////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2012  Oliver Burn
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
////////////////////////////////////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks.coding;

import com.puppycrawl.tools.checkstyle.api.Check;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.checks.CheckUtils;

/**
 * <p>
 * Checks that each variable declaration is in its own statement
 * and on its own line.
 * </p>
 * <p>
 * Rationale: <a
 * href="http://java.sun.com/docs/codeconv/html/CodeConventions.doc5.html#2991">
 * the SUN Code conventions chapter 6.1</a> recommends that
 * declarations should be one per line.
 * </p>
 * <p>
 * An example of how to configure the check is:
 * </p>
 * <pre>
 * &lt;module name="MultipleVariableDeclarations"/&gt;
 * </pre>
 * @author o_sukhodolsky
 */
public class MultipleVariableDeclarationsCheck extends Check
{
    /** Creates new instance of the check. */
    public MultipleVariableDeclarationsCheck()
    {
    }

    @Override
    public int[] getDefaultTokens()
    {
        return new int[] {TokenTypes.VARIABLE_DEF};
    }

    @Override
    public void visitToken(DetailAST aAST)
    {
        DetailAST nextNode = aAST.getNextSibling();
        final boolean isCommaSeparated =
            ((nextNode != null) && (nextNode.getType() == TokenTypes.COMMA));

        if (nextNode == null) {
            // no next statement - no check
            return;
        }

        if ((nextNode.getType() == TokenTypes.COMMA)
            || (nextNode.getType() == TokenTypes.SEMI))
        {
            nextNode = nextNode.getNextSibling();
        }

        if ((nextNode != null)
            && (nextNode.getType() == TokenTypes.VARIABLE_DEF))
        {
            final DetailAST firstNode = CheckUtils.getFirstNode(aAST);
            if (isCommaSeparated) {
                // Check if the multiple variable declarations are in a
                // for loop initializer. If they are, then no warning
                // should be displayed. Declaring multiple variables in
                // a for loop initializer is a good way to minimize
                // variable scope. Refer Feature Request Id - 2895985
                // for more details
                if (aAST.getParent().getType() != TokenTypes.FOR_INIT) {
                    log(firstNode, "multiple.variable.declarations.comma");
                }
                return;
            }

            final DetailAST lastNode = getLastNode(aAST);
            final DetailAST firstNextNode = CheckUtils.getFirstNode(nextNode);

            if (firstNextNode.getLineNo() == lastNode.getLineNo()) {
                log(firstNode, "multiple.variable.declarations");
            }
        }

    }

    /**
     * Finds sub-node for given node maximum (line, column) pair.
     * @param aNode the root of tree for search.
     * @return sub-node with maximum (line, column) pair.
     */
    private static DetailAST getLastNode(final DetailAST aNode)
    {
        DetailAST currentNode = aNode;
        DetailAST child = aNode.getFirstChild();
        while (child != null) {
            final DetailAST newNode = getLastNode(child);
            if ((newNode.getLineNo() > currentNode.getLineNo())
                || ((newNode.getLineNo() == currentNode.getLineNo())
                    && (newNode.getColumnNo() > currentNode.getColumnNo())))
            {
                currentNode = newNode;
            }
            child = child.getNextSibling();
        }

        return currentNode;
    }
}
