Copyright (c) 2019 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
    Red Hat Inc. - copied and modified for use in jdt.core.manipulation
/*******************************************************************************
 * Copyright (c) 2019 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Red Hat Inc. - copied and modified for use in jdt.core.manipulation
 *******************************************************************************/
package org.eclipse.jdt.internal.corext.fix;

import java.util.ArrayList;
import java.util.Hashtable;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;

import org.eclipse.core.runtime.CoreException;

import org.eclipse.text.edits.TextEditGroup;

import org.eclipse.jdt.core.compiler.IProblem;
import org.eclipse.jdt.core.dom.AST;
import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.ASTVisitor;
import org.eclipse.jdt.core.dom.Assignment;
import org.eclipse.jdt.core.dom.Block;
import org.eclipse.jdt.core.dom.CastExpression;
import org.eclipse.jdt.core.dom.ChildListPropertyDescriptor;
import org.eclipse.jdt.core.dom.ClassInstanceCreation;
import org.eclipse.jdt.core.dom.CompilationUnit;
import org.eclipse.jdt.core.dom.ConditionalExpression;
import org.eclipse.jdt.core.dom.EnhancedForStatement;
import org.eclipse.jdt.core.dom.Expression;
import org.eclipse.jdt.core.dom.ExpressionStatement;
import org.eclipse.jdt.core.dom.FieldAccess;
import org.eclipse.jdt.core.dom.FieldDeclaration;
import org.eclipse.jdt.core.dom.IBinding;
import org.eclipse.jdt.core.dom.IMethodBinding;
import org.eclipse.jdt.core.dom.ITypeBinding;
import org.eclipse.jdt.core.dom.IVariableBinding;
import org.eclipse.jdt.core.dom.IfStatement;
import org.eclipse.jdt.core.dom.ImportDeclaration;
import org.eclipse.jdt.core.dom.Javadoc;
import org.eclipse.jdt.core.dom.MethodDeclaration;
import org.eclipse.jdt.core.dom.MethodInvocation;
import org.eclipse.jdt.core.dom.NodeFinder;
import org.eclipse.jdt.core.dom.ParenthesizedExpression;
import org.eclipse.jdt.core.dom.PostfixExpression;
import org.eclipse.jdt.core.dom.PrefixExpression;
import org.eclipse.jdt.core.dom.QualifiedName;
import org.eclipse.jdt.core.dom.SimpleName;
import org.eclipse.jdt.core.dom.SingleVariableDeclaration;
import org.eclipse.jdt.core.dom.Statement;
import org.eclipse.jdt.core.dom.SuperMethodInvocation;
import org.eclipse.jdt.core.dom.TagElement;
import org.eclipse.jdt.core.dom.Type;
import org.eclipse.jdt.core.dom.TypeDeclarationStatement;
import org.eclipse.jdt.core.dom.VariableDeclarationExpression;
import org.eclipse.jdt.core.dom.VariableDeclarationFragment;
import org.eclipse.jdt.core.dom.VariableDeclarationStatement;
import org.eclipse.jdt.core.dom.rewrite.ASTRewrite;
import org.eclipse.jdt.core.dom.rewrite.ListRewrite;
import org.eclipse.jdt.core.manipulation.CleanUpOptionsCore;
import org.eclipse.jdt.core.manipulation.ICleanUpFixCore;

import org.eclipse.jdt.internal.core.manipulation.dom.NecessaryParenthesesChecker;
import org.eclipse.jdt.internal.core.manipulation.util.BasicElementLabels;
import org.eclipse.jdt.internal.corext.dom.ASTNodes;
import org.eclipse.jdt.internal.corext.dom.LinkedNodeFinder;
import org.eclipse.jdt.internal.corext.dom.StatementRewrite;
import org.eclipse.jdt.internal.corext.refactoring.structure.CompilationUnitRewrite;
import org.eclipse.jdt.internal.corext.util.Messages;

import org.eclipse.jdt.internal.ui.fix.UnusedCodeCleanUpCore;
import org.eclipse.jdt.internal.ui.text.correction.IProblemLocationCore;
import org.eclipse.jdt.internal.ui.text.correction.JavadocTagsSubProcessorCore;
import org.eclipse.jdt.internal.ui.text.correction.ProblemLocationCore;

Fix which removes unused code.
/**
 * Fix which removes unused code.
 */
public class UnusedCodeFixCore extends CompilationUnitRewriteOperationsFixCore {

	public static class SideEffectFinder extends ASTVisitor {

		private final ArrayList<Expression> fSideEffectNodes;

		public SideEffectFinder(ArrayList<Expression> res) {
			fSideEffectNodes= res;
		}

		@Override
		public boolean visit(Assignment node) {
			fSideEffectNodes.add(node);
			return false;
		}

		@Override
		public boolean visit(PostfixExpression node) {
			fSideEffectNodes.add(node);
			return false;
		}

		@Override
		public boolean visit(PrefixExpression node) {
			Object operator= node.getOperator();
			if (operator == PrefixExpression.Operator.INCREMENT || operator == PrefixExpression.Operator.DECREMENT) {
				fSideEffectNodes.add(node);
				return false;
			}
			return true;
		}

		@Override
		public boolean visit(MethodInvocation node) {
			fSideEffectNodes.add(node);
			return false;
		}

		@Override
		public boolean visit(ClassInstanceCreation node) {
			fSideEffectNodes.add(node);
			return false;
		}

		@Override
		public boolean visit(SuperMethodInvocation node) {
			fSideEffectNodes.add(node);
			return false;
		}
	}

	public static class RemoveImportOperation extends CompilationUnitRewriteOperation {

		private final ImportDeclaration fImportDeclaration;

		public RemoveImportOperation(ImportDeclaration importDeclaration) {
			fImportDeclaration= importDeclaration;
		}

		@Override
		public void rewriteAST(CompilationUnitRewrite cuRewrite, LinkedProposalModelCore model) throws CoreException {
			ImportDeclaration node= fImportDeclaration;
			TextEditGroup group= createTextEditGroup(FixMessages.UnusedCodeFix_RemoveImport_description, cuRewrite);
			cuRewrite.getASTRewrite().remove(node, group);
		}

	}

	
Removes the unused type parameter.
/**
	 * Removes the unused type parameter.
	 *
	 */
	public static class RemoveUnusedTypeParameterOperation extends CompilationUnitRewriteOperation {
		private final SimpleName fUnusedName;

		public RemoveUnusedTypeParameterOperation(SimpleName unusedName) {
			fUnusedName= unusedName;
		}

		@Override
		public void rewriteAST(CompilationUnitRewrite cuRewrite, LinkedProposalModelCore linkedModel) throws CoreException {
			ASTRewrite rewrite= cuRewrite.getASTRewrite();
			IBinding binding= fUnusedName.resolveBinding();
			CompilationUnit root= (CompilationUnit) fUnusedName.getRoot();
			String displayString= FixMessages.UnusedCodeFix_RemoveUnusedTypeParameter_description;
			TextEditGroup group= createTextEditGroup(displayString, cuRewrite);

			if (binding.getKind() == IBinding.TYPE) {
				ITypeBinding decl= ((ITypeBinding) binding).getTypeDeclaration();
				ASTNode declaration= root.findDeclaringNode(decl);
				if (declaration.getParent() instanceof TypeDeclarationStatement) {
					declaration= declaration.getParent();
				}
				rewrite.remove(declaration, group);
			}
		}
	}

	public static class RemoveUnusedMemberOperation extends CompilationUnitRewriteOperation {

		private final SimpleName[] fUnusedNames;
		private boolean fForceRemove;
		private int fRemovedAssignmentsCount;
		private int fAlteredAssignmentsCount;

		public RemoveUnusedMemberOperation(SimpleName[] unusedNames, boolean removeAllAsignements) {
			fUnusedNames= unusedNames;
			fForceRemove= removeAllAsignements;
		}

		@Override
		public void rewriteAST(CompilationUnitRewrite cuRewrite, LinkedProposalModelCore model) throws CoreException {
			for (SimpleName unusedName : fUnusedNames) {
				removeUnusedName(cuRewrite, unusedName);
			}
		}

		private void removeUnusedName(CompilationUnitRewrite cuRewrite, SimpleName simpleName) {
			ASTRewrite rewrite= cuRewrite.getASTRewrite();
			CompilationUnit completeRoot= cuRewrite.getRoot();

			IBinding binding= simpleName.resolveBinding();
			CompilationUnit root= (CompilationUnit) simpleName.getRoot();
			String displayString= getDisplayString(binding);
			TextEditGroup group= createTextEditGroup(displayString, cuRewrite);
			if (binding.getKind() == IBinding.METHOD) {
				IMethodBinding decl= ((IMethodBinding) binding).getMethodDeclaration();
				ASTNode declaration= root.findDeclaringNode(decl);
				rewrite.remove(declaration, group);
			} else if (binding.getKind() == IBinding.TYPE) {
				ITypeBinding decl= ((ITypeBinding) binding).getTypeDeclaration();
				ASTNode declaration= root.findDeclaringNode(decl);
				if (declaration.getParent() instanceof TypeDeclarationStatement) {
					declaration= declaration.getParent();
				}
				rewrite.remove(declaration, group);
			} else if (binding.getKind() == IBinding.VARIABLE) {
				SimpleName nameNode= (SimpleName) NodeFinder.perform(completeRoot, simpleName.getStartPosition(), simpleName.getLength());
				SimpleName[] references= LinkedNodeFinder.findByBinding(completeRoot, nameNode.resolveBinding());
				for (int i= 0; i < references.length; i++) {
					removeVariableReferences(rewrite, references[i], group);
				}

				IVariableBinding bindingDecl= ((IVariableBinding) nameNode.resolveBinding()).getVariableDeclaration();
				ASTNode declaringNode= completeRoot.findDeclaringNode(bindingDecl);
				if (declaringNode instanceof SingleVariableDeclaration) {
					removeParamTag(rewrite, (SingleVariableDeclaration) declaringNode, group);
				}
			} else {
				// unexpected
			}
		}

		private String getDisplayString(IBinding binding) {
			switch (binding.getKind()) {
				case IBinding.TYPE:
					return FixMessages.UnusedCodeFix_RemoveUnusedType_description;
				case IBinding.METHOD:
					if (((IMethodBinding) binding).isConstructor()) {
						return FixMessages.UnusedCodeFix_RemoveUnusedConstructor_description;
					} else {
						return FixMessages.UnusedCodeFix_RemoveUnusedPrivateMethod_description;
					}
				case IBinding.VARIABLE:
					if (((IVariableBinding) binding).isField()) {
						return FixMessages.UnusedCodeFix_RemoveUnusedField_description;
					} else {
						return FixMessages.UnusedCodeFix_RemoveUnusedVariabl_description;
					}
				default:
					return ""; //$NON-NLS-1$
			}
		}

		private void removeParamTag(ASTRewrite rewrite, SingleVariableDeclaration varDecl, TextEditGroup group) {
			if (varDecl.getParent() instanceof MethodDeclaration) {
				Javadoc javadoc= ((MethodDeclaration) varDecl.getParent()).getJavadoc();
				if (javadoc != null) {
					TagElement tagElement= JavadocTagsSubProcessorCore.findParamTag(javadoc, varDecl.getName().getIdentifier());
					if (tagElement != null) {
						rewrite.remove(tagElement, group);
					}
				}
			}
		}

		
Remove the field or variable declaration including the initializer.
Params:
rewrite – the AST rewriter to use
reference – a reference to the variable to remove
group – the text edit group to use/**
		 * Remove the field or variable declaration including the initializer.
		 * @param rewrite the AST rewriter to use
		 * @param reference a reference to the variable to remove
		 * @param group the text edit group to use
		 */
		private void removeVariableReferences(ASTRewrite rewrite, SimpleName reference, TextEditGroup group) {
			ASTNode parent= reference.getParent();
			while (parent instanceof QualifiedName) {
				parent= parent.getParent();
			}
			if (parent instanceof FieldAccess) {
				parent= parent.getParent();
			}

			int nameParentType= parent.getNodeType();
			if (nameParentType == ASTNode.ASSIGNMENT) {
				Assignment assignment= (Assignment) parent;
				Expression rightHand= assignment.getRightHandSide();

				ASTNode assignParent= assignment.getParent();
				if (assignParent.getNodeType() == ASTNode.EXPRESSION_STATEMENT && rightHand.getNodeType() != ASTNode.ASSIGNMENT) {
					removeVariableWithInitializer(rewrite, rightHand, assignParent, group);
				}	else {
					rewrite.replace(assignment, rewrite.createCopyTarget(rightHand), group);
				}
			} else if (nameParentType == ASTNode.SINGLE_VARIABLE_DECLARATION) {
				rewrite.remove(parent, group);
			} else if (nameParentType == ASTNode.VARIABLE_DECLARATION_FRAGMENT) {
				VariableDeclarationFragment frag= (VariableDeclarationFragment) parent;
				ASTNode varDecl= frag.getParent();
				List<VariableDeclarationFragment> fragments;
				if (varDecl instanceof VariableDeclarationExpression) {
					fragments= ((VariableDeclarationExpression) varDecl).fragments();
				} else if (varDecl instanceof FieldDeclaration) {
					fragments= ((FieldDeclaration) varDecl).fragments();
				} else {
					fragments= ((VariableDeclarationStatement) varDecl).fragments();
				}
				Expression initializer= frag.getInitializer();
				ArrayList<Expression> sideEffects= new ArrayList<>();
				if (initializer != null) {
					initializer.accept(new SideEffectFinder(sideEffects));
				}

				/*
				 * Special case for when the variable initializer is a conditional expression.
				 * Certain actions must be taken depending on where in the conditional the side effect expressions are located.
				 */
				if (initializer instanceof ConditionalExpression && varDecl instanceof VariableDeclarationStatement) {
					AST ast= rewrite.getAST();
					ConditionalExpression ce= (ConditionalExpression) initializer;

					// check if side effects and both expressions are to be removed then we remove whole statement
					if (fForceRemove || (!checkSideEffects(sideEffects) &&
							!checkCondtionalExpression(ce.getThenExpression()) &&
							!checkCondtionalExpression(ce.getElseExpression()))) {
						rewrite.remove(varDecl, group);
						return;
					}

					IfStatement ifStatement= ast.newIfStatement();
					ifStatement.setExpression((Expression) rewrite.createCopyTarget(getExpressionWithoutParenthezis(ce.getExpression())));

					Block thenBlock= ast.newBlock();
					// check if 'then' block contains code to keep
					if (checkCondtionalExpression(ce.getThenExpression())) {
						ASTNode thenExpression= rewrite.createCopyTarget(getExpressionWithoutParenthezis(ce.getThenExpression()));
						thenBlock.statements().add(ast.newExpressionStatement((Expression) thenExpression));
					}
					ifStatement.setThenStatement(thenBlock);

					// check if 'else' block contains code to keep
					if (checkCondtionalExpression(ce.getElseExpression())) {
						Block elseBlock= ast.newBlock();
						ASTNode elseExpression= rewrite.createCopyTarget(getExpressionWithoutParenthezis(ce.getElseExpression()));
						elseBlock.statements().add(ast.newExpressionStatement((Expression) elseExpression));
						ifStatement.setElseStatement(elseBlock);
					}

					rewrite.replace(varDecl, ifStatement, group);
					return;
				}

				boolean sideEffectInitializer= sideEffects.size() > 0;
				if (fragments.size() == fUnusedNames.length) {
					if (fForceRemove) {
						rewrite.remove(varDecl, group);
						return;
					}
					if (parent.getParent() instanceof FieldDeclaration) {
						rewrite.remove(varDecl, group);
						return;
					}
					if (sideEffectInitializer) {
						Statement[] wrapped= new Statement[sideEffects.size()];
						for (int i= 0; i < wrapped.length; i++) {
							Expression sideEffect= sideEffects.get(i);
							Expression movedInit= (Expression) rewrite.createMoveTarget(sideEffect);
							wrapped[i]= rewrite.getAST().newExpressionStatement(movedInit);
						}
						StatementRewrite statementRewrite= new StatementRewrite(rewrite, new ASTNode[] { varDecl });
						statementRewrite.replace(wrapped, group);
					} else {
						rewrite.remove(varDecl, group);
					}
				} else {
					if (fForceRemove) {
						rewrite.remove(frag, group);
						return;
					}
					//multiple declarations in one line
					ASTNode declaration = parent.getParent();
					if (declaration instanceof FieldDeclaration) {
						rewrite.remove(frag, group);
						return;
					}
					if (declaration instanceof VariableDeclarationStatement) {
						splitUpDeclarations(rewrite, group, frag, (VariableDeclarationStatement) declaration, sideEffects);
						rewrite.remove(frag, group);
						return;
					}
					if (declaration instanceof VariableDeclarationExpression) {
						//keep constructors and method invocations
						if (!sideEffectInitializer){
							rewrite.remove(frag, group);
						}
					}
				}
			} else if (nameParentType == ASTNode.POSTFIX_EXPRESSION || nameParentType == ASTNode.PREFIX_EXPRESSION) {
				Expression expression= (Expression)parent;
				ASTNode expressionParent= expression.getParent();
				if (expressionParent.getNodeType() == ASTNode.EXPRESSION_STATEMENT) {
					removeStatement(rewrite, expressionParent, group);
				} else {
					rewrite.remove(expression, group);
				}
			}
		}

		private static Expression getExpressionWithoutParenthezis(Expression expression) {
			Expression currExpression= expression;
			while (currExpression instanceof ParenthesizedExpression) {
				currExpression= ((ParenthesizedExpression) currExpression).getExpression();
			}
			return currExpression;
		}

		/*
		 * Return TRUE if the expression node type is a method, pre/posfix or assignment
		 */
		private static boolean checkCondtionalExpression(Expression expression) {
			int nodeType= getExpressionWithoutParenthezis(expression).getNodeType();
			if (nodeType == ASTNode.METHOD_INVOCATION ||
					nodeType == ASTNode.POSTFIX_EXPRESSION ||
					nodeType == ASTNode.PREFIX_EXPRESSION ||
					nodeType == ASTNode.ASSIGNMENT) {
				return true;
			}
			return false;
		}

		/*
		 * Return TRUE if any of the sideEffects expression node type is a method, pre/posfix or assignment
		 */
		private static boolean checkSideEffects(List<Expression> sideEffects) {
			if (sideEffects.isEmpty()) {
				return false;
			}
			for (Expression expression : sideEffects) {
				if (checkCondtionalExpression(expression)) {
					return true;
				}
			}
			return false;
		}

		private void splitUpDeclarations(ASTRewrite rewrite, TextEditGroup group, VariableDeclarationFragment frag, VariableDeclarationStatement originalStatement, List<Expression> sideEffects) {
			if (sideEffects.size() > 0) {
				ListRewrite statementRewrite= rewrite.getListRewrite(originalStatement.getParent(), (ChildListPropertyDescriptor) originalStatement.getLocationInParent());

				Statement previousStatement= originalStatement;
				for (Expression sideEffect : sideEffects) {
					Expression movedInit= (Expression) rewrite.createMoveTarget(sideEffect);
					ExpressionStatement wrapped= rewrite.getAST().newExpressionStatement(movedInit);
					statementRewrite.insertAfter(wrapped, previousStatement, group);
					previousStatement= wrapped;
				}

				VariableDeclarationStatement newDeclaration= null;
				List<VariableDeclarationFragment> fragments= originalStatement.fragments();
				int fragIndex= fragments.indexOf(frag);
				ListIterator<VariableDeclarationFragment> fragmentIterator= fragments.listIterator(fragIndex+1);
				while (fragmentIterator.hasNext()) {
					VariableDeclarationFragment currentFragment= fragmentIterator.next();
					VariableDeclarationFragment movedFragment= (VariableDeclarationFragment) rewrite.createMoveTarget(currentFragment);
					if (newDeclaration == null) {
						newDeclaration= rewrite.getAST().newVariableDeclarationStatement(movedFragment);
						Type copiedType= (Type) rewrite.createCopyTarget(originalStatement.getType());
						newDeclaration.setType(copiedType);
					} else {
						newDeclaration.fragments().add(movedFragment);
					}
				}
				if (newDeclaration != null){
					statementRewrite.insertAfter(newDeclaration, previousStatement, group);
					if (originalStatement.fragments().size() == newDeclaration.fragments().size() + 1){
						rewrite.remove(originalStatement, group);
					}
				}
			}
		}

		private void removeVariableWithInitializer(ASTRewrite rewrite, ASTNode initializerNode, ASTNode statementNode, TextEditGroup group) {
			boolean performRemove= fForceRemove;
			if (!performRemove) {
				ArrayList<Expression> sideEffectNodes= new ArrayList<>();
				initializerNode.accept(new SideEffectFinder(sideEffectNodes));
				performRemove= sideEffectNodes.isEmpty();
			}
			if (performRemove) {
				removeStatement(rewrite, statementNode, group);
				fRemovedAssignmentsCount++;
			} else {
				ASTNode initNode = rewrite.createMoveTarget(initializerNode);
				ExpressionStatement statement = rewrite.getAST().newExpressionStatement((Expression) initNode);
				rewrite.replace(statementNode, statement, null);
				fAlteredAssignmentsCount++;
			}
		}

		private void removeStatement(ASTRewrite rewrite, ASTNode statementNode, TextEditGroup group) {
			if (ASTNodes.isControlStatementBody(statementNode.getLocationInParent())) {
				rewrite.replace(statementNode, rewrite.getAST().newBlock(), group);
			} else {
				rewrite.remove(statementNode, group);
			}
		}

		@Override
		public String getAdditionalInfo() {
			StringBuilder sb=new StringBuilder();
			if (fRemovedAssignmentsCount == 1) {
				sb.append(FixMessages.UnusedCodeFix_RemoveFieldOrLocal_RemovedAssignments_preview_singular);
			} else if (fRemovedAssignmentsCount > 1) {
				sb.append(Messages.format(FixMessages.UnusedCodeFix_RemoveFieldOrLocal_RemovedAssignments_preview_plural, String.valueOf(fRemovedAssignmentsCount)));
			}
			if (fAlteredAssignmentsCount == 1) {
				sb.append(FixMessages.UnusedCodeFix_RemoveFieldOrLocal_AlteredAssignments_preview_singular);
			} else if (fAlteredAssignmentsCount > 1) {
				sb.append(Messages.format(FixMessages.UnusedCodeFix_RemoveFieldOrLocal_AlteredAssignments_preview_plural, String.valueOf(fAlteredAssignmentsCount)));
			}
			if (sb.length()>0) {
				return sb.toString();
			} else
				return null;
		}
	}

	public static class RemoveCastOperation extends CompilationUnitRewriteOperation {

		private final CastExpression fCast;

		public RemoveCastOperation(CastExpression cast) {
			fCast= cast;
		}

		@Override
		public void rewriteAST(CompilationUnitRewrite cuRewrite, LinkedProposalModelCore model) throws CoreException {

			TextEditGroup group= createTextEditGroup(FixMessages.UnusedCodeFix_RemoveCast_description, cuRewrite);

			ASTRewrite rewrite= cuRewrite.getASTRewrite();

			CastExpression cast= fCast;
			Expression expression= cast.getExpression();
			if (expression instanceof ParenthesizedExpression) {
				Expression childExpression= ((ParenthesizedExpression) expression).getExpression();
				if (NecessaryParenthesesChecker.needsParentheses(childExpression, cast, CastExpression.EXPRESSION_PROPERTY)) {
					expression= childExpression;
				}
			}

			replaceCast(cast, expression, rewrite, group);
		}
	}

	public static class RemoveAllCastOperation extends CompilationUnitRewriteOperation {

		private final LinkedHashSet<CastExpression> fUnnecessaryCasts;

		public RemoveAllCastOperation(LinkedHashSet<CastExpression> unnecessaryCasts) {
			fUnnecessaryCasts= unnecessaryCasts;
		}

		@Override
		public void rewriteAST(CompilationUnitRewrite cuRewrite, LinkedProposalModelCore model) throws CoreException {
			ASTRewrite rewrite= cuRewrite.getASTRewrite();

			TextEditGroup group= createTextEditGroup(FixMessages.UnusedCodeFix_RemoveCast_description, cuRewrite);

			while (fUnnecessaryCasts.size() > 0) {
				CastExpression castExpression= fUnnecessaryCasts.iterator().next();
				fUnnecessaryCasts.remove(castExpression);

				/*
				 * ASTRewrite doesn't allow replacing (deleting) of moved nodes. To solve problems
				 * with nested casts, we need to replace all casts at once.
				 *
				 * The loop proceeds downwards to find the innermost expression that stays in the result (downChild)
				 * and it also skips necessary parentheses.
				 */
				CastExpression down= castExpression;
				Expression downChild= down.getExpression();
				while (true) {
					if (fUnnecessaryCasts.contains(downChild)) {
						down= (CastExpression) downChild;
						fUnnecessaryCasts.remove(down);
						downChild= down.getExpression();
					} else if (downChild instanceof ParenthesizedExpression) {
						Expression downChildExpression= ((ParenthesizedExpression) downChild).getExpression();
						// is it justified that downChild is a ParenthesizedExpression?
						if (NecessaryParenthesesChecker.needsParentheses(downChildExpression, down, CastExpression.EXPRESSION_PROPERTY)) {
							// yes => continue walking down
							downChild= downChildExpression;
						} else {
							// no => stop walking
							break;
						}
					} else {
						break;
					}
				}

				// downChild is the innermost CastExpression's expression, stripped of a necessary surrounding ParenthesizedExpression
				// Move either downChild (if it doesn't need parentheses), or a parenthesized version if necessary

				replaceCast(castExpression, downChild, rewrite, group);
			}
		}
	}

	public static UnusedCodeFixCore createRemoveUnusedImportFix(CompilationUnit compilationUnit, IProblemLocationCore problem) {
		if (isUnusedImport(problem)) {
			ImportDeclaration node= getImportDeclaration(problem, compilationUnit);
			if (node != null) {
				String label= FixMessages.UnusedCodeFix_RemoveImport_description;
				RemoveImportOperation operation= new RemoveImportOperation(node);
				Map<String, String> options= new Hashtable<>();
				options.put(CleanUpConstants.REMOVE_UNUSED_CODE_IMPORTS, CleanUpOptionsCore.TRUE);
				return new UnusedCodeFixCore(label, compilationUnit, new CompilationUnitRewriteOperation[] {operation}, options);
			}
		}
		return null;
	}

	public static boolean isUnusedImport(IProblemLocationCore problem) {
		int id= problem.getProblemId();
		return id == IProblem.UnusedImport || id == IProblem.DuplicateImport || id == IProblem.ConflictingImport || id == IProblem.CannotImportPackage || id == IProblem.ImportNotFound;
	}

	public static UnusedCodeFixCore createUnusedMemberFix(CompilationUnit compilationUnit, IProblemLocationCore problem, boolean removeAllAssignements) {
		if (isUnusedMember(problem)) {
			SimpleName name= getUnusedName(compilationUnit, problem);
			if (name != null) {
				IBinding binding= name.resolveBinding();
				if (binding != null) {
					if (isFormalParameterInEnhancedForStatement(name))
						return null;

					String label= getDisplayString(name, binding, removeAllAssignements);
					RemoveUnusedMemberOperation operation= new RemoveUnusedMemberOperation(new SimpleName[] { name }, removeAllAssignements);
					return new UnusedCodeFixCore(label, compilationUnit, new CompilationUnitRewriteOperation[] { operation }, getCleanUpOptions(binding, removeAllAssignements));
				}
			}
		}
		return null;
	}

	public static UnusedCodeFixCore createUnusedTypeParameterFix(CompilationUnit compilationUnit, IProblemLocationCore problemLoc) {
		if (problemLoc.getProblemId() == IProblem.UnusedTypeParameter) {
			SimpleName name= getUnusedName(compilationUnit, problemLoc);
			if (name != null) {
				IBinding binding= name.resolveBinding();
				if (binding != null) {
					String label= FixMessages.UnusedCodeFix_RemoveUnusedTypeParameter_description;
					RemoveUnusedTypeParameterOperation operation= new RemoveUnusedTypeParameterOperation(name);
					return new UnusedCodeFixCore(label, compilationUnit, new CompilationUnitRewriteOperation[] { operation }, getCleanUpOptions(binding, false));
				}
			}
		}
		return null;
	}

	public static boolean isUnusedMember(IProblemLocationCore problem) {
		int id= problem.getProblemId();
		return id == IProblem.UnusedPrivateMethod || id == IProblem.UnusedPrivateConstructor || id == IProblem.UnusedPrivateField || id == IProblem.UnusedPrivateType
				|| id == IProblem.LocalVariableIsNeverUsed || id == IProblem.ArgumentIsNeverUsed;
	}

	public static UnusedCodeFixCore createRemoveUnusedCastFix(CompilationUnit compilationUnit, IProblemLocationCore problem) {
		if (problem.getProblemId() != IProblem.UnnecessaryCast)
			return null;

		ASTNode selectedNode= problem.getCoveringNode(compilationUnit);

		ASTNode curr= selectedNode;
		while (curr instanceof ParenthesizedExpression) {
			curr= ((ParenthesizedExpression) curr).getExpression();
		}

		if (!(curr instanceof CastExpression))
			return null;

		return new UnusedCodeFixCore(FixMessages.UnusedCodeFix_RemoveCast_description, compilationUnit, new CompilationUnitRewriteOperation[] {new RemoveCastOperation((CastExpression)curr)});
	}

	public static ICleanUpFixCore createCleanUp(CompilationUnit compilationUnit,
			boolean removeUnusedPrivateMethods,
			boolean removeUnusedPrivateConstructors,
			boolean removeUnusedPrivateFields,
			boolean removeUnusedPrivateTypes,
			boolean removeUnusedLocalVariables,
			boolean removeUnusedImports,
			boolean removeUnusedCast) {

		IProblem[] problems= compilationUnit.getProblems();
		IProblemLocationCore[] locations= new IProblemLocationCore[problems.length];
		for (int i= 0; i < problems.length; i++) {
			locations[i]= new ProblemLocationCore(problems[i]);
		}

		return createCleanUp(compilationUnit, locations,
				removeUnusedPrivateMethods,
				removeUnusedPrivateConstructors,
				removeUnusedPrivateFields,
				removeUnusedPrivateTypes,
				removeUnusedLocalVariables,
				removeUnusedImports,
				removeUnusedCast);
	}

	public static ICleanUpFixCore createCleanUp(CompilationUnit compilationUnit, IProblemLocationCore[] problems,
			boolean removeUnusedPrivateMethods,
			boolean removeUnusedPrivateConstructors,
			boolean removeUnusedPrivateFields,
			boolean removeUnusedPrivateTypes,
			boolean removeUnusedLocalVariables,
			boolean removeUnusedImports,
			boolean removeUnusedCast) {

		List<CompilationUnitRewriteOperation> result= new ArrayList<>();
		Hashtable<ASTNode, List<SimpleName>> variableDeclarations= new Hashtable<>();
		LinkedHashSet<CastExpression> unnecessaryCasts= new LinkedHashSet<>();
		for (IProblemLocationCore problem : problems) {
			int id= problem.getProblemId();

			if (removeUnusedImports && (id == IProblem.UnusedImport || id == IProblem.DuplicateImport || id == IProblem.ConflictingImport ||
				    id == IProblem.CannotImportPackage || id == IProblem.ImportNotFound))
			{
				ImportDeclaration node= UnusedCodeFixCore.getImportDeclaration(problem, compilationUnit);
				if (node != null) {
					result.add(new RemoveImportOperation(node));
				}
			}

			if ((removeUnusedPrivateMethods && id == IProblem.UnusedPrivateMethod) || (removeUnusedPrivateConstructors && id == IProblem.UnusedPrivateConstructor) ||
			    (removeUnusedPrivateTypes && id == IProblem.UnusedPrivateType)) {

				SimpleName name= getUnusedName(compilationUnit, problem);
				if (name != null) {
					IBinding binding= name.resolveBinding();
					if (binding != null) {
						result.add(new RemoveUnusedMemberOperation(new SimpleName[] {name}, false));
					}
				}
			}

			if ((removeUnusedLocalVariables && id == IProblem.LocalVariableIsNeverUsed) ||  (removeUnusedPrivateFields && id == IProblem.UnusedPrivateField)) {
				SimpleName name= getUnusedName(compilationUnit, problem);
				if (name != null) {
					IBinding binding= name.resolveBinding();
					if (binding instanceof IVariableBinding && !isFormalParameterInEnhancedForStatement(name) && (!((IVariableBinding) binding).isField() || isSideEffectFree(name, compilationUnit))) {
						VariableDeclarationFragment parent= ASTNodes.getParent(name, VariableDeclarationFragment.class);
						if (parent != null) {
							ASTNode varDecl= parent.getParent();
							if (!variableDeclarations.containsKey(varDecl)) {
								variableDeclarations.put(varDecl, new ArrayList<SimpleName>());
							}
							variableDeclarations.get(varDecl).add(name);
						} else {
							result.add(new RemoveUnusedMemberOperation(new SimpleName[] {name}, false));
						}
					}
				}
			}

			if (removeUnusedCast && id == IProblem.UnnecessaryCast) {
				ASTNode selectedNode= problem.getCoveringNode(compilationUnit);

				ASTNode curr= selectedNode;
				while (curr instanceof ParenthesizedExpression) {
					curr= ((ParenthesizedExpression) curr).getExpression();
				}

				if (curr instanceof CastExpression) {
					unnecessaryCasts.add((CastExpression) curr);
				}
			}
		}
		for (ASTNode node : variableDeclarations.keySet()) {
			List<SimpleName> names= variableDeclarations.get(node);
			result.add(new RemoveUnusedMemberOperation(names.toArray(new SimpleName[0]), false));
		}
		if (unnecessaryCasts.size() > 0)
			result.add(new RemoveAllCastOperation(unnecessaryCasts));

		if (result.isEmpty())
			return null;

		return new UnusedCodeFixCore(FixMessages.UnusedCodeFix_change_name, compilationUnit, result.toArray(new CompilationUnitRewriteOperation[result.size()]));
	}

	public static boolean isFormalParameterInEnhancedForStatement(SimpleName name) {
		return name.getParent() instanceof SingleVariableDeclaration && name.getParent().getLocationInParent() == EnhancedForStatement.PARAMETER_PROPERTY;
	}

	public static boolean isSideEffectFree(SimpleName simpleName, CompilationUnit completeRoot) {
		SimpleName nameNode= (SimpleName) NodeFinder.perform(completeRoot, simpleName.getStartPosition(), simpleName.getLength());
		SimpleName[] references= LinkedNodeFinder.findByBinding(completeRoot, nameNode.resolveBinding());
		for (SimpleName reference : references) {
			if (hasSideEffect(reference))
				return false;
		}
		return true;
	}

	private static boolean hasSideEffect(SimpleName reference) {
		ASTNode parent= reference.getParent();
		while (parent instanceof QualifiedName) {
			parent= parent.getParent();
		}
		if (parent instanceof FieldAccess) {
			parent= parent.getParent();
		}

		ASTNode node= null;
		int nameParentType= parent.getNodeType();
		if (nameParentType == ASTNode.ASSIGNMENT) {
			Assignment assignment= (Assignment) parent;
			node= assignment.getRightHandSide();
		} else if (nameParentType == ASTNode.SINGLE_VARIABLE_DECLARATION) {
			SingleVariableDeclaration decl= (SingleVariableDeclaration)parent;
			node= decl.getInitializer();
			if (node == null)
				return false;
		} else if (nameParentType == ASTNode.VARIABLE_DECLARATION_FRAGMENT) {
			node= parent;
		} else {
			return false;
		}

		ArrayList<Expression> sideEffects= new ArrayList<>();
		node.accept(new SideEffectFinder(sideEffects));
		return sideEffects.size() > 0;
	}

	public static SimpleName getUnusedName(CompilationUnit compilationUnit, IProblemLocationCore problem) {
		ASTNode selectedNode= problem.getCoveringNode(compilationUnit);

		if (selectedNode instanceof MethodDeclaration) {
			return ((MethodDeclaration) selectedNode).getName();
		} else if (selectedNode instanceof SimpleName) {
			return (SimpleName) selectedNode;
		}

		return null;
	}

	public static String getDisplayString(SimpleName simpleName, IBinding binding, boolean removeAllAssignements) {
		String name= BasicElementLabels.getJavaElementName(simpleName.getIdentifier());
		switch (binding.getKind()) {
			case IBinding.TYPE:
				return Messages.format(FixMessages.UnusedCodeFix_RemoveType_description, name);
			case IBinding.METHOD:
				if (((IMethodBinding) binding).isConstructor()) {
					return Messages.format(FixMessages.UnusedCodeFix_RemoveConstructor_description, name);
				} else {
					return Messages.format(FixMessages.UnusedCodeFix_RemoveMethod_description, name);
				}
			case IBinding.VARIABLE:
				if (removeAllAssignements) {
					return Messages.format(FixMessages.UnusedCodeFix_RemoveFieldOrLocalWithInitializer_description, name);
				} else {
					return Messages.format(FixMessages.UnusedCodeFix_RemoveFieldOrLocal_description, name);
				}
			default:
				return ""; //$NON-NLS-1$
		}
	}

	public static Map<String, String> getCleanUpOptions(IBinding binding, boolean removeAll) {
		Map<String, String> result= new Hashtable<>();

		result.put(CleanUpConstants.REMOVE_UNUSED_CODE_PRIVATE_MEMBERS, CleanUpOptionsCore.TRUE);
		switch (binding.getKind()) {
			case IBinding.TYPE:
				result.put(CleanUpConstants.REMOVE_UNUSED_CODE_PRIVATE_TYPES, CleanUpOptionsCore.TRUE);
				break;
			case IBinding.METHOD:
				if (((IMethodBinding) binding).isConstructor()) {
					result.put(CleanUpConstants.REMOVE_UNUSED_CODE_PRIVATE_CONSTRUCTORS, CleanUpOptionsCore.TRUE);
				} else {
					result.put(CleanUpConstants.REMOVE_UNUSED_CODE_PRIVATE_METHODS, CleanUpOptionsCore.TRUE);
				}
				break;
			case IBinding.VARIABLE:
				if (removeAll)
					return null;

				result.put(CleanUpConstants.REMOVE_UNUSED_CODE_PRIVATE_FELDS, CleanUpOptionsCore.TRUE);
				result.put(CleanUpConstants.REMOVE_UNUSED_CODE_LOCAL_VARIABLES, CleanUpOptionsCore.TRUE);
				break;
			default:
				break;
		}

		return result;
	}

	public static ImportDeclaration getImportDeclaration(IProblemLocationCore problem, CompilationUnit compilationUnit) {
		ASTNode selectedNode= problem.getCoveringNode(compilationUnit);
		if (selectedNode != null) {
			ASTNode node= ASTNodes.getParent(selectedNode, ASTNode.IMPORT_DECLARATION);
			if (node instanceof ImportDeclaration) {
				return (ImportDeclaration)node;
			}
		}
		return null;
	}

	private static void replaceCast(CastExpression castExpression, Expression replacement, ASTRewrite rewrite, TextEditGroup group) {
		boolean castEnclosedInNecessaryParentheses= castExpression.getParent() instanceof ParenthesizedExpression
				&& NecessaryParenthesesChecker.needsParentheses(castExpression, castExpression.getParent().getParent(), castExpression.getParent().getLocationInParent());

		ASTNode toReplace= castEnclosedInNecessaryParentheses ? castExpression.getParent() : castExpression;
		ASTNode move;
		if (NecessaryParenthesesChecker.needsParentheses(replacement, toReplace.getParent(), toReplace.getLocationInParent())) {
			if (replacement.getParent() instanceof ParenthesizedExpression) {
				move= rewrite.createMoveTarget(replacement.getParent());
			} else if (castEnclosedInNecessaryParentheses) {
				toReplace= castExpression;
				move= rewrite.createMoveTarget(replacement);
			} else {
				ParenthesizedExpression parentheses= replacement.getAST().newParenthesizedExpression();
				parentheses.setExpression((Expression) rewrite.createMoveTarget(replacement));
				move= parentheses;
			}
		} else {
			move= rewrite.createMoveTarget(replacement);
		}
		rewrite.replace(toReplace, move, group);
	}

	private final Map<String, String> fCleanUpOptions;

	private UnusedCodeFixCore(String name, CompilationUnit compilationUnit, CompilationUnitRewriteOperation[] fixRewriteOperations) {
		this(name, compilationUnit, fixRewriteOperations, null);
	}

	private UnusedCodeFixCore(String name, CompilationUnit compilationUnit, CompilationUnitRewriteOperation[] fixRewriteOperations, Map<String, String> options) {
		super(name, compilationUnit, fixRewriteOperations);
		fCleanUpOptions= options;
	}

	public UnusedCodeCleanUpCore getCleanUp() {
		if (fCleanUpOptions == null)
			return null;

		return new UnusedCodeCleanUpCore(fCleanUpOptions);
	}

}