Netcdf data files for hazard curves class

src/hazard/src/main/java/gov/usgs/earthquake/nshmp/netcdf/NetcdfDataFilesHazardCurves.java

+package gov.usgs.earthquake.nshmp.netcdf;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import gov.usgs.earthquake.nshmp.gmm.Imt;
+
+/**
+ * Read in and parse all hazard NetCDF data files.
+ *
+ * @author U.S. Geological Survey
+ */
+public class NetcdfDataFilesHazardCurves extends NetcdfDataFiles<NetcdfHazardCurves> {
+
+  public NetcdfDataFilesHazardCurves(Path netcdfPath) {
+    super(netcdfPath, NetcdfDataType.HAZARD_CURVES);
+    addAll(readFiles(netcdfPath, dataType()));
+  }
+
+  /**
+   * Returns the set of NEHRP site classes for all data files.
+   */
+  public Set<Imt> imts() {
+    return stream()
+        .flatMap(netcdf -> netcdf.netcdfData().imts().stream())
+        .sorted()
+        .collect(Collectors.toSet());
+  }
+
+  /**
+   * Returns the Netcdf object associated with a location.
+   *
+   * @param location The location to find the NetCDF object
+   * @throws IllegalArgumentException If no location is contained in a Netcdf
+   *         object.
+   */
+  public NetcdfHazardCurves netcdf(Nshm nshm) {
+    return stream()
+        .filter(netcdf -> netcdf.nshm() == nshm)
+        .findFirst()
+        .orElseThrow(() -> new IllegalArgumentException(
+            String.format("NSHM %s not found in data sets.", nshm)));
+  }
+
+  /**
+   * Returns the {@link Nshm NSHMs} associated with the data sets read in.
+   */
+  public Set<Nshm> nshms() {
+    return stream()
+        .map(netcdf -> netcdf.nshm())
+        .sorted()
+        .collect(Collectors.toSet());
+  }
+
+  @Override
+  protected List<NetcdfHazardCurves> readFiles(Path netcdfPath, NetcdfDataType dataType) {
+    try {
+      List<NetcdfHazardCurves> data = walkFiles(netcdfPath, dataType)
+          .map(NetcdfHazardCurves::new)
+          .collect(Collectors.toList());
+
+      if (data.isEmpty()) {
+        throw new FileNotFoundException("Failed to find hazard NetCDF files");
+      }
+
+      return List.copyOf(data);
+    } catch (IOException e) {
+      throw new RuntimeException("Failed to read NetCDF directory " + netcdfPath, e);
+    }
+  }
+}