Add a warning when a premium user is deleting their account

www/settings/inner.js

@@ -469,6 +469,10 @@ define([
         });
     }, true);
 
+    Messages.settings_deleteWarning = "Warning: it seems you're subscribed to a premium plan (paid or given by another user). Please cancel paid subscriptions before deleting your account as you won't be able to do it yourself once the account is deleted."; // XXX
+    Messages.settings_deleteContinue = "Delete my account"; // XXX
+    Messages.settings_deleteSubscription = "Manage my subscription"; // XXX
+
     makeBlock('delete', function(cb) { // Msg.settings_deleteHint, .settings_deleteTitle
         if (!common.isLoggedIn()) { return cb(false); }
 
@@ -488,7 +492,34 @@ define([
             classes: 'btn-danger',
             multiple: true
         }, function() {
+            nThen(function (waitFor) {
                 $button.prop('disabled', 'disabled');
+                var priv = metadataMgr.getPrivateData();
+                // Check if subscriptions are enabled and you have a premium plan
+                if (priv.plan && priv.plan !== "custom" && ApiConfig.allowSubscriptions) {
+                    // Also make sure upgradeURL is defined
+                    var url = priv.accounts && priv.accounts.upgradeURL;
+                    if (!url) { return; }
+                    url += '#mysubs';
+                    var a = h('a', { href:url }, Messages.settings_deleteSubscription);
+                    $(a).click(function (e) {
+                        e.preventDefault();
+                        common.openUnsafeURL(url);
+                    });
+                    UI.confirm(h('div', [
+                        Messages.settings_deleteWarning, h('p', a)
+                    ]), waitFor(function (yes) {
+                        if (!yes) {
+                            $button.prop('disabled', '');
+                            waitFor.abort();
+                        }
+                    }), {
+                        ok: Messages.settings_deleteContinue,
+                        okClass: 'btn.btn-danger',
+                        cancelClass: 'btn.btn-primary'
+                    });
+                }
+            }).nThen(function () {
                 var password = $form.find('#cp-settings-delete-account').val();
                 if (!password) {
                     return void UI.warn(Messages.error);
@@ -525,6 +556,7 @@ define([
                     $button.prop('disabled', '');
                 });
             });
+        });
 
         cb(form);
     }, true);