firmware: fetch changelogs in between, separate upgrade button

src/opnsense/mvc/app/views/OPNsense/Core/firmware.volt

@@ -478,6 +478,15 @@ POSSIBILITY OF SUCH DAMAGE.
         $('#upgrade').click(upgrade_ui);
         $('#audit').click(audit);
         $('#upgrade_maj').click(function () {
+            $.upgrade_needs_reboot = 1;
+            $.upgrade_action = 'maj';
+            upgrade_ui();
+        });
+        $('#checkupdate_maj').click(function () {
+            $("#checkupdate_progress").addClass("fa fa-spinner fa-pulse");
+            // empty call refreshes changelogs in the background
+            ajaxCall('/api/core/firmware/changelog/', {}, function () {
+                $("#checkupdate_progress").removeClass("fa fa-spinner fa-pulse");
                 BootstrapDialog.show({
                     type:BootstrapDialog.TYPE_WARNING,
                     title: "{{ lang._('Upgrade instructions') }}",
@@ -486,21 +495,20 @@ POSSIBILITY OF SUCH DAMAGE.
 <?php if (file_exists('/usr/local/opnsense/firmware-upgrade')): ?>
                         label: "{{ lang._('Upgrade') }}",
                         cssClass: 'btn-warning',
-                    action: function(dialogRef){
+                        action: function (dialogRef) {
                             dialogRef.close();
-                        $.upgrade_needs_reboot = 1;
-                        $.upgrade_action = 'maj';
-                        upgrade_ui();
+                            $("#upgrade").attr("style","");
                         }
                     },{
 <?php endif ?>
                         label: "{{ lang._('Close') }}",
-                    action: function(dialogRef){
+                        action: function (dialogRef) {
                             dialogRef.close();
                         }
                     }]
                 });
             });
+        });
 
         // populate package information
         packagesInfo(true);
@@ -629,7 +637,8 @@ POSSIBILITY OF SUCH DAMAGE.
 <?php if (file_exists('/usr/local/opnsense/firmware-message')): ?>
         <div id="message" style="display:none;"><?= @file_get_contents('/usr/local/opnsense/firmware-message') ?></div>
         <div class="alert alert-warning" role="alert" style="min-height: 65px;">
-            <button class='btn pull-right' id="upgrade_maj">{{ lang._('Upgrade instructions') }}</button>
+            <button class='btn btn-primary pull-right' id="upgrade_maj" style="display:none;"><i id="upgrade_progress_maj" class=""></i> {{ lang._('Upgrade now') }}</button>
+            <button class='btn pull-right' id="checkupdate_maj">{{ lang._('Check for upgrade') }}</button>
             <div style="margin-top: 8px;">{{ lang._('This software release has reached its designated end of life.') }}</div>
         </div>
 <?php endif ?>