/*
    * SPDX-FileCopyrightText: Copyright (c) 2011-2026 Yegor Bugayenko
    * SPDX-License-Identifier: MIT
    */
   package com.qulice.pmd;
   
   import com.jcabi.log.Logger;
   import java.io.File;
   import java.io.IOException;
  import java.nio.charset.Charset;
  import java.nio.file.Files;
  import java.nio.file.Paths;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  import net.sourceforge.pmd.PMDConfiguration;
  import net.sourceforge.pmd.PmdAnalysis;
  import net.sourceforge.pmd.lang.rule.RulePriority;
  import net.sourceforge.pmd.lang.rule.RuleSet;
  import net.sourceforge.pmd.reporting.Report;
  import net.sourceforge.pmd.reporting.RuleViolation;
  import org.cactoos.list.ListOf;
  
  /**
   * Validates source files via <code>PmdValidator</code>.
   * @since 0.3
   */
  final class SourceValidator {
  
      /**
       * Rules.
       */
      private final PMDConfiguration config;
  
      /**
       * Source files encoding.
       */
      private final Charset encoding;
  
      /**
       * Creates new instance of <code>SourceValidator</code>.
       * @param charset Source files encoding
       */
      SourceValidator(final Charset charset) {
          this.config = new PMDConfiguration();
          this.encoding = charset;
      }
  
      /**
       * Performs validation of the input source files.
       * @param sources Input source files
       * @param path Base path
       * @return Collection of violations
       */
      Collection<PmdError> validate(
          final Collection<File> sources, final String path) {
          final List<PmdError> errors = new ArrayList<>(0);
          try (PmdAnalysis analysis = PmdAnalysis.create(this.configured())) {
              for (final File source : sources) {
                  Logger.debug(
                      this,
                      "Processing file: %s",
                      source.toPath().toString()
                  );
                  analysis.files().addFile(source.toPath());
              }
              final Report report = analysis.performAnalysisAndCollectReport();
              report.getConfigurationErrors().stream()
                  .map(PmdError.OfConfigError::new).forEach(errors::add);
              report.getProcessingErrors().stream()
                  .filter(this::reportable)
                  .map(PmdError.OfProcessingError::new).forEach(errors::add);
              report.getViolations().stream()
                  .filter(violation -> !SourceValidator.suppressesItself(violation))
                  .map(PmdError.OfRuleViolation::new)
                  .forEach(errors::add);
          }
          return errors;
      }
  
      /**
       * How many rules the ruleset holds, once PMD has resolved the
       * categories it refers to and taken the exclusions out.
       * @return The number of rules
       */
      int rules() {
          int total = 0;
          try (PmdAnalysis analysis = PmdAnalysis.create(this.configured())) {
              for (final RuleSet set : analysis.getRulesets()) {
                  total += set.size();
              }
          }
          return total;
      }
  
      /**
       * The PMD configuration, with the Qulice ruleset in it.
       * @return Configuration to run PMD with
       */
     private PMDConfiguration configured() {
         this.config.setRuleSets(new ListOf<>("com/qulice/pmd/ruleset.xml"));
         this.config.setThreads(0);
         this.config.setMinimumPriority(RulePriority.LOW);
         this.config.setIgnoreIncrementalAnalysis(true);
         this.config.setShowSuppressedViolations(true);
         this.config.setSourceEncoding(this.encoding);
         return this.config;
     }
 
     /**
      * Tells whether a processing error should be reported as a violation.
      * Some PMD rules crash internally with an {@link IllegalStateException}
      * while analyzing perfectly valid Java. For example {@code
      * UseDiamondOperator} throws {@code "overload resolution is not
      * complete"} when it probes an overloaded method reference such as
      * {@code BigDecimal::multiply} (see #1686). PMD itself only logs such a
      * crash as a warning and keeps going, so it is a bug in the tool, not a
      * problem in the code under analysis. We do the same here: log it as a
      * warning and do not turn it into a build-breaking violation, since the
      * user cannot fix it in their code. The full stack trace is logged too,
      * so the crash can still be diagnosed and reported upstream.
      * @param error The processing error to inspect
      * @return True if it must be reported, false if it is an internal crash
      */
     private boolean reportable(final Report.ProcessingError error) {
         final boolean crash = SourceValidator.crashed(error.getError());
         if (crash) {
             Logger.warn(
                 this,
                 "PMD rule crashed on %s and was ignored: %s%n%s",
                 error.getFileId().getAbsolutePath(),
                 error.getMsg(),
                 error.getDetail()
             );
         }
         return !crash;
     }
 
     /**
      * Tells whether a throwable is (or was caused by) an internal PMD rule
      * crash, recognized by an {@link IllegalStateException} anywhere in its
      * cause chain.
      * @param error The throwable to inspect
      * @return True if the cause chain contains an IllegalStateException
      */
     private static boolean crashed(final Throwable error) {
         boolean crash = false;
         Throwable cause = error;
         while (cause != null) {
             if (cause instanceof IllegalStateException) {
                 crash = true;
                 break;
             }
             cause = cause.getCause();
         }
         return crash;
     }
 
     /**
      * Tells whether a violation reports a {@code @SuppressWarnings} that
      * tries to suppress {@code PMD.UnnecessaryWarningSuppression} itself.
      * The PMD rule cannot suppress its own violations, so suppressing it is
      * effectively a no-op and must not be reported as unused.
      * @param violation Violation to inspect
      * @return True if the violation is self-referential
      */
     private static boolean suppressesItself(final RuleViolation violation) {
         final String name = "UnnecessaryWarningSuppression";
         boolean result = false;
         if (name.equals(violation.getRule().getName())) {
             try {
                 final List<String> lines = Files.readAllLines(
                     Paths.get(violation.getFileId().getAbsolutePath())
                 );
                 final int start = Math.max(0, violation.getBeginLine() - 1);
                 final int end = Math.min(lines.size(), violation.getEndLine());
                 for (int idx = start; idx < end; ++idx) {
                     if (lines.get(idx).contains(name)) {
                         result = true;
                         break;
                     }
                 }
             } catch (final IOException ex) {
                 Logger.debug(
                     SourceValidator.class,
                     "Failed to read %s: %s",
                     violation.getFileId().getAbsolutePath(),
                     ex.getMessage()
                 );
             }
         }
         return result;
     }
 }