/*
    * SPDX-FileCopyrightText: Copyright (c) 2011-2026 Yegor Bugayenko
    * SPDX-License-Identifier: MIT
    */
   package com.qulice.pmd.rules;
   
   import java.util.List;
   import net.sourceforge.pmd.lang.java.ast.ASTArgumentList;
   import net.sourceforge.pmd.lang.java.ast.ASTBlock;
  import net.sourceforge.pmd.lang.java.ast.ASTExpression;
  import net.sourceforge.pmd.lang.java.ast.ASTReturnStatement;
  import net.sourceforge.pmd.lang.java.ast.ASTVariableDeclarator;
  import net.sourceforge.pmd.lang.java.rule.AbstractJavaRulechainRule;
  
  /**
   * Rule to check unnecessary local variables.
   *
   * @since 0.4
   */
  public final class UnnecessaryLocalRule extends AbstractJavaRulechainRule {
      public UnnecessaryLocalRule() {
          super(ASTVariableDeclarator.class);
      }
  
      @Override
      public Object visit(
          final ASTVariableDeclarator variable,
          final Object data
      ) {
          if (variable.getInitializer() != null) {
              final String name = variableName(variable);
              if (!name.isEmpty()) {
                  asCtx(data).addViolation(variable, name);
              }
          }
          return data;
      }
  
      private static boolean hasReturnOrArguments(
          final List<ASTExpression> exprs
      ) {
          boolean result = false;
          if (exprs.size() == 1) {
              final ASTExpression use = exprs.get(0);
              if (use.ancestors(ASTReturnStatement.class).toStream()
                  .findAny().isPresent()
                  || use.ancestors(ASTArgumentList.class).toStream()
                  .findAny().isPresent()
              ) {
                  result = true;
              }
          }
          return result;
      }
  
      private static String variableName(final ASTVariableDeclarator variable) {
          String result = "";
          final ASTBlock block = variable.ancestors(ASTBlock.class).first();
          if (block != null) {
              final String name = variable.getName();
              final List<ASTExpression> uses = block
                  .descendants(ASTExpression.class)
                  .filter(expr -> name.equals(expr.getImage()))
                  .toList();
              if (hasReturnOrArguments(uses)) {
                  result = name;
              }
          }
          return result;
      }
  }