<?php

class ExcelCsvWriter
{
    /**
     * @var resource
     */
    private $resultStream;

    public function __construct($stream)
    {
        $meta = stream_get_meta_data($stream);
        if ($meta['mode'] === 'r') {
            throw new \Exception('Can\'t write to read-only stream');
        }

        $this->resultStream = $stream;
        fwrite($this->resultStream, pack('C*', 0xFF, 0xFE)); // UTF16-LE BOM
        stream_filter_append($this->resultStream, 'convert.iconv.UTF-8/UTF-16LE', STREAM_FILTER_WRITE);
    }

    /**
     * @param array $row
     */
    public function writeRow($row)
    {
        array_walk($row, function(&$value) {
            if (is_float($value)) {
                $value = '="' . $value . '"';
            }
        });

        fputcsv($this->resultStream, $row, "\t", '"');
    }
}