/*
    * 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.ASTLoopStatement;
  import net.sourceforge.pmd.lang.java.ast.ASTResource;
  import net.sourceforge.pmd.lang.java.ast.ASTReturnStatement;
  import net.sourceforge.pmd.lang.java.ast.ASTVariableAccess;
  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 {
  
      /**
       * Default constructor.
       */
      public UnnecessaryLocalRule() {
          super(ASTVariableDeclarator.class);
      }
  
      @Override
      public Object visit(
          final ASTVariableDeclarator variable,
          final Object data
      ) {
          if (variable.getInitializer() != null
              && variable.ancestors(ASTResource.class).first() == null) {
              final String name = UnnecessaryLocalRule.variableName(variable);
              if (!name.isEmpty()) {
                  this.asCtx(data).addViolation(variable, name);
              }
          }
          return data;
      }
  
      private static boolean hasReturnOrArguments(
          final List<ASTVariableAccess> uses
      ) {
          boolean result = false;
          if (uses.size() == 1) {
              final ASTVariableAccess use = uses.get(0);
              final boolean loop = use.ancestors(ASTLoopStatement.class)
                  .toStream().findAny().isPresent();
              if (!loop
                  && (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
              && !UnnecessaryLocalSkips.freshState(variable.getInitializer())) {
              final String name = variable.getName();
              final List<ASTVariableAccess> uses = block
                  .descendants(ASTVariableAccess.class)
                  .crossFindBoundaries()
                  .filter(ref -> name.equals(ref.getName()))
                  .toList();
              if (UnnecessaryLocalRule.hasReturnOrArguments(uses)
                  && !UnnecessaryLocalSkips.acrossBoundary(block, name, uses.size())
                  && !UnnecessaryLocalSkips.interveningCall(variable, uses.get(0))) {
                  result = name;
              }
          }
          return result;
      }
  }