package lombok.eclipse.agent;

import org.mangosdk.spi.ProviderFor;
import org.objectweb.asm.ClassAdapter;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import static org.objectweb.asm.Opcodes.*;

@ProviderFor(EclipseTransformer.class)
public class EclipseLinkedNodeFinderTransformer implements EclipseTransformer {
	private static final String LINKED_NODE_FINDER = "org/eclipse/jdt/core/internal/corext/dom/LinkedNodeFinder";
	
	@Override public String getTargetClassName() {
		return LINKED_NODE_FINDER;
	}
	
	@Override public byte[] transform(byte[] in) {
		ClassReader reader = new ClassReader(in);
		ClassWriter writer = new ClassWriter(reader, 0);
	
		ClassAdapter adapter = new LinkedNodeFinderPatcherAdapter(writer);
		reader.accept(adapter, 0);
		return writer.toByteArray();
	}
	
	private static class LinkedNodeFinderPatcherAdapter extends ClassAdapter {
		private int originalAccess;
		private String originalDesc;
		private String originalSignature;
		private String[] originalExceptions;

		LinkedNodeFinderPatcherAdapter(ClassVisitor cv) {
			super(cv);
		}
		
		@Override public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
			if ( !name.equals("findByNode") ) return super.visitMethod(access, name, desc, signature, exceptions);
			
			originalAccess = access;
			originalDesc = desc;
			originalSignature = signature;
			originalExceptions = exceptions;
			
			return super.visitMethod(0, "findByNode0", desc, signature, exceptions);
		}
		
		private static final String SIMPLENAME = "org/eclipse/jdt/core/dom/SimpleName";
		private static final String SIMPLENAME_ARRAY = "[L" + SIMPLENAME + ";";
		private static final String ASTNODE = "Lorg/eclipse/jdt/internal/compiler/ast/ASTNode;";
		
		/*
		 * code generated by running ASMifier on:
		 * 
		public SimpleName[] findByNode(ASTNode a, SimpleName b) {
			SimpleName[] ps = this.findByNode0(a, b);
			int count = 0;
			for (int i = 0; i < ps.length; i++) {
				if ( ps[i] == null || ps[i].$generatedBy == null ) count++;
			}
			if (count == ps.length) return ps;
			SimpleName[] newPs = new SimpleName[count];
			count = 0;
			for (int i = 0; i < ps.length; i++) {
				if ( ps[i] == null || ps[i].p == null ) newPs[count++] = ps[i];
			}
			return newPs;
		}
		 */
		@Override public void visitEnd() {
			MethodVisitor mv = super.visitMethod(originalAccess, "findByNode", originalDesc, originalSignature, originalExceptions);
			mv.visitCode();
			mv.visitCode();
			mv.visitVarInsn(ALOAD, 0);
			mv.visitVarInsn(ALOAD, 1);
			mv.visitVarInsn(ALOAD, 2);
			mv.visitMethodInsn(INVOKESPECIAL, LINKED_NODE_FINDER, "findByNode0", originalDesc);
			mv.visitVarInsn(ASTORE, 3);
			mv.visitInsn(ICONST_0);
			mv.visitVarInsn(ISTORE, 4);
			mv.visitInsn(ICONST_0);
			mv.visitVarInsn(ISTORE, 5);
			Label l0 = new Label();
			mv.visitLabel(l0);
			mv.visitFrame(F_APPEND,3, new Object[] {SIMPLENAME_ARRAY, INTEGER, INTEGER}, 0, null);
			mv.visitVarInsn(ILOAD, 5);
			mv.visitVarInsn(ALOAD, 3);
			mv.visitInsn(ARRAYLENGTH);
			Label l1 = new Label();
			mv.visitJumpInsn(IF_ICMPGE, l1);
			mv.visitVarInsn(ALOAD, 3);
			mv.visitVarInsn(ILOAD, 5);
			mv.visitInsn(AALOAD);
			Label l2 = new Label();
			mv.visitJumpInsn(IFNULL, l2);
			mv.visitVarInsn(ALOAD, 3);
			mv.visitVarInsn(ILOAD, 5);
			mv.visitInsn(AALOAD);
			mv.visitFieldInsn(GETFIELD, SIMPLENAME, "$generatedBy", ASTNODE);
			Label l3 = new Label();
			mv.visitJumpInsn(IFNONNULL, l3);
			mv.visitLabel(l2);
			mv.visitFrame(F_SAME, 0, null, 0, null);
			mv.visitIincInsn(4, 1);
			mv.visitLabel(l3);
			mv.visitFrame(F_SAME, 0, null, 0, null);
			mv.visitIincInsn(5, 1);
			mv.visitJumpInsn(GOTO, l0);
			mv.visitLabel(l1);
			mv.visitFrame(F_CHOP,1, null, 0, null);
			mv.visitVarInsn(ILOAD, 4);
			mv.visitVarInsn(ALOAD, 3);
			mv.visitInsn(ARRAYLENGTH);
			Label l4 = new Label();
			mv.visitJumpInsn(IF_ICMPNE, l4);
			mv.visitVarInsn(ALOAD, 3);
			mv.visitInsn(ARETURN);
			mv.visitLabel(l4);
			mv.visitFrame(F_SAME, 0, null, 0, null);
			mv.visitVarInsn(ILOAD, 4);
			mv.visitTypeInsn(ANEWARRAY, SIMPLENAME);
			mv.visitVarInsn(ASTORE, 5);
			mv.visitInsn(ICONST_0);
			mv.visitVarInsn(ISTORE, 4);
			mv.visitInsn(ICONST_0);
			mv.visitVarInsn(ISTORE, 6);
			Label l5 = new Label();
			mv.visitLabel(l5);
			mv.visitFrame(F_APPEND,2, new Object[] {SIMPLENAME_ARRAY, INTEGER}, 0, null);
			mv.visitVarInsn(ILOAD, 6);
			mv.visitVarInsn(ALOAD, 3);
			mv.visitInsn(ARRAYLENGTH);
			Label l6 = new Label();
			mv.visitJumpInsn(IF_ICMPGE, l6);
			mv.visitVarInsn(ALOAD, 3);
			mv.visitVarInsn(ILOAD, 6);
			mv.visitInsn(AALOAD);
			Label l7 = new Label();
			mv.visitJumpInsn(IFNULL, l7);
			mv.visitVarInsn(ALOAD, 3);
			mv.visitVarInsn(ILOAD, 6);
			mv.visitInsn(AALOAD);
			mv.visitFieldInsn(GETFIELD, SIMPLENAME, "$generatedBy", ASTNODE);
			Label l8 = new Label();
			mv.visitJumpInsn(IFNONNULL, l8);
			mv.visitLabel(l7);
			mv.visitFrame(F_SAME, 0, null, 0, null);
			mv.visitVarInsn(ALOAD, 5);
			mv.visitVarInsn(ILOAD, 4);
			mv.visitIincInsn(4, 1);
			mv.visitVarInsn(ALOAD, 3);
			mv.visitVarInsn(ILOAD, 6);
			mv.visitInsn(AALOAD);
			mv.visitInsn(AASTORE);
			mv.visitLabel(l8);
			mv.visitFrame(F_SAME, 0, null, 0, null);
			mv.visitIincInsn(6, 1);
			mv.visitJumpInsn(GOTO, l5);
			mv.visitLabel(l6);
			mv.visitFrame(F_CHOP,1, null, 0, null);
			mv.visitVarInsn(ALOAD, 5);
			mv.visitInsn(ARETURN);
			mv.visitMaxs(4, 7);
			super.visitEnd();
		}
	}
}