////////////////////////////////////////////////////////////////////////////////
   // 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.naming;
  
  import java.util.regex.Pattern;
  
  import com.puppycrawl.tools.checkstyle.StatelessCheck;
  import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  
  /**
   * <p>
   * Ensures that the names of abstract classes conforming to some regular
   * expression and check that {@code abstract} modifier exists.
   * </p>
   * <p>
   * Rationale: Abstract classes are convenience base class implementations of
   * interfaces, not types as such. As such they should be named to indicate this.
   * Also if names of classes starts with 'Abstract' it's very convenient that
   * they will have abstract modifier.
   * </p>
   * <ul>
   * <li>
   * Property {@code format} - Specify valid identifiers. Default value is
   * {@code "^Abstract.+$"}.</li>
   * <li>
   * Property {@code ignoreModifier} - Control whether to ignore checking for the
   * {@code abstract} modifier on classes that match the name. Default value is
   * {@code false}.</li>
   * <li>
   * Property {@code ignoreName} - Control whether to ignore checking the name.
   * Realistically only useful if using the check to identify that match name and
   * do not have the {@code abstract} modifier. Default value is
   * {@code false}.</li>
   * </ul>
   * <p>
   * The following example shows how to configure the {@code AbstractClassName} to
   * checks names, but ignore missing {@code abstract} modifiers:
   * </p>
   * <p>Configuration:</p>
   * <pre>
   * &lt;module name="AbstractClassName"&gt;
   *   &lt;property name="ignoreModifier" value="true"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>Example:</p>
   * <pre>
   * abstract class AbstractFirstClass {} // OK
   * abstract class SecondClass {} // violation, it should match the pattern "^Abstract.+$"
   * class AbstractThirdClass {} // OK, no "abstract" modifier
   * </pre>
   * @since 3.2
   */
  @StatelessCheck
  public final class AbstractClassNameCheck extends AbstractCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_ILLEGAL_ABSTRACT_CLASS_NAME = "illegal.abstract.class.name";
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_NO_ABSTRACT_CLASS_MODIFIER = "no.abstract.class.modifier";
  
      /**
       * Control whether to ignore checking for the {@code abstract} modifier on
       * classes that match the name.
       */
      private boolean ignoreModifier;
  
      /**
       * Control whether to ignore checking the name. Realistically only useful
       * if using the check to identify that match name and do not have the
       * {@code abstract} modifier.
       */
      private boolean ignoreName;
  
     /** Specify valid identifiers. */
     private Pattern format = Pattern.compile("^Abstract.+$");
 
     /**
      * Setter to control whether to ignore checking for the {@code abstract} modifier on
      * classes that match the name.
      * @param value new value
      */
     public void setIgnoreModifier(boolean value) {
         ignoreModifier = value;
     }
 
     /**
      * Setter to control whether to ignore checking the name. Realistically only useful if
      * using the check to identify that match name and do not have the {@code abstract} modifier.
      * @param value new value.
      */
     public void setIgnoreName(boolean value) {
         ignoreName = value;
     }
 
     /**
      * Setter to specify valid identifiers.
      * @param pattern the new pattern
      */
     public void setFormat(Pattern pattern) {
         format = pattern;
     }
 
     @Override
     public int[] getDefaultTokens() {
         return getRequiredTokens();
     }
 
     @Override
     public int[] getRequiredTokens() {
         return new int[] {TokenTypes.CLASS_DEF};
     }
 
     @Override
     public int[] getAcceptableTokens() {
         return getRequiredTokens();
     }
 
     @Override
     public void visitToken(DetailAST ast) {
         visitClassDef(ast);
     }
 
     /**
      * Checks class definition.
      * @param ast class definition for check.
      */
     private void visitClassDef(DetailAST ast) {
         final String className =
             ast.findFirstToken(TokenTypes.IDENT).getText();
         if (isAbstract(ast)) {
             // if class has abstract modifier
             if (!ignoreName && !isMatchingClassName(className)) {
                 log(ast, MSG_ILLEGAL_ABSTRACT_CLASS_NAME, className, format.pattern());
             }
         }
         else if (!ignoreModifier && isMatchingClassName(className)) {
             log(ast, MSG_NO_ABSTRACT_CLASS_MODIFIER, className);
         }
     }
 
     /**
      * Checks if declared class is abstract or not.
      * @param ast class definition for check.
      * @return true if a given class declared as abstract.
      */
     private static boolean isAbstract(DetailAST ast) {
         final DetailAST abstractAST = ast.findFirstToken(TokenTypes.MODIFIERS)
             .findFirstToken(TokenTypes.ABSTRACT);
 
         return abstractAST != null;
     }
 
     /**
      * Returns true if class name matches format of abstract class names.
      * @param className class name for check.
      * @return true if class name matches format of abstract class names.
      */
     private boolean isMatchingClassName(String className) {
         return format.matcher(className).find();
     }
 
 }