Add flow node log

pom.xml

@@ -86,6 +86,16 @@
       <artifactId>workflow-step-api</artifactId>
     </dependency>
 
+    <dependency>
+      <groupId>org.jenkins-ci.plugins.workflow</groupId>
+      <artifactId>workflow-api</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>org.jenkins-ci.plugins.workflow</groupId>
+      <artifactId>workflow-job</artifactId>
+    </dependency>
+
     <!-- Commons Lang3 API -->
     <dependency>
       <groupId>io.jenkins.plugins</groupId>
@@ -99,12 +109,6 @@
       <scope>test</scope>
     </dependency>
 
-    <dependency>
-      <groupId>org.jenkins-ci.plugins.workflow</groupId>
-      <artifactId>workflow-job</artifactId>
-      <scope>test</scope>
-    </dependency>
-
     <dependency>
       <groupId>org.jenkins-ci.plugins.workflow</groupId>
       <artifactId>workflow-durable-task-step</artifactId>

src/main/java/io/jenkins/plugins/explain_error/ConsoleExplainErrorAction.java

@@ -6,9 +6,12 @@
 import jenkins.model.RunAction2;
 import java.io.IOException;
 import java.io.PrintWriter;
+import java.util.List;
 import java.util.logging.Logger;
 import javax.servlet.ServletException;
 import net.sf.json.JSONObject;
+
+import org.jenkinsci.plugins.workflow.job.WorkflowRun;
 import org.kohsuke.stapler.StaplerRequest2;
 import org.kohsuke.stapler.StaplerResponse2;
 import org.kohsuke.stapler.interceptor.RequirePOST;
@@ -86,7 +89,7 @@ public void doExplainConsoleError(StaplerRequest2 req, StaplerResponse2 rsp) thr
             }
 
             // Fetch the last N lines of the log
-            java.util.List<String> logLines = run.getLog(maxLines);
+            List<String> logLines = PipelineLogExtractor.getFailedStepLog(run, maxLines);
             String errorText = String.join("\n", logLines);
 
             ErrorExplainer explainer = new ErrorExplainer();

src/main/java/io/jenkins/plugins/explain_error/ErrorExplainer.java

@@ -11,6 +11,7 @@
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
 import org.apache.commons.lang3.StringUtils;
+import org.jenkinsci.plugins.workflow.job.WorkflowRun;
 
 /**
  * Service class responsible for explaining errors using AI.
@@ -60,7 +61,7 @@ public void explainError(Run<?, ?> run, TaskListener listener, String logPattern
     }
 
     private String extractErrorLogs(Run<?, ?> run, String logPattern, int maxLines) throws IOException {
-        List<String> logLines = run.getLog(maxLines);
+        List<String> logLines = PipelineLogExtractor.getFailedStepLog(run, maxLines);
 
         if (StringUtils.isBlank(logPattern)) {
             // Return last few lines if no pattern specified

src/main/java/io/jenkins/plugins/explain_error/PipelineLogExtractor.java

@@ -0,0 +1,88 @@
+package io.jenkins.plugins.explain_error;
+
+import org.jenkinsci.plugins.workflow.job.WorkflowRun;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+import org.jenkinsci.plugins.workflow.flow.FlowExecution;
+import org.jenkinsci.plugins.workflow.graph.FlowNode;
+import org.jenkinsci.plugins.workflow.graph.FlowGraphWalker;
+import org.jenkinsci.plugins.workflow.actions.ErrorAction;
+import org.jenkinsci.plugins.workflow.actions.LogAction;
+import hudson.console.AnnotatedLargeText;
+import hudson.console.ConsoleNote;
+import hudson.model.Run;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.StringReader;
+import java.io.StringWriter;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+
+public class PipelineLogExtractor {
+
+    private static List<String> readLimitedLog(AnnotatedLargeText<? extends FlowNode> logText,
+                                               int maxLines) {
+        StringWriter writer = new StringWriter();
+        try {
+            long offset = logText.writeLogTo(0, writer);
+            if (offset <= 0) {
+                return Collections.emptyList();
+            }
+            String cleanLog = ConsoleNote.removeNotes(writer.toString());
+            BufferedReader reader = new BufferedReader(new StringReader(cleanLog));
+            LinkedList<String> queue = new LinkedList<>();
+            String line;
+            while ((line = reader.readLine()) != null) {
+                if (queue.size() >= maxLines) {
+                    queue.removeFirst();
+                }
+                line = line.replace("\n", "").replace("\r", "");
+                queue.add(line);
+            }
+            return new ArrayList<>(queue);
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        return Collections.emptyList();
+    }
+
+    /**
+     * Extracts the log output of the specific step that caused the pipeline failure.
+     * @param run The pipeline build
+     * @return The log text of the failed step, or null if no failed step with a log is found.
+     * @throws IOException
+     */
+    public static List<String> getFailedStepLog(@NonNull  Run<?, ?> run, int maxLines) throws IOException {
+
+        if (run instanceof WorkflowRun) {
+            FlowExecution execution = ((WorkflowRun) run).getExecution();
+
+            FlowGraphWalker walker = new FlowGraphWalker(execution);
+            for (FlowNode node : walker) {
+                ErrorAction errorAction = node.getAction(ErrorAction.class);
+                if (errorAction != null) {
+                    FlowNode nodeThatThrewException = ErrorAction.findOrigin(errorAction.getError(), execution);
+                    if (nodeThatThrewException == null) {
+                        continue;
+                    }
+                    LogAction logAction = nodeThatThrewException.getAction(LogAction.class);
+                    if (logAction != null) {
+                        AnnotatedLargeText<? extends FlowNode> logText = logAction.getLogText();
+                        List<String> result = readLimitedLog(logText, maxLines);
+                        if (result == null || result.isEmpty())
+                        {
+                            continue;
+                        }
+                        return result;
+                   }
+                }
+            }
+        }
+
+        return run.getLog(maxLines);
+    }
+}