/**
 * 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.lens.cube.parse;

import static org.apache.lens.cube.parse.StorageUtil.joinWithAnd;

import java.util.Map;
import java.util.Set;

import org.apache.lens.cube.metadata.Dimension;
import org.apache.lens.server.api.error.LensException;

import org.apache.commons.lang.StringUtils;

/**
 * Dimension HQLContext.
 * <p></p>
 * Contains all the dimensions queried and their candidate dim tables Update where string with storage filters added
 * dimensions queried.
 */
abstract class DimHQLContext extends SimpleHQLContext {

  private final Map<Dimension, CandidateDim> dimsToQuery;
  private final Set<Dimension> queriedDims;
  private String where;
  protected final CubeQueryContext query;
  private final String astFromString;

  public CubeQueryContext getQuery() {
    return query;
  }
  DimHQLContext(CubeQueryContext query, Map<Dimension, CandidateDim> dimsToQuery,
    Set<Dimension> queriedDims, QueryAST ast) throws LensException {
    super(ast.getSelectString(), ast.getGroupByString(), ast.getOrderByString(),
        ast.getHavingString(), ast.getLimitValue());
    this.query = query;
    this.dimsToQuery = dimsToQuery;
    this.where = ast.getWhereString();
    this.queriedDims = queriedDims;
    this.astFromString = ast.getFromString();
  }

  protected void setMissingExpressions() throws LensException {
    setFrom(String.format(astFromString, getFromTable()));
    setWhere(joinWithAnd(
      genWhereClauseWithDimPartitions(where), getQuery().getConf().getBoolean(
        CubeQueryConfUtil.REPLACE_TIMEDIM_WITH_PART_COL, CubeQueryConfUtil.DEFAULT_REPLACE_TIMEDIM_WITH_PART_COL)
        ? getPostSelectionWhereClause() : null));
  }

  protected String getPostSelectionWhereClause() throws LensException {
    return null;
  }

  protected abstract String getFromTable() throws LensException;

  public Map<Dimension, CandidateDim> getDimsToQuery() {
    return dimsToQuery;
  }

  private String genWhereClauseWithDimPartitions(String originalWhere) {
    StringBuilder whereBuf;
    if (originalWhere != null) {
      whereBuf = new StringBuilder(originalWhere);
    } else {
      whereBuf = new StringBuilder();
    }

    // add where clause for all dimensions
    if (queriedDims != null) {
      boolean added = (originalWhere != null);
      for (Dimension dim : queriedDims) {
        CandidateDim cdim = dimsToQuery.get(dim);
        String alias = query.getAliasForTableName(dim.getName());
        if (!cdim.isWhereClauseAdded() && !StringUtils.isBlank(cdim.getWhereClause())) {
          appendWhereClause(whereBuf, StorageUtil.getWhereClause(cdim, alias), added);
          added = true;
        }
      }
    }
    if (whereBuf.length() == 0) {
      return null;
    }
    return whereBuf.toString();
  }

  static void appendWhereClause(StringBuilder filterCondition, String whereClause, boolean hasMore) {
    // Make sure we add AND only when there are already some conditions in where
    // clause
    if (hasMore && !filterCondition.toString().isEmpty() && !StringUtils.isBlank(whereClause)) {
      filterCondition.append(" AND ");
    }

    if (!StringUtils.isBlank(whereClause)) {
      filterCondition.append("(");
      filterCondition.append(whereClause);
      filterCondition.append(")");
    }
  }
}