Added regex to attachments expression

FAQ.md

@@ -2791,7 +2791,7 @@ The following extra functions are available:
 * *blocklist()* (version 1.2176-1.2178; deprecated, use *onBlocklist()* instead)
 * *onBlocklist()* (returns a boolean indicating if the sender/server is on a DNS blocklist; since version 1.2179)
 * *hasMx()* (returns a boolean indicating if the from/reply-to address has an associated MX record; since version 1.2179)
-* *attachments()* (returns an integer indicating number of attachments; since version 1.2179)
+* *attachments(regex)* (returns an integer indicating number of attachments; since version 1.2179; optional regex since version 1.2194)
 * *Jsoup()* (returns an array of selected strings; since version 1.2179)
 * *Size(array)* (returns the number of items in an array; since version 1.2179)
 * *knownContact()* (returns a boolean indicating that the from/reply-to address is in the Android address book or in the local contacts database)

app/src/main/java/eu/faircode/email/ExpressionHelper.java

@@ -312,6 +312,7 @@ public class ExpressionHelper {
         }
     }
 
+    @FunctionParameter(name = "value")
     public static class AttachmentsFunction extends AbstractFunction {
         private final Context context;
         private final EntityMessage message;
@@ -325,9 +326,19 @@ public class ExpressionHelper {
         public EvaluationValue evaluate(
                 Expression expression, Token functionToken, EvaluationValue... parameterValues) {
             int result = 0;
+            String regex = null;
 
             if (message != null) {
                 DB db = DB.getInstance(context);
+                if (parameterValues.length == 1) {
+                    regex = parameterValues[0].getStringValue();
+                    Pattern p = Pattern.compile(regex);
+                    List<EntityAttachment> attachments = db.attachment().getAttachments(message.id);
+                    if (attachments != null)
+                        for (EntityAttachment attachment : attachments)
+                            if (attachment.name != null && p.matcher(attachment.name).matches())
+                                result++;
+                } else
                     result = db.attachment().countAttachments(message.id);
             }