Suggest ex-date from DividendEvents in transaction dialog

Issue: portfolio-performance#5439

Author: buchen

name.abuchen.portfolio.ui/src/name/abuchen/portfolio/ui/dialogs/transactions/AccountTransactionDialog.java

@@ -9,6 +9,7 @@
 import java.math.RoundingMode;
 import java.text.MessageFormat;
 import java.time.LocalDate;
+import java.time.temporal.ChronoUnit;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -41,6 +42,7 @@
 import name.abuchen.portfolio.model.Client;
 import name.abuchen.portfolio.model.Portfolio;
 import name.abuchen.portfolio.model.Security;
+import name.abuchen.portfolio.model.SecurityEvent;
 import name.abuchen.portfolio.money.CurrencyConverter;
 import name.abuchen.portfolio.money.CurrencyConverterImpl;
 import name.abuchen.portfolio.money.ExchangeRateProviderFactory;
@@ -126,7 +128,8 @@ protected void createFormElements(Composite editArea) // NOSONAR
 
         var exDate = new ExDateInput(editArea);
         exDate.bindDate(Properties.exDate.name());
-        exDate.setVisible(model().supportsSecurity());
+        exDate.setVisible(model().supportsSecurity() && model().getSecurity() != null
+                        && !AccountTransactionModel.EMPTY_SECURITY.equals(model().getSecurity()));
 
         // shares
 
@@ -262,14 +265,36 @@ public void widgetSelected(SelectionEvent e)
         {
             startingWith(dateTime.button).thenRight(exDate.checkBox).thenRight(exDate.date.getControl());
 
-            var hasExDate = model().getExDate() != null;
+            var hasRealSecurity = model().getSecurity() != null
+                            && !AccountTransactionModel.EMPTY_SECURITY.equals(model().getSecurity());
+            exDate.setVisible(hasRealSecurity);
+
+            var hasExDate = hasRealSecurity && model().getExDate() != null;
             toggleExDatePicker(exDate, hasExDate);
 
             exDate.checkBox.addSelectionListener(SelectionListener.widgetSelectedAdapter(event -> {
                 var button = (Button) event.widget;
                 toggleExDatePicker(exDate, button.getSelection());
+                if (button.getSelection())
+                    suggestExDate(exDate);
                 editArea.layout();
             }));
+
+            model.addPropertyChangeListener(Properties.security.name(), event -> {
+                var newSecurity = event.getNewValue();
+                var isRealSecurity = newSecurity != null && !AccountTransactionModel.EMPTY_SECURITY.equals(newSecurity);
+                exDate.setVisible(isRealSecurity);
+                toggleExDatePicker(exDate, false);
+                editArea.layout();
+            });
+
+            model.addPropertyChangeListener(Properties.date.name(), event -> {
+                if (exDate.checkBox.isVisible() && exDate.checkBox.getSelection())
+                {
+                    suggestExDate(exDate);
+                    toggleExDatePicker(exDate, true);
+                }
+            });
         }
 
         // shares [- amount per share]
@@ -380,7 +405,17 @@ private void toggleExDatePicker(ExDateInput exDate, boolean enable)
 
         if (enable)
         {
-            model().setExDate(exDate.date.getSelection().atStartOfDay());
+            var exDateValue = model().getExDate();
+            if (exDateValue == null)
+            {
+                var txDate = model.getDate();
+                exDate.date.setSelection(txDate);
+                model().setExDate(txDate.atStartOfDay());
+            }
+            else
+            {
+                model().setExDate(exDate.date.getSelection().atStartOfDay());
+            }
         }
         else
         {
@@ -389,6 +424,36 @@ private void toggleExDatePicker(ExDateInput exDate, boolean enable)
         }
     }
 
+    private void suggestExDate(ExDateInput exDate)
+    {
+        var security = model().getSecurity();
+        if (security == null || AccountTransactionModel.EMPTY_SECURITY.equals(security))
+            return;
+
+        var txDate = model().getDate();
+
+        for (var event : security.getEvents())
+        {
+            if (!(event instanceof SecurityEvent.DividendEvent dividend))
+                continue;
+
+            var paymentDate = dividend.getPaymentDate();
+            if (paymentDate == null)
+                continue;
+
+            if (Math.abs(ChronoUnit.DAYS.between(txDate, paymentDate)) <= 5)
+            {
+                var eventExDate = dividend.getDate();
+                if (eventExDate == null)
+                    continue;
+
+                exDate.date.setSelection(eventExDate);
+                model().setExDate(eventExDate.atStartOfDay());
+                return;
+            }
+        }
+    }
+
     private ComboInput setupSecurities(Composite editArea)
     {
         List<Security> activeSecurities = new ArrayList<>();