Add various Notification template generator improvements

- Add ability to set arbitrary value for some placeholders (Fix #133)
- More Unit tests
- Improve doc

src/main/java/io/kamax/mxisd/config/threepid/medium/GenericTemplateConfig.java

@@ -77,6 +77,7 @@ public class GenericTemplateConfig {
     private String invite;
     private Session session = new Session();
     private Map<String, String> generic = new HashMap<>();
+    private Map<String, String> placeholder = new HashMap<>();
 
     public String getInvite() {
         return invite;
@@ -98,4 +99,12 @@ public class GenericTemplateConfig {
         this.generic = generic;
     }
 
+    public Map<String, String> getPlaceholder() {
+        return placeholder;
+    }
+
+    public void setPlaceholder(Map<String, String> placeholder) {
+        this.placeholder = placeholder;
+    }
+
 }

src/main/java/io/kamax/mxisd/threepid/generator/GenericTemplateNotificationGenerator.java

@@ -68,6 +68,7 @@ public abstract class GenericTemplateNotificationGenerator extends PlaceholderNo
     @Override
     public String getForReply(IThreePidInviteReply invite) {
         log.info("Generating notification content for 3PID invite");
+        invite.getInvite().getProperties().putAll(cfg.getPlaceholder());
         return populateForReply(invite, getTemplateContent(cfg.getInvite()));
     }
 

src/main/java/io/kamax/mxisd/threepid/generator/PlaceholderNotificationGenerator.java

@@ -35,6 +35,8 @@ import static io.kamax.mxisd.http.io.identity.StoreInviteRequest.Keys.SenderDisp
 
 public abstract class PlaceholderNotificationGenerator {
 
+    public static final String RegisterUrl = "REGISTER_URL";
+
     private MatrixConfig mxCfg;
     private ServerConfig srvCfg;
 
@@ -76,8 +78,10 @@ public abstract class PlaceholderNotificationGenerator {
         String senderNameOrId = StringUtils.defaultIfBlank(senderName, invite.getInvite().getSender().getId());
         String roomName = invite.getInvite().getProperties().getOrDefault(RoomName, "");
         String roomNameOrId = StringUtils.defaultIfBlank(roomName, invite.getInvite().getRoomId());
+        String registerUrl = StringUtils.defaultIfBlank(invite.getInvite().getProperties().get(RegisterUrl), "https://" + mxCfg.getDomain());
 
         return populateForCommon(tpid, input)
+                .replace("%" + RegisterUrl + "%", registerUrl)
                 .replace("%SENDER_ID%", invite.getInvite().getSender().getId())
                 .replace("%SENDER_NAME%", senderName)
                 .replace("%SENDER_NAME_OR_ID%", senderNameOrId)
@@ -102,10 +106,6 @@ public abstract class PlaceholderNotificationGenerator {
                 .replace("%NEXT_URL%", validationLink);
     }
 
-    protected String populateForRemoteValidation(IThreePidSession session, String input) {
-        return populateForValidation(session, input);
-    }
-
     protected String populateForFraudulentUndind(ThreePid tpid, String input) {
         return populateForCommon(tpid, input);
     }