package inference.axioms;

import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import exceptions.SubstituteFailedException;
import inference.InferenceRule;
import models.Position;
import models.algebra.Variable;
import models.formulas.Formula;
import models.formulas.meta.MetaDependencyFormula;
import models.terms.meta.MatchConstraint;
import models.terms.meta.MetaDynamicDependency;
import models.terms.meta.MetaEvaluatableTermVariable;
import models.terms.meta.MetaRDLTerm;
import models.terms.meta.MetaTermGenerator;

public class ArgumentReduction extends InferenceRule {

	public ArgumentReduction() {
		super("Argument Reduction");
		
		assumptions.add(new MetaDependencyFormula(
				new MetaDynamicDependency(
						new MetaTermGenerator() {
							@Override
							public MetaRDLTerm generate(int curIndex, int curDepth, int maxIndex, int maxDepth, Map<Object, Object> context) {
								curIndex -= 1;
								context.put("k", curIndex);
								return new MetaEvaluatableTermVariable(new Variable("ue" + curIndex));
							}
						},
						new MetaEvaluatableTermVariable(new Variable("te"))
				)
		));
		
		assumptions.add(new MetaDependencyFormula(
				new MetaDynamicDependency(
						new MetaTermGenerator() {
							@Override
							public MetaRDLTerm generate(int curIndex, int curDepth, int maxIndex, int maxDepth, Map<Object, Object> context) {
								curIndex -= 2;
								return new MetaEvaluatableTermVariable(new Variable("ue" + curIndex));
							}
						},
						new MetaEvaluatableTermVariable(new Variable("se")),
						new MetaEvaluatableTermVariable(new Variable("te"))
				)
		));
		
		conclusion = new MetaDependencyFormula(
				new MetaDynamicDependency(
						new MetaTermGenerator() {
							@Override
							public MetaRDLTerm generate(int curIndex, int curDepth, int maxIndex, int maxDepth, Map<Object, Object> context) {
								curIndex -= 1;
								return new MetaEvaluatableTermVariable(new Variable("ue" + curIndex));
							}
						},
						new MetaEvaluatableTermVariable(new Variable("se"))
				)
		);
		
	}
	
	public Set<Formula> derive(List<Formula> assumptions, MatchConstraint constraint) {
		Set<Formula> result = new HashSet<>();
		if (this.assumptions.size() != assumptions.size()) {
			return new HashSet<>();
		}
		
		Set<MatchConstraint> matchResult = assumptionMatch(assumptions, constraint);
		
		for (MatchConstraint res: matchResult) {
			try {
				res.getContext().put(new Position(), (Integer) res.getContext().get(new Position()) - 1);
				result.add(this.conclusion.substitution(res.getBinding(), res.getContext()));
			} catch (SubstituteFailedException e) {
				continue;
			}
		}
		return result;
	}
	
}