//Dstl (c) Crown Copyright 2017
package uk.gov.dstl.baleen.uima.utils;

import static java.util.stream.Collectors.toList;

import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.apache.uima.jcas.tcas.Annotation;
import org.apache.uima.resource.ResourceInitializationException;
import org.reflections.Reflections;

import com.google.common.collect.ImmutableSet;

import uk.gov.dstl.baleen.core.utils.BuilderUtils;
import uk.gov.dstl.baleen.exceptions.InvalidParameterException;
import uk.gov.dstl.baleen.types.BaleenAnnotation;
import uk.gov.dstl.baleen.types.structure.Structure;

/**
 * Utility for working with {@link Structure}
 *
 */
public class StructureUtil {

  /** The Constant DEFAULT STRUCTURAL PACKAGE. */
  private static final String DEFAULT_STRUCTURAL_PACKAGE = Structure.class.getPackage().getName();

  /** The Constant DEFAULT BALEEN ANNOTAITON PACKAGE. */
  private static final String DEFAULT_ANNOTATION_PACKAGE =
      BaleenAnnotation.class.getPackage().getName();

  /**
   * Private constructor
   */
  private StructureUtil() {
    // Util class
  }

  /**
   * Get all the structure classes
   *
   * @return the structure classes
   * @throws ResourceInitializationException
   */
  public static Set<Class<? extends Structure>> getStructureClasses()
      throws ResourceInitializationException {

    return getStructureClasses(null);
  }

  /**
   * Get the given structure classes from by name or return all classes if null or empty
   *
   * @param typeNames the types to get
   * @return the structure classes
   * @throws ResourceInitializationException
   */
  public static Set<Class<? extends Structure>> getStructureClasses(String[] typeNames)
      throws ResourceInitializationException {

    Set<Class<? extends Structure>> structuralClasses = new HashSet<>();
    if (typeNames == null || typeNames.length == 0) {
      Reflections reflections = new Reflections(DEFAULT_STRUCTURAL_PACKAGE);
      structuralClasses = reflections.getSubTypesOf(Structure.class);
    } else {
      for (final String typeName : typeNames) {
        try {
          structuralClasses
              .add(BuilderUtils.getClassFromString(typeName, DEFAULT_STRUCTURAL_PACKAGE));
        } catch (final InvalidParameterException e) {
          throw new ResourceInitializationException(e);
        }
      }
    }
    return structuralClasses;
  }

  /**
   * Get the sub types of the given baleen annotation type
   *
   * @param annotaitonType the parent type name
   * @return the annotation classes
   * @throws ResourceInitializationException
   */
  public static Set<Class<? extends BaleenAnnotation>> getAnnotationClasses(
      Class<? extends BaleenAnnotation> annotaitonType) throws ResourceInitializationException {
    Reflections reflections = new Reflections(DEFAULT_ANNOTATION_PACKAGE);
    return ImmutableSet.copyOf(reflections.getSubTypesOf(annotaitonType));
  }

  /**
   * Filter the given annotations to only those contained in the given set
   *
   * @param collection the collection to filter
   * @param annotationTypes the set of annotation classes to keep
   * @return the filtered list of the annotations
   */
  @SuppressWarnings("unchecked")
  public static <T> List<T> filterAnnotations(Collection<? extends Annotation> collection,
      Set<Class<? extends T>> annotationTypes) {
    return (List<T>) collection.stream().filter(s -> annotationTypes.contains(s.getClass()))
        .collect(toList());
  }
}