added interface system handler to loader

src/main/java/gov/usgs/earthquake/nshmp/model/ModelLoader.java

@@ -9,6 +9,7 @@ import static gov.usgs.earthquake.nshmp.model.ModelFiles.TREE_INFO;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.checkGridDataDirectory;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.checkSourceTree;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readCalcConfig;
+import static gov.usgs.earthquake.nshmp.model.ModelFiles.readCrustalSystemRuptureSet;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readDecollementConfig;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readFaultClusterSet;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readFaultConfig;
@@ -23,6 +24,7 @@ import static gov.usgs.earthquake.nshmp.model.ModelFiles.readInterfaceClusterSet
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readInterfaceConfig;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readInterfaceFeatures;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readInterfaceRuptureSet;
+import static gov.usgs.earthquake.nshmp.model.ModelFiles.readInterfaceSystemRuptureSet;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readMfdConfig;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readMfdMap;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readModelInfo;
@@ -33,7 +35,6 @@ import static gov.usgs.earthquake.nshmp.model.ModelFiles.readSiteData;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readSlabConfig;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readSlabRuptureSets;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readSourceTree;
-import static gov.usgs.earthquake.nshmp.model.ModelFiles.readSystemRuptureSet;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readTreeInfo;
 import static gov.usgs.earthquake.nshmp.model.ModelFiles.readZoneConfig;
 import static gov.usgs.earthquake.nshmp.model.SourceType.DECOLLEMENT;
@@ -103,7 +104,8 @@ abstract class ModelLoader {
 
   public static void main(String[] args) throws IOException {
 
-    Path testModel = Paths.get("../nshm-conus-2018-5.2.x-maint");
+    Path testModel = Paths.get("../nshm-prvi");
+    // Path testModel = Paths.get("../nshm-conus-2018-5.2.x-maint");
     // Path testModel = Paths.get("../nshm-conus");
     // Path testModel = Paths.get("../nshm-alaska");
     // Path testModel = Paths.get("../nshm-alaska-2007-2.2.x-maint");
@@ -728,7 +730,7 @@ abstract class ModelLoader {
           processSystemBranch(child, treeBuilder, data);
         }
       } else {
-        SystemRuptureSet srs = readSystemRuptureSet(dir, data).orElseThrow();
+        SystemRuptureSet srs = readCrustalSystemRuptureSet(dir, data).orElseThrow();
         treeBuilder.addLeaf(branch, srs);
         // add features to 'data'
         // TODO: revisit, do we want parent sections??
@@ -913,10 +915,15 @@ abstract class ModelLoader {
 
       System.out.println("    tree: [" + info.id + "] " + root.relativize(dir));
 
-      data.interfaceFeatureMap(readInterfaceFeatures(dir).orElseThrow());
+      /* Load features if 'classic' subduction model */
+      var interfaceSections = readInterfaceFeatures(dir);
+      interfaceSections.ifPresent(data::interfaceFeatureMap);
 
-      List<Feature> features = ModelData.featureMapToList(
-          data.interfaceFeatureMap().orElseThrow().values());
+      /* Set flag to process a logic-tree of fault-system solutions. */
+      boolean interfaceSystemTree = interfaceSections.isEmpty();
+
+      // List<Feature> features = ModelData.featureMapToList(
+      // data.interfaceFeatureMap().orElseThrow().values());
 
       SourceTree.Builder treeBuilder = SourceTree.builder()
           .path(dir)
@@ -925,11 +932,23 @@ abstract class ModelLoader {
           .setting(data.tectonicSetting())
           .type(INTERFACE)
           .gmms(data.gmms())
-          .features(features)
+          // .features(features)
           .root(tree);
 
       for (Branch<Path> branch : tree) {
-        processBranch(branch, treeBuilder, ModelData.copyOf(data));
+        if (interfaceSystemTree) {
+          processSystemBranch(branch, treeBuilder, data);
+        } else {
+          processBranch(branch, treeBuilder, data);
+        }
+      }
+
+      if (data.systemFeatureMap().isPresent()) {
+        treeBuilder.features(ModelData.featureMapToList(
+            data.systemFeatureMap().orElseThrow().values()));
+      } else {
+        treeBuilder.features(ModelData.featureMapToList(
+            data.interfaceFeatureMap().orElseThrow().values()));
       }
 
       return treeBuilder.build();
@@ -1036,6 +1055,35 @@ abstract class ModelLoader {
         treeBuilder.addLeaf(pathTree.get(i), crsList.get(i));
       }
     }
+
+    /* Process fault system source tree branches. */
+    private void processSystemBranch(
+        Branch<Path> branch,
+        SourceTree.Builder treeBuilder,
+        ModelData data) {
+
+      /*
+       * No configuration overrides are currently expected for
+       * fault-system-solutions so this is simpler than above.
+       */
+      Path dir = branch.value();
+      System.out.println("  branch:        " + root.relativize(dir));
+      Optional<LogicTree<Path>> tree = readSourceTree(dir);
+      if (tree.isPresent()) {
+        LogicTree<Path> children = tree.orElseThrow();
+        treeBuilder.addBranches(branch, children);
+        for (Branch<Path> child : children) {
+          processSystemBranch(child, treeBuilder, data);
+        }
+      } else {
+        SystemRuptureSet srs = readInterfaceSystemRuptureSet(dir, data).orElseThrow();
+        treeBuilder.addLeaf(branch, srs);
+        // add features to 'data'
+        // TODO: revisit, do we want parent sections??
+        data.systemFeatureMap(srs.sectionMap);
+      }
+    }
+
   }
 
   static List<SourceTree> gridSources(