<?php
/**
 * All helpder functions for this plugin can be found here
 */

/**
 * Sends out a full HTML mail
 *
 * @param array $options In the format:
 *     to => STR|ARR of recipients in RFC-2822 format (http://www.faqs.org/rfcs/rfc2822.html)
 *     from => STR of senden in RFC-2822 format (http://www.faqs.org/rfcs/rfc2822.html)
 *     subject => STR with the subject of the message
 *     body => STR with the message body
 *     plaintext_message STR with the plaintext version of the message
 *     html_message => STR with the HTML version of the message
 *     cc => NULL|STR|ARR of CC recipients in RFC-2822 format (http://www.faqs.org/rfcs/rfc2822.html)
 *     bcc => NULL|STR|ARR of BCC recipients in RFC-2822 format (http://www.faqs.org/rfcs/rfc2822.html)
 *     date => NULL|UNIX timestamp with the date the message was created
 *     attachments => NULL|ARR of array(array('mimetype', 'filename', 'content'))
 *
 * @return bool
 */
function html_email_handler_send_email(array $options = null) {
	static $limit_subject;
	
	$site = elgg_get_site_entity();
	
	// make site email
	$site_from = html_email_handler_make_rfc822_address($site);
	
	// get sendmail options
	$sendmail_options = html_email_handler_get_sendmail_options();
	
	if (!isset($limit_subject)) {
		$limit_subject = false;
		
		if (elgg_get_plugin_setting("limit_subject", "html_email_handler") == "yes") {
			$limit_subject = true;
		}
	}
	
	// set default options
	$default_options = array(
		"to" => array(),
		"from" => $site_from,
		"subject" => "",
		"html_message" => "",
		"plaintext_message" => "",
		"cc" => array(),
		"bcc" => array(),
		"date" => null,
	);
	
	// merge options
	$options = array_merge($default_options, $options);
	
	// redo to/from for notifications
	$notification = elgg_extract('notification', $options);
	if (!empty($notification) && ($notification instanceof \Elgg\Notifications\Notification)) {
		$recipient = $notification->getRecipient();
		$sender = $notification->getSender();
		
		$options['to'] = html_email_handler_make_rfc822_address($recipient);
		if (!isset($options['recipient'])) {
			$options['recipient'] = $recipient;
		}
		
		if (!($sender instanceof \ElggUser) && $sender->email) {
			$options['from'] = html_email_handler_make_rfc822_address($sender);
		} else {
			$options['from'] = $site_from;
		}
	}
	
	// check options
	if (!empty($options["to"]) && !is_array($options["to"])) {
		$options["to"] = array($options["to"]);
	}
	if (!empty($options["cc"]) && !is_array($options["cc"])) {
		$options["cc"] = array($options["cc"]);
	}
	if (!empty($options["bcc"]) && !is_array($options["bcc"])) {
		$options["bcc"] = array($options["bcc"]);
	}
	
	if (empty($options['html_message']) && empty($options['plaintext_message'])) {
		$options['html_message'] = html_email_handler_make_html_body($options);
		$options['plaintext_message'] = $options['body'];
	}
	
	// can we send a message
	if (empty($options["to"]) || (empty($options["html_message"]) && empty($options["plaintext_message"]))) {
		return false;
	}
	
	// start preparing
	// Facyla : better without spaces and special chars
	//$boundary = uniqid($site->name);
	$boundary = uniqid(elgg_get_friendly_title($site->name));
	
	$headers = $options['headers'];
	
	// start building headers
	if (!empty($options["from"])) {
		$headers['From'] = $options['from'];
	} else {
		$headers['From'] = $site_from;
	}
	
	// check CC mail
	if (!empty($options["cc"])) {
		$headers['Cc'] = implode(', ', $options['cc']);
	}
	
	// check BCC mail
	if (!empty($options["bcc"])) {
		$headers['Bcc'] = implode(', ', $options['bcc']);
	}
	
	// add a date header
	if (!empty($options["date"])) {
		$headers['Date'] = date('r', $options['date']);
	}
	
	$headers['X-Mailer'] = ' PHP/' . phpversion();
	$headers['MIME-Version'] = '1.0';
	
	// Facyla : try to add attchments if set
	$attachments = "";
	// Allow to add single or multiple attachments
	if (!empty($options["attachments"])) {
		
		$attachment_counter = 0;
		foreach ($options["attachments"] as $attachment) {
			
			// Alternatively fetch content based on an absolute path to a file on server:
			if (empty($attachment["content"]) && !empty($attachment["filepath"])) {
				$attachment["content"] = chunk_split(base64_encode(file_get_contents($attachment["filepath"])));
			}
			
			// Cannot attach an empty file in any case..
			if (empty($attachment["content"])) {
				continue;
			}
			
			// Count valid attachments
			$attachment_counter++;
			
			// Use defaults for other less critical settings
			if (empty($attachment["mimetype"])) {
				$attachment["mimetype"] = "application/octet-stream";
			}
			if (empty($attachment["filename"])) {
				$attachment["filename"] = "file_" . $attachment_counter;
			}
			
			$attachments .= "Content-Type: {" . $attachment["mimetype"] . "};" . PHP_EOL . " name=\"" . $attachment["filename"] . "\"" . PHP_EOL;
			$attachments .= "Content-Disposition: attachment;" . PHP_EOL . " filename=\"" . $attachment["filename"] . "\"" . PHP_EOL;
			$attachments .= "Content-Transfer-Encoding: base64" . PHP_EOL . PHP_EOL;
			$attachments .= $attachment["content"] . PHP_EOL . PHP_EOL;
			$attachments .= "--mixed--" . $boundary . PHP_EOL;
		}
	}
	
	// Use attachments headers for real only if they are valid
	if (!empty($attachments)) {
		$headers['Content-Type'] = "multipart/mixed; boundary=\"mixed--{$boundary}\"";
	} else {
		$headers['Content-Type'] = "multipart/alternative; boundary=\"{$boundary}\"";
	}
	
	$header_eol = "\r\n";
	if (elgg_get_config('broken_mta')) {
		// Allow non-RFC 2822 mail headers to support some broken MTAs
		$header_eol = "\n";
	}
	
	// stringify headers
	$headers_string = '';
	foreach ($headers as $key => $value) {
		$headers_string .= "$key: $value{$header_eol}";
	}
	
	// start building the message
	$message = "";
	
	// TEXT part of message
	$plaintext_message = elgg_extract("plaintext_message", $options);
	if (!empty($plaintext_message)) {
		// normalize URL's in the text
		$plaintext_message = html_email_handler_normalize_urls($plaintext_message);
		
		// add boundry / content type
		$message .= "--" . $boundary . PHP_EOL;
		$message .= "Content-Type: text/plain; charset=\"utf-8\"" . PHP_EOL;
		$message .= "Content-Transfer-Encoding: base64" . PHP_EOL . PHP_EOL;
		
		// add content
		$message .= chunk_split(base64_encode($plaintext_message)) . PHP_EOL . PHP_EOL;
	}
	
	// HTML part of message
	$html_message = elgg_extract("html_message", $options);
	if (!empty($html_message)) {
		$html_boundary = $boundary;
		
		// normalize URL's in the text
		$html_message = html_email_handler_normalize_urls($html_message);
		$html_message = html_email_handler_base64_encode_images($html_message);
		
		$image_attachments = html_email_handler_attach_images($html_message);
		if (is_array($image_attachments)) {
			$html_boundary .= "-alt";
			$html_message = elgg_extract("text", $image_attachments);
			
			$message .= "--" . $boundary . PHP_EOL;
			$message .= "Content-Type: multipart/related; boundary=\"$html_boundary\"" . PHP_EOL . PHP_EOL;
		}
		
		// add boundry / content type
		$message .= "--" . $html_boundary . PHP_EOL;
		$message .= "Content-Type: text/html; charset=\"utf-8\"" . PHP_EOL;
		$message .= "Content-Transfer-Encoding: base64" . PHP_EOL . PHP_EOL;
		
		// add content
		$message .= chunk_split(base64_encode($html_message)) . PHP_EOL;
		
		if (is_array($image_attachments)) {
			$images = elgg_extract("images", $image_attachments);
			
			foreach ($images as $image_info) {
				$message .= "--" . $html_boundary . PHP_EOL;
				$message .= "Content-Type: " . elgg_extract("content_type", $image_info) . "; charset=\"utf-8\"" . PHP_EOL;
				$message .= "Content-Disposition: inline; filename=\"" . elgg_extract("name", $image_info) . "\"" . PHP_EOL;
				$message .= "Content-ID: <" . elgg_extract("uid", $image_info) . ">" . PHP_EOL;
				$message .= "Content-Transfer-Encoding: base64" . PHP_EOL . PHP_EOL;
				
				// add content
				$message .= chunk_split(elgg_extract("data", $image_info)) . PHP_EOL;
			}
			
			$message .= "--" . $html_boundary . "--" . PHP_EOL;
		}
	}
	
	// Final boundry
	$message .= "--" . $boundary . "--" . PHP_EOL;
	
	// Facyla : FILE part of message
	if (!empty($attachments)) {
		// Build strings that will be added before TEXT/HTML message
		$before_message = "--mixed--" . $boundary . PHP_EOL;
		$before_message .= "Content-Type: multipart/alternative; boundary=\"" . $boundary . "\"" . PHP_EOL . PHP_EOL;
		
		// Build strings that will be added after TEXT/HTML message
		$after_message = PHP_EOL;
		$after_message .= "--mixed--" . $boundary . PHP_EOL;
		$after_message .= $attachments;
		
		// Wrap TEXT/HTML message into mixed message content
		$message = $before_message . PHP_EOL . $message . PHP_EOL . $after_message;
	}
	
	// convert to to correct format
	$to = implode(", ", $options["to"]);
	
	// encode subject to handle special chars
	$subject = $options["subject"];
	$subject = html_entity_decode($subject, ENT_QUOTES, 'UTF-8'); // Decode any html entities
	if ($limit_subject) {
		$subject = elgg_get_excerpt($subject, 175);
	}
	$subject = "=?UTF-8?B?" . base64_encode($subject) . "?=";
	
	return mail($to, $subject, $message, $headers_string, $sendmail_options);
}

/**
 * This function converts CSS to inline style, the CSS needs to be found in a <style> element
 *
 * @param string $html_text the html text to be converted
 *
 * @return false|string
 */
function html_email_handler_css_inliner($html_text) {
	$result = false;
	
	if (!empty($html_text) && defined("XML_DOCUMENT_NODE")) {
		$css = "";
		
		// set custom error handling
		libxml_use_internal_errors(true);
		
		$dom = new DOMDocument();
		$dom->loadHTML($html_text);
		
		$styles = $dom->getElementsByTagName("style");
		
		if (!empty($styles)) {
			$style_count = $styles->length;
			
			for ($i = 0; $i < $style_count; $i++) {
				$css .= $styles->item($i)->nodeValue;
			}
		}
		
		// clear error log
		libxml_clear_errors();
		
		$emo = new Pelago\Emogrifier($html_text, $css);
		$result = $emo->emogrify();
	}
	
	return $result;
}

/**
 * Make the HTML body from a $options array
 *
 * @param array  $options the options
 * @param string $body    the message body
 *
 * @return string
 */
function html_email_handler_make_html_body($options = "", $body = "") {
	global $CONFIG;
	
	if (!is_array($options)) {
		elgg_deprecated_notice("html_email_handler_make_html_body now takes an array as param, please update your code", "1.9");
		
		$options = array(
			"subject" => $options,
			"body" => $body
		);
	}
	
	$defaults = array(
		"subject" => "",
		"body" => "",
		"language" => get_current_language()
	);
	
	$options = array_merge($defaults, $options);
	
	$options['body'] = parse_urls($options['body']);
	
	// in some cases when pagesetup isn't done yet this can cause problems
	// so manualy set is to done
	$unset = false;
	if (!isset($CONFIG->pagesetupdone)) {
		$unset = true;
		$CONFIG->pagesetupdone = true;
	}
	
	// generate HTML mail body
	$result = elgg_view("html_email_handler/notification/body", $options);
	
	// do we need to restore pagesetup
	if ($unset) {
		unset($CONFIG->pagesetupdone);
	}
	
	if (defined("XML_DOCUMENT_NODE")) {
		if ($transform = html_email_handler_css_inliner($result)) {
			$result = $transform;
		}
	}
	
	return $result;
}

/**
 * Get the plugin settings for sendmail
 *
 * @return string
 */
function html_email_handler_get_sendmail_options() {
	static $result;
	
	if (!isset($result)) {
		$result = "";
		
		$setting = elgg_get_plugin_setting("sendmail_options", "html_email_handler");
		if (!empty($setting)) {
			$result = $setting;
		}
	}
	
	return $result;
}

/**
 * This function build an RFC822 compliant address
 *
 * This function requires the option 'entity'
 *
 * @param ElggEntity $entity       entity to use as the basis for the address
 * @param bool       $use_fallback provides a fallback email if none defined
 *
 * @return string the correctly formatted address
 */
function html_email_handler_make_rfc822_address(ElggEntity $entity, $use_fallback = true) {
	// get the email address of the entity
	$email = $entity->email;
	if (empty($email) && $use_fallback) {
		// no email found, fallback to site email
		$site = elgg_get_site_entity();
		
		$email = $site->email;
		if (empty($email)) {
			// no site email, default to noreply
			$email = "noreply@" . $site->getDomain();
		}
	}
	
	// build the RFC822 format
	if (!empty($entity->name)) {
		$name = $entity->name;
		if (strstr($name, ",")) {
			$name = '"' . $name . '"'; // Protect the name with quotations if it contains a comma
		}
		
		$name = "=?UTF-8?B?" . base64_encode($name) . "?="; // Encode the name. If may content non ASCII chars.
		$email = $name . " <" . $email . ">";
	}
	
	return $email;
}

/**
 * Normalize all URL's in the text to full URL's
 *
 * @param string $text the text to check for URL's
 *
 * @return string
 */
function html_email_handler_normalize_urls($text) {
	static $pattern = '/\s(?:href|src)=([\'"]\S+[\'"])/i';
	
	if (empty($text)) {
		return $text;
	}
	
	// find all matches
	$matches = array();
	preg_match_all($pattern, $text, $matches);
	
	if (empty($matches) || !isset($matches[1])) {
		return $text;
	}
	
	// go through all the matches
	$urls = $matches[1];
	$urls = array_unique($urls);
	
	foreach ($urls as $url) {
		// remove wrapping quotes from the url
		$real_url = substr($url, 1, -1);
		// normalize url
		$new_url = elgg_normalize_url($real_url);
		// make the correct replacement string
		$replacement = str_replace($real_url, $new_url, $url);
	
		// replace the url in the content
		$text = str_replace($url, $replacement, $text);
	}
	
	return $text;
}

/**
 * Convert images to inline images
 *
 * This can be enabled with a plugin setting (default: off)
 *
 * @param string $text the text of the message to embed the images from
 *
 * @return string
 */
function html_email_handler_base64_encode_images($text) {
	static $plugin_setting;
	
	if (empty($text)) {
		return $text;
	}
	
	if (!isset($plugin_setting)) {
		$plugin_setting = false;
		
		if (elgg_get_plugin_setting("embed_images", "html_email_handler", "no") === "base64") {
			$plugin_setting = true;
		}
	}
	
	if (!$plugin_setting) {
		return $text;
	}
	
	$image_urls = html_email_handler_find_images($text);
	if (empty($image_urls)) {
		return $text;
	}
	
	foreach ($image_urls as $url) {
		// remove wrapping quotes from the url
		$image_url = substr($url, 1, -1);
		
		// get the image contents
		$contents = html_email_handler_get_image($image_url);
		if (empty($contents)) {
			continue;
		}
		
		// build inline image
		$replacement = str_replace($image_url, "data:" . $contents, $url);
		
		// replace in text
		$text = str_replace($url, $replacement, $text);
	}
	
	return $text;
}

/**
 * Get the contents of an image url for embedding
 *
 * @param string $image_url the URL of the image
 *
 * @return false|string
 */
function html_email_handler_get_image($image_url) {
	static $proxy_host;
	static $proxy_port;
	static $session_cookie;
	static $cache_dir;
	
	if (empty($image_url)) {
		return false;
	}
	$image_url = htmlspecialchars_decode($image_url);
	$image_url = elgg_normalize_url($image_url);
	
	// check cache
	if (!isset($cache_dir)) {
		$cache_dir = elgg_get_config("dataroot") . "html_email_handler/image_cache/";
		if (!is_dir($cache_dir)) {
			mkdir($cache_dir, "0755", true);
		}
	}
	
	$cache_file = md5($image_url);
	if (file_exists($cache_dir . $cache_file)) {
		return file_get_contents($cache_dir . $cache_file);
	}
	
	// build cURL options
	$ch = curl_init($image_url);
	
	curl_setopt($ch, CURLOPT_HEADER, false);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
	curl_setopt($ch, CURLOPT_TIMEOUT, 5);
	
	// set proxy settings
	if (!isset($proxy_host)) {
		$proxy_host = false;
		
		$setting = elgg_get_plugin_setting("proxy_host", "html_email_handler");
		if (!empty($setting)) {
			$proxy_host = $setting;
		}
	}
	
	if ($proxy_host) {
		curl_setopt($ch, CURLOPT_PROXY, $proxy_host);
	}
	
	if (!isset($proxy_port)) {
		$proxy_port = false;
		
		$setting = (int) elgg_get_plugin_setting("proxy_port", "html_email_handler");
		if ($setting > 0) {
			$proxy_port = $setting;
		}
	}
	
	if ($proxy_port) {
		curl_setopt($ch, CURLOPT_PROXYPORT, $proxy_port);
	}
	
	// check if local url, so we can send Elgg cookies
	if (strpos($image_url, elgg_get_site_url()) !== false) {
		if (!isset($session_cookie)) {
			$session_cookie = false;
			
			$cookie_settings = elgg_get_config("cookie");
			if (!empty($cookie_settings)) {
				$cookie_name = elgg_extract("name", $cookie_settings["session"]);
				
				$session_cookie = $cookie_name . "=" . session_id();
			}
		}
		
		if ($session_cookie) {
			curl_setopt($ch, CURLOPT_COOKIE, $session_cookie);
		}
	}
	
	// get the image
	$contents = curl_exec($ch);
	$content_type = curl_getinfo($ch, CURLINFO_CONTENT_TYPE);
	$http_code = (int) curl_getinfo($ch, CURLINFO_HTTP_CODE);
	
	curl_close($ch);
	
	if (empty($contents) || ($http_code !== 200)) {
		return false;
	}
	
	// build a valid uri
	// https://en.wikipedia.org/wiki/Data_URI_scheme
	$base64_result = $content_type . ";charset=UTF-8;base64," . base64_encode($contents);
	
	// write to cache
	file_put_contents($cache_dir . $cache_file, $base64_result);
	
	// return result
	return $base64_result;
}

/**
 * Find img src's in text
 *
 * @param string $text the text to search though
 *
 * @return false|array
 */
function html_email_handler_find_images($text) {
	static $pattern = '/\ssrc=([\'"]\S+[\'"])/i';
	
	if (empty($text)) {
		return false;
	}
	
	// find all matches
	$matches = array();
	preg_match_all($pattern, $text, $matches);
	
	if (empty($matches) || !isset($matches[1])) {
		return false;
	}
	
	// return all the found image urls
	return array_unique($matches[1]);
}

/**
 * Get information needed for attaching the images to the e-mail
 *
 * @param string $text the html text to search images in
 *
 * @return string|array
 */
function html_email_handler_attach_images($text) {
	static $plugin_setting;
	
	if (empty($text)) {
		return $text;
	}
	
	// get plugin setting for replacement
	if (!isset($plugin_setting)) {
		$plugin_setting = false;
	
		if (elgg_get_plugin_setting("embed_images", "html_email_handler", "no") === "attach") {
			$plugin_setting = true;
		}
	}
	
	// check plugin setting
	if (!$plugin_setting) {
		return $text;
	}
	
	// get images
	$image_urls = html_email_handler_find_images($text);
	if (empty($image_urls)) {
		return $text;
	}
	
	$result = array(
		"images" => array()
	);
	
	foreach ($image_urls as $url) {
		// remove wrapping quotes from the url
		$image_url = substr($url, 1, -1);
		
		// get the image contents
		$contents = html_email_handler_get_image($image_url);
		if (empty($contents)) {
			continue;
		}
		
		// make different parts of the result
		list($content_type, $data) = explode(";charset=UTF-8;base64,", $contents);
		
		// Unique ID
		$uid = uniqid();
		
		$result["images"][] = array(
			"uid" => $uid,
			"content_type" => $content_type,
			"data" => $data,
			"name" => basename($image_url)
		);
		
		// replace url in the text with uid
		$replacement = str_replace($image_url, "cid:" . $uid, $url);
		
		$text = str_replace($url, $replacement, $text);
	}
	
	// return new text
	$result["text"] = $text;
	
	// return result
	return $result;
}