///////////////////////////////////////////////////////////////////////////////////////////////
   // 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;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Optional;
  import java.util.regex.Pattern;
  
  import javax.annotation.Nullable;
  
  import com.puppycrawl.tools.checkstyle.StatelessCheck;
  import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
  import com.puppycrawl.tools.checkstyle.api.AuditEvent;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
  
  /**
   * <div>
   * Maintains a set of check suppressions from {@code @SuppressWarnings} annotations.
   * It allows to prevent Checkstyle from reporting violations from parts of code that were
   * annotated with {@code @SuppressWarnings} and using name of the check to be excluded.
   * It is possible to suppress all the checkstyle warnings with the argument {@code "all"}.
   * You can also use a {@code checkstyle:} prefix to prevent compiler
   * from processing these annotations.
   * You can also define aliases for check names that need to be suppressed.
   * </div>
   *
   * @since 5.7
   */
  @StatelessCheck
  public class SuppressWarningsHolder
      extends AbstractCheck {
  
      /**
       * Optional prefix for warning suppressions that are only intended to be
       * recognized by checkstyle. For instance, to suppress {@code
       * FallThroughCheck} only in checkstyle (and not in javac), use the
       * suppression {@code "checkstyle:fallthrough"} or {@code "checkstyle:FallThrough"}.
       * To suppress the warning in both tools, just use {@code "fallthrough"}.
       */
      private static final String CHECKSTYLE_PREFIX = "checkstyle:";
  
      /** Java.lang namespace prefix, which is stripped from SuppressWarnings. */
      private static final String JAVA_LANG_PREFIX = "java.lang.";
  
      /** Suffix to be removed from subclasses of Check. */
      private static final String CHECK_SUFFIX = "check";
  
      /** Special warning id for matching all the warnings. */
      private static final String ALL_WARNING_MATCHING_ID = "all";
  
      /** A map from check source names to suppression aliases. */
      private static final Map<String, String> CHECK_ALIAS_MAP = new HashMap<>();
  
      /**
       * A thread-local holder for the list of suppression entries for the last
       * file parsed.
       */
      private static final ThreadLocal<List<Entry>> ENTRIES =
              ThreadLocal.withInitial(ArrayList::new);
  
      /**
       * Compiled pattern used to match whitespace in text block content.
       */
      private static final Pattern WHITESPACE = Pattern.compile("\\s+");
  
      /**
       * Compiled pattern used to match preceding newline in text block content.
       */
      private static final Pattern NEWLINE = Pattern.compile("\\n");
  
      /**
       * Creates a new {@code SuppressWarningsHolder} instance.
       */
      public SuppressWarningsHolder() {
          // no code by default
      }
 
     /**
      * Returns the default alias for the source name of a check, which is the
      * source name in lower case with any dotted prefix or "Check"/"check"
      * suffix removed.
      *
      * @param sourceName the source name of the check (generally the class
      *        name)
      * @return the default alias for the given check
      */
     public static String getDefaultAlias(String sourceName) {
         int endIndex = sourceName.length();
         final String sourceNameLower = sourceName.toLowerCase(Locale.ENGLISH);
         if (sourceNameLower.endsWith(CHECK_SUFFIX)) {
             endIndex -= CHECK_SUFFIX.length();
         }
         final int startIndex = sourceNameLower.lastIndexOf('.') + 1;
         return sourceNameLower.substring(startIndex, endIndex);
     }
 
     /**
      * Returns the alias of simple check name for a check, The alias is
      * for the form of CheckNameCheck or CheckName.
      *
      * @param sourceName the source name of the check (generally the class
      *        name)
      * @return the alias of the simple check name for the given check
      */
     @Nullable
     private static String getSimpleNameAlias(String sourceName) {
         final String checkName = CommonUtil.baseClassName(sourceName);
         final String checkNameSuffix = "Check";
         // check alias for the CheckNameCheck
         String checkAlias = CHECK_ALIAS_MAP.get(checkName);
         if (checkAlias == null && checkName.endsWith(checkNameSuffix)) {
             final int checkStartIndex = checkName.length() - checkNameSuffix.length();
             final String checkNameWithoutSuffix = checkName.substring(0, checkStartIndex);
             // check alias for the CheckName
             checkAlias = CHECK_ALIAS_MAP.get(checkNameWithoutSuffix);
         }
 
         return checkAlias;
     }
 
     /**
      * Returns the alias for the source name of a check. If an alias has been
      * explicitly registered via {@link #setAliasList(String...)}, that
      * alias is returned; otherwise, the default alias is used.
      *
      * @param sourceName the source name of the check (generally the class
      *        name)
      * @return the current alias for the given check
      */
     public static String getAlias(String sourceName) {
         String checkAlias = CHECK_ALIAS_MAP.get(sourceName);
         if (checkAlias == null) {
             checkAlias = getSimpleNameAlias(sourceName);
         }
         if (checkAlias == null) {
             checkAlias = getDefaultAlias(sourceName);
         }
         return checkAlias;
     }
 
     /**
      * Registers an alias for the source name of a check.
      *
      * @param sourceName the source name of the check (generally the class
      *        name)
      * @param checkAlias the alias used in {@link SuppressWarnings} annotations
      */
     private static void registerAlias(String sourceName, String checkAlias) {
         CHECK_ALIAS_MAP.put(sourceName, checkAlias);
     }
 
     /**
      * Setter to specify aliases for check names that can be used in code
      * within {@code SuppressWarnings} in a format of comma separated attribute=value entries.
      * The attribute is the fully qualified name of the Check and value is its alias.
      *
      * @param aliasList comma-separated alias assignments
      * @throws IllegalArgumentException when alias item does not have '='
      * @since 5.7
      */
     public void setAliasList(String... aliasList) {
         for (String sourceAlias : aliasList) {
             final int index = sourceAlias.indexOf('=');
             if (index > 0) {
                 registerAlias(sourceAlias.substring(0, index), sourceAlias
                     .substring(index + 1));
             }
             else if (!sourceAlias.isEmpty()) {
                 throw new IllegalArgumentException(
                     "'=' expected in alias list item: " + sourceAlias);
             }
         }
     }
 
     /**
      * Checks for a suppression of a check with the given source name and
      * location in the last file processed.
      *
      * @param event audit event.
      * @return whether the check with the given name is suppressed at the given
      *         source location
      */
     public static boolean isSuppressed(AuditEvent event) {
         final List<Entry> entries = ENTRIES.get();
         final String sourceName = event.getSourceName();
         final String checkAlias = getAlias(sourceName);
         final int line = event.getLine();
         final int column = event.getColumn();
         boolean suppressed = false;
         for (Entry entry : entries) {
             final boolean afterStart = isSuppressedAfterEventStart(line, column, entry);
             final boolean beforeEnd = isSuppressedBeforeEventEnd(line, column, entry);
             final String checkName = entry.checkName();
             final boolean nameMatches =
                 ALL_WARNING_MATCHING_ID.equals(checkName)
                     || checkName.equalsIgnoreCase(checkAlias)
                     || getDefaultAlias(checkName).equalsIgnoreCase(checkAlias)
                     || getDefaultAlias(sourceName).equalsIgnoreCase(checkName);
             if (afterStart && beforeEnd
                     && (nameMatches || checkName.equals(event.getModuleId()))) {
                 suppressed = true;
                 break;
             }
         }
         return suppressed;
     }
 
     /**
      * Checks whether suppression entry position is after the audit event occurrence position
      * in the source file.
      *
      * @param line the line number in the source file where the event occurred.
      * @param column the column number in the source file where the event occurred.
      * @param entry suppression entry.
      * @return true if suppression entry position is after the audit event occurrence position
      *         in the source file.
      */
     private static boolean isSuppressedAfterEventStart(int line, int column, Entry entry) {
         return entry.firstLine() < line
             || entry.firstLine() == line
             && (column == 0 || entry.firstColumn() <= column);
     }
 
     /**
      * Checks whether suppression entry position is before the audit event occurrence position
      * in the source file.
      *
      * @param line the line number in the source file where the event occurred.
      * @param column the column number in the source file where the event occurred.
      * @param entry suppression entry.
      * @return true if suppression entry position is before the audit event occurrence position
      *         in the source file.
      */
     private static boolean isSuppressedBeforeEventEnd(int line, int column, Entry entry) {
         return entry.lastLine() > line
             || entry.lastLine() == line && entry
                 .lastColumn() >= column;
     }
 
     @Override
     public int[] getDefaultTokens() {
         return getRequiredTokens();
     }
 
     @Override
     public int[] getAcceptableTokens() {
         return getRequiredTokens();
     }
 
     @Override
     public int[] getRequiredTokens() {
         return new int[] {TokenTypes.ANNOTATION};
     }
 
     @Override
     public void beginTree(DetailAST rootAST) {
         ENTRIES.get().clear();
     }
 
     @Override
     public void visitToken(DetailAST ast) {
         // check whether annotation is SuppressWarnings
         // expected children: AT ( IDENT | DOT ) LPAREN <values> RPAREN
         String identifier = getIdentifier(getNthChild(ast, 1));
         if (identifier.startsWith(JAVA_LANG_PREFIX)) {
             identifier = identifier.substring(JAVA_LANG_PREFIX.length());
         }
         if ("SuppressWarnings".equals(identifier)) {
             getAnnotationTarget(ast).ifPresent(targetAST -> {
                 addSuppressions(getAllAnnotationValues(ast), targetAST);
             });
         }
     }
 
     /**
      * Method to populate list of suppression entries.
      *
      * @param values
      *            - list of check names
      * @param targetAST
      *            - annotation target
      */
     private static void addSuppressions(List<String> values, DetailAST targetAST) {
         // get text range of target
         final int firstLine = targetAST.getLineNo();
         final int firstColumn = targetAST.getColumnNo();
         final DetailAST nextAST = targetAST.getNextSibling();
         final int lastLine;
         final int lastColumn;
         if (nextAST == null) {
             lastLine = Integer.MAX_VALUE;
             lastColumn = Integer.MAX_VALUE;
         }
         else {
             lastLine = nextAST.getLineNo();
             lastColumn = nextAST.getColumnNo();
         }
 
         final List<Entry> entries = ENTRIES.get();
         for (String value : values) {
             // strip off the checkstyle-only prefix if present
             final String checkName = removeCheckstylePrefixIfExists(value);
             entries.add(new Entry(checkName, firstLine, firstColumn,
                     lastLine, lastColumn));
         }
     }
 
     /**
      * Method removes checkstyle prefix (checkstyle:) from check name if exists.
      *
      * @param checkName
      *            - name of the check
      * @return check name without prefix
      */
     private static String removeCheckstylePrefixIfExists(String checkName) {
         String result = checkName;
         if (checkName.startsWith(CHECKSTYLE_PREFIX)) {
             result = checkName.substring(CHECKSTYLE_PREFIX.length());
         }
         return result;
     }
 
     /**
      * Get all annotation values.
      *
      * @param ast annotation token
      * @return list values
      * @throws IllegalArgumentException if there is an unknown annotation value type.
      */
     private static List<String> getAllAnnotationValues(DetailAST ast) {
         // get values of annotation
         List<String> values = List.of();
         final DetailAST lparenAST = ast.findFirstToken(TokenTypes.LPAREN);
         if (lparenAST != null) {
             final DetailAST nextAST = lparenAST.getNextSibling();
             final int nextType = nextAST.getType();
             switch (nextType) {
                 case TokenTypes.EXPR, TokenTypes.ANNOTATION_ARRAY_INIT ->
                     values = getAnnotationValues(nextAST);
                 case TokenTypes.ANNOTATION_MEMBER_VALUE_PAIR ->
                     // expected children: IDENT ASSIGN ( EXPR |
                     // ANNOTATION_ARRAY_INIT )
                     values = getAnnotationValues(getNthChild(nextAST, 2));
                 case TokenTypes.RPAREN -> {
                     // no value present (not valid Java)
                 }
                 default ->
                     // unknown annotation value type (new syntax?)
                     throw new IllegalArgumentException("Unexpected AST: " + nextAST);
             }
         }
         return values;
     }
 
     /**
      * Get target of annotation.
      *
      * @param ast the AST node to get the child of
      * @return get target of annotation
      * @throws IllegalArgumentException if there is an unexpected container type.
      */
     private static Optional<DetailAST> getAnnotationTarget(DetailAST ast) {
         DetailAST current = ast.getParent();
         while (current.getType() == TokenTypes.ANNOTATION_ARRAY_INIT) {
             current = current.getParent();
         }
         return switch (current.getType()) {
             case TokenTypes.MODIFIERS, TokenTypes.ANNOTATIONS, TokenTypes.ANNOTATION,
                  TokenTypes.ANNOTATION_MEMBER_VALUE_PAIR -> Optional.of(current.getParent());
             case TokenTypes.LITERAL_DEFAULT -> Optional.empty();
             default -> throw new IllegalArgumentException("Unexpected container AST: " + current);
         };
     }
 
     /**
      * Returns the n'th child of an AST node.
      *
      * @param ast the AST node to get the child of
      * @param index the index of the child to get
      * @return the n'th child of the given AST node, or {@code null} if none
      */
     private static DetailAST getNthChild(DetailAST ast, int index) {
         DetailAST child = ast.getFirstChild();
         for (int i = 0; i < index && child != null; i++) {
             child = child.getNextSibling();
         }
         return child;
     }
 
     /**
      * Returns the Java identifier represented by an AST.
      *
      * @param ast an AST node for an IDENT or DOT
      * @return the Java identifier represented by the given AST subtree
      * @throws IllegalArgumentException if the AST is invalid
      */
     private static String getIdentifier(DetailAST ast) {
         if (ast == null) {
             throw new IllegalArgumentException("Identifier AST expected, but get null.");
         }
         final String identifier;
         if (ast.getType() == TokenTypes.IDENT) {
             identifier = ast.getText();
         }
         else {
             identifier = getIdentifier(ast.getFirstChild()) + "."
                 + getIdentifier(ast.getLastChild());
         }
         return identifier;
     }
 
     /**
      * Returns the literal string expression represented by an AST.
      *
      * @param ast an AST node for an EXPR
      * @return the Java string represented by the given AST expression
      *         or empty string if expression is too complex
      * @throws IllegalArgumentException if the AST is invalid
      */
     private static String getStringExpr(DetailAST ast) {
         final DetailAST firstChild = ast.getFirstChild();
 
         return switch (firstChild.getType()) {
             case TokenTypes.STRING_LITERAL -> {
                 // NOTE: escaped characters are not unescaped
                 final String quotedText = firstChild.getText();
                 yield quotedText.substring(1, quotedText.length() - 1);
             }
             case TokenTypes.IDENT -> firstChild.getText();
             case TokenTypes.DOT -> firstChild.getLastChild().getText();
             case TokenTypes.TEXT_BLOCK_LITERAL_BEGIN -> {
                 final String textBlockContent = firstChild.getFirstChild().getText();
                 yield getContentWithoutPrecedingWhitespace(textBlockContent);
             }
             default ->
                 // annotations with complex expressions cannot suppress warnings
                 "";
         };
     }
 
     /**
      * Returns the annotation values represented by an AST.
      *
      * @param ast an AST node for an EXPR or ANNOTATION_ARRAY_INIT
      * @return the list of Java string represented by the given AST for an
      *         expression or annotation array initializer
      * @throws IllegalArgumentException if the AST is invalid
      */
     private static List<String> getAnnotationValues(DetailAST ast) {
         return switch (ast.getType()) {
             case TokenTypes.EXPR -> List.of(getStringExpr(ast));
             case TokenTypes.ANNOTATION_ARRAY_INIT -> findAllExpressionsInChildren(ast);
             default -> throw new IllegalArgumentException(
                     "Expression or annotation array initializer AST expected: " + ast);
         };
     }
 
     /**
      * Method looks at children and returns list of expressions in strings.
      *
      * @param parent ast, that contains children
      * @return list of expressions in strings
      */
     private static List<String> findAllExpressionsInChildren(DetailAST parent) {
         final List<String> valueList = new ArrayList<>();
         DetailAST childAST = parent.getFirstChild();
         while (childAST != null) {
             if (childAST.getType() == TokenTypes.EXPR) {
                 valueList.add(getStringExpr(childAST));
             }
             childAST = childAST.getNextSibling();
         }
         return valueList;
     }
 
     /**
      * Remove preceding newline and whitespace from the content of a text block.
      *
      * @param textBlockContent the actual text in a text block.
      * @return content of text block with preceding whitespace and newline removed.
      */
     private static String getContentWithoutPrecedingWhitespace(String textBlockContent) {
         final String contentWithNoPrecedingNewline =
             NEWLINE.matcher(textBlockContent).replaceAll("");
         return WHITESPACE.matcher(contentWithNoPrecedingNewline).replaceAll("");
     }
 
     @Override
     public void destroy() {
         super.destroy();
         ENTRIES.remove();
     }
 
     /**
      * Records a particular suppression for a region of a file.
      *
      * @param checkName   the source name of the suppressed check
      * @param firstLine   the first line of the suppression region
      * @param firstColumn the first column of the suppression region
      * @param lastLine    the last line of the suppression region
      * @param lastColumn  the last column of the suppression region
      */
     private record Entry(String checkName, int firstLine,
                          int firstColumn, int lastLine, int lastColumn) {
 
     }
 
 }