/*
 * Copyright 2000-2014 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.inspections;

import javax.annotation.Nonnull;

import org.jetbrains.annotations.Nls;
import com.intellij.codeInspection.LocalInspectionToolSession;
import com.intellij.codeInspection.ProblemsHolder;
import com.intellij.psi.PsiElement;
import com.intellij.psi.PsiElementVisitor;
import com.jetbrains.python.PyBundle;
import com.jetbrains.python.inspections.quickfix.PyReplaceTupleWithListQuickFix;
import com.jetbrains.python.psi.PyAssignmentStatement;
import com.jetbrains.python.psi.PyExpression;
import com.jetbrains.python.psi.PyReferenceExpression;
import com.jetbrains.python.psi.PySubscriptionExpression;
import com.jetbrains.python.psi.types.PyTupleType;
import com.jetbrains.python.psi.types.PyType;

/**
 * @author Alexey.Ivanov
 */
public class PyTupleItemAssignmentInspection extends PyInspection
{
	@Nls
	@Nonnull
	@Override
	public String getDisplayName()
	{
		return PyBundle.message("INSP.NAME.tuple.item.assignment");
	}

	@Nonnull
	@Override
	public PsiElementVisitor buildVisitor(@Nonnull ProblemsHolder holder, boolean isOnTheFly, @Nonnull LocalInspectionToolSession session)
	{
		return new Visitor(holder, session);
	}

	private static class Visitor extends PyInspectionVisitor
	{

		public Visitor(final ProblemsHolder holder, LocalInspectionToolSession session)
		{
			super(holder, session);
		}

		@Override
		public void visitPyAssignmentStatement(PyAssignmentStatement node)
		{
			PyExpression[] targets = node.getTargets();
			if(targets.length == 1 && targets[0] instanceof PySubscriptionExpression)
			{
				PySubscriptionExpression subscriptionExpression = (PySubscriptionExpression) targets[0];
				if(subscriptionExpression.getOperand() instanceof PyReferenceExpression)
				{
					PyReferenceExpression referenceExpression = (PyReferenceExpression) subscriptionExpression.getOperand();
					PsiElement element = referenceExpression.followAssignmentsChain(getResolveContext()).getElement();
					if(element instanceof PyExpression)
					{
						PyExpression expression = (PyExpression) element;
						PyType type = myTypeEvalContext.getType(expression);
						if(type instanceof PyTupleType)
						{
							registerProblem(node, PyBundle.message("INSP.tuples.never.assign.items"), new PyReplaceTupleWithListQuickFix());
						}
					}
				}
			}
		}
	}
}
