content: /**
   * Copyright (c) 2017-2018 Siemens AG
   * All rights reserved.
   * 
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   * 
   * 1) Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   * 
   * 2) Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  package at.ac.tuwien.kr.alpha.core.solver.heuristics;
  
  import static at.ac.tuwien.kr.alpha.core.programs.atoms.Literals.atomOf;
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  import java.util.Collection;
  import java.util.function.Function;
  import java.util.function.Predicate;
  import java.util.stream.Collectors;
  
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  
  import at.ac.tuwien.kr.alpha.api.config.SystemConfig;
  import at.ac.tuwien.kr.alpha.api.programs.ProgramParser;
  import at.ac.tuwien.kr.alpha.core.common.AtomStore;
  import at.ac.tuwien.kr.alpha.core.common.AtomStoreImpl;
  import at.ac.tuwien.kr.alpha.core.common.NoGood;
  import at.ac.tuwien.kr.alpha.core.grounder.Grounder;
  import at.ac.tuwien.kr.alpha.core.grounder.NaiveGrounder;
  import at.ac.tuwien.kr.alpha.core.parser.ProgramParserImpl;
  import at.ac.tuwien.kr.alpha.core.programs.CompiledProgram;
  import at.ac.tuwien.kr.alpha.core.programs.InternalProgram;
  import at.ac.tuwien.kr.alpha.core.programs.transformation.NormalizeProgramTransformation;
  import at.ac.tuwien.kr.alpha.core.solver.NaiveNoGoodStore;
  import at.ac.tuwien.kr.alpha.core.solver.TestableChoiceManager;
  import at.ac.tuwien.kr.alpha.core.solver.TrailAssignment;
  import at.ac.tuwien.kr.alpha.core.solver.WritableAssignment;
  
  /**
   * Tests assumptions made by {@link DependencyDrivenHeuristic} and other domain-independent heuristics.
   * Even if these test cases do not test {@link DependencyDrivenHeuristic} directly,
   * it will break if these test cases break.
   * 
   * Copyright (c) 2017-2018 Siemens AG
   *
   */
  public class AlphaHeuristicTestAssumptions {
  
  	private final ProgramParser parser = new ProgramParserImpl();
  	private final NormalizeProgramTransformation normalizer = new NormalizeProgramTransformation(SystemConfig.DEFAULT_AGGREGATE_REWRITING_CONFIG);
  	private final Function<String, CompiledProgram> parseAndPreprocess = (str) -> {
  		return InternalProgram.fromNormalProgram(normalizer.apply(parser.parse(str)));
  	};
  
  	private Grounder grounder;
  	private WritableAssignment assignment;
  	private TestableChoiceManager choiceManager;
  	private AtomStore atomStore;
  
  	@BeforeEach
  	public void setUp() {
  		String testProgram = ""
  				+ "b1."
  				+ "b2."
  				+ "{b3}."
  				+ "{b4}."
  				+ "h :- b1, b2, not b3, not b4.";
  		CompiledProgram internalProgram = parseAndPreprocess.apply(testProgram);
  		atomStore = new AtomStoreImpl();
  		grounder = new NaiveGrounder(internalProgram, atomStore, true);
  		assignment = new TrailAssignment(atomStore);
  		choiceManager = new TestableChoiceManager(assignment, new NaiveNoGoodStore(assignment));
  	}
  
  	@Test
  	public void testNumbersOfNoGoods_GrounderIsAtomChoicePoint() {
  		testNumbersOfNoGoods(atomStore::isAtomChoicePoint);
  	}
  
  	@Test
  	public void testNumbersOfNoGoods_ChoiceManagerIsAtomChoice() {
  		testNumbersOfNoGoods(choiceManager::isAtomChoice);
  	}
  
  	private void testNumbersOfNoGoods(Predicate<? super Integer> isRuleBody) {
  		int n = 0;
  		int bodyNotHead = 0;
  		int bodyElementsNotBody = 0;
  		int noHead = 0;
  		int other = 0;
  
  		Collection<NoGood> noGoods = getNoGoods();
  		assignment.growForMaxAtomId();
  		choiceManager.growForMaxAtomId(atomStore.getMaxAtomId());
  		choiceManager.addChoiceInformation(grounder.getChoiceAtoms(), grounder.getHeadsToBodies());
  		for (NoGood noGood : noGoods) {
  			n++;
  			boolean knownType = false;
  			if (DependencyDrivenHeuristic.isBodyNotHead(noGood, isRuleBody)) {
  				bodyNotHead++;
  				knownType = true;
  			}
  			if (DependencyDrivenHeuristic.isBodyElementsNotBody(noGood, isRuleBody)) {
  				bodyElementsNotBody++;
  				knownType = true;
  			}
  			if (!noGood.hasHead()) {
  				noHead++;
  				knownType = true;
  			}
  			if (!knownType) {
  				other++;
  			}
  		}
  
  		System.out.println(noGoods.stream().map(atomStore::noGoodToString).collect(Collectors.joining(", ")));
  
  		assertEquals(5, bodyNotHead, "Unexpected number of bodyNotHead nogoods");
  		assertEquals(5, bodyElementsNotBody, "Unexpected number of bodyElementsNotBody nogoods");
  		assertGreaterThan("Unexpected number of nogoods without head", 4, noHead);
  
  		// there may be other nogoods (e.g. for ChoiceOn, ChoiceOff) which we do not care for here
  		System.out.println("Total number of NoGoods: " + n);
  		System.out.println("Number of NoGoods of unknown type: " + other);
  	}
  
  	@Test
  	public void testIsAtomChoice_GrounderIsAtomChoicePoint() {
  		testIsAtomChoice(atomStore::isAtomChoicePoint);
  	}
  
  	@Test
  	public void testIsAtomChoice_ChoiceManagerIsAtomChoice() {
  		testIsAtomChoice(choiceManager::isAtomChoice);
  	}
  
  	private void testIsAtomChoice(Predicate<? super Integer> isRuleBody) {
  		Collection<NoGood> noGoods = getNoGoods();
  		assignment.growForMaxAtomId();
  		choiceManager.growForMaxAtomId(atomStore.getMaxAtomId());
  		choiceManager.addChoiceInformation(grounder.getChoiceAtoms(), grounder.getHeadsToBodies());
  		for (NoGood noGood : noGoods) {
  			for (Integer literal : noGood) {
  				int atom = atomOf(literal);
  				String atomToString = atomStore.atomToString(atom);
  				if (atomToString.startsWith("_R_")) {
  					assertTrue(isRuleBody.test(atom), "Atom not choice: " + atomToString);
  				}
  			}
  		}
  	}
  
  	private Collection<NoGood> getNoGoods() {
  		return grounder.getNoGoods(null).values();
  	}
  
  	private void assertGreaterThan(String message, long expected, long actual) {
  		assertTrue(actual > expected, message);
  	}
  }
  