////////////////////////////////////////////////////////////////////////////////
   // 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 java.net.URI;
  import java.util.Collections;
  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.CheckstyleException;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.ExternalResourceHolder;
  import com.puppycrawl.tools.checkstyle.api.FullIdent;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  
  /**
   * Check that controls what can be imported in each package and file. Useful
   * for ensuring that application layering is not violated. Ideas on how the
   * check can be improved include support for:
   * <ul>
   * <li>
   * Change the default policy that if a package being checked does not
   * match any guards, then it is allowed. Currently defaults to disallowed.
   * </li>
   * </ul>
   *
   */
  @FileStatefulCheck
  public class ImportControlCheck extends AbstractCheck implements ExternalResourceHolder {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_MISSING_FILE = "import.control.missing.file";
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_UNKNOWN_PKG = "import.control.unknown.pkg";
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_DISALLOWED = "import.control.disallowed";
  
      /**
       * A part of message for exception.
       */
      private static final String UNABLE_TO_LOAD = "Unable to load ";
  
      /** Location of import control file. */
      private URI file;
  
      /** The filepath pattern this check applies to. */
      private Pattern path = Pattern.compile(".*");
      /** Whether to process the current file. */
      private boolean processCurrentFile;
  
      /** The root package controller. */
      private PkgImportControl root;
      /** The package doing the import. */
      private String packageName;
      /** The file name doing the import. */
      private String fileName;
  
      /**
       * The package controller for the current file. Used for performance
       * optimisation.
       */
      private AbstractImportControl currentImportControl;
  
      @Override
      public int[] getDefaultTokens() {
          return getRequiredTokens();
      }
  
      @Override
     public int[] getAcceptableTokens() {
         return getRequiredTokens();
     }
 
     @Override
     public int[] getRequiredTokens() {
         return new int[] {TokenTypes.PACKAGE_DEF, TokenTypes.IMPORT, TokenTypes.STATIC_IMPORT, };
     }
 
     @Override
     public void beginTree(DetailAST rootAST) {
         currentImportControl = null;
         processCurrentFile = path.matcher(getFileContents().getFileName()).find();
         fileName = getFileContents().getText().getFile().getName();
 
         final int period = fileName.lastIndexOf('.');
 
         if (period != -1) {
             fileName = fileName.substring(0, period);
         }
     }
 
     @Override
     public void visitToken(DetailAST ast) {
         if (processCurrentFile) {
             if (ast.getType() == TokenTypes.PACKAGE_DEF) {
                 if (root == null) {
                     log(ast, MSG_MISSING_FILE);
                 }
                 else {
                     packageName = getPackageText(ast);
                     currentImportControl = root.locateFinest(packageName, fileName);
                     if (currentImportControl == null) {
                         log(ast, MSG_UNKNOWN_PKG);
                     }
                 }
             }
             else if (currentImportControl != null) {
                 final String importText = getImportText(ast);
                 final AccessResult access = currentImportControl.checkAccess(packageName, fileName,
                         importText);
                 if (access != AccessResult.ALLOWED) {
                     log(ast, MSG_DISALLOWED, importText);
                 }
             }
         }
     }
 
     @Override
     public Set<String> getExternalResourceLocations() {
         return Collections.singleton(file.toString());
     }
 
     /**
      * Returns package text.
      * @param ast PACKAGE_DEF ast node
      * @return String that represents full package name
      */
     private static String getPackageText(DetailAST ast) {
         final DetailAST nameAST = ast.getLastChild().getPreviousSibling();
         return FullIdent.createFullIdent(nameAST).getText();
     }
 
     /**
      * Returns import text.
      * @param ast ast node that represents import
      * @return String that represents importing class
      */
     private static String getImportText(DetailAST ast) {
         final FullIdent imp;
         if (ast.getType() == TokenTypes.IMPORT) {
             imp = FullIdent.createFullIdentBelow(ast);
         }
         else {
             // know it is a static import
             imp = FullIdent.createFullIdent(ast
                     .getFirstChild().getNextSibling());
         }
         return imp.getText();
     }
 
     /**
      * Set the name for the file containing the import control
      * configuration. It can also be a URL or resource in the classpath.
      * It will cause the file to be loaded.
      * @param uri the uri of the file to load.
      * @throws IllegalArgumentException on error loading the file.
      */
     public void setFile(URI uri) {
         // Handle empty param
         if (uri != null) {
             try {
                 root = ImportControlLoader.load(uri);
                 file = uri;
             }
             catch (CheckstyleException ex) {
                 throw new IllegalArgumentException(UNABLE_TO_LOAD + uri, ex);
             }
         }
     }
 
     /**
      * Set the file path pattern that this check applies to.
      * @param pattern the file path regex this check should apply to.
      */
     public void setPath(Pattern pattern) {
         path = pattern;
     }
 
 }