/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.phoenix.coprocessor;

import static org.apache.phoenix.util.PhoenixRuntime.CONNECTIONLESS;
import static org.apache.phoenix.util.PhoenixRuntime.JDBC_PROTOCOL;
import static org.apache.phoenix.util.PhoenixRuntime.JDBC_PROTOCOL_SEPARATOR;

import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.BitSet;
import java.util.List;

import org.apache.phoenix.compile.ColumnResolver;
import org.apache.phoenix.compile.CreateTableCompiler;
import org.apache.phoenix.compile.ExpressionCompiler;
import org.apache.phoenix.compile.FromCompiler;
import org.apache.phoenix.compile.StatementContext;
import org.apache.phoenix.compile.WhereCompiler;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.jdbc.PhoenixConnection;
import org.apache.phoenix.jdbc.PhoenixStatement;
import org.apache.phoenix.parse.ParseNode;
import org.apache.phoenix.parse.SQLParser;
import org.apache.phoenix.parse.SelectStatement;
import org.apache.phoenix.schema.ColumnNotFoundException;
import org.apache.phoenix.schema.PColumn;
import org.apache.phoenix.schema.PColumnImpl;
import org.apache.phoenix.schema.PTable;
import org.apache.phoenix.schema.PTableImpl;
import org.apache.phoenix.schema.TableRef;
import org.apache.phoenix.util.MetaDataUtil;

import org.apache.phoenix.thirdparty.com.google.common.collect.Lists;


public class WhereConstantParser {

    public static PTable addViewInfoToPColumnsIfNeeded(PTable view) throws SQLException {
        byte[][] viewColumnConstantsToBe = new byte[view.getColumns().size()][];
        if (view.getViewStatement() == null) {
        	return view;
        }
        SelectStatement select = new SQLParser(view.getViewStatement()).parseQuery();
        ParseNode whereNode = select.getWhere();
        ColumnResolver resolver = FromCompiler.getResolver(new TableRef(view));

        try (PhoenixConnection conn = getConnectionlessConnection()) {
            StatementContext context = new StatementContext(new PhoenixStatement(conn), resolver);

            Expression expression;
            try {
                expression = WhereCompiler.compile(context, whereNode);
            } catch (ColumnNotFoundException e) {
                // if we could not find a column used in the view statement
                // (which means its was dropped) this view is not valid any more
                return null;
            }
            CreateTableCompiler.ViewWhereExpressionVisitor visitor = new CreateTableCompiler
                    .ViewWhereExpressionVisitor(view, viewColumnConstantsToBe);
            expression.accept(visitor);

            BitSet isViewColumnReferencedToBe = new BitSet(view.getColumns().size());
            // Used to track column references in a view
            ExpressionCompiler expressionCompiler = new CreateTableCompiler
                    .ColumnTrackingExpressionCompiler(context, isViewColumnReferencedToBe);
            whereNode.accept(expressionCompiler);

            List<PColumn> result = Lists.newArrayList();
            for (PColumn column : PTableImpl.getColumnsToClone(view)) {
                boolean isViewReferenced = isViewColumnReferencedToBe.get(column.getPosition());
                if ((visitor.isUpdatable() || view.getPKColumns()
                        .get(MetaDataUtil.getAutoPartitionColIndex(view)).equals(column))
                        && viewColumnConstantsToBe[column.getPosition()] != null) {
                    result.add(new PColumnImpl(column,
                            viewColumnConstantsToBe[column.getPosition()], isViewReferenced));
                }
                // If view is not updatable, viewColumnConstants should be empty. We will still
                // inherit our parent viewConstants, but we have no additional ones.
                else if (isViewReferenced ){
                    result.add(new PColumnImpl(column, column.getViewConstant(), isViewReferenced));
                } else {
                    result.add(column);
                }
            }
            return PTableImpl.builderWithColumns(view, result)
                    .build();
        }
    }

    private static PhoenixConnection getConnectionlessConnection() throws SQLException {
        return DriverManager
            .getConnection(JDBC_PROTOCOL + JDBC_PROTOCOL_SEPARATOR + CONNECTIONLESS)
            .unwrap(PhoenixConnection.class);
    }

}
