<?php

namespace Qs\Export;

use Closure;
use Exception;
use Qs\Options;
use Qs\String;

class Csv
{
    /** @var string */
    protected $_fileName;

    /** @var array */
    protected $_columns;

    /** @var Closure */
    protected $_rowCallback;

    public function __construct(array $options = [])
    {
        Options::setOptions($this, $options);
        return $this;
    }

    protected function _sendHeaders()
    {
        $fileName = $this->getFileName();
        header('Expires: Sat, 01 Jan 2000 00:00:00 GMT');
        header('Last-Modified: ' . gmdate('D, d M Y H:i:s') . ' GMT');
        header('Cache-Control: no-cache, must-revalidate');
        header('Pragma: no-cache');
        header('Content-type: text/comma-separated-values');
        header('Content-Disposition: attachment; filename="' . $this->_escapeAttachmentName($fileName) . '"');
        return $this;
    }

    protected function _escapeAttachmentName($name)
    {
        $disabledCharacters = ['<', '>', '\\', '"', '/', ':', '|', '?', '*'];
        return str_replace($disabledCharacters, '', $name);
    }

    public function export()
    {
        $rowCallback = $this->getRowCallback();
        $columns = $this->getColumns();

        $fp = fopen('php://output', 'w');
        $this->_sendHeaders();
        fputcsv($fp, $columns);
        $blankRow = array_fill_keys(array_keys($columns), '');
        while (($row = $rowCallback())) {
            $row = array_intersect_key($row, $columns);
            $row = array_merge($blankRow, $row);
            fputcsv($fp, $row);
        }
        fclose($fp);
        exit;
    }

    public function setColumns(array $columns)
    {
        $this->_columns = $columns;
        return $this;
    }

    public function getColumns()
    {
        if (null == $this->_columns) {
            throw new Exception('Required option is missing "' . __CLASS__ . '->_columns"');
        }
        return $this->_columns;
    }

    public function setFileName($fileName)
    {
        $this->_fileName = String::fill($fileName, ['date' => '"' . date('F j, Y')]);
        return $this;
    }

    public function getFileName()
    {
        if (null == $this->_fileName) {
            throw new Exception('Required option is missing "' . __CLASS__ . '->_fileName"');
        }
        return $this->_fileName;
    }

    public function setRowCallback(Closure $rowCallback)
    {
        if (!$rowCallback instanceof Closure) {
            throw new Exception('Wrong callback');
        }
        $this->_rowCallback = $rowCallback;
        return $this;
    }

    public function getRowCallback()
    {
        return $this->_rowCallback;
    }
}