j "k', 'l m'],
            ['"aaa"', '"bbb"'],
        ]);
    }

    private function sendHeader(string $filename)
    {
        $filename = preg_replace("/[^a-zA-Z0-9.-]+/", "", $filename);

        header('Content-Type: text/csv');
        header('Content-Transfer-Encoding: binary');
        header('Content-Description: File Transfer');
        header('Content-Disposition: attachment; filename="'.$filename .'"');
    }

    private function sendData(array $headers, array $rows)
    {
        $handle = fopen('php://output', 'w');

        fputcsv($handle, $headers);

        foreach($rows as $row) {
            fputcsv($handle, $row);
        }

        fclose($handle);

        die();
    }
}