package org.geogebra.common.kernel.cas;

import org.geogebra.common.kernel.Construction;
import org.geogebra.common.kernel.StringTemplate;
import org.geogebra.common.kernel.algos.AlgoElement;
import org.geogebra.common.kernel.arithmetic.MyArbitraryConstant;
import org.geogebra.common.kernel.commands.Commands;
import org.geogebra.common.kernel.geos.GeoElement;
import org.geogebra.common.kernel.geos.GeoNumberValue;
import org.geogebra.common.kernel.geos.GeoNumeric;
import org.geogebra.common.util.MyMath;

/**
 * Algorithm for NextPrime and PreviousPrime
 */
public class AlgoNextPreviousPrime extends AlgoElement implements UsesCAS {

	private GeoNumberValue init;
	private GeoNumeric result;
	private boolean next;

	/**
	 * @param cons
	 *            construction
	 * @param label
	 *            label for output
	 * @param init
	 *            where to start seeking from primes
	 * @param next
	 *            true for NextPrime, false for PreviousPrime
	 */
	public AlgoNextPreviousPrime(Construction cons, String label,
			GeoNumberValue init, boolean next) {
		super(cons);
		this.init = init;
		this.next = next;
		result = new GeoNumeric(cons);
		setInputOutput();
		compute();
		result.setLabel(label);
	}

	@Override
	protected void setInputOutput() {
		setOnlyOutput(result);
		input = new GeoElement[] { init.toGeoElement() };
		setDependencies();
	}

	private MyArbitraryConstant arbconst = new MyArbitraryConstant(this);

	@Override
	public void compute() {
		if (!init.isDefined() || init.getDouble() > MyMath.LARGEST_INTEGER) {
			result.setUndefined();
			return;
		}
		StringBuilder sb = new StringBuilder(30);
		sb.append(next ? "NextPrime(" : "PreviousPrime(");
		sb.append(init.toValueString(StringTemplate.maxPrecision));
		sb.append(")");
		try {
			String functionOut = kernel.evaluateCachedGeoGebraCAS(sb.toString(),
					arbconst);
			if (functionOut == null || functionOut.length() == 0) {
				result.setUndefined();
			} else {
				// read result back into function
				result.setValue(Double.parseDouble(functionOut));
			}
		} catch (Throwable e) {
			result.setUndefined();
		}

	}

	@Override
	public Commands getClassName() {
		return next ? Commands.NextPrime : Commands.PreviousPrime;
	}

	/**
	 * @return resulting prime
	 */
	public GeoNumeric getResult() {
		return result;
	}

	// Locus equability makes no sense here

}