package sk.stuba.fiit.perconik.core.java.dom;

import java.nio.file.Path;
import java.nio.file.Paths;

import com.google.common.base.Function;

import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.StructuralPropertyDescriptor;

import sk.stuba.fiit.perconik.eclipse.jdt.core.dom.NodeType;

public class NodePaths {
  static final String unknownPathName = "_";

  static final String variableSeparator = ",";

  static final Path singleUnknownPath = Paths.get(unknownPathName);

  private static final NodePathExtractor<?> namePathExtractor = NodePathExtractor.using(PathNameStrategy.NAME);

  private static final NodePathExtractor<?> typePathExtractor = NodePathExtractor.using(PathNameStrategy.TYPE);

  private NodePaths() {}

  public static String unknownPathName() {
    return unknownPathName;
  }

  public static String variableSeparator() {
    return variableSeparator;
  }

  private enum PathNameStrategy implements Function<ASTNode, String> {
    NAME {
      public String apply(final ASTNode node) {
        if (node == null) {
          return unknownPathName;
        }

        for (StructuralPropertyDescriptor descriptor: Nodes.structuralProperties(node)) {
          if (descriptor.getId().equals("name")) {
            return node.getStructuralProperty(descriptor).toString();
          }
        }

        return unknownPathName;
      }

      @Override
      public String toString() {
        return "name";
      }
    },

    TYPE {
      public String apply(final ASTNode node) {
        return node != null ? NodeType.valueOf(node).getName() : unknownPathName;
      }

      @Override
      public String toString() {
        return "type";
      }
    };
  }

  private static <N extends ASTNode> NodePathExtractor<N> cast(final NodePathExtractor<?> extractor) {
    // only for stateless internal singletons shared across all types
    @SuppressWarnings("unchecked")
    NodePathExtractor<N> result = (NodePathExtractor<N>) extractor;

    return result;
  }

  public static <N extends ASTNode> NodePathExtractor<N> namePathExtractor() {
    return cast(namePathExtractor);
  }

  public static <N extends ASTNode> NodePathExtractor<N> typePathExtractor() {
    return cast(typePathExtractor);
  }
}