使用ZipArhive将文件压缩为URL

Question

I have a WordPress site where users are gonna be able to download one, or multiple pdf files. So far I just coded without using any WordPress functionalities and with having the files on my computer. But in the future, I want to be able to add a file using Advanced Custom Fields (or something similar) which means that I won't have the files in a folder and will have to use URL's instead. At least I think? And when I use the same code, but with URL's (see below), it doesn't work.

So how can I create a zip file from a URL using ZipArchive?

<?php
    if(isset($_POST['createzip']))
    {
        $files = $_POST['files'];
        $zipname = time().".zip"; // Zip name
        $zip = new ZipArchive(); // Load zip library
        $zip->open($zipname, ZipArchive::CREATE);
        foreach ($files as $file) {
            $zip->addFile($file);
        }
        $zip->close();
    // push to download the zip
        header('Content-Type: application/zip');
        header('Content-disposition: attachment; filename='.$zipname);
        header('Content-Length: ' . filesize($zipname));
        readfile($zipname);
    }
?>

<h1> hej här kan du zippa lite filer</h1>

<form name="zips" method="post">
    <input type="checkbox" name="files" value="http://www.unstraight.org/wp-content/uploads/2015/08/seger3.jpg">
    <p>Seger</p>
    <input type="checkbox" name="files" value="http://www.unstraight.org/wp-content/uploads/dlm_uploads/2015/12/Ovningar-medelsvara.pdf">
    <p>Övningar </p>
    <input type="checkbox" name="files" value="http://www.unstraight.org/wp-content/uploads/2015/07/User-Agreement-.pdf">
    <p>Medlemskort </p>
    <input type="checkbox" name="files[]" value="men.pdf">
    <p>Män och Jämställdhet </p>
    <input type="submit" name="createzip" value="Download as ZIP">
</form>

Answer 1

You can retrieve the document from the URL and then use ZipArchive::addFromString.

Documentation: http://php.net/manual/en/ziparchive.addfromstring.php

The code might look something like this:

foreach ($files as $file) {
    if(preg_match('/^https?\:/', $file)) {

        // Looks like a URL

        // Generate a file name for including in the zip
        $url_components = explode('/', $file);
        $file_name = array_pop($url_components);

        // Make sure we only have safe characters in the filename
        $file_name = preg_replace('/[^A-z0-9_\.-]/', '', $file_name);

        // If all else fails, default to a random filename
        if(empty($file_name)) $file_name = time() . rand(10000, 99999);

        // Make sure we have a .pdf extension
        if(!preg_match('/\.pdf$/', $file_name)) $file_name .= '.pdf';

        // Download file
        $ch = curl_init($file);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
        $file_content = curl_exec($ch);
        curl_close($ch);

        // Add to zip
        $zip->addFromString($file_name, $file_content);

    } else {

        // Looks like a local file
        $zip->addFile($file);

    }
}