/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community 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://opensource.org/licenses/ecl2.txt
   *
   * 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.opencastproject.assetmanager.impl.query;
  
  import org.opencastproject.assetmanager.api.query.Predicate;
  import org.opencastproject.assetmanager.impl.RuntimeTypes;
  
  import com.entwinemedia.fn.Fn2;
  import com.mysema.query.jpa.impl.JPAQueryFactory;
  import com.mysema.query.types.expr.BooleanExpression;
  
  public abstract class AbstractPredicate implements Predicate, QueryContributor {
    private final AbstractPredicate self = this;
  
    /**
     * Join two predicates by <code>op</code>.
     */
    private Predicate binaryOp(
        final Predicate right,
        final Fn2<BooleanExpression, BooleanExpression, BooleanExpression> op
    ) {
      return new AbstractPredicate() {
        @Override public SelectQueryContribution contributeSelect(JPAQueryFactory f) {
          final SelectQueryContribution cLeft = self.contributeSelect(f);
          final SelectQueryContribution cRight = RuntimeTypes.convert(right).contributeSelect(f);
          return SelectQueryContribution.mk()
                  .from(cLeft.from.append(cRight.from))
                  .join(cLeft.join.append(cRight.join))
                  .where(JpaFns.op(op, cLeft.where, cRight.where));
        }
  
        @Override public DeleteQueryContribution contributeDelete(String owner) {
          final DeleteQueryContribution cLeft = self.contributeDelete(owner);
          final DeleteQueryContribution cRight = RuntimeTypes.convert(right).contributeDelete(owner);
          return DeleteQueryContribution.mk()
                  .from(cLeft.from.append(cRight.from))
                  .where(JpaFns.op(op, cLeft.where, cRight.where));
        }
      };
    }
  
    @Override public Predicate and(final Predicate right) {
      return binaryOp(right, JpaFns.and);
    }
  
    @Override public Predicate or(final Predicate right) {
      return binaryOp(right, JpaFns.or);
    }
  
    @Override public Predicate not() {
      return new AbstractPredicate() {
        @Override public SelectQueryContribution contributeSelect(JPAQueryFactory f) {
          final SelectQueryContribution c = self.contributeSelect(f);
          return SelectQueryContribution.mk().from(c.from).join(c.join).where(c.where.map(JpaFns.not));
        }
  
        @Override public DeleteQueryContribution contributeDelete(String owner) {
          final DeleteQueryContribution c = self.contributeDelete(owner);
          return DeleteQueryContribution.mk().from(c.from).where(c.where.then(JpaFns.not));
        }
      };
    }
  }