///////////////////////////////////////////////////////////////////////////////////////////////
   // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
   // Copyright (C) 2001-2026 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.ArrayDeque;
  import java.util.Deque;
  import java.util.HashSet;
  import java.util.Set;
  
  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.TokenTypes;
  import com.puppycrawl.tools.checkstyle.utils.CheckUtil;
  import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
  
  /**
   * <div>
   * Disallows assignment of parameters.
   * </div>
   *
   * <p>
   * Rationale:
   * Parameter assignment is often considered poor
   * programming practice. Forcing developers to declare
   * parameters as final is often onerous. Having a check
   * ensure that parameters are never assigned would give
   * the best of both worlds.
   * </p>
   *
   * @since 3.2
   */
  @FileStatefulCheck
  public final class ParameterAssignmentCheck extends AbstractCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY = "parameter.assignment";
  
      /** Stack of methods' parameters. */
      private final Deque<Set<String>> parameterNamesStack = new ArrayDeque<>();
      /** Current set of parameters. */
      private Set<String> parameterNames;
  
      /**
       * Creates a new {@code ParameterAssignmentCheck} instance.
       */
      public ParameterAssignmentCheck() {
          // no code by default
      }
  
      @Override
      public int[] getDefaultTokens() {
          return getRequiredTokens();
      }
  
      @Override
      public int[] getRequiredTokens() {
          return new int[] {
              TokenTypes.CTOR_DEF,
              TokenTypes.METHOD_DEF,
              TokenTypes.ASSIGN,
              TokenTypes.PLUS_ASSIGN,
              TokenTypes.MINUS_ASSIGN,
              TokenTypes.STAR_ASSIGN,
              TokenTypes.DIV_ASSIGN,
              TokenTypes.MOD_ASSIGN,
              TokenTypes.SR_ASSIGN,
              TokenTypes.BSR_ASSIGN,
              TokenTypes.SL_ASSIGN,
              TokenTypes.BAND_ASSIGN,
              TokenTypes.BXOR_ASSIGN,
              TokenTypes.BOR_ASSIGN,
              TokenTypes.INC,
              TokenTypes.POST_INC,
              TokenTypes.DEC,
              TokenTypes.POST_DEC,
              TokenTypes.LAMBDA,
          };
      }
 
     @Override
     public int[] getAcceptableTokens() {
         return getRequiredTokens();
     }
 
     @Override
     public void beginTree(DetailAST rootAST) {
         // clear data
         parameterNamesStack.clear();
         parameterNames = Set.of();
     }
 
     @Override
     public void visitToken(DetailAST ast) {
         final int type = ast.getType();
         if (TokenUtil.isOfType(type, TokenTypes.CTOR_DEF, TokenTypes.METHOD_DEF)) {
             visitMethodDef(ast);
         }
         else if (type == TokenTypes.LAMBDA) {
             if (ast.getParent().getType() != TokenTypes.SWITCH_RULE) {
                 visitLambda(ast);
             }
         }
         else {
             checkNestedIdent(ast);
         }
     }
 
     @Override
     public void leaveToken(DetailAST ast) {
         final int type = ast.getType();
         if (TokenUtil.isOfType(type, TokenTypes.CTOR_DEF, TokenTypes.METHOD_DEF)
                 || type == TokenTypes.LAMBDA
                 && ast.getParent().getType() != TokenTypes.SWITCH_RULE) {
             parameterNames = parameterNamesStack.pop();
         }
     }
 
     /**
      * Check if nested ident is parameter.
      *
      * @param ast parent of node of ident
      */
     private void checkNestedIdent(DetailAST ast) {
         final DetailAST identAST = ast.getFirstChild();
 
         if (identAST != null
             && identAST.getType() == TokenTypes.IDENT
             && parameterNames.contains(identAST.getText())) {
             log(ast, MSG_KEY, identAST.getText());
         }
     }
 
     /**
      * Creates new set of parameters and store old one in stack.
      *
      * @param ast a method to process.
      */
     private void visitMethodDef(DetailAST ast) {
         parameterNamesStack.push(parameterNames);
         parameterNames = new HashSet<>();
 
         visitMethodParameters(ast.findFirstToken(TokenTypes.PARAMETERS));
     }
 
     /**
      * Creates new set of parameters and store old one in stack.
      *
      * @param lambdaAst node of type {@link TokenTypes#LAMBDA}.
      */
     private void visitLambda(DetailAST lambdaAst) {
         parameterNamesStack.push(parameterNames);
         parameterNames = new HashSet<>();
 
         DetailAST parameterAst = lambdaAst.findFirstToken(TokenTypes.PARAMETERS);
         if (parameterAst == null) {
             parameterAst = lambdaAst.getFirstChild();
         }
         visitLambdaParameters(parameterAst);
     }
 
     /**
      * Creates new parameter set for given method.
      *
      * @param ast a method for process.
      */
     private void visitMethodParameters(DetailAST ast) {
         visitParameters(ast);
     }
 
     /**
      * Creates new parameter set for given lambda expression.
      *
      * @param ast a lambda expression parameter to process
      */
     private void visitLambdaParameters(DetailAST ast) {
         if (ast.getType() == TokenTypes.IDENT) {
             parameterNames.add(ast.getText());
         }
         else {
             visitParameters(ast);
         }
     }
 
     /**
      * Visits parameter list and adds parameter names to the set.
      *
      * @param parametersAst ast node of type {@link TokenTypes#PARAMETERS}.
      */
     private void visitParameters(DetailAST parametersAst) {
         DetailAST parameterDefAST =
             parametersAst.findFirstToken(TokenTypes.PARAMETER_DEF);
 
         while (parameterDefAST != null) {
             if (!CheckUtil.isReceiverParameter(parameterDefAST)) {
                 final DetailAST param =
                     parameterDefAST.findFirstToken(TokenTypes.IDENT);
                 parameterNames.add(param.getText());
             }
             parameterDefAST = parameterDefAST.getNextSibling();
         }
     }
 
 }