Added message language to rules

FAQ.md

@@ -3028,6 +3028,7 @@ The following extra operators are available:
 The following extra functions are available:
 
 * *header("name")* (returns an array of header values for the named header)
+* *message("language")* returns the two letter [ISO language code](https://en.wikipedia.org/wiki/List_of_ISO_639_language_codes) of a message; note that it cannot always be determined and that it can be incorrect (since version 1.2330)
 * *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)
@@ -3050,6 +3051,8 @@ Example conditions:
 
 ```AI("Is the message below a scam? Answer in English with just yes or no.") contains "yes"```
 
+```COALESCE(message("language")) == "en"```
+
 <br>
 
 **Actions**

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

@@ -108,7 +108,7 @@ public class ExpressionHelper {
         }
 
         HeaderFunction fHeader = new HeaderFunction(headers);
-        MessageFunction fMessage = new MessageFunction(message);
+        MessageFunction fMessage = new MessageFunction(context, message, doc);
         BlocklistFunction fBlocklist = new BlocklistFunction(context, message, headers);
         MxFunction fMx = new MxFunction(context, message);
         AttachmentsFunction fAttachments = new AttachmentsFunction(context, message);
@@ -189,7 +189,7 @@ public class ExpressionHelper {
                 Token token = node.getToken();
                 Log.i("EXPR token=" + token.getType() + ":" + token.getValue());
                 if (token.getType() == Token.TokenType.FUNCTION &&
-                        "AI".equalsIgnoreCase(token.getValue())) {
+                        ("AI".equalsIgnoreCase(token.getValue()) || "message".equalsIgnoreCase(token.getValue()))) {
                     Log.i("EXPR needs body");
                     return true;
                 }
@@ -232,10 +232,14 @@ public class ExpressionHelper {
 
     @FunctionParameter(name = "value")
     public static class MessageFunction extends AbstractFunction {
+        private Context context;
         private final EntityMessage message;
+        private final Document doc;
 
-        MessageFunction(EntityMessage message) {
+        MessageFunction(Context context, EntityMessage message, Document doc) {
+            this.context = context;
             this.message = message;
+            this.doc = doc;
         }
 
         @Override
@@ -246,6 +250,16 @@ public class ExpressionHelper {
             try {
                 if (parameterValues.length == 1) {
                     String name = parameterValues[0].getStringValue();
+                    if ("language".equalsIgnoreCase(name)) {
+                        String language;
+                        if (message.language == null)
+                            language = (doc == null ? null : HtmlHelper.getLanguage(context, message.subject, doc.text()));
+                        else
+                            language = message.language;
+                        Log.i("EXPR language=" + language);
+                        if (language != null)
+                            result.add(language);
+                    } else {
                         if (name != null && message != null) {
                             Field field = message.getClass().getField(name);
                             field.setAccessible(true);
@@ -254,12 +268,14 @@ public class ExpressionHelper {
                                 result.add(value);
                         }
                     }
+                }
             } catch (Throwable ex) {
                 Log.e("EXPR", ex);
             }
 
-            Log.i("EXPR message(" + parameterValues[0] + ")=" + TextUtils.join(", ", result));
+            EvaluationValue val = EvaluationValue.of(result, ExpressionConfiguration.defaultConfiguration());
-            return EvaluationValue.of(result, ExpressionConfiguration.defaultConfiguration());
+            Log.i("EXPR message(" + parameterValues[0] + ")=" + TextUtils.join(", ", result) + " val=" + val);
+            return val;
         }
     }
 

index.html

@@ -1658,6 +1658,7 @@ X-Google-Original-From: Somebody &lt;somebody+extra@example.org&gt;</code></pre>
 <p>The following extra functions are available:</p>
 <ul>
 <li><em>header(“name”)</em> (returns an array of header values for the named header)</li>
+<li><em>message(“language”)</em> returns the two letter <a href="https://en.wikipedia.org/wiki/List_of_ISO_639_language_codes">ISO language code</a> of a message; note that it cannot always be determined and that it can be incorrect (since version 1.2330)</li>
 <li><em>blocklist()</em> (version 1.2176-1.2178; deprecated, use <em>onBlocklist()</em> instead)</li>
 <li><em>onBlocklist()</em> (returns a boolean indicating if the sender/server is on a DNS blocklist; since version 1.2179)</li>
 <li><em>hasMx()</em> (returns a boolean indicating if the from/reply-to address has an associated MX record; since version 1.2179)</li>
@@ -1674,6 +1675,7 @@ X-Google-Original-From: Somebody &lt;somebody+extra@example.org&gt;</code></pre>
 <p><code>!onBlocklist() &amp;&amp; hasMx() &amp;&amp; attachments() &gt; 0</code></p>
 <p><code>(received + 7*24*60*60*1000) &lt; DT_DATE_TO_EPOCH(DT_NOW())</code></p>
 <p><code>AI("Is the message below a scam? Answer in English with just yes or no.") contains "yes"</code></p>
+<p><code>COALESCE(message("language")) == "en"</code></p>
 <p><br></p>
 <p><strong>Actions</strong></p>
 <p>You can select one of these actions to apply to matching messages:</p>