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/*
* SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
*
* SPDX-License-Identifier: EPL-2.0
*/
package tools.refinery.store.reasoning.lifting;
import tools.refinery.store.query.Constraint;
import tools.refinery.store.query.dnf.Dnf;
import tools.refinery.store.query.dnf.DnfClause;
import tools.refinery.store.query.literal.*;
import tools.refinery.store.query.term.NodeVariable;
import tools.refinery.store.query.term.ParameterDirection;
import tools.refinery.store.query.term.Variable;
import tools.refinery.store.reasoning.ReasoningAdapter;
import tools.refinery.store.reasoning.literal.Concreteness;
import tools.refinery.store.reasoning.literal.ModalConstraint;
import tools.refinery.store.reasoning.literal.Modality;
import java.util.*;
import java.util.stream.Collectors;
class ClauseLifter {
private final Modality modality;
private final Concreteness concreteness;
private final DnfClause clause;
private final Set<NodeVariable> quantifiedVariables;
private final Set<NodeVariable> existentialQuantifiersToAdd;
public ClauseLifter(Modality modality, Concreteness concreteness, Dnf dnf, DnfClause clause) {
this.modality = modality;
this.concreteness = concreteness;
this.clause = clause;
quantifiedVariables = getQuantifiedNodeVariables(dnf, clause);
existentialQuantifiersToAdd = new LinkedHashSet<>(quantifiedVariables);
}
private static Set<NodeVariable> getQuantifiedNodeVariables(Dnf dnf, DnfClause clause) {
var quantifiedVariables = clause.positiveVariables().stream()
.filter(Variable::isNodeVariable)
.map(Variable::asNodeVariable)
.collect(Collectors.toCollection(LinkedHashSet::new));
for (var symbolicParameter : dnf.getSymbolicParameters()) {
if (symbolicParameter.getVariable() instanceof NodeVariable nodeParameter) {
quantifiedVariables.remove(nodeParameter);
}
}
return Collections.unmodifiableSet(quantifiedVariables);
}
public List<Literal> liftClause() {
var liftedLiterals = new ArrayList<Literal>();
for (var literal : clause.literals()) {
var liftedLiteral = liftLiteral(literal);
liftedLiterals.add(liftedLiteral);
}
var existsConstraint = ModalConstraint.of(modality, concreteness, ReasoningAdapter.EXISTS_SYMBOL);
for (var quantifiedVariable : existentialQuantifiersToAdd) {
liftedLiterals.add(existsConstraint.call(quantifiedVariable));
}
return liftedLiterals;
}
private Literal liftLiteral(Literal literal) {
if (literal instanceof CallLiteral callLiteral) {
return liftCallLiteral(callLiteral);
} else if (literal instanceof EquivalenceLiteral equivalenceLiteral) {
return liftEquivalenceLiteral(equivalenceLiteral);
} else if (literal instanceof ConstantLiteral ||
literal instanceof AssignLiteral<?> ||
literal instanceof CheckLiteral) {
return literal;
} else if (literal instanceof AbstractCountLiteral<?>) {
throw new IllegalArgumentException("Count literal %s cannot be lifted".formatted(literal));
} else if (literal instanceof AggregationLiteral<?, ?>) {
throw new IllegalArgumentException("Aggregation literal %s cannot be lifted".formatted(literal));
} else if (literal instanceof RepresentativeElectionLiteral) {
throw new IllegalArgumentException("SCC literal %s cannot be lifted".formatted(literal));
} else {
throw new IllegalArgumentException("Unknown literal to lift: " + literal);
}
}
private Literal liftCallLiteral(CallLiteral callLiteral) {
var polarity = callLiteral.getPolarity();
return switch (polarity) {
case POSITIVE -> {
Constraint target = callLiteral.getTarget();
var arguments = callLiteral.getArguments();
yield ModalConstraint.of(modality, concreteness, target).call(CallPolarity.POSITIVE, arguments);
}
case NEGATIVE -> callNegationHelper(callLiteral);
case TRANSITIVE -> callTransitiveHelper(callLiteral);
};
}
private Literal callNegationHelper(CallLiteral callLiteral) {
var target = callLiteral.getTarget();
var originalArguments = callLiteral.getArguments();
var negatedModality = modality.negate();
var privateVariables = callLiteral.getPrivateVariables(clause.positiveVariables());
if (privateVariables.isEmpty()) {
// If there is no universal quantification, we may directly call the original Dnf.
return ModalConstraint.of(negatedModality, concreteness, target)
.call(CallPolarity.NEGATIVE, originalArguments);
}
var builder = Dnf.builder("%s#negation#%s#%s#%s"
.formatted(target.name(), modality, concreteness, privateVariables));
var uniqueOriginalArguments = List.copyOf(new LinkedHashSet<>(originalArguments));
var alwaysInputVariables = callLiteral.getInputVariables(Set.of());
for (var variable : uniqueOriginalArguments) {
var direction = alwaysInputVariables.contains(variable) ? ParameterDirection.IN : ParameterDirection.OUT;
builder.parameter(variable, direction);
}
var literals = new ArrayList<Literal>();
var liftedConstraint = ModalConstraint.of(negatedModality, concreteness, target);
literals.add(liftedConstraint.call(CallPolarity.POSITIVE, originalArguments));
var existsConstraint = ModalConstraint.of(negatedModality, concreteness, ReasoningAdapter.EXISTS_SYMBOL);
for (var variable : uniqueOriginalArguments) {
if (privateVariables.contains(variable)) {
literals.add(existsConstraint.call(variable));
}
}
builder.clause(literals);
var liftedTarget = builder.build();
return liftedTarget.call(CallPolarity.NEGATIVE, uniqueOriginalArguments);
}
private Literal callTransitiveHelper(CallLiteral callLiteral) {
var target = callLiteral.getTarget();
var originalArguments = callLiteral.getArguments();
var liftedTarget = ModalConstraint.of(modality, concreteness, target);
var existsConstraint = ModalConstraint.of(modality, concreteness, ReasoningAdapter.EXISTS_SYMBOL);
var existingEndHelperName = "%s#exisitingEnd#%s#%s".formatted(target.name(), modality, concreteness);
var existingEndHelper = Dnf.of(existingEndHelperName, builder -> {
var start = builder.parameter("start");
var end = builder.parameter("end");
builder.clause(
liftedTarget.call(start, end),
existsConstraint.call(end)
);
});
// The start and end of a transitive path is always a node.
var pathEnd = (NodeVariable) originalArguments.get(1);
if (quantifiedVariables.contains(pathEnd)) {
// The end of the path needs existential quantification anyway, so we don't need a second helper.
// We replace the call to EXISTS with the transitive path call.
existentialQuantifiersToAdd.remove(pathEnd);
return existingEndHelper.call(CallPolarity.TRANSITIVE, originalArguments);
}
var transitiveHelperName = "%s#transitive#%s#%s".formatted(target.name(), modality, concreteness);
var transitiveHelper = Dnf.of(transitiveHelperName, builder -> {
var start = builder.parameter("start");
var end = builder.parameter("end");
// Make sure the end of the path is not existentially quantified.
builder.clause(liftedTarget.call(start, end));
builder.clause(middle -> List.of(
existingEndHelper.callTransitive(start, middle),
liftedTarget.call(middle, end)
));
});
return transitiveHelper.call(CallPolarity.POSITIVE, originalArguments);
}
private Literal liftEquivalenceLiteral(EquivalenceLiteral equivalenceLiteral) {
if (equivalenceLiteral.isPositive()) {
return ModalConstraint.of(modality, concreteness, ReasoningAdapter.EQUALS_SYMBOL)
.call(CallPolarity.POSITIVE, equivalenceLiteral.getLeft(), equivalenceLiteral.getRight());
}
return ModalConstraint.of(modality.negate(), concreteness, ReasoningAdapter.EQUALS_SYMBOL)
.call(CallPolarity.NEGATIVE, equivalenceLiteral.getLeft(), equivalenceLiteral.getRight());
}
}
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