Fix bug where zipdownload ignored files with the same name (#5777)

Adding a counter before .(extension) to files with same name on zip.
Before only the last file on message with equals names was added on zip

plugins/zipdownload/zipdownload.php

@@ -18,6 +18,8 @@ class zipdownload extends rcube_plugin
 
     private $charset = 'ASCII';
 
+    private $names = [];
+
     // RFC4155: mbox date format
     const MBOX_DATE_FORMAT = 'D M d H:i:s Y';
 
@@ -141,18 +143,8 @@ class zipdownload extends rcube_plugin
         foreach ($message->attachments as $part) {
             $pid      = $part->mime_id;
             $part     = $message->mime_parts[$pid];
-            $filename = $part->filename;
-
-            if ($filename === null || $filename === '') {
-                $ext      = (array) rcube_mime::get_mime_extensions($part->mimetype);
-                $ext      = array_shift($ext);
-                $filename = $rcmail->gettext('messagepart') . ' ' . $pid;
-                if ($ext) {
-                    $filename .= '.' . $ext;
-                }
-            }
+            $disp_name = $this->_create_displayname($part);
 
-            $disp_name   = $this->_convert_filename($filename);
             $tmpfn       = tempnam($temp_dir, 'zipattach');
             $tmpfp       = fopen($tmpfn, 'w');
             $tempfiles[] = $tmpfn;
@@ -190,6 +182,48 @@ class zipdownload extends rcube_plugin
             }
         }
     }
+    
+    
+    /**
+     * Create and get display name of attachment part to add on zip file
+     *
+     * @param $part stdClass Part of attachment on message
+     *
+     * @return string Display name of attachment part
+     */
+    private function _create_displayname($part)
+    {
+        $rcmail    = rcmail::get_instance();
+        $filename = $part->filename;
+
+        if ($filename === null || $filename === '') {
+            $ext      = (array) rcube_mime::get_mime_extensions($part->mimetype);
+            $ext      = array_shift($ext);
+            $filename = $rcmail->gettext('messagepart') . ' ' . $part->mime_id;
+            if ($ext) {
+                $filename .= '.' . $ext;
+            }
+        }
+
+        $displayname   = $this->_convert_filename($filename);
+        /**
+         * Adding a number before dot of extension on a name of file with same name on zip
+         * Ext: attach(1).txt on attach filename that has a attach.txt filename on same zip
+         */
+        if (in_array($displayname, $this->names)) {
+            $attachNumber = 1;
+            list($filename, $ext) = preg_split("/\.(?=[^\.]*$)/", $displayname);
+            foreach ($this->names as $name) {
+                if (preg_match("/{$filename}\((\d+)\)\.{$ext}/", $name, $match)) {
+                    $attachNumber =  ((int) $match[1]) + 1;
+                }
+            }
+            $displayname = $filename . '(' .$attachNumber . ').' . $ext;
+        }
+        $this->names[] = $displayname;
+
+        return $displayname;
+    }
 
     /**
      * Helper method to packs all the given messages into a zip archive