/**
 * Copyright (C) 2010-2017 Gordon Fraser, Andrea Arcuri and EvoSuite
 * contributors
 *
 * This file is part of EvoSuite.
 *
 * EvoSuite is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3.0 of the License, or
 * (at your option) any later version.
 *
 * EvoSuite is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with EvoSuite. If not, see <http://www.gnu.org/licenses/>.
 */
/**
 * 
 */
package org.evosuite.instrumentation.mutation;

import java.lang.reflect.Modifier;
import java.util.LinkedList;
import java.util.List;

import org.evosuite.coverage.mutation.Mutation;
import org.evosuite.coverage.mutation.MutationPool;
import org.evosuite.graphs.cfg.BytecodeInstruction;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.InsnList;
import org.objectweb.asm.tree.InsnNode;
import org.objectweb.asm.tree.LabelNode;
import org.objectweb.asm.tree.LdcInsnNode;
import org.objectweb.asm.tree.MethodInsnNode;
import org.objectweb.asm.tree.MethodNode;
import org.objectweb.asm.tree.analysis.Frame;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * <p>DeleteStatement class.</p>
 *
 * @author Gordon Fraser
 */
public class DeleteStatement implements MutationOperator {

	private static Logger logger = LoggerFactory.getLogger(DeleteStatement.class);

	public static final String NAME = "DeleteStatement";
	
	/* (non-Javadoc)
	 * @see org.evosuite.cfg.instrumentation.MutationOperator#apply(org.objectweb.asm.tree.MethodNode, java.lang.String, java.lang.String, org.evosuite.cfg.BytecodeInstruction)
	 */
	/** {@inheritDoc} */
	@Override
	public List<Mutation> apply(MethodNode mn, String className, String methodName,
	        BytecodeInstruction instruction, Frame frame) {

		List<Mutation> mutations = new LinkedList<Mutation>();

		MethodInsnNode node = (MethodInsnNode) instruction.getASMNode();
		Type returnType = Type.getReturnType(node.desc);

		// insert mutation into bytecode with conditional
		InsnList mutation = new InsnList();
		logger.info("Mutation deletestatement for statement " + node.name + node.desc);
		for (Type argType : Type.getArgumentTypes(node.desc)) {
			if (argType.getSize() == 0)
				logger.info("Ignoring parameter of type " + argType);
			else if (argType.getSize() == 2) {
				mutation.insert(new InsnNode(Opcodes.POP2));
				logger.debug("Deleting parameter of 2 type " + argType);
			} else {
				logger.debug("Deleting parameter of 1 type " + argType);
				mutation.insert(new InsnNode(Opcodes.POP));
			}
		}
		if (node.getOpcode() == Opcodes.INVOKEVIRTUAL) {
			logger.debug("Deleting callee of type " + node.owner);
			mutation.add(new InsnNode(Opcodes.POP));
		} else if (node.getOpcode() == Opcodes.INVOKEINTERFACE) {
			boolean isStatic = false;
			try {
				Class<?> clazz = Class.forName(node.owner.replace('/', '.'), false, DeleteStatement.class.getClassLoader());
				for (java.lang.reflect.Method method : clazz.getMethods()) {
					if (method.getName().equals(node.name)) {
						if (Type.getMethodDescriptor(method).equals(node.desc)) {
							if (Modifier.isStatic(method.getModifiers()))
								isStatic = true;
						}
					}
				}
			} catch (ClassNotFoundException e) {
				logger.warn("Could not find class: " + node.owner
				        + ", this is likely a severe problem");
			}
			if (!isStatic) {
				logger.info("Deleting callee of type " + node.owner);
				mutation.add(new InsnNode(Opcodes.POP));
			}
		}
		mutation.add(getDefault(returnType));

		// insert mutation into pool
		Mutation mutationObject = MutationPool.addMutation(className,
		                                                   methodName,
		                                                   NAME + " "
		                                                           + node.name
		                                                           + node.desc,
		                                                   instruction,
		                                                   mutation,
		                                                   Mutation.getDefaultInfectionDistance());

		mutations.add(mutationObject);
		return mutations;
	}

	private static AbstractInsnNode getDefault(Type type) {
		if (type.equals(Type.BOOLEAN_TYPE)) {
			return new LdcInsnNode(0);
		} else if (type.equals(Type.INT_TYPE)) {
			return new LdcInsnNode(0);
		} else if (type.equals(Type.BYTE_TYPE)) {
			return new LdcInsnNode(0);
		} else if (type.equals(Type.CHAR_TYPE)) {
			return new LdcInsnNode(0);
		} else if (type.equals(Type.DOUBLE_TYPE)) {
			return new LdcInsnNode(0.0);
		} else if (type.equals(Type.FLOAT_TYPE)) {
			return new LdcInsnNode(0.0F);
		} else if (type.equals(Type.INT_TYPE)) {
			return new LdcInsnNode(0);
		} else if (type.equals(Type.LONG_TYPE)) {
			return new LdcInsnNode(0L);
		} else if (type.equals(Type.SHORT_TYPE)) {
			return new LdcInsnNode(0);
		} else if (type.equals(Type.VOID_TYPE)) {
			return new LabelNode();
		} else {
			return new InsnNode(Opcodes.ACONST_NULL);
		}
	}

	/* (non-Javadoc)
	 * @see org.evosuite.cfg.instrumentation.mutation.MutationOperator#isApplicable(org.evosuite.cfg.BytecodeInstruction)
	 */
	/** {@inheritDoc} */
	@Override
	public boolean isApplicable(BytecodeInstruction instruction) {
		return instruction.isMethodCall()
		        && instruction.getASMNode().getOpcode() != Opcodes.INVOKESPECIAL;
	}
}