/**
 * ***************************************************************************** Copyright (c) 2000,
 * 2013 IBM Corporation and others. All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0 which accompanies this
 * distribution, and is available at http://www.eclipse.org/legal/epl-v10.html
 *
 * <p>Contributors: IBM Corporation - initial API and implementation Benjamin Muskalla
 * <bmuskalla@eclipsesource.com> - [extract method] Extract method and continue
 * https://bugs.eclipse.org/bugs/show_bug.cgi?id=48056 Benjamin Muskalla
 * <bmuskalla@eclipsesource.com> - [extract method] Name ambiguous return value in error message -
 * https://bugs.eclipse.org/bugs/show_bug.cgi?id=50607
 * *****************************************************************************
 */
package org.eclipse.jdt.internal.corext.refactoring.code;

import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.eclipse.che.jdt.util.JavaModelUtil;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.compiler.ITerminalSymbols;
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.Annotation;
import org.eclipse.jdt.core.dom.AnnotationTypeDeclaration;
import org.eclipse.jdt.core.dom.AnonymousClassDeclaration;
import org.eclipse.jdt.core.dom.Assignment;
import org.eclipse.jdt.core.dom.Block;
import org.eclipse.jdt.core.dom.BodyDeclaration;
import org.eclipse.jdt.core.dom.BreakStatement;
import org.eclipse.jdt.core.dom.ClassInstanceCreation;
import org.eclipse.jdt.core.dom.CompilationUnit;
import org.eclipse.jdt.core.dom.ConstructorInvocation;
import org.eclipse.jdt.core.dom.ContinueStatement;
import org.eclipse.jdt.core.dom.DoStatement;
import org.eclipse.jdt.core.dom.EnhancedForStatement;
import org.eclipse.jdt.core.dom.Expression;
import org.eclipse.jdt.core.dom.FieldAccess;
import org.eclipse.jdt.core.dom.FieldDeclaration;
import org.eclipse.jdt.core.dom.ForStatement;
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.Initializer;
import org.eclipse.jdt.core.dom.LabeledStatement;
import org.eclipse.jdt.core.dom.LambdaExpression;
import org.eclipse.jdt.core.dom.Message;
import org.eclipse.jdt.core.dom.MethodDeclaration;
import org.eclipse.jdt.core.dom.Name;
import org.eclipse.jdt.core.dom.PrimitiveType;
import org.eclipse.jdt.core.dom.QualifiedName;
import org.eclipse.jdt.core.dom.SimpleName;
import org.eclipse.jdt.core.dom.Statement;
import org.eclipse.jdt.core.dom.StructuralPropertyDescriptor;
import org.eclipse.jdt.core.dom.SuperConstructorInvocation;
import org.eclipse.jdt.core.dom.SwitchCase;
import org.eclipse.jdt.core.dom.SwitchStatement;
import org.eclipse.jdt.core.dom.ThisExpression;
import org.eclipse.jdt.core.dom.TryStatement;
import org.eclipse.jdt.core.dom.Type;
import org.eclipse.jdt.core.dom.TypeDeclaration;
import org.eclipse.jdt.core.dom.VariableDeclaration;
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.WhileStatement;
import org.eclipse.jdt.core.dom.rewrite.ImportRewrite;
import org.eclipse.jdt.core.dom.rewrite.ImportRewrite.ImportRewriteContext;
import org.eclipse.jdt.internal.corext.codemanipulation.ContextSensitiveImportRewriteContext;
import org.eclipse.jdt.internal.corext.dom.ASTNodeFactory;
import org.eclipse.jdt.internal.corext.dom.ASTNodes;
import org.eclipse.jdt.internal.corext.dom.Bindings;
import org.eclipse.jdt.internal.corext.dom.LocalVariableIndex;
import org.eclipse.jdt.internal.corext.dom.Selection;
import org.eclipse.jdt.internal.corext.dom.TokenScanner;
import org.eclipse.jdt.internal.corext.refactoring.Checks;
import org.eclipse.jdt.internal.corext.refactoring.RefactoringCoreMessages;
import org.eclipse.jdt.internal.corext.refactoring.base.JavaStatusContext;
import org.eclipse.jdt.internal.corext.refactoring.code.flow.FlowContext;
import org.eclipse.jdt.internal.corext.refactoring.code.flow.FlowInfo;
import org.eclipse.jdt.internal.corext.refactoring.code.flow.InOutFlowAnalyzer;
import org.eclipse.jdt.internal.corext.refactoring.code.flow.InputFlowAnalyzer;
import org.eclipse.jdt.internal.corext.refactoring.util.CodeAnalyzer;
import org.eclipse.jdt.internal.corext.util.Messages;
import org.eclipse.jdt.internal.ui.text.correction.ASTResolving;
import org.eclipse.jdt.internal.ui.viewsupport.BasicElementLabels;
import org.eclipse.jdt.internal.ui.viewsupport.BindingLabelProvider;
import org.eclipse.jdt.ui.JavaElementLabels;
import org.eclipse.jface.text.IRegion;
import org.eclipse.ltk.core.refactoring.RefactoringStatus;

/* package */ class ExtractMethodAnalyzer extends CodeAnalyzer {

  public static final int ERROR = -2;
  public static final int UNDEFINED = -1;
  public static final int NO = 0;
  public static final int EXPRESSION = 1;
  public static final int ACCESS_TO_LOCAL = 2;
  public static final int RETURN_STATEMENT_VOID = 3;
  public static final int RETURN_STATEMENT_VALUE = 4;
  public static final int MULTIPLE = 5;

  /** This is either a method declaration or an initializer */
  private BodyDeclaration fEnclosingBodyDeclaration;

  private IMethodBinding fEnclosingMethodBinding;
  private int fMaxVariableId;

  private int fReturnKind;
  private Type fReturnType;
  private ITypeBinding fReturnTypeBinding;

  private FlowInfo fInputFlowInfo;
  private FlowContext fInputFlowContext;

  private IVariableBinding[] fArguments;
  private IVariableBinding[] fMethodLocals;
  private ITypeBinding[] fTypeVariables;

  private IVariableBinding fReturnValue;
  private IVariableBinding[] fCallerLocals;
  private IVariableBinding fReturnLocal;

  private ITypeBinding[] fAllExceptions;
  private ITypeBinding fExpressionBinding;

  private boolean fForceStatic;
  private boolean fIsLastStatementSelected;
  private SimpleName fEnclosingLoopLabel;

  public ExtractMethodAnalyzer(ICompilationUnit unit, Selection selection) throws CoreException {
    super(unit, selection, false);
  }

  public BodyDeclaration getEnclosingBodyDeclaration() {
    return fEnclosingBodyDeclaration;
  }

  public int getReturnKind() {
    return fReturnKind;
  }

  public boolean extractsExpression() {
    return fReturnKind == EXPRESSION;
  }

  public Type getReturnType() {
    return fReturnType;
  }

  public ITypeBinding getReturnTypeBinding() {
    return fReturnTypeBinding;
  }

  public boolean generateImport() {
    switch (fReturnKind) {
      case EXPRESSION:
        return true;
      default:
        return false;
    }
  }

  public IVariableBinding[] getArguments() {
    return fArguments;
  }

  public IVariableBinding[] getMethodLocals() {
    return fMethodLocals;
  }

  public IVariableBinding getReturnValue() {
    return fReturnValue;
  }

  public IVariableBinding[] getCallerLocals() {
    return fCallerLocals;
  }

  public IVariableBinding getReturnLocal() {
    return fReturnLocal;
  }

  public ITypeBinding getExpressionBinding() {
    return fExpressionBinding;
  }

  public boolean getForceStatic() {
    return fForceStatic;
  }

  public ITypeBinding[] getTypeVariables() {
    return fTypeVariables;
  }

  //---- Activation checking ---------------------------------------------------------------------------

  boolean isValidDestination(ASTNode node) {
    boolean isInterface = node instanceof TypeDeclaration && ((TypeDeclaration) node).isInterface();
    return !(node instanceof AnnotationTypeDeclaration)
        && !(isInterface && !JavaModelUtil.is18OrHigher(fCUnit.getJavaProject()));
  }

  public RefactoringStatus checkInitialConditions(ImportRewrite rewriter) {
    RefactoringStatus result = getStatus();
    checkExpression(result);
    if (result.hasFatalError()) return result;

    List<ASTNode> validDestinations = new ArrayList<ASTNode>();
    ASTNode destination = ASTResolving.findParentType(fEnclosingBodyDeclaration.getParent());
    while (destination != null) {
      if (isValidDestination(destination)) {
        validDestinations.add(destination);
      }
      destination = ASTResolving.findParentType(destination.getParent());
    }
    if (validDestinations.size() == 0) {
      result.addFatalError(RefactoringCoreMessages.ExtractMethodAnalyzer_no_valid_destination_type);
      return result;
    }

    fReturnKind = UNDEFINED;
    fMaxVariableId = LocalVariableIndex.perform(fEnclosingBodyDeclaration);
    if (analyzeSelection(result).hasFatalError()) return result;

    int returns = fReturnKind == NO ? 0 : 1;
    if (fReturnValue != null) {
      fReturnKind = ACCESS_TO_LOCAL;
      returns++;
    }
    if (isExpressionSelected()) {
      fReturnKind = EXPRESSION;
      returns++;
    }

    if (returns > 1) {
      result.addFatalError(
          RefactoringCoreMessages.ExtractMethodAnalyzer_ambiguous_return_value,
          JavaStatusContext.create(fCUnit, getSelection()));
      fReturnKind = MULTIPLE;
      return result;
    }
    initReturnType(rewriter);
    return result;
  }

  private void checkExpression(RefactoringStatus status) {
    ASTNode[] nodes = getSelectedNodes();
    if (nodes != null && nodes.length == 1) {
      ASTNode node = nodes[0];
      if (node instanceof Type) {
        status.addFatalError(
            RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_extract_type_reference,
            JavaStatusContext.create(fCUnit, node));
      } else if (node.getLocationInParent() == SwitchCase.EXPRESSION_PROPERTY) {
        status.addFatalError(
            RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_extract_switch_case,
            JavaStatusContext.create(fCUnit, node));
      } else if (node instanceof Annotation || ASTNodes.getParent(node, Annotation.class) != null) {
        status.addFatalError(
            RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_extract_from_annotation,
            JavaStatusContext.create(fCUnit, node));
      }
    }
  }

  private void initReturnType(ImportRewrite rewriter) {
    AST ast = fEnclosingBodyDeclaration.getAST();
    fReturnType = null;
    fReturnTypeBinding = null;
    switch (fReturnKind) {
      case ACCESS_TO_LOCAL:
        VariableDeclaration declaration =
            ASTNodes.findVariableDeclaration(fReturnValue, fEnclosingBodyDeclaration);
        fReturnType =
            ASTNodeFactory.newType(
                ast,
                declaration,
                rewriter,
                new ContextSensitiveImportRewriteContext(declaration, rewriter));
        if (declaration.resolveBinding() != null) {
          fReturnTypeBinding = declaration.resolveBinding().getType();
        }
        break;
      case EXPRESSION:
        Expression expression = (Expression) getFirstSelectedNode();
        if (expression.getNodeType() == ASTNode.CLASS_INSTANCE_CREATION) {
          fExpressionBinding = ((ClassInstanceCreation) expression).getType().resolveBinding();
        } else {
          fExpressionBinding = expression.resolveTypeBinding();
        }
        if (fExpressionBinding != null) {
          if (fExpressionBinding.isNullType()) {
            getStatus()
                .addFatalError(
                    RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_extract_null_type,
                    JavaStatusContext.create(fCUnit, expression));
          } else {
            ITypeBinding normalizedBinding =
                Bindings.normalizeForDeclarationUse(fExpressionBinding, ast);
            if (normalizedBinding != null) {
              ImportRewriteContext context =
                  new ContextSensitiveImportRewriteContext(fEnclosingBodyDeclaration, rewriter);
              fReturnType = rewriter.addImport(normalizedBinding, ast, context);
              fReturnTypeBinding = normalizedBinding;
            }
          }
        } else {
          fReturnType = ast.newPrimitiveType(PrimitiveType.VOID);
          fReturnTypeBinding = ast.resolveWellKnownType("void"); //$NON-NLS-1$
          getStatus()
              .addError(
                  RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_determine_return_type,
                  JavaStatusContext.create(fCUnit, expression));
        }
        break;
      case RETURN_STATEMENT_VALUE:
        LambdaExpression enclosingLambdaExpr =
            ASTResolving.findEnclosingLambdaExpression(getFirstSelectedNode());
        if (enclosingLambdaExpr != null) {
          fReturnType = ASTNodeFactory.newReturnType(enclosingLambdaExpr, ast, rewriter, null);
          IMethodBinding methodBinding = enclosingLambdaExpr.resolveMethodBinding();
          fReturnTypeBinding = methodBinding != null ? methodBinding.getReturnType() : null;
        } else if (fEnclosingBodyDeclaration.getNodeType() == ASTNode.METHOD_DECLARATION) {
          fReturnType = ((MethodDeclaration) fEnclosingBodyDeclaration).getReturnType2();
          fReturnTypeBinding = fReturnType != null ? fReturnType.resolveBinding() : null;
        }
        break;
      default:
        fReturnType = ast.newPrimitiveType(PrimitiveType.VOID);
        fReturnTypeBinding = ast.resolveWellKnownType("void"); //$NON-NLS-1$
    }
    if (fReturnType == null) {
      fReturnType = ast.newPrimitiveType(PrimitiveType.VOID);
      fReturnTypeBinding = ast.resolveWellKnownType("void"); //$NON-NLS-1$
    }
  }

  //	 !!! -- +/- same as in ExtractTempRefactoring
  public boolean isLiteralNodeSelected() {
    ASTNode[] nodes = getSelectedNodes();
    if (nodes.length != 1) return false;
    ASTNode node = nodes[0];
    switch (node.getNodeType()) {
      case ASTNode.BOOLEAN_LITERAL:
      case ASTNode.CHARACTER_LITERAL:
      case ASTNode.NULL_LITERAL:
      case ASTNode.NUMBER_LITERAL:
        return true;

      default:
        return false;
    }
  }

  //---- Input checking -----------------------------------------------------------------------------------

  public void checkInput(RefactoringStatus status, String methodName, ASTNode destination) {
    ITypeBinding[] arguments = getArgumentTypes();
    ITypeBinding type = ASTNodes.getEnclosingType(destination);
    status.merge(Checks.checkMethodInType(type, methodName, arguments));
    ITypeBinding superClass = type.getSuperclass();
    if (superClass != null) {
      status.merge(Checks.checkMethodInHierarchy(superClass, methodName, null, arguments));
    }
    for (ITypeBinding superInterface : type.getInterfaces()) {
      status.merge(Checks.checkMethodInHierarchy(superInterface, methodName, null, arguments));
    }
  }

  private ITypeBinding[] getArgumentTypes() {
    ITypeBinding[] result = new ITypeBinding[fArguments.length];
    for (int i = 0; i < fArguments.length; i++) {
      result[i] = fArguments[i].getType();
    }
    return result;
  }

  private RefactoringStatus analyzeSelection(RefactoringStatus status) {
    fInputFlowContext = new FlowContext(0, fMaxVariableId + 1);
    fInputFlowContext.setConsiderAccessMode(true);
    fInputFlowContext.setComputeMode(FlowContext.ARGUMENTS);

    InOutFlowAnalyzer flowAnalyzer = new InOutFlowAnalyzer(fInputFlowContext);
    fInputFlowInfo = flowAnalyzer.perform(getSelectedNodes());

    if (fInputFlowInfo.branches()) {
      String canHandleBranchesProblem = canHandleBranches();
      if (canHandleBranchesProblem != null) {
        status.addFatalError(
            canHandleBranchesProblem, JavaStatusContext.create(fCUnit, getSelection()));
        fReturnKind = ERROR;
        return status;
      }
    }
    if (fInputFlowInfo.isValueReturn()) {
      fReturnKind = RETURN_STATEMENT_VALUE;
    } else if (fInputFlowInfo.isVoidReturn()
        || (fInputFlowInfo.isPartialReturn() && isVoidMethod() && isLastStatementSelected())) {
      fReturnKind = RETURN_STATEMENT_VOID;
    } else if (fInputFlowInfo.isNoReturn()
        || fInputFlowInfo.isThrow()
        || fInputFlowInfo.isUndefined()) {
      fReturnKind = NO;
    }

    if (fReturnKind == UNDEFINED) {
      status.addError(
          RefactoringCoreMessages.FlowAnalyzer_execution_flow,
          JavaStatusContext.create(fCUnit, getSelection()));
      fReturnKind = NO;
    }
    computeInput();
    computeExceptions();
    computeOutput(status);
    if (status.hasFatalError()) return status;

    adjustArgumentsAndMethodLocals();
    compressArrays();
    return status;
  }

  private String canHandleBranches() {
    if (fReturnValue != null) return RefactoringCoreMessages.ExtractMethodAnalyzer_branch_mismatch;

    ASTNode[] selectedNodes = getSelectedNodes();
    final ASTNode lastSelectedNode = selectedNodes[selectedNodes.length - 1];
    Statement body = getParentLoopBody(lastSelectedNode.getParent());
    if (!(body instanceof Block))
      return RefactoringCoreMessages.ExtractMethodAnalyzer_branch_mismatch;

    if (body != lastSelectedNode) {
      Block block = (Block) body;
      List<Statement> statements = block.statements();
      ASTNode lastStatementInLoop = statements.get(statements.size() - 1);
      if (lastSelectedNode != lastStatementInLoop)
        return RefactoringCoreMessages.ExtractMethodAnalyzer_branch_mismatch;
    }

    final String continueMatchesLoopProblem[] = {null};
    for (int i = 0; i < selectedNodes.length; i++) {
      final ASTNode astNode = selectedNodes[i];
      astNode.accept(
          new ASTVisitor() {
            ArrayList<String> fLocalLoopLabels = new ArrayList<String>();

            @Override
            public boolean visit(BreakStatement node) {
              SimpleName label = node.getLabel();
              if (label != null && !fLocalLoopLabels.contains(label.getIdentifier())) {
                continueMatchesLoopProblem[0] =
                    Messages.format(
                        RefactoringCoreMessages.ExtractMethodAnalyzer_branch_break_mismatch,
                        new Object[] {("break " + label.getIdentifier())}); //$NON-NLS-1$
              }
              return false;
            }

            @Override
            public boolean visit(LabeledStatement node) {
              SimpleName label = node.getLabel();
              if (label != null) fLocalLoopLabels.add(label.getIdentifier());
              return true;
            }

            @Override
            public void endVisit(ContinueStatement node) {
              SimpleName label = node.getLabel();
              if (label != null && !fLocalLoopLabels.contains(label.getIdentifier())) {
                if (fEnclosingLoopLabel == null
                    || !label.getIdentifier().equals(fEnclosingLoopLabel.getIdentifier())) {
                  continueMatchesLoopProblem[0] =
                      Messages.format(
                          RefactoringCoreMessages.ExtractMethodAnalyzer_branch_continue_mismatch,
                          new Object[] {"continue " + label.getIdentifier()}); //$NON-NLS-1$
                }
              }
            }
          });
    }
    return continueMatchesLoopProblem[0];
  }

  private Statement getParentLoopBody(ASTNode node) {
    Statement stmt = null;
    ASTNode start = node;
    while (start != null
        && !(start instanceof ForStatement)
        && !(start instanceof DoStatement)
        && !(start instanceof WhileStatement)
        && !(start instanceof EnhancedForStatement)
        && !(start instanceof SwitchStatement)) {
      start = start.getParent();
    }
    if (start instanceof ForStatement) {
      stmt = ((ForStatement) start).getBody();
    } else if (start instanceof DoStatement) {
      stmt = ((DoStatement) start).getBody();
    } else if (start instanceof WhileStatement) {
      stmt = ((WhileStatement) start).getBody();
    } else if (start instanceof EnhancedForStatement) {
      stmt = ((EnhancedForStatement) start).getBody();
    }
    if (start != null && start.getParent() instanceof LabeledStatement) {
      LabeledStatement labeledStatement = (LabeledStatement) start.getParent();
      fEnclosingLoopLabel = labeledStatement.getLabel();
    }
    return stmt;
  }

  private boolean isVoidMethod() {
    ITypeBinding binding = null;
    LambdaExpression enclosingLambdaExpr =
        ASTResolving.findEnclosingLambdaExpression(getFirstSelectedNode());
    if (enclosingLambdaExpr != null) {
      IMethodBinding methodBinding = enclosingLambdaExpr.resolveMethodBinding();
      if (methodBinding != null) {
        binding = methodBinding.getReturnType();
      }
    } else {
      // if we have an initializer
      if (fEnclosingMethodBinding == null) return true;
      binding = fEnclosingMethodBinding.getReturnType();
    }
    if (fEnclosingBodyDeclaration
        .getAST()
        .resolveWellKnownType("void")
        .equals(binding)) //$NON-NLS-1$
    return true;
    return false;
  }

  public boolean isLastStatementSelected() {
    return fIsLastStatementSelected;
  }

  private void computeLastStatementSelected() {
    ASTNode[] nodes = getSelectedNodes();
    if (nodes.length == 0) {
      fIsLastStatementSelected = false;
    } else {
      Block body = null;
      LambdaExpression enclosingLambdaExpr =
          ASTResolving.findEnclosingLambdaExpression(getFirstSelectedNode());
      if (enclosingLambdaExpr != null) {
        ASTNode lambdaBody = enclosingLambdaExpr.getBody();
        if (lambdaBody instanceof Block) {
          body = (Block) lambdaBody;
        } else {
          fIsLastStatementSelected = true;
          return;
        }
      } else {
        if (fEnclosingBodyDeclaration instanceof MethodDeclaration) {
          body = ((MethodDeclaration) fEnclosingBodyDeclaration).getBody();
        } else if (fEnclosingBodyDeclaration instanceof Initializer) {
          body = ((Initializer) fEnclosingBodyDeclaration).getBody();
        }
      }
      if (body != null) {
        List<Statement> statements = body.statements();
        if (statements.size() > 0) {
          fIsLastStatementSelected =
              nodes[nodes.length - 1] == statements.get(statements.size() - 1);
        } else {
          fIsLastStatementSelected = true;
        }
      }
    }
  }

  private void computeInput() {
    int argumentMode =
        FlowInfo.READ | FlowInfo.READ_POTENTIAL | FlowInfo.WRITE_POTENTIAL | FlowInfo.UNKNOWN;
    fArguments = removeSelectedDeclarations(fInputFlowInfo.get(fInputFlowContext, argumentMode));
    fMethodLocals =
        removeSelectedDeclarations(
            fInputFlowInfo.get(fInputFlowContext, FlowInfo.WRITE | FlowInfo.WRITE_POTENTIAL));
    fTypeVariables = computeTypeVariables(fInputFlowInfo.getTypeVariables());
  }

  private IVariableBinding[] removeSelectedDeclarations(IVariableBinding[] bindings) {
    List<IVariableBinding> result = new ArrayList<IVariableBinding>(bindings.length);
    Selection selection = getSelection();
    for (int i = 0; i < bindings.length; i++) {
      ASTNode decl =
          ((CompilationUnit) fEnclosingBodyDeclaration.getRoot()).findDeclaringNode(bindings[i]);
      if (!selection.covers(decl)) result.add(bindings[i]);
    }
    return result.toArray(new IVariableBinding[result.size()]);
  }

  private ITypeBinding[] computeTypeVariables(ITypeBinding[] bindings) {
    Selection selection = getSelection();
    Set<ITypeBinding> result = new HashSet<ITypeBinding>();
    // first remove all type variables that come from outside of the method
    // or are covered by the selection
    CompilationUnit compilationUnit = (CompilationUnit) fEnclosingBodyDeclaration.getRoot();
    for (int i = 0; i < bindings.length; i++) {
      ASTNode decl = compilationUnit.findDeclaringNode(bindings[i]);
      if (decl == null
          || (!selection.covers(decl) && decl.getParent() instanceof MethodDeclaration))
        result.add(bindings[i]);
    }
    // all all type variables which are needed since a local variable uses it
    for (int i = 0; i < fArguments.length; i++) {
      IVariableBinding arg = fArguments[i];
      ITypeBinding type = arg.getType();
      if (type != null && type.isTypeVariable()) {
        ASTNode decl = compilationUnit.findDeclaringNode(type);
        if (decl == null
            || (!selection.covers(decl) && decl.getParent() instanceof MethodDeclaration))
          result.add(type);
      }
    }
    return result.toArray(new ITypeBinding[result.size()]);
  }

  private void computeOutput(RefactoringStatus status) {
    // First find all writes inside the selection.
    FlowContext flowContext = new FlowContext(0, fMaxVariableId + 1);
    flowContext.setConsiderAccessMode(true);
    flowContext.setComputeMode(FlowContext.RETURN_VALUES);
    FlowInfo returnInfo = new InOutFlowAnalyzer(flowContext).perform(getSelectedNodes());
    IVariableBinding[] returnValues =
        returnInfo.get(flowContext, FlowInfo.WRITE | FlowInfo.WRITE_POTENTIAL | FlowInfo.UNKNOWN);

    // Compute a selection that exactly covers the selected nodes
    IRegion region = getSelectedNodeRange();
    Selection selection = Selection.createFromStartLength(region.getOffset(), region.getLength());

    List<IVariableBinding> localReads = new ArrayList<IVariableBinding>();
    flowContext.setComputeMode(FlowContext.ARGUMENTS);
    FlowInfo argInfo =
        new InputFlowAnalyzer(flowContext, selection, true).perform(fEnclosingBodyDeclaration);
    IVariableBinding[] reads =
        argInfo.get(flowContext, FlowInfo.READ | FlowInfo.READ_POTENTIAL | FlowInfo.UNKNOWN);
    outer:
    for (int i = 0; i < returnValues.length && localReads.size() < returnValues.length; i++) {
      IVariableBinding binding = returnValues[i];
      for (int x = 0; x < reads.length; x++) {
        if (reads[x] == binding) {
          localReads.add(binding);
          fReturnValue = binding;
          continue outer;
        }
      }
    }
    switch (localReads.size()) {
      case 0:
        fReturnValue = null;
        break;
      case 1:
        break;
      default:
        fReturnValue = null;
        StringBuffer affectedLocals = new StringBuffer();
        for (int i = 0; i < localReads.size(); i++) {
          IVariableBinding binding = localReads.get(i);
          String bindingName =
              BindingLabelProvider.getBindingLabel(
                  binding,
                  BindingLabelProvider.DEFAULT_TEXTFLAGS | JavaElementLabels.F_PRE_TYPE_SIGNATURE);
          affectedLocals.append(bindingName);
          if (i != localReads.size() - 1) {
            affectedLocals.append('\n');
          }
        }
        String message =
            MessageFormat.format(
                RefactoringCoreMessages.ExtractMethodAnalyzer_assignments_to_local,
                new Object[] {affectedLocals.toString()});
        status.addFatalError(message, JavaStatusContext.create(fCUnit, getSelection()));
        return;
    }
    List<IVariableBinding> callerLocals = new ArrayList<IVariableBinding>(5);
    FlowInfo localInfo =
        new InputFlowAnalyzer(flowContext, selection, false).perform(fEnclosingBodyDeclaration);
    IVariableBinding[] writes =
        localInfo.get(flowContext, FlowInfo.WRITE | FlowInfo.WRITE_POTENTIAL | FlowInfo.UNKNOWN);
    for (int i = 0; i < writes.length; i++) {
      IVariableBinding write = writes[i];
      if (getSelection().covers(ASTNodes.findDeclaration(write, fEnclosingBodyDeclaration)))
        callerLocals.add(write);
    }
    fCallerLocals = callerLocals.toArray(new IVariableBinding[callerLocals.size()]);
    if (fReturnValue != null
        && getSelection().covers(ASTNodes.findDeclaration(fReturnValue, fEnclosingBodyDeclaration)))
      fReturnLocal = fReturnValue;
  }

  private void adjustArgumentsAndMethodLocals() {
    for (int i = 0; i < fArguments.length; i++) {
      IVariableBinding argument = fArguments[i];
      // Both arguments and locals consider FlowInfo.WRITE_POTENTIAL. But at the end a variable
      // can either be a local of an argument. Fix this based on the compute return type which
      // didn't exist when we computed the locals and arguments (see computeInput())
      if (fInputFlowInfo.hasAccessMode(fInputFlowContext, argument, FlowInfo.WRITE_POTENTIAL)) {
        if (argument != fReturnValue) fArguments[i] = null;
        // We didn't remove the argument. So we have to remove the local declaration
        if (fArguments[i] != null) {
          for (int l = 0; l < fMethodLocals.length; l++) {
            if (fMethodLocals[l] == argument) fMethodLocals[l] = null;
          }
        }
      }
    }
  }

  private void compressArrays() {
    fArguments = compressArray(fArguments);
    fCallerLocals = compressArray(fCallerLocals);
    fMethodLocals = compressArray(fMethodLocals);
  }

  private IVariableBinding[] compressArray(IVariableBinding[] array) {
    if (array == null) return null;
    int size = 0;
    for (int i = 0; i < array.length; i++) {
      if (array[i] != null) size++;
    }
    if (size == array.length) return array;
    IVariableBinding[] result = new IVariableBinding[size];
    for (int i = 0, r = 0; i < array.length; i++) {
      if (array[i] != null) result[r++] = array[i];
    }
    return result;
  }

  //---- Change creation ----------------------------------------------------------------------------------

  public void aboutToCreateChange() {}

  //---- Exceptions -----------------------------------------------------------------------------------------

  public ITypeBinding[] getExceptions(boolean includeRuntimeExceptions) {
    if (includeRuntimeExceptions) return fAllExceptions;
    List<ITypeBinding> result = new ArrayList<ITypeBinding>(fAllExceptions.length);
    for (int i = 0; i < fAllExceptions.length; i++) {
      ITypeBinding exception = fAllExceptions[i];
      if (!includeRuntimeExceptions && Bindings.isRuntimeException(exception)) continue;
      result.add(exception);
    }
    return result.toArray(new ITypeBinding[result.size()]);
  }

  private void computeExceptions() {
    fAllExceptions = ExceptionAnalyzer.perform(getSelectedNodes());
  }

  //---- Special visitor methods ---------------------------------------------------------------------------

  @Override
  protected void handleNextSelectedNode(ASTNode node) {
    super.handleNextSelectedNode(node);
    checkParent(node);
  }

  @Override
  protected boolean handleSelectionEndsIn(ASTNode node) {
    invalidSelection(
        RefactoringCoreMessages.StatementAnalyzer_doesNotCover,
        JavaStatusContext.create(fCUnit, node));
    return super.handleSelectionEndsIn(node);
  }

  private void checkParent(ASTNode node) {
    ASTNode firstParent = getFirstSelectedNode().getParent();
    do {
      node = node.getParent();
      if (node == firstParent) return;
    } while (node != null);
    invalidSelection(RefactoringCoreMessages.ExtractMethodAnalyzer_parent_mismatch);
  }

  @Override
  public void endVisit(CompilationUnit node) {
    RefactoringStatus status = getStatus();
    superCall:
    {
      if (status.hasFatalError()) break superCall;
      if (!hasSelectedNodes()) {
        ASTNode coveringNode = getLastCoveringNode();
        if (coveringNode instanceof Block
            && coveringNode.getParent() instanceof MethodDeclaration) {
          MethodDeclaration methodDecl = (MethodDeclaration) coveringNode.getParent();
          Message[] messages = ASTNodes.getMessages(methodDecl, ASTNodes.NODE_ONLY);
          if (messages.length > 0) {
            status.addFatalError(
                Messages.format(
                    RefactoringCoreMessages.ExtractMethodAnalyzer_compile_errors,
                    BasicElementLabels.getJavaElementName(methodDecl.getName().getIdentifier())),
                JavaStatusContext.create(fCUnit, methodDecl));
            break superCall;
          }
        }
        status.addFatalError(RefactoringCoreMessages.ExtractMethodAnalyzer_invalid_selection);
        break superCall;
      }
      fEnclosingBodyDeclaration =
          (BodyDeclaration) ASTNodes.getParent(getFirstSelectedNode(), BodyDeclaration.class);
      if (fEnclosingBodyDeclaration == null
          || (fEnclosingBodyDeclaration.getNodeType() != ASTNode.METHOD_DECLARATION
              && fEnclosingBodyDeclaration.getNodeType() != ASTNode.FIELD_DECLARATION
              && fEnclosingBodyDeclaration.getNodeType() != ASTNode.INITIALIZER)) {
        status.addFatalError(RefactoringCoreMessages.ExtractMethodAnalyzer_invalid_selection);
        break superCall;
      } else if (ASTNodes.getEnclosingType(fEnclosingBodyDeclaration) == null) {
        status.addFatalError(
            RefactoringCoreMessages.ExtractMethodAnalyzer_compile_errors_no_parent_binding);
        break superCall;
      } else if (fEnclosingBodyDeclaration.getNodeType() == ASTNode.METHOD_DECLARATION) {
        fEnclosingMethodBinding = ((MethodDeclaration) fEnclosingBodyDeclaration).resolveBinding();
      }
      if (!isSingleExpressionOrStatementSet()) {
        status.addFatalError(
            RefactoringCoreMessages.ExtractMethodAnalyzer_single_expression_or_set);
        break superCall;
      }
      if (isExpressionSelected()) {
        ASTNode expression = getFirstSelectedNode();
        if (expression instanceof Name) {
          Name name = (Name) expression;
          if (name.resolveBinding() instanceof ITypeBinding) {
            status.addFatalError(
                RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_extract_type_reference);
            break superCall;
          }
          if (name.resolveBinding() instanceof IMethodBinding) {
            status.addFatalError(
                RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_extract_method_name_reference);
            break superCall;
          }
          if (name.resolveBinding() instanceof IVariableBinding) {
            StructuralPropertyDescriptor locationInParent = name.getLocationInParent();
            if (locationInParent == QualifiedName.NAME_PROPERTY
                || (locationInParent == FieldAccess.NAME_PROPERTY
                    && !(((FieldAccess) name.getParent()).getExpression()
                        instanceof ThisExpression))) {
              status.addFatalError(
                  RefactoringCoreMessages
                      .ExtractMethodAnalyzer_cannot_extract_part_of_qualified_name);
              break superCall;
            }
          }
          if (name.isSimpleName() && ((SimpleName) name).isDeclaration()) {
            status.addFatalError(
                RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_extract_name_in_declaration);
            break superCall;
          }
        }
        fForceStatic =
            ASTNodes.getParent(expression, ASTNode.SUPER_CONSTRUCTOR_INVOCATION) != null
                || ASTNodes.getParent(expression, ASTNode.CONSTRUCTOR_INVOCATION) != null;
      }
      status.merge(LocalTypeAnalyzer.perform(fEnclosingBodyDeclaration, getSelection()));
      computeLastStatementSelected();
    }
    super.endVisit(node);
  }

  @Override
  public boolean visit(AnonymousClassDeclaration node) {
    boolean result = super.visit(node);
    if (isFirstSelectedNode(node)) {
      invalidSelection(
          RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_extract_anonymous_type,
          JavaStatusContext.create(fCUnit, node));
      return false;
    }
    return result;
  }

  @Override
  public boolean visit(Assignment node) {
    boolean result = super.visit(node);
    if ((getSelection().covers(node.getLeftHandSide())
            && !getSelection().covers(node.getRightHandSide()))
        || getSelection().coveredBy(node.getLeftHandSide())) {
      invalidSelection(
          RefactoringCoreMessages.ExtractMethodAnalyzer_leftHandSideOfAssignment,
          JavaStatusContext.create(fCUnit, node));
      return false;
    }
    return result;
  }

  @Override
  public boolean visit(DoStatement node) {
    boolean result = super.visit(node);

    try {
      int actionStart =
          getTokenScanner()
              .getTokenEndOffset(ITerminalSymbols.TokenNamedo, node.getStartPosition());
      if (getSelection().getOffset() == actionStart) {
        invalidSelection(
            RefactoringCoreMessages.ExtractMethodAnalyzer_after_do_keyword,
            JavaStatusContext.create(fCUnit, getSelection()));
        return false;
      }
    } catch (CoreException e) {
      // ignore
    }

    return result;
  }

  @Override
  public boolean visit(LambdaExpression node) {
    Selection selection = getSelection();
    int selectionStart = selection.getOffset();
    int selectionExclusiveEnd = selection.getExclusiveEnd();
    int lambdaStart = node.getStartPosition();
    int lambdaExclusiveEnd = lambdaStart + node.getLength();
    ASTNode body = node.getBody();
    int bodyStart = body.getStartPosition();
    int bodyExclusiveEnd = bodyStart + body.getLength();

    boolean isValidSelection = false;
    if ((body instanceof Block)
        && (bodyStart < selectionStart && selectionExclusiveEnd <= bodyExclusiveEnd)) {
      // if selection is inside lambda body's block
      isValidSelection = true;
    } else if (body instanceof Expression) {
      try {
        TokenScanner scanner = new TokenScanner(fCUnit);
        int arrowExclusiveEnd =
            scanner.getTokenEndOffset(ITerminalSymbols.TokenNameARROW, lambdaStart);
        if (selectionStart >= arrowExclusiveEnd) {
          isValidSelection = true;
        }
      } catch (CoreException e) {
        // ignore
      }
    }
    if (selectionStart <= lambdaStart && selectionExclusiveEnd >= lambdaExclusiveEnd) {
      // if selection covers the lambda node
      isValidSelection = true;
    }

    if (!isValidSelection) {
      return false;
    }
    return super.visit(node);
  }

  @Override
  public boolean visit(MethodDeclaration node) {
    Block body = node.getBody();
    if (body == null) return false;
    Selection selection = getSelection();
    int nodeStart = body.getStartPosition();
    int nodeExclusiveEnd = nodeStart + body.getLength();
    // if selection node inside of the method body ignore method
    if (!(nodeStart < selection.getOffset() && selection.getExclusiveEnd() < nodeExclusiveEnd))
      return false;
    return super.visit(node);
  }

  @Override
  public boolean visit(ConstructorInvocation node) {
    return visitConstructorInvocation(node, super.visit(node));
  }

  @Override
  public boolean visit(SuperConstructorInvocation node) {
    return visitConstructorInvocation(node, super.visit(node));
  }

  private boolean visitConstructorInvocation(ASTNode node, boolean superResult) {
    if (getSelection().getVisitSelectionMode(node) == Selection.SELECTED) {
      invalidSelection(
          RefactoringCoreMessages.ExtractMethodAnalyzer_super_or_this,
          JavaStatusContext.create(fCUnit, node));
      return false;
    }
    return superResult;
  }

  @Override
  public boolean visit(VariableDeclarationFragment node) {
    boolean result = super.visit(node);
    if (isFirstSelectedNode(node)) {
      if (node.getParent() instanceof FieldDeclaration) {
        invalidSelection(
            RefactoringCoreMessages
                .ExtractMethodAnalyzer_cannot_extract_variable_declaration_fragment_from_field,
            JavaStatusContext.create(fCUnit, node));
      } else {
        invalidSelection(
            RefactoringCoreMessages
                .ExtractMethodAnalyzer_cannot_extract_variable_declaration_fragment,
            JavaStatusContext.create(fCUnit, node));
      }
      return false;
    }
    return result;
  }

  @Override
  public void endVisit(FieldDeclaration node) {
    if (contains(getSelectedNodes(), node.fragments())) {
      invalidSelection(
          RefactoringCoreMessages
              .ExtractMethodAnalyzer_cannot_extract_variable_declaration_fragment_from_field,
          JavaStatusContext.create(fCUnit, node));
    }
    super.endVisit(node);
  }

  @Override
  public void endVisit(ForStatement node) {
    if (getSelection().getEndVisitSelectionMode(node) == Selection.AFTER) {
      if (node.initializers().contains(getFirstSelectedNode())) {
        invalidSelection(
            RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_extract_for_initializer,
            JavaStatusContext.create(fCUnit, getSelection()));
      } else if (node.updaters().contains(getLastSelectedNode())) {
        invalidSelection(
            RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_extract_for_updater,
            JavaStatusContext.create(fCUnit, getSelection()));
      }
    }
    super.endVisit(node);
  }

  @Override
  public void endVisit(EnhancedForStatement node) {
    if (getSelection().getEndVisitSelectionMode(node) == Selection.AFTER) {
      if (node.getParameter() == getFirstSelectedNode()) {
        invalidSelection(
            RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_extract_for_initializer,
            JavaStatusContext.create(fCUnit, getSelection()));
      }
    }
    super.endVisit(node);
  }

  @Override
  public void endVisit(VariableDeclarationExpression node) {
    if (getSelection().getEndVisitSelectionMode(node) == Selection.SELECTED
        && getFirstSelectedNode() == node) {
      if (node.getLocationInParent() == TryStatement.RESOURCES_PROPERTY) {
        invalidSelection(
            RefactoringCoreMessages.ExtractMethodAnalyzer_resource_in_try_with_resources,
            JavaStatusContext.create(fCUnit, getSelection()));
      }
    }
    checkTypeInDeclaration(node.getType());
    super.endVisit(node);
  }

  @Override
  public void endVisit(VariableDeclarationStatement node) {
    checkTypeInDeclaration(node.getType());
    super.endVisit(node);
  }

  private boolean isFirstSelectedNode(ASTNode node) {
    return getSelection().getVisitSelectionMode(node) == Selection.SELECTED
        && getFirstSelectedNode() == node;
  }

  private void checkTypeInDeclaration(Type node) {
    if (getSelection().getEndVisitSelectionMode(node) == Selection.SELECTED
        && getFirstSelectedNode() == node) {
      invalidSelection(
          RefactoringCoreMessages.ExtractMethodAnalyzer_cannot_extract_variable_declaration,
          JavaStatusContext.create(fCUnit, getSelection()));
    }
  }

  private boolean isSingleExpressionOrStatementSet() {
    ASTNode first = getFirstSelectedNode();
    if (first == null) return true;
    if (first instanceof Expression && getSelectedNodes().length != 1) return false;
    return true;
  }
}
