///////////////////////////////////////////////////////////////////////////////////////////////
   // 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.HashSet;
  import java.util.Locale;
  import java.util.Objects;
  import java.util.Set;
  import java.util.regex.Pattern;
  
  import javax.annotation.Nullable;
  
  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.Scope;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.utils.CheckUtil;
  import com.puppycrawl.tools.checkstyle.utils.ScopeUtil;
  import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
  
  /**
   * <div>
   * Checks that a local variable or a parameter does not shadow
   * a field that is defined in the same class.
   * </div>
   *
   * <p>
   * Notes:
   * It is possible to configure the check to ignore all property setter methods.
   * </p>
   *
   * <p>
   * A method is recognized as a setter if it is in the following form
   * </p>
   * {@snippet lang="text" :
   * ${returnType} set${Name}(${anyType} ${name}) { ... }
   * }
   *
   * <p>
   * where ${anyType} is any primitive type, class or interface name;
   * ${name} is name of the variable that is being set and ${Name} its
   * capitalized form that appears in the method name. By default, it is expected
   * that setter returns void, i.e. ${returnType} is 'void'. For example
   * </p>
   * {@snippet lang="text" :
   * void setTime(long time) {  }
   * }
   *
   * <p>
   * Any other return types will not let method match a setter pattern. However,
   * by setting <em>setterCanReturnItsClass</em> property to <em>true</em>
   * definition of a setter is expanded, so that setter return type can also be
   * a class in which setter is declared. For example
   * </p>
   * {@snippet lang="text" :
   * class PageBuilder {
   *   PageBuilder setName(String name) {  }
   * }
   * }
   *
   * <p>
   * Such methods are known as chain-setters and a common when Builder-pattern
   * is used. Property <em>setterCanReturnItsClass</em> has effect only if
   * <em>ignoreSetter</em> is set to true.
   * </p>
   *
   * @since 3.0
   */
  @FileStatefulCheck
  public class HiddenFieldCheck
      extends AbstractCheck {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY = "hidden.field";
  
      /**
       * Stack of sets of field names,
       * one for each class of a set of nested classes.
      */
     private FieldFrame frame;
 
     /** Define the RegExp for names of variables and parameters to ignore. */
     private Pattern ignoreFormat;
 
     /**
      * Allow to ignore the parameter of a property setter method.
      */
     private boolean ignoreSetter;
 
     /**
      * Allow to expand the definition of a setter method to include methods
      * that return the class' instance.
      */
     private boolean setterCanReturnItsClass;
 
     /** Control whether to ignore constructor parameters. */
     private boolean ignoreConstructorParameter;
 
     /** Control whether to ignore parameters of abstract methods. */
     private boolean ignoreAbstractMethods;
 
     /**
      * Creates a new {@code HiddenFieldCheck} instance.
      */
     public HiddenFieldCheck() {
         // no code by default
     }
 
     @Override
     public int[] getDefaultTokens() {
         return getAcceptableTokens();
     }
 
     @Override
     public int[] getAcceptableTokens() {
         return new int[] {
             TokenTypes.VARIABLE_DEF,
             TokenTypes.PARAMETER_DEF,
             TokenTypes.CLASS_DEF,
             TokenTypes.ENUM_DEF,
             TokenTypes.ENUM_CONSTANT_DEF,
             TokenTypes.PATTERN_VARIABLE_DEF,
             TokenTypes.LAMBDA,
             TokenTypes.RECORD_DEF,
             TokenTypes.RECORD_COMPONENT_DEF,
             TokenTypes.COMPACT_COMPILATION_UNIT,
         };
     }
 
     @Override
     public int[] getRequiredTokens() {
         return new int[] {
             TokenTypes.CLASS_DEF,
             TokenTypes.ENUM_DEF,
             TokenTypes.ENUM_CONSTANT_DEF,
             TokenTypes.RECORD_DEF,
             TokenTypes.COMPACT_COMPILATION_UNIT,
         };
     }
 
     @Override
     public void beginTree(DetailAST rootAST) {
         frame = new FieldFrame(null, true, null);
     }
 
     @Override
     public void visitToken(DetailAST ast) {
         final int type = ast.getType();
         switch (type) {
             case TokenTypes.VARIABLE_DEF,
                  TokenTypes.PARAMETER_DEF,
                  TokenTypes.PATTERN_VARIABLE_DEF,
                  TokenTypes.RECORD_COMPONENT_DEF -> processVariable(ast);
             case TokenTypes.LAMBDA -> processLambda(ast);
             default -> visitOtherTokens(ast, type);
         }
     }
 
     /**
      * Process a lambda token.
      * Checks whether a lambda parameter shadows a field.
      * Note, that when parameter of lambda expression is untyped,
      * ANTLR parses the parameter as an identifier.
      *
      * @param ast the lambda token.
      */
     private void processLambda(DetailAST ast) {
         final DetailAST firstChild = ast.getFirstChild();
         if (TokenUtil.isOfType(firstChild, TokenTypes.IDENT)) {
             final String untypedLambdaParameterName = firstChild.getText();
             if (frame.containsStaticField(untypedLambdaParameterName)
                 || isInstanceField(firstChild, untypedLambdaParameterName)) {
                 log(firstChild, MSG_KEY, untypedLambdaParameterName);
             }
         }
     }
 
     /**
      * Called to process tokens other than {@link TokenTypes#VARIABLE_DEF}
      * and {@link TokenTypes#PARAMETER_DEF}.
      *
      * @param ast token to process
      * @param type type of the token
      */
     private void visitOtherTokens(DetailAST ast, int type) {
         // A more thorough check of enum constant class bodies is
         // possible (checking for hidden fields against the enum
         // class body in addition to enum constant class bodies)
         // but not attempted as it seems out of the scope of this
         // check.
         final DetailAST typeMods = ast.findFirstToken(TokenTypes.MODIFIERS);
         final boolean isStaticInnerType =
                 typeMods != null
                         && typeMods.findFirstToken(TokenTypes.LITERAL_STATIC) != null
                         // inner record is implicitly static
                         || ast.getType() == TokenTypes.RECORD_DEF;
         final String frameName;
 
         if (type == TokenTypes.CLASS_DEF
                 || type == TokenTypes.ENUM_DEF) {
             frameName = ast.findFirstToken(TokenTypes.IDENT).getText();
         }
         else {
             frameName = null;
         }
         final FieldFrame newFrame = new FieldFrame(frame, isStaticInnerType, frameName);
 
         // add fields to container
         final DetailAST objBlock = getFieldContainer(ast);
         // enum constants may not have bodies
         if (objBlock != null) {
             DetailAST child = objBlock.getFirstChild();
             while (child != null) {
                 if (child.getType() == TokenTypes.VARIABLE_DEF) {
                     final String name =
                         child.findFirstToken(TokenTypes.IDENT).getText();
                     final DetailAST mods =
                         child.findFirstToken(TokenTypes.MODIFIERS);
                     if (mods.findFirstToken(TokenTypes.LITERAL_STATIC) == null) {
                         newFrame.addInstanceField(name);
                     }
                     else {
                         newFrame.addStaticField(name);
                     }
                 }
                 child = child.getNextSibling();
             }
         }
         if (ast.getType() == TokenTypes.RECORD_DEF) {
             final DetailAST recordComponents =
                 ast.findFirstToken(TokenTypes.RECORD_COMPONENTS);
 
             // For each record component definition, we will add it to this frame.
             TokenUtil.forEachChild(recordComponents,
                 TokenTypes.RECORD_COMPONENT_DEF, node -> {
                     final String name = node.findFirstToken(TokenTypes.IDENT).getText();
                     newFrame.addInstanceField(name);
                 });
         }
         // push container
         frame = newFrame;
     }
 
     /**
      * Gets the member container for field declaration harvesting.
      *
      * @param ast the type definition node.
      * @return the member container, either the compact compilation unit
      *     itself or the OBJBLOCK child of a standard type definition.
      */
     @Nullable
     private static DetailAST getFieldContainer(DetailAST ast) {
         final DetailAST result;
         if (ast.getType() == TokenTypes.COMPACT_COMPILATION_UNIT) {
             result = ast;
         }
         else {
             result = ast.findFirstToken(TokenTypes.OBJBLOCK);
         }
         return result;
     }
 
     @Override
     public void leaveToken(DetailAST ast) {
         if (ast.getType() == TokenTypes.CLASS_DEF
             || ast.getType() == TokenTypes.ENUM_DEF
             || ast.getType() == TokenTypes.ENUM_CONSTANT_DEF
             || ast.getType() == TokenTypes.RECORD_DEF) {
             // pop
             frame = frame.getParent();
         }
     }
 
     /**
      * Process a variable token.
      * Check whether a local variable or parameter shadows a field.
      * Store a field for later comparison with local variables and parameters.
      *
      * @param ast the variable token.
      */
     private void processVariable(DetailAST ast) {
         if (!ScopeUtil.isInInterfaceOrAnnotationBlock(ast)
             && !CheckUtil.isReceiverParameter(ast)
             && (ScopeUtil.isLocalVariableDef(ast)
                 || ast.getType() == TokenTypes.PARAMETER_DEF
                 || ast.getType() == TokenTypes.PATTERN_VARIABLE_DEF)) {
             // local variable or parameter. Does it shadow a field?
             final DetailAST nameAST = ast.findFirstToken(TokenTypes.IDENT);
             final String name = nameAST.getText();
 
             if ((frame.containsStaticField(name) || isInstanceField(ast, name))
                     && !isMatchingRegexp(name)
                     && !isIgnoredParam(ast, name)) {
                 log(nameAST, MSG_KEY, name);
             }
         }
     }
 
     /**
      * Checks whether method or constructor parameter is ignored.
      *
      * @param ast the parameter token.
      * @param name the parameter name.
      * @return true if parameter is ignored.
      */
     private boolean isIgnoredParam(DetailAST ast, String name) {
         return isIgnoredSetterParam(ast, name)
             || isIgnoredConstructorParam(ast)
             || isIgnoredParamOfAbstractMethod(ast);
     }
 
     /**
      * Check for instance field.
      *
      * @param ast token
      * @param name identifier of token
      * @return true if instance field
      */
     private boolean isInstanceField(DetailAST ast, String name) {
         return !isInStatic(ast) && frame.containsInstanceField(name);
     }
 
     /**
      * Check name by regExp.
      *
      * @param name string value to check
      * @return true is regexp is matching
      */
     private boolean isMatchingRegexp(String name) {
         return ignoreFormat != null && ignoreFormat.matcher(name).find();
     }
 
     /**
      * Determines whether an AST node is in a static method or static
      * initializer.
      *
      * @param ast the node to check.
      * @return true if ast is in a static method or a static block;
      */
     private static boolean isInStatic(DetailAST ast) {
         DetailAST parent = ast.getParent();
         boolean inStatic = false;
 
         while (parent != null && !inStatic) {
             if (parent.getType() == TokenTypes.STATIC_INIT) {
                 inStatic = true;
             }
             else if (parent.getType() == TokenTypes.METHOD_DEF
                         && !ScopeUtil.isInScope(parent, Scope.ANONINNER)
                         || parent.getType() == TokenTypes.VARIABLE_DEF) {
                 final DetailAST mods =
                     parent.findFirstToken(TokenTypes.MODIFIERS);
                 inStatic = mods.findFirstToken(TokenTypes.LITERAL_STATIC) != null;
                 break;
             }
             else {
                 parent = parent.getParent();
             }
         }
         return inStatic;
     }
 
     /**
      * Decides whether to ignore an AST node that is the parameter of a
      * setter method, where the property setter method for field 'xyz' has
      * name 'setXyz', one parameter named 'xyz', and return type void
      * (default behavior) or return type is name of the class in which
      * such method is declared (allowed only if
      * {@link #setSetterCanReturnItsClass(boolean)} is called with
      * value <em>true</em>).
      *
      * @param ast the AST to check.
      * @param name the name of ast.
      * @return true if ast should be ignored because check property
      *     ignoreSetter is true and ast is the parameter of a setter method.
      */
     private boolean isIgnoredSetterParam(DetailAST ast, String name) {
         boolean isIgnoredSetterParam = false;
         if (ignoreSetter) {
             final DetailAST parametersAST = ast.getParent();
             final DetailAST methodAST = parametersAST.getParent();
             if (parametersAST.getChildCount() == 1
                 && methodAST.getType() == TokenTypes.METHOD_DEF
                 && isSetterMethod(methodAST, name)) {
                 isIgnoredSetterParam = true;
             }
         }
         return isIgnoredSetterParam;
     }
 
     /**
      * Determine if a specific method identified by methodAST and a single
      * variable name parameterName is a setter. This recognition partially depends
      * on setterCanReturnItsClass property.
      *
      * @param methodAST AST corresponding to a method call
      * @param parameterName name of single parameter of this method.
      * @return true of false indicating of method is a setter or not.
      */
     private boolean isSetterMethod(DetailAST methodAST, String parameterName) {
         final String methodName =
             methodAST.findFirstToken(TokenTypes.IDENT).getText();
         boolean isSetterMethod = false;
 
         if (("set" + capitalize(parameterName)).equals(methodName)) {
             // method name did match set${Name}(${anyType} ${parameterName})
             // where ${Name} is capitalized version of ${parameterName}
             // therefore this method is potentially a setter
             final DetailAST typeAST = methodAST.findFirstToken(TokenTypes.TYPE);
             final String returnType = typeAST.getFirstChild().getText();
             if (typeAST.findFirstToken(TokenTypes.LITERAL_VOID) != null
                     || setterCanReturnItsClass && frame.isEmbeddedIn(returnType)) {
                 // this method has signature
                 //
                 //     void set${Name}(${anyType} ${name})
                 //
                 // and therefore considered to be a setter
                 //
                 // or
                 //
                 // return type is not void, but it is the same as the class
                 // where method is declared and setterCanReturnItsClass
                 // is set to true
                 isSetterMethod = true;
             }
         }
 
         return isSetterMethod;
     }
 
     /**
      * Capitalizes a given property name the way we expect to see it in
      * a setter name.
      *
      * @param name a property name
      * @return capitalized property name
      */
     private static String capitalize(final String name) {
         String setterName = name;
         // we should not capitalize the first character if the second
         // one is a capital one, since according to JavaBeans spec
         // setFooBar() is a setter for FooBar property, not for fooBar one.
         if (name.length() == 1 || !Character.isUpperCase(name.charAt(1))) {
             setterName = name.substring(0, 1).toUpperCase(Locale.ENGLISH) + name.substring(1);
         }
         return setterName;
     }
 
     /**
      * Decides whether to ignore an AST node that is the parameter of a
      * constructor.
      *
      * @param ast the AST to check.
      * @return true if ast should be ignored because check property
      *     ignoreConstructorParameter is true and ast is a constructor parameter.
      */
     private boolean isIgnoredConstructorParam(DetailAST ast) {
         boolean result = false;
         if (ignoreConstructorParameter
                 && ast.getType() == TokenTypes.PARAMETER_DEF) {
             final DetailAST parametersAST = ast.getParent();
             final DetailAST constructorAST = parametersAST.getParent();
             result = constructorAST.getType() == TokenTypes.CTOR_DEF;
         }
         return result;
     }
 
     /**
      * Decides whether to ignore an AST node that is the parameter of an
      * abstract method.
      *
      * @param ast the AST to check.
      * @return true if ast should be ignored because check property
      *     ignoreAbstractMethods is true and ast is a parameter of abstract methods.
      */
     private boolean isIgnoredParamOfAbstractMethod(DetailAST ast) {
         boolean result = false;
         if (ignoreAbstractMethods) {
             final DetailAST method = ast.getParent().getParent();
             if (method.getType() == TokenTypes.METHOD_DEF) {
                 final DetailAST mods = method.findFirstToken(TokenTypes.MODIFIERS);
                 result = mods.findFirstToken(TokenTypes.ABSTRACT) != null;
             }
         }
         return result;
     }
 
     /**
      * Setter to define the RegExp for names of variables and parameters to ignore.
      *
      * @param pattern a pattern.
      * @since 3.2
      */
     public void setIgnoreFormat(Pattern pattern) {
         ignoreFormat = pattern;
     }
 
     /**
      * Setter to allow to ignore the parameter of a property setter method.
      *
      * @param ignoreSetter decide whether to ignore the parameter of
      *     a property setter method.
      * @since 3.2
      */
     public void setIgnoreSetter(boolean ignoreSetter) {
         this.ignoreSetter = ignoreSetter;
     }
 
     /**
      * Setter to allow to expand the definition of a setter method to include methods
      * that return the class' instance.
      *
      * @param setterCanReturnItsClass if true then setter can return
      *        either void or class in which it is declared. If false then
      *        in order to be recognized as setter method (otherwise
      *        already recognized as a setter) must return void.  Later is
      *        the default behavior.
      * @since 6.3
      */
     public void setSetterCanReturnItsClass(
         boolean setterCanReturnItsClass) {
         this.setterCanReturnItsClass = setterCanReturnItsClass;
     }
 
     /**
      * Setter to control whether to ignore constructor parameters.
      *
      * @param ignoreConstructorParameter decide whether to ignore
      *     constructor parameters.
      * @since 3.2
      */
     public void setIgnoreConstructorParameter(
         boolean ignoreConstructorParameter) {
         this.ignoreConstructorParameter = ignoreConstructorParameter;
     }
 
     /**
      * Setter to control whether to ignore parameters of abstract methods.
      *
      * @param ignoreAbstractMethods decide whether to ignore
      *     parameters of abstract methods.
      * @since 4.0
      */
     public void setIgnoreAbstractMethods(
         boolean ignoreAbstractMethods) {
         this.ignoreAbstractMethods = ignoreAbstractMethods;
     }
 
     /**
      * Holds the names of static and instance fields of a type.
      */
     private static final class FieldFrame {
 
         /** Name of the frame, such name of the class or enum declaration. */
         private final String frameName;
 
         /** Is this a static inner type. */
         private final boolean staticType;
 
         /** Parent frame. */
         private final FieldFrame parent;
 
         /** Set of instance field names. */
         private final Set<String> instanceFields = new HashSet<>();
 
         /** Set of static field names. */
         private final Set<String> staticFields = new HashSet<>();
 
         /**
          * Creates new frame.
          *
          * @param parent parent frame.
          * @param staticType is this a static inner type (class or enum).
          * @param frameName name associated with the frame, which can be a
          */
         private FieldFrame(FieldFrame parent, boolean staticType, String frameName) {
             this.parent = parent;
             this.staticType = staticType;
             this.frameName = frameName;
         }
 
         /**
          * Adds an instance field to this FieldFrame.
          *
          * @param field  the name of the instance field.
          */
         /* package */ void addInstanceField(String field) {
             instanceFields.add(field);
         }
 
         /**
          * Adds a static field to this FieldFrame.
          *
          * @param field  the name of the instance field.
          */
         /* package */ void addStaticField(String field) {
             staticFields.add(field);
         }
 
         /**
          * Determines whether this FieldFrame contains an instance field.
          *
          * @param field the field to check
          * @return true if this FieldFrame contains instance field
          */
         /* package */ boolean containsInstanceField(String field) {
             FieldFrame currentParent = parent;
             boolean contains = instanceFields.contains(field);
             boolean isStaticType = staticType;
             while (!isStaticType && !contains) {
                 contains = currentParent.instanceFields.contains(field);
                 isStaticType = currentParent.staticType;
                 currentParent = currentParent.parent;
             }
             return contains;
         }
 
         /**
          * Determines whether this FieldFrame contains a static field.
          *
          * @param field the field to check
          * @return true if this FieldFrame contains static field
          */
         /* package */ boolean containsStaticField(String field) {
             FieldFrame currentParent = parent;
             boolean contains = staticFields.contains(field);
             while (currentParent != null && !contains) {
                 contains = currentParent.staticFields.contains(field);
                 currentParent = currentParent.parent;
             }
             return contains;
         }
 
         /**
          * Getter for parent frame.
          *
          * @return parent frame.
          */
         /* package */ FieldFrame getParent() {
             return parent;
         }
 
         /**
          * Check if current frame is embedded in class or enum with
          * specific name.
          *
          * @param classOrEnumName name of class or enum that we are looking
          *     for in the chain of field frames.
          *
          * @return true if current frame is embedded in class or enum
          *     with name classOrNameName
          */
         private boolean isEmbeddedIn(String classOrEnumName) {
             FieldFrame currentFrame = this;
             boolean isEmbeddedIn = false;
             while (currentFrame != null) {
                 if (Objects.equals(currentFrame.frameName, classOrEnumName)) {
                     isEmbeddedIn = true;
                     break;
                 }
                 currentFrame = currentFrame.parent;
             }
             return isEmbeddedIn;
         }
 
     }
 
 }