package Sequenic.T2ext.CoverageEngine.ga;

import java.lang.reflect.Field;
import java.util.Iterator;
import java.util.List;

import org.apache.bcel.Repository;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.generic.BIPUSH;
import org.apache.bcel.generic.ClassGen;
import org.apache.bcel.generic.GETFIELD;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.MethodGen;
import org.apache.bcel.util.InstructionFinder;

import Sequenic.T2.Seq.Trace;
import Sequenic.T2.Seq.TraceExecInfo;
import Sequenic.T2ext.CoverageEngine.BaseEngine;
import Sequenic.T2ext.Instrumenter.Sensor;

/**
 * This GA evaluator searches for an if(int==constant) pattern in the CUT and can
 * calculate the fitness based on the distance between the ints.
 * 
 * @author Christiaan Hees
 */
public class IntEqualsIntEvaluator extends Evaluator {
	private String i1;
	private Number i2;
	
	public IntEqualsIntEvaluator(BaseEngine engine) {
		super(engine);

		JavaClass clazz = null;
		try {
			clazz = Repository.lookupClass(engine.t2covAnalyzer.getC());
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
			System.exit(1);
		}
		ClassGen cGen = new ClassGen(clazz);
		for(Method m : cGen.getMethods()) {
			MethodGen mGen = new MethodGen(m, cGen.getClassName(), cGen.getConstantPool());
			
			// Search for if(int==int)
			InstructionFinder finder = new InstructionFinder(mGen.getInstructionList());
			Iterator i = finder.search("aload_0 getfield bipush if_icmpne");
			while(i.hasNext()) {
				// TODO what if you find more than 1 of these patterns?
				InstructionHandle[] match = (InstructionHandle[]) i.next();
				
				GETFIELD getfield = (GETFIELD) match[1].getInstruction();
				i1 = getfield.getFieldName(cGen.getConstantPool());
				
				BIPUSH bipush = (BIPUSH) match[2].getInstruction();
				i2 = bipush.getValue();
				
				containingMethod = m.getName();
				
				System.out.println("Found if(int==constant) pattern in "
						+ containingMethod + ": " + i1 + " " + i2);
			}
		}
	}
	
	public double getFitness(Trace candidate, List<? extends Trace> population) {
		// Execute the trace and calculate the fitness based on the 3 ints
		Sensor.ejectObservations();
		TraceExecInfo info = engine.executeT2Trace(candidate);
		Class c = engine.t2covAnalyzer.getC();
		try {
			Field f1 = c.getDeclaredField(i1);
			f1.setAccessible(true);
			// TODO is this obj actually the one we need?
			Object obj = info.lastStepResult.receiverObj;
			if(obj == null) return 1000; // FIXME Double.MAX_VALUE;
			return Math.abs((double)f1.getInt(obj) - i2.doubleValue());
		} catch (Exception e) {
			e.printStackTrace();
		}
		return 0;
	}
}