////////////////////////////////////////////////////////////////////////////////
   // 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.imports;
  
  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.FullIdent;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
  
  /**
   * <p>
   * Check that finds static imports.
   * </p>
   * <p>
   * Rationale: Importing static members can lead to naming conflicts
   * between class' members. It may lead to poor code readability since it
   * may no longer be clear what class a member resides (without looking
   * at the import statement).
   * </p>
   * <p>
   * An example of how to configure the check is:
   * </p>
   * <pre>
   * &lt;module name="AvoidStaticImport"&gt;
   *   &lt;property name="excludes"
   *       value="java.lang.System.out,java.lang.Math.*"/&gt;
   * &lt;/module&gt;
   * </pre>
   * The optional "excludes" property allows for certain classes via a star
   * notation to be excluded such as java.lang.Math.* or specific
   * static members to be excluded like java.lang.System.out for a variable
   * or java.lang.Math.random for a method.
   *
   * <p>
   * If you exclude a starred import on a class this automatically
   * excludes each member individually.
   * </p>
   *
   * <p>
   * For example:
   * Excluding java.lang.Math.* will allow the import of
   * each static member in the Math class individually like
   * java.lang.Math.PI
   * </p>
   */
  @StatelessCheck
  public class AvoidStaticImportCheck
      extends AbstractCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY = "import.avoidStatic";
  
      /** The classes/static members to exempt from this check. */
      private String[] excludes = CommonUtil.EMPTY_STRING_ARRAY;
  
      @Override
      public int[] getDefaultTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getAcceptableTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getRequiredTokens() {
          return new int[] {TokenTypes.STATIC_IMPORT};
      }
  
      /**
       * Sets the list of classes or static members to be exempt from the check.
       * @param excludes a list of fully-qualified class names/specific
       *     static members where static imports are ok
       */
      public void setExcludes(String... excludes) {
          this.excludes = excludes.clone();
     }
 
     @Override
     public void visitToken(final DetailAST ast) {
         final DetailAST startingDot =
             ast.getFirstChild().getNextSibling();
         final FullIdent name = FullIdent.createFullIdent(startingDot);
 
         if (!isExempt(name.getText())) {
             log(startingDot.getLineNo(), MSG_KEY, name.getText());
         }
     }
 
     /**
      * Checks if a class or static member is exempt from known excludes.
      *
      * @param classOrStaticMember
      *                the class or static member
      * @return true if except false if not
      */
     private boolean isExempt(String classOrStaticMember) {
         boolean exempt = false;
 
         for (String exclude : excludes) {
             if (classOrStaticMember.equals(exclude)
                     || isStarImportOfPackage(classOrStaticMember, exclude)) {
                 exempt = true;
                 break;
             }
         }
         return exempt;
     }
 
     /**
      * Returns true if classOrStaticMember is a starred name of package,
      *  not just member name.
      * @param classOrStaticMember - full name of member
      * @param exclude - current exclusion
      * @return true if member in exclusion list
      */
     private static boolean isStarImportOfPackage(String classOrStaticMember, String exclude) {
         boolean result = false;
         if (exclude.endsWith(".*")) {
             //this section allows explicit imports
             //to be exempt when configured using
             //a starred import
             final String excludeMinusDotStar =
                 exclude.substring(0, exclude.length() - 2);
             if (classOrStaticMember.startsWith(excludeMinusDotStar)
                     && !classOrStaticMember.equals(excludeMinusDotStar)) {
                 final String member = classOrStaticMember.substring(
                         excludeMinusDotStar.length() + 1);
                 //if it contains a dot then it is not a member but a package
                 if (member.indexOf('.') == -1) {
                     result = true;
                 }
             }
         }
         return result;
     }
 
 }