package jetbrains.buildServer.profile;

import com.yourkit.api.Controller;
import jetbrains.buildServer.log.Loggers;

/**
 * Allows to profile TeamCity server.
 */
@SuppressWarnings("WeakerAccess")
public class Profiler {
  private Controller myController;
  private final Object myProfLock = new Object();
  private Mode myMode = Mode.ENABLED;

  public enum Mode {
    ENABLED, CPU_PROF_STARTED, CAPTURING, MEMORY_CAPTURE_IN_PROGRESS
  }

  public Profiler() {
  }

  public void startProfiler() throws Exception {
    synchronized (myProfLock) {
      if (myMode != Mode.ENABLED)
        throw new Exception("Profiling is running (" + myMode.name() + ").");
      if (myController != null)
        throw new Exception("Profiler is locked (another profiling session is running).");
      myController = new Controller();
      Loggers.SERVER.info("profiler starting: stopping current profiling session... mode = " + myMode);
      myController.stopCPUProfiling();
      Loggers.SERVER.info("profiler starting: stopped");
      try {
        Loggers.SERVER.info("profiler starting: starting current profiling session...");
        myController.startCPUSampling(null);;
        Loggers.SERVER.info("profiler starting: started");
      } catch (Exception e) {
        resetState();
        throw e;
      }
      myMode = Mode.CPU_PROF_STARTED;
    }
  }

  public String captureMemorySnapshot() throws Exception {
    synchronized (myProfLock) {
      if (myMode != Mode.ENABLED)
        throw new Exception("Profiler is locked (current mode is " + myMode.name() + ").");
      if (myController != null)
        throw new Exception("Profiler is locked (another profiling session is running).");
      String result;
      try {
        myController = new Controller();
        Loggers.SERVER.info("profiler: starting memory snapshot dump...");
        myMode = Mode.MEMORY_CAPTURE_IN_PROGRESS;
        result = myController.captureMemorySnapshot();
        Loggers.SERVER.info("profiler:  memory snapshot done: " + result);
      } finally {
        resetState();
      }
      return result;
    }
  }

  public String captureAndStop() throws Exception {
    String result;

    synchronized (myProfLock) {
      if (myMode != Mode.CPU_PROF_STARTED)
        throw new Exception("CPU profiling is not running (" + myMode.name() + ").");
      if (myController == null)
        throw new Exception("No profiling session is running.");
      myMode = Mode.CAPTURING;
      try {
        Loggers.SERVER.info("profiler capturing: capturing...");
        result = myController.captureSnapshot(Controller.SNAPSHOT_WITHOUT_HEAP);
        Loggers.SERVER.info("profiler capturing: Snapshot saved to " + result);
      } finally {
        myMode = Mode.CPU_PROF_STARTED;
        try {
          Loggers.SERVER.info("profiler capturing: stopping current profiling session... mode = " + myMode);
          myController.stopCPUProfiling();
          Loggers.SERVER.info("profiler capturing: stopped");
        } finally {
          resetState();
        }
      }
    }

    return result;
  }

  public void stopProfiler() throws Exception {
    synchronized (myProfLock) {
      try {
        Loggers.SERVER.info("profiler stopping: stopping current profiling session... mode = " + myMode);
        myController.stopCPUProfiling();
        Loggers.SERVER.info("profiler stopping: stopped");

      } finally {
        resetState();
      }
    }
  }

  private void resetState() {
    myController = null;
    myMode = Mode.ENABLED;
  }

  public Mode getMode() {
    return myMode;
  }
}