Allow jsoup text expressions

FAQ.md

@@ -2571,9 +2571,16 @@ Note that email addresses are formatted like this:
 "Somebody" <somebody@example.org>
 ``
 
-Note that message texts are normalized, which means that all whitespaces (spaces, tabs, line breaks, etc) are replaced by a single space.
+Note that message texts are normalized when not using a regex, which means that all whitespaces (spaces, tabs, line breaks, etc) are replaced by a single space.
 This makes it easier to match texts on multiple lines or when the line break is at different places.
 
+Since version 1.1996 it is possible to use [Jsoup selectors](https://jsoup.org/cookbook/extracting-data/selector-syntax) to match HTML elements,
+by prefixing the selector by *jsoup:* and entering it as text contains condition, like for example:
+
+```
+html > body > div > a[href=https://example.org]
+```
+
 You can use multiple rules, possibly with a *stop processing*, for an *or* or a *not* condition.
 
 Matching is not case sensitive, unless you use [regular expressions](https://en.wikipedia.org/wiki/Regular_expression).

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

@@ -126,6 +126,7 @@ public class EntityRule {
     static final String EXTRA_SUBJECT = "subject";
     static final String EXTRA_RECEIVED = "received";
 
+    private static final String JSOUP_PREFIX = "jsoup:";
     private static final long SEND_DELAY = 5000L; // milliseconds
 
     private static final ExecutorService executor = Helper.getBackgroundExecutor(1, "rule");
@@ -365,7 +366,9 @@ public class EntityRule {
                 boolean regex = jbody.getBoolean("regex");
                 boolean skip_quotes = jbody.optBoolean("skip_quotes");
 
-                if (!regex)
+                boolean jsoup = value.startsWith(JSOUP_PREFIX);
+
+                if (!regex && !jsoup)
                     value = value.replaceAll("\\s+", " ");
 
                 if (html == null && message.content) {
@@ -386,9 +389,15 @@ public class EntityRule {
                 Document d = JsoupEx.parse(html);
                 if (skip_quotes)
                     d.select("blockquote").remove();
-                String text = d.body().text();
-                if (!matches(context, message, value, text, regex))
-                    return false;
+                if (jsoup) {
+                    String selector = value.substring(JSOUP_PREFIX.length());
+                    if (d.select(selector).size() == 0)
+                        return false;
+                } else {
+                    String text = d.body().text();
+                    if (!matches(context, message, value, text, regex))
+                        return false;
+                }
             }
 
             // Date