Add some validations to User Metrics creation and modification

Enable accept only when boty symbol and name are non empty
Warn on name and symbol collisions to avoid silently discarded
metrics or metrics not usable from formulas
Complements 635eccd001, related to #2279

src/Gui/EditUserMetricDialog.cpp

@@ -27,9 +27,11 @@
 #include "DataFilter.h"
 #include "Zones.h"
 #include "HrZones.h"
+#include "RideMetric.h"
 
 #include <QFont>
 #include <QFontMetrics>
+#include <QMessageBox>
 
 static bool insensitiveLessThan(const QString &a, const QString &b)
 {
@@ -255,10 +257,35 @@ EditUserMetricDialog::EditUserMetricDialog(QWidget *parent, Context *context, Us
 
     mainLayout->addLayout(head);
 
+    connect(symbol, SIGNAL(textChanged(const QString &)), SLOT(enableOk()));
+    connect(name, SIGNAL(textChanged(const QString &)), SLOT(enableOk()));
+
     connect(test, SIGNAL(clicked()), this, SLOT(refreshStats()));
     connect(context, SIGNAL(rideSelected(RideItem*)), this, SLOT(refreshStats()));
     connect (cancelButton, SIGNAL(clicked()), this, SLOT(reject()));
     connect (okButton, SIGNAL(clicked()), this, SLOT(okClicked()));
+
+    // initialize button state
+    enableOk();
+}
+
+void
+EditUserMetricDialog::enableOk()
+{
+    okButton->setEnabled(!symbol->text().isEmpty() && !name->text().isEmpty());
+}
+
+bool
+EditUserMetricDialog::validSettings()
+{
+    // user metrics are silently discarded if the symbol is already in use
+    const RideMetric* metric = RideMetricFactory::instance().rideMetric(symbol->text());
+    if (metric && !metric->isUser()) {
+        QMessageBox::critical(this, tr("User Metric"), tr("Symbol already in use by a Builtin metric"));
+        return false;
+    }
+
+    return true;
 }
 
 void
@@ -284,6 +311,9 @@ EditUserMetricDialog::setSettings(UserMetricSettings &here)
 void
 EditUserMetricDialog::okClicked()
 {
+    // validate input
+    if (!validSettings()) return;
+
     // fetch current state
     setSettings(settings);
 

src/Gui/Pages.cpp

@@ -3172,6 +3172,14 @@ CustomMetricsPage::refreshTable()
             continue;
         }
 
+        // user metrics are silently discarded if the symbol is already in use
+        if (!table->findItems(m.symbol, Qt::MatchExactly, 0).isEmpty())
+            QMessageBox::warning(this, tr("User Metrics"), tr("Duplicate Symbol: %1, one metric will be discarded").arg(m.symbol));
+
+        // duplicate names are allowed, but not recommended
+        if (!table->findItems(m.name, Qt::MatchExactly, 1).isEmpty())
+            QMessageBox::warning(this, tr("User Metrics"), tr("Duplicate Name: %1, one metric will not be acessible in formulas").arg(m.name));
+
         QTreeWidgetItem *add = new QTreeWidgetItem(table->invisibleRootItem());
         add->setText(0, m.symbol);
         add->setToolTip(0, m.description);

src/Metrics/UserMetricSettings.h

@@ -97,9 +97,11 @@ class EditUserMetricDialog : public QDialog {
         // the current ride, time to compute all rides)
         void refreshStats();
         void okClicked();
+        void enableOk();
 
     private:
 
+        bool validSettings();
         void setSettings(UserMetricSettings &);
 
         Context *context;