[license] Handle the case where all the licenses are optional

- If all of the licenses are optional, you should be able to
   continue without accepting. Refactor to a single visible
   slot to check the conditions.
 - Always set the globalsettings value; to "false" on entry
   to make sure it's there.
 - When setting the list of entries, check the conditions
   (because if the list is empty, or all of them are optional,
   then it's ok to continue).

FIXES #1124
FIXES #1125

src/modules/license/LicensePage.cpp

@@ -106,24 +106,9 @@ LicensePage::LicensePage(QWidget *parent)
                                     "padding: 2px; }" );
     ui->acceptFrame->layout()->setMargin( CalamaresUtils::defaultFontHeight() / 2 );
 
-    connect( ui->acceptCheckBox, &QCheckBox::toggled,
-             this, [ this ]( bool checked )
-    {
-        Calamares::JobQueue::instance()->globalStorage()->insert( "licenseAgree", checked );
-        m_isNextEnabled = checked;
-        if ( !checked )
-        {
-            ui->acceptFrame->setStyleSheet( "#acceptFrame { border: 1px solid red;"
-                                            "background-color: #fff8f8;"
-                                            "border-radius: 4px;"
-                                            "padding: 2px; }" );
-        }
-        else
-        {
-            ui->acceptFrame->setStyleSheet( "#acceptFrame { padding: 3px }" );
-        }
-        emit nextStatusChanged( checked );
-    } );
+    updateGlobalStorage( false );  // Have not agreed yet
+
+    connect( ui->acceptCheckBox, &QCheckBox::toggled, this, &LicensePage::checkAcceptance );
 
     CALAMARES_RETRANSLATE(
         ui->acceptCheckBox->setText( tr( "I accept the terms and conditions above." ) );
@@ -137,9 +122,12 @@ LicensePage::setEntries( const QList< LicenseEntry >& entriesList )
     CalamaresUtils::clearLayout( ui->licenseEntriesLayout );
 
     const bool required = std::any_of( entriesList.cbegin(), entriesList.cend(), []( const LicenseEntry& e ){ return e.m_required; });
+    if ( entriesList.isEmpty() )
+        m_allLicensesOptional = true;
+    else
+        m_allLicensesOptional = !required;
 
-    m_isNextEnabled = !required;
-    nextStatusChanged( m_isNextEnabled );
+    checkAcceptance( false );
 
     CALAMARES_RETRANSLATE(
         if ( required )
@@ -245,3 +233,28 @@ LicensePage::isNextEnabled() const
 {
     return m_isNextEnabled;
 }
+
+void
+LicensePage::updateGlobalStorage( bool v )
+{
+    Calamares::JobQueue::instance()->globalStorage()->insert( "licenseAgree", v );
+}
+
+void LicensePage::checkAcceptance( bool checked )
+{
+    updateGlobalStorage( checked );
+
+    m_isNextEnabled = checked || m_allLicensesOptional;
+    if ( !m_isNextEnabled )
+    {
+        ui->acceptFrame->setStyleSheet( "#acceptFrame { border: 1px solid red;"
+                                        "background-color: #fff8f8;"
+                                        "border-radius: 4px;"
+                                        "padding: 2px; }" );
+    }
+    else
+    {
+        ui->acceptFrame->setStyleSheet( "#acceptFrame { padding: 3px }" );
+    }
+    emit nextStatusChanged( checked );
+}

src/modules/license/LicensePage.h

@@ -70,13 +70,31 @@ public:
     void setEntries( const QList< LicenseEntry >& entriesList );
 
     bool isNextEnabled() const;
+
+public slots:
+    /** @brief Check if the user can continue
+     *
+     * The user can continue if
+     *  - none of the licenses are required, or
+     *  - the user has ticked the "OK" box.
+     * This function calls updateGlobalStorage() as needed, and updates
+     * the appearance of the page as needed. @p checked indicates whether
+     * the checkbox has been ticked or not.
+     */
+    void checkAcceptance( bool checked );
+
 signals:
     void nextStatusChanged( bool status );
 
 private:
-    Ui::LicensePage* ui;
+    /** @brief Update the global storage "licenseAgree" key. */
+    void updateGlobalStorage( bool v );
 
     bool m_isNextEnabled;
+    bool m_allLicensesOptional;  //< all the licenses passed to setEntries are not-required
+
+    Ui::LicensePage* ui;
+
 };
 
 #endif //LICENSEPAGE_H