Fix order of plugin nodes

scm-webapp/src/main/java/sonia/scm/plugin/SmpNodeBuilder.java

@@ -0,0 +1,50 @@
+package sonia.scm.plugin;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+class SmpNodeBuilder {
+
+  List<PluginNode> buildNodeTree(ExplodedSmp[] smps) {
+    return buildNodeTree(Arrays.asList(smps));
+  }
+
+  List<PluginNode> buildNodeTree(Collection<ExplodedSmp> smps) {
+
+    Set<String> availablePlugins = smps.stream().map(smp -> smp.getPlugin().getInformation().getName()).collect(Collectors.toSet());
+
+    smps.forEach(smp -> this.assertDependenciesFulfilled(availablePlugins, smp));
+
+    List<PluginNode> nodes = smps.stream().map(PluginNode::new).collect(Collectors.toList());
+
+    nodes.forEach(node -> {
+      ExplodedSmp smp = node.getPlugin();
+      nodes.forEach(otherNode -> {
+
+        if (smp.getPlugin().getDependenciesInclusiveOptionals().contains(otherNode.getId())
+          && !otherNode.getChildren().contains(node)) {
+          otherNode.addChild(node);
+        }
+      });
+    });
+
+    return nodes;
+  }
+
+  private void assertDependenciesFulfilled(Set<String> availablePlugins, ExplodedSmp smp) {
+    smp.getPlugin().getDependencies().forEach(dependency -> {
+      if (!availablePlugins.contains(dependency)) {
+        throw new PluginNotInstalledException(
+          String.format(
+            "dependency %s of %s is not installed",
+            dependency,
+            smp.getPlugin().getInformation().getName()
+          )
+        );
+      }
+    });
+  }
+}