Extract the email addresses from a block of text containing strictly formatted, delimited values

Question

I have an ICS file that will be uploaded in my server when a meeting created in google calendar, yahoo calendar, etc.... I have parsed date, organizer, etc,. from the ics file. But i can't able to get the attendees list. Below is the code will be in the ICS file.

BEGIN:VEVENT

ATTENDEE;RSVP=TRUE:mailto:xxxxxxx

  xx@xxx.com
ATTENDEE;RSVP=TRUE:mailto:yyy@yyy.com

ATTENDEE;RSVP=TRUE:mailto:zzz@zzz.com

ATTENDEE;RSVP=TRUE:mailto:aaa@aaa.com

CLASS:PUBLIC

From the above code, I need the email ID's associated with mailto parameter. Please help me to achieve this.

<?php
$cal = file_get_contents("ics_files/outlook.ics");
$cal = str_replace("\n", "", $cal);
preg_match_all('/mailto:(.*?)ATTENDEE/', $cal, $attendees);
?>

Answer 1

If you remove the pre-formatting line that removes newlines (\n) from the ics data, a straightforward regex can be used:

/mailto:(.*?)(?:ATTENDEE;|CLASS:)/s

The /s tells the regex-engine to match newline characters with the .. If you wanted to drop the /s, you could instead use:

/mailto:((?:\r\n|\n|.)*?)(?:ATTENDEE;|CLASS:)/

Using PHP's preg_match_all():

preg_match_all('/mailto:(.*?)(?:ATTENDEE;|CLASS:)/s', $cal, $attendees);

The output:

print_r($attendees[1]);

Array (
    [0] => xxxxxxx

  xx@xxx.com
    [1] => yyy@yyy.com
    [2] => zzz@zzz.com
    [3] => aaa@aaa.com
)

You can then iterate over the $attendees[1] array and apply any email-address logic / formatting you wish.

Example:

foreach ($attendees[1] as $attendee) {
    // remove any extra spaces/newlines from the address
    $attendee = trim(preg_replace('/\s\s+/', ' ', str_replace("\n", ' ', $attendee)));

    // split the address into any available name/email-address combination
    $address = explode(' ', $attendee);

    echo $address[0];
    if (!empty($address[1])) {
        // there is a name/email-address combination available
        echo ' <' . $address[1] . '>';
    }
    echo "\n";
}

Output:

xxxxxxx <xx@xxx.com>
yyy@yyy.com
zzz@zzz.com
aaa@aaa.com