/**
 * Copyright (C) 2009-2013 FoundationDB, LLC
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.foundationdb.sql.optimizer;

import com.foundationdb.sql.parser.*;

import com.foundationdb.sql.StandardException;

import java.util.*;

/**
 * A <code>NodeFactory</code> that knows how to properly clone bindings.
 */
public class BindingNodeFactory extends NodeFactory
{
    private NodeFactory inner;

    private Map<QueryTreeNode,QueryTreeNode> nodeMap;
    private Collection<QueryTreeNode> bindingsToCopy;

    public static void wrap(SQLParser parser) {
        NodeFactory nodeFactory = parser.getNodeFactory();
        if (!(nodeFactory instanceof BindingNodeFactory))
            parser.setNodeFactory(new BindingNodeFactory(nodeFactory));
    }

    /** Construct BindingNodeFactory encapsulating original. */
    public BindingNodeFactory(NodeFactory inner) {
        this.inner = inner;
    }

    /** Create node: just passes along to encapsulated. */
    public QueryTreeNode getNode(int nodeType, SQLParserContext pc)
            throws StandardException {
        return inner.getNode(nodeType, pc);
    }

    /** Copy node: pass along, but keep track mappings for those kinds
     * of nodes that are used in bindings. */
    public QueryTreeNode copyNode(QueryTreeNode node, SQLParserContext pc)
            throws StandardException {
        boolean newMap = false;
        if (nodeMap == null) {
            nodeMap = new HashMap<>();
            bindingsToCopy = new ArrayList<>();
            newMap = true;
        }
        try {
            QueryTreeNode result = inner.copyNode(node, pc);
            if ((node instanceof FromTable) ||
                (node instanceof ResultColumn))
                nodeMap.put(node, result);
            return result;
        }
        finally {
            if (newMap) {
                copyBindings();
                nodeMap = null;
                bindingsToCopy = null;
            }
        }
    }

    /** Copy user data, which is known to be a appropriate binding object. */
    public Object copyUserData(QueryTreeNode node, Object userData)
            throws StandardException {
        if ((userData instanceof TableBinding) ||
            (userData instanceof ColumnBinding)) {
            // Remember to fix later after all copies done.
            bindingsToCopy.add(node);
        }
        // Just return same data for now.
        return userData;
    }
    
    /** Do the actual binding copies.
     * Deferred like this so that it does not matter what order the tree
     * is traversed during the node copy.
     */
    protected void copyBindings() throws StandardException {
        for (QueryTreeNode node : bindingsToCopy) {
            Object userData = node.getUserData();
            if (userData instanceof TableBinding)
                userData = new TableBinding((TableBinding)userData);
            else if (userData instanceof ColumnBinding) {
                ColumnBinding cb = (ColumnBinding)userData;
                FromTable oldFromTable = cb.getFromTable();
                FromTable newFromTable = (FromTable)nodeMap.get(oldFromTable);
                if (newFromTable == null)
                    newFromTable = oldFromTable; // Not cloned in this subtree.
                ResultColumn oldResultColumn = cb.getResultColumn();
                if (oldResultColumn == null) {
                    userData = new ColumnBinding(newFromTable,
                                                 cb.getColumn(), cb.isNullable());
                }
                else {
                    ResultColumn newResultColumn = (ResultColumn)nodeMap.get(oldResultColumn);
                    if (newResultColumn == null)
                        newResultColumn = oldResultColumn;
                    userData = new ColumnBinding(newFromTable, newResultColumn);
                }
            }
            else {
                continue;
            }
            node.setUserData(userData);
        }
    }

}