<?php

# This program is in the public domain within the United States. Additionally,
# we waive copyright and related rights in the work worldwide through the CC0
# 1.0 Universal public domain dedication, which can be found at
# http://creativecommons.org/publicdomain/zero/1.0/


# This function will SAFELY send e-mail (ie you can pass parameters to it
# that you got from a form and not worry about header injection.) Weird
# characters are stripped from the $subject and from the real names, but e-mail
# addresses are not modified at all.

# RETURN values:
#     0: e-mail successfully accepted for delivery
#     1: badly formatted "from" address
#     2: badly formatted "to" address
#     5: message rejected by mail() (reason unknown)

# You cannot pass more than one address to any parameter
# address fields (from, to, cc, bcc) can be in either of these formats:
# 1) me@foo.com  2) Me Who <me@foo.com>
# returns 0 on success
function email($from, $to, $subject, $message, $reply_to = '', $cc = '', $bcc = '') {
	if(($from = email_header($from)) === false) { return 1; }
	if(($to   = email_header($to))   === false) { return 2; }
	if(($cc   = email_header($cc))   === false) { return 3; }
	if(($bcc  = email_header($bcc))  === false) { return 4; }
	if($from == '') { return 1; }
	if($to   == '') { return 2; }

	#FIXME should allow many more characters here
	$subject = preg_replace("|[^a-z0-9 _/#'.:&,-]|i", '_', $subject);

	$headers = "From: $from";
	if($reply_to) {
		$headers .= "\r\nReply-To: $reply_to";
	}
	if($cc) {
		$headers .= "\r\nCC: $cc";
	}
	if($bcc) {
		$headers .= "\r\nBCC: $bcc";
	}
	$headers .= "\r\nContent-type: text/plain; charset=UTF-8";

	if(mail($to, $subject, $message, $headers)) {
		return 0;
	} else {
		return 5;
	}
}
	

# This function probably isn't useful appart from writing functions like email() above.

# addr can be in these formats:
# 1) me@foo.com  2) Me Who <me@foo.com>  3)
# returns false, or a valid format 2 above, except if input is an empty string, it'll return an empty string
function email_header($addr) {
	if($addr == '') {
		return '';
	}

	if(preg_match('|<.*>$|', $addr) === 1) {
		# format 2
		$div = strrpos($addr, '<');
		$name = substr($addr, 0 , $div);
		$name = rtrim($name);
		$email = substr($addr, $div + 1, -1);
	} else {
		$email = $addr;
		$name = preg_replace('|@.*|', '', $addr);
	}

	if(!valid_email($email)) {
		return false;
	}

	#FIXME should allow many more characters here
	$name = preg_replace("|[^a-z0-9 _/'.-]|i", '_', $name);

	return $name . ' <' . $email . '>';
}
	

# return true if e-mail is formatted like a valid email address
function valid_email($email) {
	return preg_match('|^[0-9a-zA-Z_~.+-]+@[0-9a-zA-Z.-]+\.[a-z]+$|', $email) === 1;
}