Implements Log capture feature

Author: rexrk

ai-exception-insights-starter/src/main/java/io/github/rexrk/exception/insights/capture/LogAppenderRegistrar.java

@@ -0,0 +1,29 @@
+package io.github.rexrk.exception.insights.capture;
+
+import ch.qos.logback.classic.Logger;
+import ch.qos.logback.classic.LoggerContext;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.beans.factory.DisposableBean;
+
+public class LogAppenderRegistrar implements InitializingBean, DisposableBean {
+
+    private final RingBufferLogAppender appender;
+
+    public LogAppenderRegistrar(RingBufferLogAppender appender) {
+        this.appender = appender;
+    }
+
+    @Override
+    public void afterPropertiesSet() {
+        LoggerContext context = (LoggerContext) LoggerFactory.getILoggerFactory();
+        appender.setContext(context);
+        appender.start();
+        context.getLogger(Logger.ROOT_LOGGER_NAME).addAppender(appender);
+    }
+
+    @Override
+    public void destroy() {
+        appender.stop(); // clean detach on app shutdown
+    }
+}

ai-exception-insights-starter/src/main/java/io/github/rexrk/exception/insights/capture/RingBufferLogAppender.java

@@ -0,0 +1,57 @@
+package io.github.rexrk.exception.insights.capture;
+
+import ch.qos.logback.classic.Level;
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.classic.spi.IThrowableProxy;
+import ch.qos.logback.core.AppenderBase;
+import io.github.rexrk.exception.insights.model.LogLine;
+
+import java.time.Instant;
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Deque;
+import java.util.List;
+
+public class RingBufferLogAppender extends AppenderBase<ILoggingEvent> {
+
+    private final int bufferSize;
+    private final Deque<LogLine> buffer;
+
+    public RingBufferLogAppender(int bufferSize) {
+        this.bufferSize = bufferSize;
+        this.buffer = new ArrayDeque<>(bufferSize);
+    }
+
+    @Override
+    protected synchronized void append(ILoggingEvent event) {
+        if (!event.getLevel().isGreaterOrEqual(Level.WARN)) return;
+
+        if (buffer.size() == bufferSize) {
+            buffer.pollFirst();
+        }
+
+        buffer.addLast(new LogLine(
+            event.getLevel().toString(),
+            event.getFormattedMessage(),
+            event.getLoggerName(),
+            event.getThreadName(),
+            throwableClass(event.getThrowableProxy()),
+            throwableMessage(event.getThrowableProxy()),
+            Instant.ofEpochMilli(event.getTimeStamp())
+        ));
+    }
+
+    public synchronized List<LogLine> drainRecent(int limit) {
+        List<LogLine> all = new ArrayList<>(buffer);
+        int from = Math.max(0, all.size() - limit);
+        return all.subList(from, all.size());
+    }
+
+    private String throwableClass(IThrowableProxy proxy) {
+        return proxy != null ? proxy.getClassName() : null;
+    }
+
+    private String throwableMessage(IThrowableProxy proxy) {
+        return proxy != null ? proxy.getMessage() : null;
+    }
+}