content: /**
   * Copyright (c) 2017-2021, the Alpha Team.
   * All rights reserved.
   * <p>
   * Additional changes made by Siemens.
   * <p>
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   * <p>
   * 1) Redistributions of source code must retain the above copyright notice, this
   * list of conditions and the following disclaimer.
   * <p>
   * 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.
   * <p>
   * 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.commons.programs.atoms;
  
  import java.util.Collections;
  import java.util.List;
  import java.util.stream.Collectors;
  
  import org.apache.commons.collections4.ListUtils;
  
  import at.ac.tuwien.kr.alpha.api.common.fixedinterpretations.PredicateInterpretation;
  import at.ac.tuwien.kr.alpha.api.grounder.Substitution;
  import at.ac.tuwien.kr.alpha.api.programs.Predicate;
  import at.ac.tuwien.kr.alpha.api.programs.atoms.ExternalAtom;
  import at.ac.tuwien.kr.alpha.api.programs.literals.ExternalLiteral;
  import at.ac.tuwien.kr.alpha.api.programs.terms.Term;
  import at.ac.tuwien.kr.alpha.commons.programs.literals.Literals;
  import at.ac.tuwien.kr.alpha.commons.programs.terms.Terms;
  import at.ac.tuwien.kr.alpha.commons.util.Util;
  
  class ExternalAtomImpl extends AbstractAtom implements ExternalAtom {
  
  	private final List<Term> input;
  	private final List<Term> output;
  
  	protected final Predicate predicate;
  	protected final PredicateInterpretation interpretation;
  
  	ExternalAtomImpl(Predicate predicate, PredicateInterpretation interpretation, List<Term> input, List<Term> output) {
  		if (predicate == null) {
  			throw new IllegalArgumentException("predicate must not be null!");
  		}
  		if (interpretation == null) {
  			throw new IllegalArgumentException("interpretation must not be null!");
  		}
  		if (input == null) {
  			throw new IllegalArgumentException("input must not be null!");
  		}
  		if (output == null) {
  			throw new IllegalArgumentException("output must not be null!");
  		}
  		this.predicate = predicate;
  		this.interpretation = interpretation;
  		this.input = input;
  		this.output = output;
  	}
  
  	@Override
  	public boolean hasOutput() {
  		return !output.isEmpty();
  	}
  
  	@Override
  	public Predicate getPredicate() {
  		return predicate;
  	}
  
  	@Override
  	public PredicateInterpretation getInterpretation() {
  		return interpretation;
  	}
  
  	@Override
  	public List<Term> getInput() {
  		return Collections.unmodifiableList(input);
  	}
  
  	@Override
  	public List<Term> getOutput() {
  		return Collections.unmodifiableList(output);
  	}
  
  	@Override
  	public List<Term> getTerms() {
  		return ListUtils.union(input, output);
  	}
  
  	@Override
  	public boolean isGround() {
  		for (Term t : input) {
  			if (!t.isGround()) {
  				return false;
  			}
  		}
  		for (Term t : output) {
  			if (!t.isGround()) {
  				return false;
  			}
  		}
  		return true;
  	}
  
  	@Override
  	public ExternalAtomImpl substitute(Substitution substitution) {
  		List<Term> substitutedInput = this.input.stream().map(t -> t.substitute(substitution)).collect(Collectors.toList());
  		List<Term> substitutedOutput = this.output.stream().map(t -> t.substitute(substitution)).collect(Collectors.toList());
  		return new ExternalAtomImpl(predicate, interpretation, substitutedInput, substitutedOutput);
  	}
  
  	@Override
  	public ExternalLiteral toLiteral(boolean positive) {
  		return Literals.fromAtom(this, positive);
  	}
  
  	@Override
  	public String toString() {
  		String result = "&" + predicate.getName();
  		if (!input.isEmpty()) {
  			result += Util.join("[", input, "]");
  		}
  		if (!output.isEmpty()) {
  			result += Util.join("(", output, ")");
  		}
  		return result;
  	}
  
  	/**
  	 * Creates a new {@link ExternalAtom} with input and output term lists set according to the given term list.
  	 * Callers are responsible for making sure the given term list contains the right number of terms. For an external atom with n input and m
  	 * output terms, terms[0..n-1] is interpreted as input terms for the new atom, terms[n..(n + m)-1] are taken to be output terms.
  	 */
  	@Override
  	public ExternalAtom withTerms(List<Term> terms) {
  		if (terms.size() != this.input.size() + this.output.size()) {
  			throw new IllegalArgumentException(
  					"Cannot apply term list " + terms.toString() + " to external atom " + this.toString() + ", terms has invalid size!");
  		}
  		List<Term> newInput = terms.subList(0, this.input.size());
  		List<Term> newOutput = terms.subList(this.input.size(), terms.size());
  		return new ExternalAtomImpl(this.predicate, this.interpretation, newInput, newOutput);
  	}
  
  	@Override
  	public int hashCode() {
  		final int prime = 31;
  		int result = 1;
  		result = prime * result + this.input.hashCode();
  		result = prime * result + this.output.hashCode();
  		result = prime * result + this.predicate.hashCode();
  		return result;
  	}
  
  	@Override
  	public boolean equals(Object obj) {
  		if (this == obj) {
  			return true;
  		}
  		if (obj == null) {
  			return false;
  		}
  		if (!(obj instanceof ExternalAtom)) {
  			return false;
  		}
  		ExternalAtom other = (ExternalAtom) obj;
  		if (!this.input.equals(other.getInput())) {
  			return false;
  		}
  		if (!this.output.equals(other.getOutput())) {
  			return false;
  		}
  		if (!this.predicate.equals(other.getPredicate())) {
  			return false;
  		}
  		return true;
  	}
  
  	@Override
  	public ExternalAtomImpl normalizeVariables(String prefix, int counterStartingValue) {
  		List<Term> renamedInput = Terms.renameTerms(this.input, prefix + "_IN_", counterStartingValue);
  		List<Term> renamedOutput = Terms.renameTerms(this.output, prefix + "_OUT_", counterStartingValue);
  		return new ExternalAtomImpl(this.predicate, this.interpretation, renamedInput, renamedOutput);
  	}
  
  }
  