/*******************************************************************************
 * Copyright (c) 2000, 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
 *     Pierre-Yves B. <pyvesdev@gmail.com> - [inline] Allow inlining of local variable initialized to null. - https://bugs.eclipse.org/93850
 *******************************************************************************/
package org.eclipse.jdt.internal.corext.refactoring.code;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.SubProgressMonitor;

import org.eclipse.text.edits.TextEditGroup;

import org.eclipse.ltk.core.refactoring.Change;
import org.eclipse.ltk.core.refactoring.Refactoring;
import org.eclipse.ltk.core.refactoring.RefactoringChangeDescriptor;
import org.eclipse.ltk.core.refactoring.RefactoringDescriptor;
import org.eclipse.ltk.core.refactoring.RefactoringStatus;

import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.core.NamingConventions;
import org.eclipse.jdt.core.SourceRange;
import org.eclipse.jdt.core.dom.AST;
import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.AbstractTypeDeclaration;
import org.eclipse.jdt.core.dom.Annotation;
import org.eclipse.jdt.core.dom.BodyDeclaration;
import org.eclipse.jdt.core.dom.CompilationUnit;
import org.eclipse.jdt.core.dom.EnumDeclaration;
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.IExtendedModifier;
import org.eclipse.jdt.core.dom.ITypeBinding;
import org.eclipse.jdt.core.dom.Initializer;
import org.eclipse.jdt.core.dom.Javadoc;
import org.eclipse.jdt.core.dom.MethodDeclaration;
import org.eclipse.jdt.core.dom.Modifier;
import org.eclipse.jdt.core.dom.Name;
import org.eclipse.jdt.core.dom.NullLiteral;
import org.eclipse.jdt.core.dom.QualifiedName;
import org.eclipse.jdt.core.dom.SimpleName;
import org.eclipse.jdt.core.dom.SwitchCase;
import org.eclipse.jdt.core.dom.Type;
import org.eclipse.jdt.core.dom.VariableDeclarationFragment;
import org.eclipse.jdt.core.dom.rewrite.ASTRewrite;
import org.eclipse.jdt.core.dom.rewrite.ImportRewrite;
import org.eclipse.jdt.core.dom.rewrite.ImportRewrite.ImportRewriteContext;
import org.eclipse.jdt.core.dom.rewrite.ImportRewrite.TypeLocation;
import org.eclipse.jdt.core.dom.rewrite.ListRewrite;
import org.eclipse.jdt.core.manipulation.CodeGeneration;
import org.eclipse.jdt.core.refactoring.CompilationUnitChange;
import org.eclipse.jdt.core.refactoring.IJavaRefactorings;
import org.eclipse.jdt.core.refactoring.descriptors.ExtractConstantDescriptor;
import org.eclipse.jdt.core.refactoring.descriptors.JavaRefactoringDescriptor;

import org.eclipse.jdt.internal.core.manipulation.StubUtility;
import org.eclipse.jdt.internal.core.manipulation.dom.ASTResolving;
import org.eclipse.jdt.internal.core.manipulation.util.BasicElementLabels;
import org.eclipse.jdt.internal.core.refactoring.descriptors.RefactoringSignatureDescriptorFactory;
import org.eclipse.jdt.internal.corext.Corext;
import org.eclipse.jdt.internal.corext.codemanipulation.ContextSensitiveImportRewriteContext;
import org.eclipse.jdt.internal.corext.dom.ASTNodes;
import org.eclipse.jdt.internal.corext.dom.Bindings;
import org.eclipse.jdt.internal.corext.dom.ScopeAnalyzer;
import org.eclipse.jdt.internal.corext.dom.fragments.ASTFragmentFactory;
import org.eclipse.jdt.internal.corext.dom.fragments.IASTFragment;
import org.eclipse.jdt.internal.corext.dom.fragments.IExpressionFragment;
import org.eclipse.jdt.internal.corext.fix.LinkedProposalModel;
import org.eclipse.jdt.internal.corext.fix.LinkedProposalPositionGroup;
import org.eclipse.jdt.internal.corext.refactoring.Checks;
import org.eclipse.jdt.internal.corext.refactoring.JDTRefactoringDescriptorComment;
import org.eclipse.jdt.internal.corext.refactoring.JavaRefactoringArguments;
import org.eclipse.jdt.internal.corext.refactoring.JavaRefactoringDescriptorUtil;
import org.eclipse.jdt.internal.corext.refactoring.RefactoringCoreMessages;
import org.eclipse.jdt.internal.corext.refactoring.base.RefactoringStatusCodes;
import org.eclipse.jdt.internal.corext.refactoring.rename.RefactoringAnalyzeUtil;
import org.eclipse.jdt.internal.corext.refactoring.structure.CompilationUnitRewrite;
import org.eclipse.jdt.internal.corext.refactoring.util.RefactoringASTParser;
import org.eclipse.jdt.internal.corext.util.JdtFlags;
import org.eclipse.jdt.internal.corext.util.Messages;

import org.eclipse.jdt.internal.ui.preferences.JavaPreferencesSettings;
import org.eclipse.jdt.internal.ui.text.correction.ModifierCorrectionSubProcessorCore;

public class ExtractConstantRefactoring extends Refactoring {

	private static final String ATTRIBUTE_REPLACE= "replace"; //$NON-NLS-1$
	private static final String ATTRIBUTE_QUALIFY= "qualify"; //$NON-NLS-1$
	private static final String ATTRIBUTE_VISIBILITY= "visibility"; //$NON-NLS-1$

	private static final String MODIFIER= "static final"; //$NON-NLS-1$

	private static final String KEY_NAME= "name"; //$NON-NLS-1$
	private static final String KEY_TYPE= "type"; //$NON-NLS-1$

	private CompilationUnitRewrite fCuRewrite;
	private int fSelectionStart;
	private int fSelectionLength;
	private ICompilationUnit fCu;

	private IExpressionFragment fSelectedExpression;
	private Type fConstantTypeCache;
	private boolean fReplaceAllOccurrences= true; //default value
	private boolean fQualifyReferencesWithDeclaringClassName= false;	//default value

	private String fVisibility= JdtFlags.VISIBILITY_STRING_PRIVATE; //default value
	private boolean fTargetIsInterface= false;
	private String fConstantName;
	private String[] fExcludedVariableNames;

	private boolean fSelectionAllStaticFinal;
	private boolean fAllStaticFinalCheckPerformed= false;

	//Constant Declaration Location
	private BodyDeclaration fToInsertAfter;
	private boolean fInsertFirst;

	private CompilationUnitChange fChange;
	private String[] fGuessedConstNames;

	private LinkedProposalModel fLinkedProposalModel;
	private boolean fCheckResultForCompileProblems;

	/**
	 * Creates a new extract constant refactoring
	 * @param unit the compilation unit, or <code>null</code> if invoked by scripting
	 * @param selectionStart start
	 * @param selectionLength length
	 */
	public ExtractConstantRefactoring(ICompilationUnit unit, int selectionStart, int selectionLength) {
		Assert.isTrue(selectionStart >= 0);
		Assert.isTrue(selectionLength >= 0);
		fSelectionStart= selectionStart;
		fSelectionLength= selectionLength;
		fCu= unit;
		fCuRewrite= null;
		fLinkedProposalModel= null;
		fConstantName= ""; //$NON-NLS-1$
		fCheckResultForCompileProblems= true;
	}

	public ExtractConstantRefactoring(CompilationUnit astRoot, int selectionStart, int selectionLength) {
		Assert.isTrue(selectionStart >= 0);
		Assert.isTrue(selectionLength >= 0);
		Assert.isTrue(astRoot.getTypeRoot() instanceof ICompilationUnit);

		fSelectionStart= selectionStart;
		fSelectionLength= selectionLength;
		fCu= (ICompilationUnit) astRoot.getTypeRoot();
		fCuRewrite= new CompilationUnitRewrite(fCu, astRoot);
		fLinkedProposalModel= null;
		fConstantName= ""; //$NON-NLS-1$
		fCheckResultForCompileProblems= true;
	}

    public ExtractConstantRefactoring(JavaRefactoringArguments arguments, RefactoringStatus status) {
   		this((ICompilationUnit) null, 0, 0);
   		RefactoringStatus initializeStatus= initialize(arguments);
   		status.merge(initializeStatus);
    }

	public void setCheckResultForCompileProblems(boolean checkResultForCompileProblems) {
		fCheckResultForCompileProblems= checkResultForCompileProblems;
	}

	public void setLinkedProposalModel(LinkedProposalModel linkedProposalModel) {
		fLinkedProposalModel= linkedProposalModel;
	}

	@Override
	public String getName() {
		return RefactoringCoreMessages.ExtractConstantRefactoring_name;
	}

	public boolean replaceAllOccurrences() {
		return fReplaceAllOccurrences;
	}

	public void setReplaceAllOccurrences(boolean replaceAllOccurrences) {
		fReplaceAllOccurrences= replaceAllOccurrences;
	}

	public void setVisibility(String am) {
		Assert.isTrue(
			am == JdtFlags.VISIBILITY_STRING_PRIVATE || am == JdtFlags.VISIBILITY_STRING_PROTECTED || am == JdtFlags.VISIBILITY_STRING_PACKAGE || am == JdtFlags.VISIBILITY_STRING_PUBLIC
		);
		fVisibility= am;
	}

	public String getVisibility() {
		return fVisibility;
	}

	public boolean getTargetIsInterface() {
		return fTargetIsInterface;
	}

	public boolean qualifyReferencesWithDeclaringClassName() {
		return fQualifyReferencesWithDeclaringClassName;
	}

	public void setQualifyReferencesWithDeclaringClassName(boolean qualify) {
		fQualifyReferencesWithDeclaringClassName= qualify;
	}

	public String guessConstantName() {
		String[] proposals= guessConstantNames();
		if (proposals.length > 0)
			return proposals[0];
		else
			return fConstantName;
	}

	/**
	 * @return proposed variable names (may be empty, but not null).
	 * The first proposal should be used as "best guess" (if it exists).
	 */
	public String[] guessConstantNames() {
		if (fGuessedConstNames == null) {
			try {
				Expression expression= getSelectedExpression().getAssociatedExpression();
				if (expression != null) {
					ITypeBinding binding= guessBindingForReference(expression);
					fGuessedConstNames= StubUtility.getVariableNameSuggestions(NamingConventions.VK_STATIC_FINAL_FIELD, fCu.getJavaProject(), binding, expression, Arrays.asList(getExcludedVariableNames()));
				}
			} catch (JavaModelException e) {
			}
			if (fGuessedConstNames == null)
				fGuessedConstNames= new String[0];
		}
		return fGuessedConstNames;
	}


	private String[] getExcludedVariableNames() {
		if (fExcludedVariableNames == null) {
			try {
				IExpressionFragment expr= getSelectedExpression();
				Collection<String> takenNames= new ScopeAnalyzer(fCuRewrite.getRoot()).getUsedVariableNames(expr.getStartPosition(), expr.getLength());
				fExcludedVariableNames= takenNames.toArray(new String[takenNames.size()]);
			} catch (JavaModelException e) {
				fExcludedVariableNames= new String[0];
			}
		}
		return fExcludedVariableNames;
	}

	@Override
	public RefactoringStatus checkInitialConditions(IProgressMonitor pm) throws CoreException {
		try {
			pm.beginTask("", 7); //$NON-NLS-1$

			RefactoringStatus result= Checks.validateEdit(fCu, getValidationContext(), pm);
			if (result.hasFatalError())
				return result;
			pm.worked(1);

			if (fCuRewrite == null) {
				CompilationUnit cuNode= RefactoringASTParser.parseWithASTProvider(fCu, true, new SubProgressMonitor(pm, 3));
				fCuRewrite= new CompilationUnitRewrite(fCu, cuNode);
			} else {
				pm.worked(3);
			}
			result.merge(checkSelection(new SubProgressMonitor(pm, 3)));

			if (result.hasFatalError())
				return result;

			if (isLiteralNodeSelected())
				fReplaceAllOccurrences= false;

			if (isInTypeDeclarationAnnotation(getSelectedExpression().getAssociatedNode())) {
				fVisibility= JdtFlags.VISIBILITY_STRING_PACKAGE;
			}

			ITypeBinding targetType= getContainingTypeBinding();
			if (targetType.isInterface()) {
				fTargetIsInterface= true;
				fVisibility= JdtFlags.VISIBILITY_STRING_PUBLIC;
			}

			return result;
		} finally {
			pm.done();
		}
	}

	public boolean selectionAllStaticFinal() {
		Assert.isTrue(fAllStaticFinalCheckPerformed);
		return fSelectionAllStaticFinal;
	}

	private void checkAllStaticFinal() throws JavaModelException {
		fSelectionAllStaticFinal= ConstantChecks.isStaticFinalConstant(getSelectedExpression());
		fAllStaticFinalCheckPerformed= true;
	}

	private RefactoringStatus checkSelection(IProgressMonitor pm) throws JavaModelException {
		try {
			pm.beginTask("", 2); //$NON-NLS-1$

			IExpressionFragment selectedExpression= getSelectedExpression();

			if (selectedExpression == null) {
				String message= RefactoringCoreMessages.ExtractConstantRefactoring_select_expression;
				return CodeRefactoringUtil.checkMethodSyntaxErrors(fSelectionStart, fSelectionLength, fCuRewrite.getRoot(), message);
			}
			pm.worked(1);

			RefactoringStatus result= new RefactoringStatus();
			result.merge(checkExpression());
			if (result.hasFatalError())
				return result;
			pm.worked(1);

			return result;
		} finally {
			pm.done();
		}
	}

	private RefactoringStatus checkExpressionBinding() throws JavaModelException {
		return checkExpressionFragmentIsRValue();
	}

	private RefactoringStatus checkExpressionFragmentIsRValue() throws JavaModelException {
		/* Moved this functionality to Checks, to allow sharing with
		   ExtractTempRefactoring, others */
		switch(Checks.checkExpressionIsRValue(getSelectedExpression().getAssociatedExpression())) {
			case Checks.NOT_RVALUE_MISC:
				return RefactoringStatus.createStatus(RefactoringStatus.FATAL, RefactoringCoreMessages.ExtractConstantRefactoring_select_expression, null, Corext.getPluginId(), RefactoringStatusCodes.EXPRESSION_NOT_RVALUE, null);
			case Checks.NOT_RVALUE_VOID:
				return RefactoringStatus.createStatus(RefactoringStatus.FATAL, RefactoringCoreMessages.ExtractConstantRefactoring_no_void, null, Corext.getPluginId(), RefactoringStatusCodes.EXPRESSION_NOT_RVALUE_VOID, null);
			case Checks.IS_RVALUE_GUESSED:
			case Checks.IS_RVALUE:
				return new RefactoringStatus();
			default:
				Assert.isTrue(false); return null;
		}
	}

	private ITypeBinding guessBindingForReference(Expression expression) {
		ITypeBinding binding= expression.resolveTypeBinding();
		if (binding == null) {
			binding= ASTResolving.guessBindingForReference(expression);
		}
		return binding;
	}

	//	 !!! -- same as in ExtractTempRefactoring
	private boolean isLiteralNodeSelected() throws JavaModelException {
		IExpressionFragment fragment= getSelectedExpression();
		if (fragment == null)
			return false;
		Expression expression= fragment.getAssociatedExpression();
		if (expression == null)
			return false;
		switch (expression.getNodeType()) {
			case ASTNode.BOOLEAN_LITERAL :
			case ASTNode.CHARACTER_LITERAL :
			case ASTNode.NULL_LITERAL :
			case ASTNode.NUMBER_LITERAL :
				return true;

			default :
				return false;
		}
	}

	private RefactoringStatus checkExpression() throws JavaModelException {
		RefactoringStatus result= new RefactoringStatus();
		result.merge(checkExpressionBinding());
		if(result.hasFatalError())
			return result;
		checkAllStaticFinal();

		IExpressionFragment selectedExpression= getSelectedExpression();
		Expression associatedExpression= selectedExpression.getAssociatedExpression();
		if (associatedExpression instanceof NullLiteral)
			result.merge(RefactoringStatus.createFatalErrorStatus(RefactoringCoreMessages.ExtractConstantRefactoring_null_literals));
		else if (!ConstantChecks.isLoadTimeConstant(selectedExpression))
			result.merge(RefactoringStatus.createFatalErrorStatus(RefactoringCoreMessages.ExtractConstantRefactoring_not_load_time_constant));
		else if (associatedExpression instanceof SimpleName) {
			if (associatedExpression.getParent() instanceof QualifiedName && associatedExpression.getLocationInParent() == QualifiedName.NAME_PROPERTY
					|| associatedExpression.getParent() instanceof FieldAccess && associatedExpression.getLocationInParent() == FieldAccess.NAME_PROPERTY)
				return RefactoringStatus.createFatalErrorStatus(RefactoringCoreMessages.ExtractConstantRefactoring_select_expression);
		}

		return result;
	}

	public void setConstantName(String newName) {
		Assert.isNotNull(newName);
		fConstantName= newName;
	}

	public String getConstantName() {
		return fConstantName;
	}

	/**
	 * This method performs checks on the constant name which are
	 * quick enough to be performed every time the ui input component
	 * contents are changed.
	 *
	 * @return return the resulting status
	 * @throws JavaModelException thrown when the operation could not be executed
	 */
	public RefactoringStatus checkConstantNameOnChange() throws JavaModelException {
		if (Arrays.asList(getExcludedVariableNames()).contains(fConstantName))
			return RefactoringStatus.createErrorStatus(Messages.format(RefactoringCoreMessages.ExtractConstantRefactoring_another_variable, BasicElementLabels.getJavaElementName(getConstantName())));
		return Checks.checkConstantName(fConstantName, fCu);
	}

	// !! similar to ExtractTempRefactoring equivalent
	public String getConstantSignaturePreview() throws JavaModelException {
		String space= " "; //$NON-NLS-1$
		return getVisibility() + space + MODIFIER + space + getConstantTypeName() + space + fConstantName;
	}

	public CompilationUnitChange createTextChange(IProgressMonitor pm) throws CoreException {
		createConstantDeclaration();
		replaceExpressionsWithConstant();
		return fCuRewrite.createChange(RefactoringCoreMessages.ExtractConstantRefactoring_change_name, true, pm);
	}


	@Override
	public RefactoringStatus checkFinalConditions(IProgressMonitor pm) throws CoreException {
		pm.beginTask(RefactoringCoreMessages.ExtractConstantRefactoring_checking_preconditions, 2);

		/* Note: some checks are performed on change of input widget
		 * values. (e.g. see ExtractConstantRefactoring.checkConstantNameOnChange())
		 */

		//TODO: possibly add more checking for name conflicts that might
		//      lead to a change in behavior

		try {
			createConstantDeclaration();
			replaceExpressionsWithConstant();
			fChange= fCuRewrite.createChange(RefactoringCoreMessages.ExtractConstantRefactoring_change_name, true, new SubProgressMonitor(pm, 1));

			return fCheckResultForCompileProblems ? RefactoringAnalyzeUtil.checkNewSource(fChange, fCu, fCuRewrite.getRoot(), pm) : new RefactoringStatus();
		} finally {
			fConstantTypeCache= null;
			fCuRewrite.clearASTAndImportRewrites();
			pm.done();
		}
	}

	private void createConstantDeclaration() throws CoreException {
		Type type= getConstantType();

		IExpressionFragment fragment= getSelectedExpression();
		Expression initializer= getSelectedExpression().createCopyTarget(fCuRewrite.getASTRewrite(), true);

		AST ast= fCuRewrite.getAST();
		VariableDeclarationFragment variableDeclarationFragment= ast.newVariableDeclarationFragment();
		variableDeclarationFragment.setName(ast.newSimpleName(fConstantName));
		variableDeclarationFragment.setInitializer(initializer);

		FieldDeclaration fieldDeclaration= ast.newFieldDeclaration(variableDeclarationFragment);
		fieldDeclaration.setType(type);
		Modifier.ModifierKeyword accessModifier= Modifier.ModifierKeyword.toKeyword(fVisibility);
		if (accessModifier != null)
			fieldDeclaration.modifiers().add(ast.newModifier(accessModifier));
		fieldDeclaration.modifiers().add(ast.newModifier(Modifier.ModifierKeyword.STATIC_KEYWORD));
		fieldDeclaration.modifiers().add(ast.newModifier(Modifier.ModifierKeyword.FINAL_KEYWORD));

		boolean createComments= JavaPreferencesSettings.getCodeGenerationSettings(fCu.getJavaProject()).createComments;
		if (createComments) {
			String comment= CodeGeneration.getFieldComment(fCu, getConstantTypeName(), fConstantName, StubUtility.getLineDelimiterUsed(fCu));
			if (comment != null && comment.length() > 0) {
				Javadoc doc= (Javadoc) fCuRewrite.getASTRewrite().createStringPlaceholder(comment, ASTNode.JAVADOC);
				fieldDeclaration.setJavadoc(doc);
			}
		}

		AbstractTypeDeclaration parent= getContainingTypeDeclarationNode();
		ListRewrite listRewrite= fCuRewrite.getASTRewrite().getListRewrite(parent, parent.getBodyDeclarationsProperty());
		TextEditGroup msg= fCuRewrite.createGroupDescription(RefactoringCoreMessages.ExtractConstantRefactoring_declare_constant);
		if (insertFirst()) {
			listRewrite.insertFirst(fieldDeclaration, msg);
		} else {
			listRewrite.insertAfter(fieldDeclaration, getNodeToInsertConstantDeclarationAfter(), msg);
		}

		if (fLinkedProposalModel != null) {
			ASTRewrite rewrite= fCuRewrite.getASTRewrite();
			LinkedProposalPositionGroup nameGroup= fLinkedProposalModel.getPositionGroup(KEY_NAME, true);
			nameGroup.addPosition(rewrite.track(variableDeclarationFragment.getName()), true);

			String[] nameSuggestions= guessConstantNames();
			if (nameSuggestions.length > 0 && !nameSuggestions[0].equals(fConstantName)) {
				nameGroup.addProposal(fConstantName, null, nameSuggestions.length + 1);
			}
			for (int i= 0; i < nameSuggestions.length; i++) {
				nameGroup.addProposal(nameSuggestions[i], null, nameSuggestions.length - i);
			}

			LinkedProposalPositionGroup typeGroup= fLinkedProposalModel.getPositionGroup(KEY_TYPE, true);
			typeGroup.addPosition(rewrite.track(type), true);

			ITypeBinding typeBinding= guessBindingForReference(fragment.getAssociatedExpression());
			if (typeBinding != null) {
				ITypeBinding[] relaxingTypes= ASTResolving.getNarrowingTypes(ast, typeBinding);
				for (int i= 0; i < relaxingTypes.length; i++) {
					typeGroup.addProposal(relaxingTypes[i], fCuRewrite.getCu(), relaxingTypes.length - i);
				}
			}
			boolean isInterface= parent.resolveBinding() != null && parent.resolveBinding().isInterface();
			ModifierCorrectionSubProcessorCore.installLinkedVisibilityProposals(fLinkedProposalModel, rewrite, fieldDeclaration.modifiers(), isInterface);
		}
	}

	private Type getConstantType() throws JavaModelException {
		if (fConstantTypeCache == null) {
			IExpressionFragment fragment= getSelectedExpression();
			ITypeBinding typeBinding= guessBindingForReference(fragment.getAssociatedExpression());
			AST ast= fCuRewrite.getAST();
			typeBinding= Bindings.normalizeForDeclarationUse(typeBinding, ast);
			ImportRewrite importRewrite= fCuRewrite.getImportRewrite();
			ImportRewriteContext context= new ContextSensitiveImportRewriteContext(fCuRewrite.getRoot(), fSelectionStart, importRewrite);
			fConstantTypeCache= importRewrite.addImport(typeBinding, ast, context, TypeLocation.FIELD);
		}
		return fConstantTypeCache;
	}

	@Override
	public Change createChange(IProgressMonitor monitor) throws CoreException {
		ExtractConstantDescriptor descriptor= createRefactoringDescriptor();
		fChange.setDescriptor(new RefactoringChangeDescriptor(descriptor));
		return fChange;
	}

	private ExtractConstantDescriptor createRefactoringDescriptor() {
		final Map<String, String> arguments= new HashMap<>();
		String project= null;
		IJavaProject javaProject= fCu.getJavaProject();
		if (javaProject != null)
			project= javaProject.getElementName();
		int flags= JavaRefactoringDescriptor.JAR_REFACTORING | JavaRefactoringDescriptor.JAR_SOURCE_ATTACHMENT;
		if (JdtFlags.getVisibilityCode(fVisibility) != Modifier.PRIVATE)
			flags|= RefactoringDescriptor.STRUCTURAL_CHANGE;

		final String expression= ASTNodes.asString(fSelectedExpression.getAssociatedExpression());
		final String description= Messages.format(RefactoringCoreMessages.ExtractConstantRefactoring_descriptor_description_short, BasicElementLabels.getJavaElementName(fConstantName));
		final String header= Messages.format(RefactoringCoreMessages.ExtractConstantRefactoring_descriptor_description, new String[] { BasicElementLabels.getJavaElementName(fConstantName), BasicElementLabels.getJavaCodeString(expression)});
		final JDTRefactoringDescriptorComment comment= new JDTRefactoringDescriptorComment(project, this, header);
		comment.addSetting(Messages.format(RefactoringCoreMessages.ExtractConstantRefactoring_constant_name_pattern, BasicElementLabels.getJavaElementName(fConstantName)));
		comment.addSetting(Messages.format(RefactoringCoreMessages.ExtractConstantRefactoring_constant_expression_pattern, BasicElementLabels.getJavaCodeString(expression)));
		String visibility= fVisibility;
		if ("".equals(visibility)) //$NON-NLS-1$
			visibility= RefactoringCoreMessages.ExtractConstantRefactoring_default_visibility;
		comment.addSetting(Messages.format(RefactoringCoreMessages.ExtractConstantRefactoring_visibility_pattern, visibility));
		if (fReplaceAllOccurrences)
			comment.addSetting(RefactoringCoreMessages.ExtractConstantRefactoring_replace_occurrences);
		if (fQualifyReferencesWithDeclaringClassName)
			comment.addSetting(RefactoringCoreMessages.ExtractConstantRefactoring_qualify_references);
		arguments.put(JavaRefactoringDescriptorUtil.ATTRIBUTE_INPUT, JavaRefactoringDescriptorUtil.elementToHandle(project, fCu));
		arguments.put(JavaRefactoringDescriptorUtil.ATTRIBUTE_NAME, fConstantName);
		arguments.put(JavaRefactoringDescriptorUtil.ATTRIBUTE_SELECTION, Integer.valueOf(fSelectionStart).toString() + " " + Integer.valueOf(fSelectionLength).toString()); //$NON-NLS-1$
		arguments.put(ATTRIBUTE_REPLACE, Boolean.valueOf(fReplaceAllOccurrences).toString());
		arguments.put(ATTRIBUTE_QUALIFY, Boolean.valueOf(fQualifyReferencesWithDeclaringClassName).toString());
		arguments.put(ATTRIBUTE_VISIBILITY, Integer.valueOf(JdtFlags.getVisibilityCode(fVisibility)).toString());

		ExtractConstantDescriptor descriptor= RefactoringSignatureDescriptorFactory.createExtractConstantDescriptor(project, description, comment.asString(), arguments, flags);
		return descriptor;
	}

	private void replaceExpressionsWithConstant() throws JavaModelException {
		ASTRewrite astRewrite= fCuRewrite.getASTRewrite();
		AST ast= astRewrite.getAST();

		for (IASTFragment fragment : getFragmentsToReplace()) {
			ASTNode node= fragment.getAssociatedNode();
			boolean inTypeDeclarationAnnotation= isInTypeDeclarationAnnotation(node);
			if (inTypeDeclarationAnnotation && JdtFlags.VISIBILITY_STRING_PRIVATE == getVisibility())
				continue;

			SimpleName ref= ast.newSimpleName(fConstantName);
			Name replacement= ref;
			boolean qualifyReference= qualifyReferencesWithDeclaringClassName();
			if (!qualifyReference) {
				qualifyReference= inTypeDeclarationAnnotation;
			}
			if (qualifyReference) {
				replacement= ast.newQualifiedName(ast.newSimpleName(getContainingTypeBinding().getName()), ref);
			}
			TextEditGroup description= fCuRewrite.createGroupDescription(RefactoringCoreMessages.ExtractConstantRefactoring_replace);

			fragment.replace(astRewrite, replacement, description);
			if (fLinkedProposalModel != null)
				fLinkedProposalModel.getPositionGroup(KEY_NAME, true).addPosition(astRewrite.track(ref), false);
		}
	}

	private boolean isInTypeDeclarationAnnotation(ASTNode node) throws JavaModelException {
		Annotation enclosingAnnotation= ASTNodes.getParent(node, Annotation.class);
		return enclosingAnnotation != null && enclosingAnnotation.getParent() == getContainingTypeDeclarationNode();
	}

	private void computeConstantDeclarationLocation() throws JavaModelException {
		if (isDeclarationLocationComputed())
			return;

		BodyDeclaration lastStaticDependency= null;
		Iterator<BodyDeclaration> decls= getContainingTypeDeclarationNode().bodyDeclarations().iterator();

		while (decls.hasNext()) {
			BodyDeclaration decl= decls.next();

			int modifiers;
			if (decl instanceof FieldDeclaration)
				modifiers= ((FieldDeclaration) decl).getModifiers();
			else if (decl instanceof Initializer)
				modifiers= ((Initializer) decl).getModifiers();
			else {
				continue; /* this declaration is not a field declaration
				              or initializer, so the placement of the constant
				              declaration relative to it does not matter */
			}

			if (Modifier.isStatic(modifiers) && depends(getSelectedExpression(), decl))
				lastStaticDependency= decl;
		}

		if(lastStaticDependency == null)
			fInsertFirst= true;
		else
			fToInsertAfter= lastStaticDependency;
	}

	/* bd is a static field declaration or static initializer */
	private static boolean depends(IExpressionFragment selected, BodyDeclaration bd) {
		/* We currently consider selected to depend on bd only if db includes a declaration
		 * of a static field on which selected depends.
		 *
		 * A more accurate strategy might be to also check if bd contains (or is) a
		 * static initializer containing code which changes the value of a static field on
		 * which selected depends.  However, if a static is written to multiple times within
		 * during class initialization, it is difficult to predict which value should be used.
		 * This would depend on which value is used by expressions instances for which the new
		 * constant will be substituted, and there may be many of these; in each, the
		 * static field in question may have taken on a different value (if some of these uses
		 * occur within static initializers).
		 */

		if(bd instanceof FieldDeclaration) {
			FieldDeclaration fieldDecl = (FieldDeclaration) bd;
			for(Iterator<VariableDeclarationFragment> fragments = fieldDecl.fragments().iterator(); fragments.hasNext();) {
				VariableDeclarationFragment fragment = fragments.next();
				SimpleName staticFieldName = fragment.getName();
				if(selected.getSubFragmentsMatching(ASTFragmentFactory.createFragmentForFullSubtree(staticFieldName)).length != 0)
					return true;
			}
		}
		return false;
	}

	private boolean isDeclarationLocationComputed() {
		return fInsertFirst == true || fToInsertAfter != null;
	}

	private boolean insertFirst() throws JavaModelException {
		if(!isDeclarationLocationComputed())
			computeConstantDeclarationLocation();
		return fInsertFirst;
	}

	private BodyDeclaration getNodeToInsertConstantDeclarationAfter() throws JavaModelException {
		if(!isDeclarationLocationComputed())
			computeConstantDeclarationLocation();
		return fToInsertAfter;
	}

	private String getConstantTypeName() throws JavaModelException {
		return ASTNodes.asString(getConstantType());
	}

	private static boolean isStaticFieldOrStaticInitializer(BodyDeclaration node) {
		if(node instanceof MethodDeclaration || node instanceof AbstractTypeDeclaration)
			return false;

		int modifiers;
		if(node instanceof FieldDeclaration) {
			modifiers = ((FieldDeclaration) node).getModifiers();
		} else if(node instanceof Initializer) {
			modifiers = ((Initializer) node).getModifiers();
		} else {
			Assert.isTrue(false);
			return false;
		}

		if(!Modifier.isStatic(modifiers))
			return false;

		return true;
	}

	/*
	 * Elements returned by next() are BodyDeclaration or Annotation instances.
	 */
	private Iterator<ASTNode> getReplacementScope() throws JavaModelException {
		boolean declPredecessorReached= false;

		Collection<ASTNode> scope= new ArrayList<>();

		AbstractTypeDeclaration containingType= getContainingTypeDeclarationNode();
		if (containingType instanceof EnumDeclaration) {
			// replace in all enum constants bodies
			EnumDeclaration enumDeclaration= (EnumDeclaration) containingType;
			scope.addAll(enumDeclaration.enumConstants());
		}

		for (Iterator<IExtendedModifier> iter= containingType.modifiers().iterator(); iter.hasNext();) {
			IExtendedModifier modifier= iter.next();
			if (modifier instanceof Annotation) {
				scope.add((ASTNode) modifier);
			}
		}

		for (Iterator<BodyDeclaration> bodyDeclarations = containingType.bodyDeclarations().iterator(); bodyDeclarations.hasNext();) {
		    BodyDeclaration bodyDeclaration= bodyDeclarations.next();

		    if(bodyDeclaration == getNodeToInsertConstantDeclarationAfter())
		    	declPredecessorReached= true;

		    if(insertFirst() || declPredecessorReached || !isStaticFieldOrStaticInitializer(bodyDeclaration))
		    	scope.add(bodyDeclaration);
		}
		return scope.iterator();
	}

	private IASTFragment[] getFragmentsToReplace() throws JavaModelException {
		List<IASTFragment> toReplace = new ArrayList<>();
		if (fReplaceAllOccurrences) {
			Iterator<ASTNode> replacementScope = getReplacementScope();
			while(replacementScope.hasNext()) {
				ASTNode scope= replacementScope.next();
				IASTFragment[] allMatches= ASTFragmentFactory.createFragmentForFullSubtree(scope).getSubFragmentsMatching(getSelectedExpression());
				IASTFragment[] replaceableMatches = retainOnlyReplacableMatches(allMatches);
				Collections.addAll(toReplace, replaceableMatches);
			}
		} else if (canReplace(getSelectedExpression()))
			toReplace.add(getSelectedExpression());
		return toReplace.toArray(new IASTFragment[toReplace.size()]);
	}

	// !! - like one in ExtractTempRefactoring
	private static IASTFragment[] retainOnlyReplacableMatches(IASTFragment[] allMatches) {
		List<IASTFragment> result= new ArrayList<>(allMatches.length);
		for (IASTFragment match : allMatches) {
			if (canReplace(match)) {
				result.add(match);
			}
		}
		return result.toArray(new IASTFragment[result.size()]);
	}

	// !! - like one in ExtractTempRefactoring
	private static boolean canReplace(IASTFragment fragment) {
		ASTNode node= fragment.getAssociatedNode();
		ASTNode parent= node.getParent();
		if (parent instanceof VariableDeclarationFragment) {
			VariableDeclarationFragment vdf= (VariableDeclarationFragment) parent;
			if (node.equals(vdf.getName()))
				return false;
		}
		if (parent instanceof ExpressionStatement)
			return false;
		if (parent instanceof SwitchCase) {
			if (node instanceof Name) {
				Name name= (Name) node;
				ITypeBinding typeBinding= name.resolveTypeBinding();
				if (typeBinding != null) {
					return !typeBinding.isEnum();
				}
			}
		}
		return true;
	}

	private IExpressionFragment getSelectedExpression() throws JavaModelException {
		if(fSelectedExpression != null)
			return fSelectedExpression;

		IASTFragment selectedFragment= ASTFragmentFactory.createFragmentForSourceRange(new SourceRange(fSelectionStart, fSelectionLength), fCuRewrite.getRoot(), fCu);

		if (selectedFragment instanceof IExpressionFragment
				&& ! Checks.isInsideJavadoc(selectedFragment.getAssociatedNode())) {
			fSelectedExpression= (IExpressionFragment) selectedFragment;
		}

		if (fSelectedExpression != null && Checks.isEnumCase(fSelectedExpression.getAssociatedExpression().getParent())) {
			fSelectedExpression= null;
		}

		return fSelectedExpression;
	}

	/**
	 * Returns the type to which the new constant will be added to. It is the first non-anonymous parent.
	 * @return the type to add the new constant to
	 *
	 * @throws JavaModelException shouldn't happen
	 */
	private AbstractTypeDeclaration getContainingTypeDeclarationNode() throws JavaModelException {
		AbstractTypeDeclaration result= ASTNodes.getParent(getSelectedExpression().getAssociatedNode(), AbstractTypeDeclaration.class);
		Assert.isNotNull(result);
		return result;
	}

	private ITypeBinding getContainingTypeBinding() throws JavaModelException {
		ITypeBinding result= getContainingTypeDeclarationNode().resolveBinding();
		Assert.isNotNull(result);
		return result;
	}

	private RefactoringStatus initialize(JavaRefactoringArguments arguments) {
		final String selection= arguments.getAttribute(JavaRefactoringDescriptorUtil.ATTRIBUTE_SELECTION);
		if (selection != null) {
			int offset= -1;
			int length= -1;
			final StringTokenizer tokenizer= new StringTokenizer(selection);
			if (tokenizer.hasMoreTokens())
				offset= Integer.valueOf(tokenizer.nextToken()).intValue();
			if (tokenizer.hasMoreTokens())
				length= Integer.valueOf(tokenizer.nextToken()).intValue();
			if (offset >= 0 && length >= 0) {
				fSelectionStart= offset;
				fSelectionLength= length;
			} else
				return RefactoringStatus.createFatalErrorStatus(Messages.format(RefactoringCoreMessages.InitializableRefactoring_illegal_argument, new Object[] { selection, JavaRefactoringDescriptorUtil.ATTRIBUTE_SELECTION}));
		} else
			return RefactoringStatus.createFatalErrorStatus(Messages.format(RefactoringCoreMessages.InitializableRefactoring_argument_not_exist, JavaRefactoringDescriptorUtil.ATTRIBUTE_SELECTION));
		final String handle= arguments.getAttribute(JavaRefactoringDescriptorUtil.ATTRIBUTE_INPUT);
		if (handle != null) {
			final IJavaElement element= JavaRefactoringDescriptorUtil.handleToElement(arguments.getProject(), handle, false);
			if (element == null || !element.exists() || element.getElementType() != IJavaElement.COMPILATION_UNIT)
				return JavaRefactoringDescriptorUtil.createInputFatalStatus(element, getName(), IJavaRefactorings.EXTRACT_CONSTANT);
			else
				fCu= (ICompilationUnit) element;
		} else
			return RefactoringStatus.createFatalErrorStatus(Messages.format(RefactoringCoreMessages.InitializableRefactoring_argument_not_exist, JavaRefactoringDescriptorUtil.ATTRIBUTE_INPUT));
		final String visibility= arguments.getAttribute(ATTRIBUTE_VISIBILITY);
		if (visibility != null && !"".equals(visibility)) {//$NON-NLS-1$
			int flag= 0;
			try {
				flag= Integer.parseInt(visibility);
			} catch (NumberFormatException exception) {
				return RefactoringStatus.createFatalErrorStatus(Messages.format(RefactoringCoreMessages.InitializableRefactoring_argument_not_exist, ATTRIBUTE_VISIBILITY));
			}
			fVisibility= JdtFlags.getVisibilityString(flag);
		}
		final String name= arguments.getAttribute(JavaRefactoringDescriptorUtil.ATTRIBUTE_NAME);
		if (name != null && !"".equals(name)) //$NON-NLS-1$
			fConstantName= name;
		else
			return RefactoringStatus.createFatalErrorStatus(Messages.format(RefactoringCoreMessages.InitializableRefactoring_argument_not_exist, JavaRefactoringDescriptorUtil.ATTRIBUTE_NAME));
		final String replace= arguments.getAttribute(ATTRIBUTE_REPLACE);
		if (replace != null) {
			fReplaceAllOccurrences= Boolean.valueOf(replace).booleanValue();
		} else
			return RefactoringStatus.createFatalErrorStatus(Messages.format(RefactoringCoreMessages.InitializableRefactoring_argument_not_exist, ATTRIBUTE_REPLACE));
		final String declareFinal= arguments.getAttribute(ATTRIBUTE_QUALIFY);
		if (declareFinal != null) {
			fQualifyReferencesWithDeclaringClassName= Boolean.valueOf(declareFinal).booleanValue();
		} else
			return RefactoringStatus.createFatalErrorStatus(Messages.format(RefactoringCoreMessages.InitializableRefactoring_argument_not_exist, ATTRIBUTE_QUALIFY));
		return new RefactoringStatus();
	}
}