package inference.axioms;

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

import exceptions.SubstituteFailedException;
import inference.EquationAxiom;
import models.algebra.Variable;
import models.formulas.Formula;
import models.formulas.meta.MetaEquationFormula;
import models.terms.EvaluatableTerm;
import models.terms.meta.MatchConstraint;
import models.terms.meta.MetaDynamicDependencyTerm;
import models.terms.meta.MetaEvaluatableTermVariable;
import models.terms.meta.MetaRDLTerm;
import models.terms.meta.MetaTermGenerator;

public class Identity extends EquationAxiom{

	public Identity() {
		super("Identity");
		this.conclusion = new MetaEquationFormula(
				new MetaDynamicDependencyTerm(
						new MetaTermGenerator() {
							@Override
							public MetaRDLTerm generate(int curIndex, int curDepth, int maxIndex, int maxDepth, Map<String, Object> context) {
								curIndex -= 2;
								if (curIndex % 2 == 0) {
									return new MetaEvaluatableTermVariable(new Variable("ue" + curIndex / 2));
								}
								return new MetaEvaluatableTermVariable(new Variable("ve" + curIndex / 2));
							}
						},
						new MetaEvaluatableTermVariable(new Variable("se")),
						new MetaEvaluatableTermVariable(new Variable("se")),
						new MetaEvaluatableTermVariable(new Variable("te"))
				),
				new MetaEvaluatableTermVariable(new Variable("te"))
		);
	}
	
	@Override
	public Set<EvaluatableTerm> apply(List<Formula>assumptions,  EvaluatableTerm term, MatchConstraint constraint) {
		Set<EvaluatableTerm> result = new HashSet<>();
		boolean isLeft = true;
		if (assumptions.size() < this.assumptions.size()) {
			return new HashSet<>();
		}
		Set<MatchConstraint> matchResult = assumptionMatch(assumptions, constraint);
		
		Set<MatchConstraint> conclusionMatchResult = conclusionLeftSideHandMatch(term, matchResult);
		if (conclusionMatchResult.isEmpty()) {
			isLeft = false;
			conclusionMatchResult = conclusionRightSideHandMatch(term, matchResult);
			if (conclusionMatchResult.isEmpty()) {
				return new HashSet<>();
			}
		}
		MetaEquationFormula metaConclusion = (MetaEquationFormula) this.conclusion;
		for (MatchConstraint matchRes: conclusionMatchResult) {
			try {
				if (isLeft) {
					result.add((EvaluatableTerm)((MetaRDLTerm) metaConclusion.getRightSideHand()).substitute(matchRes.getBinding(), matchRes.getContext()));
				} else {
					result.add((EvaluatableTerm)((MetaRDLTerm) metaConclusion.getLeftSideHand()).substitute(matchRes.getBinding(), matchRes.getContext()));
				}
			} catch (SubstituteFailedException e) {
				continue;
			}
		}
		return result;
	}
	
}