package Sequenic.T2ext.Instrumenter;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.util.TraceClassVisitor;

/**
 * A Class Instrumenter using ASM.
 * 
 * The existing insturmenter:
 * -Did not instrument constructors and static initializers.
 * -Was very cluttered, requiring ugly hacks to add functionality necessary to generate labeled CFGs
 * -Required the instrumentee Class to be in the Classpath, 
 *  which caused conflicts when multiple versions of the same class needed instrumentation.
 * -Generated very long redundant paths for loops (see Examples.ExponentialLoop). 
 * -Could not handle exceptional flow. 
 * 
 * Most of these could be fixed without resorting to the ASM library,
 * but BCEL is slow, not maintained and old, while ASM is newer, faster and being maintained.
 * And regarding exceptional flow, it seems as if BCEL does not expose enough information to handle it properly.
 * 
 * Perhaps it is better and easier to just rewrite the Instrumenter using ASM than to hack the old Instrumenter.
 * 
 * NOTE: this class is just a proposal.
 * 
 * @author Jeiel Schalkwijk
 *
 */

public class ClassIntrumenter_ASM {
	
	private final int flags;	
	
	public ClassIntrumenter_ASM(int flags) {
		this.flags = flags;
	}
	
	/** same as instrumenter(0).
	 * 
	 * @return
	 */
	public static ClassIntrumenter_ASM instrumenter() {
		return new ClassIntrumenter_ASM(0);
	}
	
	public static ClassIntrumenter_ASM instrumenter(int flags) {
		return new ClassIntrumenter_ASM(flags);
	}
	
	/** If the filename is not yet instrumented, it will be instrumented.
	 * If instrumented two additional files are created with the following extension:
	 * .orgclass = the original (uninstrumented) version of the file, created by renaming the original file.
	 * .cfgs     = A CFGBunchFile containing the CFGs of the methods in the class.
	 * 
	 * @param filename - name of the .class file
	 * @return true if filename was not yet instrumented
	 * @throws IOException 
	 * @throws FileNotFoundException 
	 */
	public boolean instrument(String filename) throws FileNotFoundException, IOException {
		FileInputStream f = new FileInputStream(filename);
		ClassReader cr = new ClassReader(f);
		ClassWriter cw = new ClassWriter(cr,0); //flags: ClassWriter.COMPUTE_FRAMES + ClassWriter.COMPUTE_MAXS
//		ClassVisitor cv = new Injector(cw,Granularity.CLASS);
		TraceClassVisitor cv = new TraceClassVisitor(cw,new PrintWriter(System.out)); //print visitor.
		cr.accept(cv, 0);// flags: SKIP_FRAMES, SKIP_DEBUG, SKIP_CODE, EXPAND_FRAMES
//		byte[] instrumentedVersion = cw.toByteArray();		
		f.close();
		return false;
	}	
	
	public static void main(String[] args) {
		try
		{
			//Yes, classinv is also instrumented and CFGized
//			CFGBunchFile orig = CFGBunchFile.load("MyArrayList_mutated_versions/v0/java_1_4/util/MyArrayList.cfgs");
//			for(CFG c : orig.cfgs)
//			System.out.println(c.methodName);
			
			//Print (un)instrumented class files:
			//instrumenter().instrument(new File("MyArrayList_mutated_versions/v0/java_1_4/util/MyArrayList.orgclass").getAbsolutePath());
			//instrumenter().instrument("MyArrayList_mutated_versions/v0/java_1_4/util/MyArrayList.class");
						
		}catch (Exception e)
		{
			e.printStackTrace();
		}
	}
	
}