/*
 * Copyright 2000-2013 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.psi.impl;

import com.intellij.lang.ASTNode;
import com.intellij.psi.PsiElement;
import com.intellij.psi.PsiPolyVariantReference;
import com.intellij.psi.PsiReference;
import com.intellij.psi.util.QualifiedName;
import com.jetbrains.python.PyElementTypes;
import com.jetbrains.python.PyNames;
import com.jetbrains.python.PyTokenTypes;
import com.jetbrains.python.PythonDialectsTokenSetProvider;
import com.jetbrains.python.psi.*;
import com.jetbrains.python.psi.impl.references.PyOperatorReference;
import com.jetbrains.python.psi.resolve.PyResolveContext;
import com.jetbrains.python.psi.types.PyType;
import com.jetbrains.python.psi.types.TypeEvalContext;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

/**
 * @author yole
 */
public class PyPrefixExpressionImpl extends PyElementImpl implements PyPrefixExpression {
  public PyPrefixExpressionImpl(ASTNode astNode) {
    super(astNode);
  }

  @Override
  public PyExpression getOperand() {
    return (PyExpression)childToPsi(PythonDialectsTokenSetProvider.INSTANCE.getExpressionTokens(), 0);
  }

  @Nullable
  public PsiElement getPsiOperator() {
    final ASTNode node = getNode();
    final ASTNode child = node.findChildByType(PyElementTypes.UNARY_OPS);
    return child != null ? child.getPsi() : null;
  }

  @NotNull
  @Override
  public PyElementType getOperator() {
    final PsiElement op = getPsiOperator();
    assert op != null;
    return (PyElementType)op.getNode().getElementType();
  }

  @Override
  protected void acceptPyVisitor(PyElementVisitor pyVisitor) {
    pyVisitor.visitPyPrefixExpression(this);
  }

  @Override
  public PsiReference getReference() {
    return getReference(PyResolveContext.noImplicits());
  }

  @NotNull
  @Override
  public PsiPolyVariantReference getReference(PyResolveContext context) {
    return new PyOperatorReference(this, context);
  }

  @Override
  public PyType getType(@NotNull TypeEvalContext context, @NotNull TypeEvalContext.Key key) {
    if (getOperator() == PyTokenTypes.NOT_KEYWORD) {
      return PyBuiltinCache.getInstance(this).getBoolType();
    }
    final PsiReference ref = getReference(PyResolveContext.noImplicits().withTypeEvalContext(context));
    final PsiElement resolved = ref.resolve();
    if (resolved instanceof Callable) {
      // TODO: Make PyPrefixExpression a PyCallSiteExpression, use getCallType() here and analyze it in PyTypeChecker.analyzeCallSite()
      return ((Callable)resolved).getReturnType(context, key);
    }
    return null;
  }

  @Override
  public PyExpression getQualifier() {
    return getOperand();
  }

  @Nullable
  @Override
  public QualifiedName asQualifiedName() {
    return PyPsiUtils.asQualifiedName(this);
  }

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

  @Override
  public String getReferencedName() {
    PyElementType t = getOperator();
    if (t == PyTokenTypes.PLUS) {
      return PyNames.POS;
    }
    else if (t == PyTokenTypes.MINUS) {
      return PyNames.NEG;
    }
    return getOperator().getSpecialMethodName();
  }

  @Override
  public ASTNode getNameElement() {
    final PsiElement op = getPsiOperator();
    return op != null ? op.getNode() : null;
  }
}