/*
 * Copyright 2000-2017 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.jetbrains.python.ast;

import com.intellij.lang.ASTNode;
import com.jetbrains.python.PyTokenTypes;
import com.jetbrains.python.PythonDialectsTokenSetProvider;
import org.jetbrains.annotations.ApiStatus;
import org.jetbrains.annotations.Nullable;

@ApiStatus.Experimental
public interface PyAstReferenceExpression extends PyAstQualifiedExpression, PyAstReferenceOwner {
  PyAstReferenceExpression[] EMPTY_ARRAY = new PyAstReferenceExpression[0];

  @Override
  default @Nullable PyAstExpression getQualifier() {
    final ASTNode[] nodes = getNode().getChildren(PythonDialectsTokenSetProvider.getInstance().getExpressionTokens());
    return (PyAstExpression)(nodes.length == 1 ? nodes[0].getPsi() : null);
  }

  @Override
  default boolean isQualified() {
    return getQualifier() != null;
  }

  @Override
  default @Nullable String getReferencedName() {
    final ASTNode nameElement = getNameElement();
    return nameElement != null ? nameElement.getText() : null;
  }

  @Override
  default @Nullable ASTNode getNameElement() {
    return getNode().findChildByType(PyTokenTypes.IDENTIFIER);
  }

  @Override
  default @Nullable String getName() {
    return getReferencedName();
  }

  @Override
  default void acceptPyVisitor(PyAstElementVisitor pyVisitor) {
    pyVisitor.visitPyReferenceExpression(this);
  }
}
