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package com.artemis.weaver;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.List;

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.tree.ClassNode;

import com.artemis.ClassUtil;
import com.artemis.Weaver;
import com.artemis.meta.ClassMetadata;
import com.artemis.meta.ClassMetadataUtil;
import com.artemis.weaver.packed.ExternalFieldClassTransformer;

/**
 * Rewrites access to packed components so that related classes can
 * access packed components with direct field access, syntactically.
 */
public class ComponentAccessTransmuter extends CallableTransmuter implements Opcodes {
	private List packed;
	private ClassReader cr;
	
	public ComponentAccessTransmuter(String file, ClassReader cr, List packedComponents) {
		super(file);
		this.cr = cr;
		this.packed = packedComponents;
	}
	
	@Override
	protected ClassMetadata process(String file) throws FileNotFoundException, IOException {
		boolean changed = compileClass(file);
		return changed ? Weaver.scan(cr) : null;
	}

	private boolean compileClass(String file) {
		ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES);
		
		ExternalFieldClassTransformer transformer = new ExternalFieldClassTransformer(null, packed);
		ClassNode cn = transformer.transform(cr);
		
		if (!transformer.isComponentAccessChanged())
			return false;
		
		try {
			cn.accept(cw);
			if (file != null)
				ClassUtil.writeClass(cw, file);
			
			return true;
			
		} catch (Exception e) {
			e.printStackTrace();
			return false;
		}
	}
}