Fixed explosion of generated autolink text

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

@@ -127,11 +127,13 @@ public class HtmlHelper {
 
     static String autolink(String text) {
         Matcher matcher = pattern.matcher(text);
+        StringBuffer sb = new StringBuffer();
         while (matcher.find()) {
             String ref = matcher.group();
-            text = text.replace(ref, String.format("<a href=\"%s\">%s</a>", ref, ref));
+            matcher.appendReplacement(sb, String.format("<a href=\"%s\">%s</a>", ref, ref));
         }
-        return text;
+        matcher.appendTail(sb);
+        return sb.toString();
     }
 
     static Drawable decodeImage(String source, Context context, long id, boolean show) {

app/src/test/java/eu/faircode/email/HtmlHelperTest.java

@@ -50,59 +50,23 @@ class HtmlHelperTest {
         testAutolink(
                 "http://example.org/ and http://example.org/subdir/",
 
-                // FIXME: Each URL must be linked to its exact address, not just to a prefix.
+                // Each URL must be linked to its exact address, not just to a prefix.
                 "" +
                         "<a href=\"http://example.org/\">http://example.org/</a> and " +
-                        "<a href=\"http://example.org/\">http://example.org/</a>subdir/"
+                        "<a href=\"http://example.org/subdir/\">http://example.org/subdir/</a>"
         );
 
         testAutolink(
                 "http://example.org/ and http://example.org/ and http://example.org/",
 
-                // FIXME: Even when the same URL is mentioned multiple times,
+                // When the same URL is mentioned multiple times,
                 // each of the URLs must only appear a single time.
                 "" +
-                        "<a href=\"" +
-                        "<a href=\"" +
                         "<a href=\"http://example.org/\">http://example.org/</a>" +
-                        "\">" +
-                        "<a href=\"http://example.org/\">http://example.org/</a>" +
-                        "</a>" +
-                        "\">" +
-                        "<a href=\"" +
-                        "<a href=\"http://example.org/\">http://example.org/</a>" +
-                        "\">" +
-                        "<a href=\"http://example.org/\">http://example.org/</a>" +
-                        "</a>" +
-                        "</a>" +
                         " and " +
-                        "<a href=\"" +
-                        "<a href=\"" +
-                        "<a href=\"http://example.org/\">http://example.org/</a>" +
-                        "\">" +
-                        "<a href=\"http://example.org/\">http://example.org/</a>" +
-                        "</a>" +
-                        "\">" +
-                        "<a href=\"" +
                         "<a href=\"http://example.org/\">http://example.org/</a>" +
-                        "\">" +
-                        "<a href=\"http://example.org/\">http://example.org/</a>" +
-                        "</a>" +
-                        "</a>" +
                         " and " +
-                        "<a href=\"" +
-                        "<a href=\"" +
-                        "<a href=\"http://example.org/\">http://example.org/</a>" +
-                        "\">" +
-                        "<a href=\"http://example.org/\">http://example.org/</a>" +
-                        "</a>" +
-                        "\">" +
-                        "<a href=\"" +
-                        "<a href=\"http://example.org/\">http://example.org/</a>" +
-                        "\">" +
-                        "<a href=\"http://example.org/\">http://example.org/</a>" +
-                        "</a>" +
-                        "</a>"
+                        "<a href=\"http://example.org/\">http://example.org/</a>"
         );
     }