package org.checkerframework.dataflow.cfg.node;

import com.sun.source.tree.LambdaExpressionTree;
import com.sun.source.tree.MemberReferenceTree;
import com.sun.source.tree.Tree;
import java.util.Collection;
import java.util.Collections;
import java.util.Objects;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.checkerframework.javacutil.BugInCF;
import org.checkerframework.javacutil.TreeUtils;

/**
 * A node for member references and lambdas.
 *
 * <p>The {@link Node#type} of a FunctionalInterfaceNode is determined by the assignment context the
 * member reference or lambda is used in.
 *
 * <pre>
 *   <em>FunctionalInterface func = param1, param2, ... &rarr; statement</em>
 * </pre>
 *
 * <pre>
 *   <em>FunctionalInterface func = param1, param2, ... &rarr; { ... }</em>
 * </pre>
 *
 * <pre>
 *   <em>FunctionalInterface func = member reference</em>
 * </pre>
 */
public class FunctionalInterfaceNode extends Node {

  protected final Tree tree;

  public FunctionalInterfaceNode(MemberReferenceTree tree) {
    super(TreeUtils.typeOf(tree));
    this.tree = tree;
  }

  public FunctionalInterfaceNode(LambdaExpressionTree tree) {
    super(TreeUtils.typeOf(tree));
    this.tree = tree;
  }

  @Override
  public Tree getTree() {
    return tree;
  }

  @Override
  public <R, P> R accept(NodeVisitor<R, P> visitor, P p) {
    return visitor.visitMemberReference(this, p);
  }

  @Override
  public String toString() {
    if (tree instanceof LambdaExpressionTree) {
      return "FunctionalInterfaceNode:" + ((LambdaExpressionTree) tree).getBodyKind();
    } else if (tree instanceof MemberReferenceTree) {
      return "FunctionalInterfaceNode:" + ((MemberReferenceTree) tree).getName();
    } else {
      // This should never happen.
      throw new BugInCF("Invalid tree in FunctionalInterfaceNode");
    }
  }

  @Override
  public boolean equals(@Nullable Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }

    FunctionalInterfaceNode that = (FunctionalInterfaceNode) o;

    return tree != null ? tree.equals(that.tree) : that.tree == null;
  }

  @Override
  public int hashCode() {
    return Objects.hash(tree);
  }

  @Override
  public Collection<Node> getOperands() {
    return Collections.emptyList();
  }
}