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Simple persistent scheduler for scheduled tasks, recurring or ad-hoc.

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/*
 * Copyright (C) Gustav Karlsson
 *
 * 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.github.kagkarlsson.scheduler.jdbc;

import static java.util.Optional.empty;
import static java.util.stream.Collectors.joining;

import com.github.kagkarlsson.shaded.jdbc.PreparedStatementSetter;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;

class QueryBuilder {
  private final String tableName;
  private final List andConditions = new ArrayList<>();
  private Optional orderBy = empty();

  QueryBuilder(String tableName) {
    this.tableName = tableName;
  }

  static QueryBuilder selectFromTable(String tableName) {
    return new QueryBuilder(tableName);
  }

  QueryBuilder andCondition(AndCondition andCondition) {
    andConditions.add(andCondition);
    return this;
  }

  QueryBuilder orderBy(String orderBy) {
    this.orderBy = Optional.of(orderBy);
    return this;
  }

  String getQuery() {
    StringBuilder s = new StringBuilder();
    s.append("select * from ").append(tableName);

    if (!andConditions.isEmpty()) {
      s.append(" where ");
      s.append(andConditions.stream().map(AndCondition::getQueryPart).collect(joining(" and ")));
    }

    orderBy.ifPresent(o -> s.append(" order by ").append(o));

    return s.toString();
  }

  PreparedStatementSetter getPreparedStatementSetter() {
    return p -> {
      int parameterIndex = 1;
      for (AndCondition andCondition : andConditions) {
        parameterIndex = andCondition.setParameters(p, parameterIndex);
      }
    };
  }
}