////////////////////////////////////////////////////////////////////////////////
   // checkstyle: Checks Java source code for adherence to a set of rules.
   // Copyright (C) 2001-2019 the original author or authors.
   //
   // This library is free software; you can redistribute it and/or
   // modify it under the terms of the GNU Lesser General Public
   // License as published by the Free Software Foundation; either
   // version 2.1 of the License, or (at your option) any later version.
   //
  // This library is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  // Lesser General Public License for more details.
  //
  // You should have received a copy of the GNU Lesser General Public
  // License along with this library; if not, write to the Free Software
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  ////////////////////////////////////////////////////////////////////////////////
  
  package com.puppycrawl.tools.checkstyle.checks.coding;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  import java.util.regex.Pattern;
  
  import com.puppycrawl.tools.checkstyle.FileStatefulCheck;
  import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.FullIdent;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
  
  /**
   * Checks that particular classes or interfaces are never used.
   *
   * <p>Rationale:
   * Helps reduce coupling on concrete classes.
   *
   * <p>Check has following properties:
   *
   * <p><b>illegalAbstractClassNameFormat</b> - Pattern for illegal abstract class names.
   *
   * <p><b>legalAbstractClassNames</b> - Abstract classes that may be used as types.
   *
   * <p><b>illegalClassNames</b> - Classes that should not be used as types in variable
     declarations, return values or parameters.
   * It is possible to set illegal class names via short or
   * <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-6.html#jls-6.7">
   *  canonical</a> name.
   *  Specifying illegal type invokes analyzing imports and Check puts violations at
   *   corresponding declarations
   *  (of variables, methods or parameters). This helps to avoid ambiguous cases, e.g.:
   *
   * <p>{@code java.awt.List} was set as illegal class name, then, code like:
   *
   * <p>{@code
   * import java.util.List;<br>
   * ...<br>
   * List list; //No violation here
   * }
   *
   * <p>will be ok.
   *
   * <p><b>validateAbstractClassNames</b> - controls whether to validate abstract class names.
   * Default value is <b>false</b>
   * </p>
   *
   * <p><b>ignoredMethodNames</b> - Methods that should not be checked.
   *
   * <p><b>memberModifiers</b> - To check only methods and fields with any of the specified modifiers.
   * This property does not affect method calls nor method references.
   *
   * <p>In most cases it's justified to put following classes to <b>illegalClassNames</b>:
   * <ul>
   * <li>GregorianCalendar</li>
   * <li>Hashtable</li>
   * <li>ArrayList</li>
   * <li>LinkedList</li>
   * <li>Vector</li>
   * </ul>
   *
   * <p>as methods that are differ from interface methods are rear used, so in most cases user will
   *  benefit from checking for them.
   * </p>
   *
   */
  @FileStatefulCheck
  public final class IllegalTypeCheck extends AbstractCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY = "illegal.type";
  
      /** Types illegal by default. */
     private static final String[] DEFAULT_ILLEGAL_TYPES = {
         "HashSet",
         "HashMap",
         "LinkedHashMap",
         "LinkedHashSet",
         "TreeSet",
         "TreeMap",
         "java.util.HashSet",
         "java.util.HashMap",
         "java.util.LinkedHashMap",
         "java.util.LinkedHashSet",
         "java.util.TreeSet",
         "java.util.TreeMap",
     };
 
     /** Default ignored method names. */
     private static final String[] DEFAULT_IGNORED_METHOD_NAMES = {
         "getInitialContext",
         "getEnvironment",
     };
 
     /** Illegal classes. */
     private final Set<String> illegalClassNames = new HashSet<>();
     /** Illegal short classes. */
     private final Set<String> illegalShortClassNames = new HashSet<>();
     /** Legal abstract classes. */
     private final Set<String> legalAbstractClassNames = new HashSet<>();
     /** Methods which should be ignored. */
     private final Set<String> ignoredMethodNames = new HashSet<>();
     /** Check methods and fields with only corresponding modifiers. */
     private List<Integer> memberModifiers;
 
     /** The regexp to match against. */
     private Pattern illegalAbstractClassNameFormat = Pattern.compile("^(.*[.])?Abstract.*$");
 
     /**
      * Controls whether to validate abstract class names.
      */
     private boolean validateAbstractClassNames;
 
     /** Creates new instance of the check. */
     public IllegalTypeCheck() {
         setIllegalClassNames(DEFAULT_ILLEGAL_TYPES);
         setIgnoredMethodNames(DEFAULT_IGNORED_METHOD_NAMES);
     }
 
     /**
      * Set the format for the specified regular expression.
      * @param pattern a pattern.
      */
     public void setIllegalAbstractClassNameFormat(Pattern pattern) {
         illegalAbstractClassNameFormat = pattern;
     }
 
     /**
      * Sets whether to validate abstract class names.
      * @param validateAbstractClassNames whether abstract class names must be ignored.
      */
     public void setValidateAbstractClassNames(boolean validateAbstractClassNames) {
         this.validateAbstractClassNames = validateAbstractClassNames;
     }
 
     @Override
     public int[] getDefaultTokens() {
         return getAcceptableTokens();
     }
 
     @Override
     public int[] getAcceptableTokens() {
         return new int[] {
             TokenTypes.ANNOTATION_FIELD_DEF,
             TokenTypes.CLASS_DEF,
             TokenTypes.IMPORT,
             TokenTypes.INTERFACE_DEF,
             TokenTypes.METHOD_CALL,
             TokenTypes.METHOD_DEF,
             TokenTypes.METHOD_REF,
             TokenTypes.PARAMETER_DEF,
             TokenTypes.VARIABLE_DEF,
         };
     }
 
     @Override
     public void beginTree(DetailAST rootAST) {
         illegalShortClassNames.clear();
 
         for (String s : illegalClassNames) {
             if (s.indexOf('.') == -1) {
                 illegalShortClassNames.add(s);
             }
         }
     }
 
     @Override
     public int[] getRequiredTokens() {
         return new int[] {TokenTypes.IMPORT};
     }
 
     @Override
     public void visitToken(DetailAST ast) {
         switch (ast.getType()) {
             case TokenTypes.CLASS_DEF:
             case TokenTypes.INTERFACE_DEF:
                 visitTypeDef(ast);
                 break;
             case TokenTypes.METHOD_CALL:
             case TokenTypes.METHOD_REF:
                 visitMethodCallOrRef(ast);
                 break;
             case TokenTypes.METHOD_DEF:
                 visitMethodDef(ast);
                 break;
             case TokenTypes.VARIABLE_DEF:
             case TokenTypes.ANNOTATION_FIELD_DEF:
                 visitVariableDef(ast);
                 break;
             case TokenTypes.PARAMETER_DEF:
                 visitParameterDef(ast);
                 break;
             case TokenTypes.IMPORT:
                 visitImport(ast);
                 break;
             default:
                 throw new IllegalStateException(ast.toString());
         }
     }
 
     /**
      * Checks if current method's return type or variable's type is verifiable
      * according to <b>memberModifiers</b> option.
      * @param methodOrVariableDef METHOD_DEF or VARIABLE_DEF ast node.
      * @return true if member is verifiable according to <b>memberModifiers</b> option.
      */
     private boolean isVerifiable(DetailAST methodOrVariableDef) {
         boolean result = true;
         if (memberModifiers != null) {
             final DetailAST modifiersAst = methodOrVariableDef
                     .findFirstToken(TokenTypes.MODIFIERS);
             result = isContainVerifiableType(modifiersAst);
         }
         return result;
     }
 
     /**
      * Checks is modifiers contain verifiable type.
      *
      * @param modifiers
      *            parent node for all modifiers
      * @return true if method or variable can be verified
      */
     private boolean isContainVerifiableType(DetailAST modifiers) {
         boolean result = false;
         if (modifiers.getFirstChild() != null) {
             for (DetailAST modifier = modifiers.getFirstChild(); modifier != null;
                      modifier = modifier.getNextSibling()) {
                 if (memberModifiers.contains(modifier.getType())) {
                     result = true;
                     break;
                 }
             }
         }
         return result;
     }
 
     /**
      * Checks the super type and implemented interfaces of a given type.
      * @param typeDef class or interface for check.
      */
     private void visitTypeDef(DetailAST typeDef) {
         if (isVerifiable(typeDef)) {
             checkTypeParameters(typeDef);
             final DetailAST extendsClause = typeDef.findFirstToken(TokenTypes.EXTENDS_CLAUSE);
             if (extendsClause != null) {
                 checkBaseTypes(extendsClause);
             }
             final DetailAST implementsClause = typeDef.findFirstToken(TokenTypes.IMPLEMENTS_CLAUSE);
             if (implementsClause != null) {
                 checkBaseTypes(implementsClause);
             }
         }
     }
 
     /**
      * Checks return type of a given method.
      * @param methodDef method for check.
      */
     private void visitMethodDef(DetailAST methodDef) {
         if (isVerifiable(methodDef) && isCheckedMethod(methodDef)) {
             checkClassName(methodDef);
         }
     }
 
     /**
      * Checks type of parameters.
      * @param parameterDef parameter list for check.
      */
     private void visitParameterDef(DetailAST parameterDef) {
         final DetailAST grandParentAST = parameterDef.getParent().getParent();
 
         if (grandParentAST.getType() == TokenTypes.METHOD_DEF
             && isCheckedMethod(grandParentAST)
             && isVerifiable(grandParentAST)) {
             checkClassName(parameterDef);
         }
     }
 
     /**
      * Checks type of given variable.
      * @param variableDef variable to check.
      */
     private void visitVariableDef(DetailAST variableDef) {
         if (isVerifiable(variableDef)) {
             checkClassName(variableDef);
         }
     }
 
     /**
      * Checks the type arguments of given method call/reference.
      * @param methodCallOrRef method call/reference to check.
      */
     private void visitMethodCallOrRef(DetailAST methodCallOrRef) {
         checkTypeArguments(methodCallOrRef);
     }
 
     /**
      * Checks imported type (as static and star imports are not supported by Check,
      *  only type is in the consideration).<br>
      * If this type is illegal due to Check's options - puts violation on it.
      * @param importAst {@link TokenTypes#IMPORT Import}
      */
     private void visitImport(DetailAST importAst) {
         if (!isStarImport(importAst)) {
             final String canonicalName = getImportedTypeCanonicalName(importAst);
             extendIllegalClassNamesWithShortName(canonicalName);
         }
     }
 
     /**
      * Checks if current import is star import. E.g.:
      * <p>
      * {@code
      * import java.util.*;
      * }
      * </p>
      * @param importAst {@link TokenTypes#IMPORT Import}
      * @return true if it is star import
      */
     private static boolean isStarImport(DetailAST importAst) {
         boolean result = false;
         DetailAST toVisit = importAst;
         while (toVisit != null) {
             toVisit = getNextSubTreeNode(toVisit, importAst);
             if (toVisit != null && toVisit.getType() == TokenTypes.STAR) {
                 result = true;
                 break;
             }
         }
         return result;
     }
 
     /**
      * Checks type and type arguments/parameters of given method, parameter, variable or
      * method call/reference.
      * @param ast node to check.
      */
     private void checkClassName(DetailAST ast) {
         final DetailAST type = ast.findFirstToken(TokenTypes.TYPE);
         checkType(type);
         checkTypeParameters(ast);
     }
 
     /**
      * Checks the identifier of the given type.
      * @param type node to check.
      */
     private void checkIdent(DetailAST type) {
         final FullIdent ident = FullIdent.createFullIdent(type);
         if (isMatchingClassName(ident.getText())) {
             log(ident.getDetailAst(), MSG_KEY, ident.getText());
         }
     }
 
     /**
      * Checks the {@code extends} or {@code implements} statement.
      * @param clause DetailAST for either {@link TokenTypes#EXTENDS_CLAUSE} or
      *               {@link TokenTypes#IMPLEMENTS_CLAUSE}
      */
     private void checkBaseTypes(DetailAST clause) {
         DetailAST child = clause.getFirstChild();
         while (child != null) {
             if (child.getType() == TokenTypes.IDENT) {
                 checkIdent(child);
             }
             else if (child.getType() == TokenTypes.TYPE_ARGUMENTS) {
                 TokenUtil.forEachChild(child, TokenTypes.TYPE_ARGUMENT, this::checkType);
             }
             child = child.getNextSibling();
         }
     }
 
     /**
      * Checks the given type, its arguments and parameters.
      * @param type node to check.
      */
     private void checkType(DetailAST type) {
         checkIdent(type.getFirstChild());
         checkTypeArguments(type);
         checkTypeBounds(type);
     }
 
     /**
      * Checks the upper and lower bounds for the given type.
      * @param type node to check.
      */
     private void checkTypeBounds(DetailAST type) {
         final DetailAST upperBounds = type.findFirstToken(TokenTypes.TYPE_UPPER_BOUNDS);
         if (upperBounds != null) {
             checkType(upperBounds);
         }
         final DetailAST lowerBounds = type.findFirstToken(TokenTypes.TYPE_LOWER_BOUNDS);
         if (lowerBounds != null) {
             checkType(lowerBounds);
         }
     }
 
     /**
      * Checks the type parameters of the node.
      * @param node node to check.
      */
     private void checkTypeParameters(final DetailAST node) {
         final DetailAST typeParameters = node.findFirstToken(TokenTypes.TYPE_PARAMETERS);
         if (typeParameters != null) {
             TokenUtil.forEachChild(typeParameters, TokenTypes.TYPE_PARAMETER, this::checkType);
         }
     }
 
     /**
      * Checks the type arguments of the node.
      * @param node node to check.
      */
     private void checkTypeArguments(final DetailAST node) {
         DetailAST typeArguments = node.findFirstToken(TokenTypes.TYPE_ARGUMENTS);
         if (typeArguments == null) {
             typeArguments = node.getFirstChild().findFirstToken(TokenTypes.TYPE_ARGUMENTS);
         }
 
         if (typeArguments != null) {
             TokenUtil.forEachChild(typeArguments, TokenTypes.TYPE_ARGUMENT, this::checkType);
         }
     }
 
     /**
      * Returns true if given class name is one of illegal classes or else false.
      * @param className class name to check.
      * @return true if given class name is one of illegal classes
      *         or if it matches to abstract class names pattern.
      */
     private boolean isMatchingClassName(String className) {
         final String shortName = className.substring(className.lastIndexOf('.') + 1);
         return illegalClassNames.contains(className)
                 || illegalShortClassNames.contains(shortName)
                 || validateAbstractClassNames
                     && !legalAbstractClassNames.contains(className)
                     && illegalAbstractClassNameFormat.matcher(className).find();
     }
 
     /**
      * Extends illegal class names set via imported short type name.
      * @param canonicalName
      *  <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-6.html#jls-6.7">
      *  Canonical</a> name of imported type.
      */
     private void extendIllegalClassNamesWithShortName(String canonicalName) {
         if (illegalClassNames.contains(canonicalName)) {
             final String shortName = canonicalName
                 .substring(canonicalName.lastIndexOf('.') + 1);
             illegalShortClassNames.add(shortName);
         }
     }
 
     /**
      * Gets imported type's
      * <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-6.html#jls-6.7">
      *  canonical name</a>.
      * @param importAst {@link TokenTypes#IMPORT Import}
      * @return Imported canonical type's name.
      */
     private static String getImportedTypeCanonicalName(DetailAST importAst) {
         final StringBuilder canonicalNameBuilder = new StringBuilder(256);
         DetailAST toVisit = importAst;
         while (toVisit != null) {
             toVisit = getNextSubTreeNode(toVisit, importAst);
             if (toVisit != null && toVisit.getType() == TokenTypes.IDENT) {
                 if (canonicalNameBuilder.length() > 0) {
                     canonicalNameBuilder.append('.');
                 }
                 canonicalNameBuilder.append(toVisit.getText());
             }
         }
         return canonicalNameBuilder.toString();
     }
 
     /**
      * Gets the next node of a syntactical tree (child of a current node or
      * sibling of a current node, or sibling of a parent of a current node).
      * @param currentNodeAst Current node in considering
      * @param subTreeRootAst SubTree root
      * @return Current node after bypassing, if current node reached the root of a subtree
      *        method returns null
      */
     private static DetailAST
         getNextSubTreeNode(DetailAST currentNodeAst, DetailAST subTreeRootAst) {
         DetailAST currentNode = currentNodeAst;
         DetailAST toVisitAst = currentNode.getFirstChild();
         while (toVisitAst == null) {
             toVisitAst = currentNode.getNextSibling();
             if (toVisitAst == null) {
                 if (currentNode.getParent().equals(subTreeRootAst)) {
                     break;
                 }
                 currentNode = currentNode.getParent();
             }
         }
         return toVisitAst;
     }
 
     /**
      * Returns true if method has to be checked or false.
      * @param ast method def to check.
      * @return true if we should check this method.
      */
     private boolean isCheckedMethod(DetailAST ast) {
         final String methodName =
             ast.findFirstToken(TokenTypes.IDENT).getText();
         return !ignoredMethodNames.contains(methodName);
     }
 
     /**
      * Set the list of illegal variable types.
      * @param classNames array of illegal variable types
      * @noinspection WeakerAccess
      */
     public void setIllegalClassNames(String... classNames) {
         illegalClassNames.clear();
         Collections.addAll(illegalClassNames, classNames);
     }
 
     /**
      * Set the list of ignore method names.
      * @param methodNames array of ignored method names
      * @noinspection WeakerAccess
      */
     public void setIgnoredMethodNames(String... methodNames) {
         ignoredMethodNames.clear();
         Collections.addAll(ignoredMethodNames, methodNames);
     }
 
     /**
      * Set the list of legal abstract class names.
      * @param classNames array of legal abstract class names
      * @noinspection WeakerAccess
      */
     public void setLegalAbstractClassNames(String... classNames) {
         Collections.addAll(legalAbstractClassNames, classNames);
     }
 
     /**
      * Set the list of member modifiers (of methods and fields) which should be checked.
      * @param modifiers String contains modifiers.
      */
     public void setMemberModifiers(String modifiers) {
         final List<Integer> modifiersList = new ArrayList<>();
         for (String modifier : modifiers.split(",")) {
             modifiersList.add(TokenUtil.getTokenId(modifier.trim()));
         }
         memberModifiers = modifiersList;
     }
 
 }