package org.checkerframework.dataflow.cfg.node;

import com.sun.source.tree.ExpressionTree;
import java.util.Collection;
import java.util.Collections;
import java.util.Objects;
import javax.lang.model.util.Types;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.checkerframework.javacutil.TreeUtils;

/** A node for the single expression body of a single expression lambda. */
public class LambdaResultExpressionNode extends Node {

  protected final ExpressionTree tree;
  protected final @Nullable Node result;

  public LambdaResultExpressionNode(ExpressionTree t, @Nullable Node result, Types types) {
    super(TreeUtils.typeOf(t));
    this.result = result;
    tree = t;
  }

  /**
   * Returns the final node of the CFG corresponding to the lambda expression body (see {@link
   * #getTree()}).
   */
  public @Nullable Node getResult() {
    return result;
  }

  /**
   * Returns the {@link ExpressionTree} corresponding to the body of a lambda expression with an
   * expression body (e.g. X for ({@code o -> X}) where X is an expression and not a {...} block).
   */
  @Override
  public ExpressionTree getTree() {
    return tree;
  }

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

  @Override
  public String toString() {
    if (result != null) {
      return "-> " + result;
    }
    return "-> ()";
  }

  @Override
  public boolean equals(@Nullable Object obj) {
    // No need to compare tree, since in a well-formed LambdaResultExpressionNode, result will
    // be the same only when tree is the same (this is similar to ReturnNode).
    if (!(obj instanceof LambdaResultExpressionNode)) {
      return false;
    }
    LambdaResultExpressionNode other = (LambdaResultExpressionNode) obj;
    return Objects.equals(result, other.result);
  }

  @Override
  public int hashCode() {
    // No need to incorporate tree, since in a well-formed LambdaResultExpressionNode, result
    // will be the same only when tree is the same (this is similar to ReturnNode).
    return Objects.hash(LambdaResultExpressionNode.class, result);
  }

  @Override
  public Collection<Node> getOperands() {
    if (result == null) {
      return Collections.emptyList();
    } else {
      return Collections.singletonList(result);
    }
  }
}