/*
    * Oceanus: Java Utilities
    * Copyright 2012-2026. Tony Washer
    *
    * Licensed under the Apache License, Version 2.0 (the "License"); you may not
    * use this file except in compliance with the License.  You may obtain a copy
    * of the License at
    *
    *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
   * License for the specific language governing permissions and limitations under
   * the License.
   */
  package io.github.tonywasher.joceanus.oceanus.profile;
  
  import io.github.tonywasher.joceanus.oceanus.decimal.OceanusDecimal;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  
  /**
   * Profile data.
   */
  public class OceanusProfile {
      /**
       * number of decimals for elapsed.
       */
      private static final int NUM_DECIMALS = 6;
  
      /**
       * Step name.
       */
      private final String theName;
  
      /**
       * Status.
       */
      private OceanusProfileStatus theStatus;
  
      /**
       * Start time.
       */
      private final long theStart;
  
      /**
       * Elapsed (in milliseconds).
       */
      private OceanusDecimal theElapsed;
  
      /**
       * Hidden Elapsed (in milliseconds).
       */
      private OceanusDecimal theHidden;
  
      /**
       * Current subTask.
       */
      private OceanusProfile theCurrentTask;
  
      /**
       * List of subTasks.
       */
      private List<OceanusProfile> theSubTasks;
  
      /**
       * Constructor.
       *
       * @param pName the name of the step
       */
      public OceanusProfile(final String pName) {
          /* Record the name and start the timer */
          theName = pName;
          theStart = System.nanoTime();
          theStatus = OceanusProfileStatus.RUNNING;
      }
  
      /**
       * Obtain the name of the profile.
       *
       * @return the name
       */
      public String getName() {
          return theName;
      }
  
      /**
       * Obtain the status of the profile.
       *
       * @return the status
       */
      public OceanusProfileStatus getStatus() {
          return theStatus.isRunning()
                  ? theStatus
                  : null;
     }
 
     /**
      * Obtain the elapsed time of the profile.
      *
      * @return the elapsedTime
      */
     public OceanusDecimal getElapsed() {
         return theStatus.isRunning()
                 ? null
                 : theElapsed;
     }
 
     /**
      * Obtain the hidden time of the profile.
      *
      * @return the hiddenTime
      */
     public OceanusDecimal getHidden() {
         return theHidden;
     }
 
     /**
      * Obtain the subtask iterator.
      *
      * @return the iterator
      */
     public Iterator<OceanusProfile> subTaskIterator() {
         return theSubTasks == null ? Collections.emptyIterator() : theSubTasks.iterator();
     }
 
     /**
      * Start a new subTask.
      *
      * @param pName the name of the subTask
      * @return the new task
      */
     public OceanusProfile startTask(final String pName) {
         /* If we are currently running */
         if (theStatus.isRunning()) {
             /* Prepare for the task */
             prepareForTask();
 
             /* Loop through the subTasks */
             for (OceanusProfile myProfile : theSubTasks) {
                 /* Check for duplicate name */
                 if (pName.equals(myProfile.getName())) {
                     throw new IllegalArgumentException("Duplicate Task - " + pName);
                 }
             }
 
             /* Create the new task */
             final OceanusProfile myTask = new OceanusProfile(pName);
             theSubTasks.add(myTask);
             theCurrentTask = myTask;
         }
 
         /* Return the current task */
         return theCurrentTask;
     }
 
     /**
      * Prepare for the task.
      */
     private void prepareForTask() {
         /* End any subTask */
         endSubTask();
 
         /* If we do not currently have a subTask list */
         if (theSubTasks == null) {
             /* Create the list */
             theSubTasks = new ArrayList<>();
         }
     }
 
     /**
      * End any subTask.
      */
     private void endSubTask() {
         /* If we have a subTask */
         if (theCurrentTask != null) {
             /* End the current task */
             theCurrentTask.end();
             theCurrentTask = null;
         }
     }
 
     /**
      * End the task.
      */
     public void end() {
         /* If we are currently running */
         if (theStatus.isRunning()) {
             /* End any subTasks */
             endSubTask();
 
             /* Stop the task and calculate the elapsed time */
             final long myEnd = System.nanoTime();
             theElapsed = new OceanusDecimal(myEnd - theStart, NUM_DECIMALS);
             theHidden = theSubTasks == null
                     ? null
                     : calculateHidden();
 
             /* Mark time as stopped */
             theStatus = OceanusProfileStatus.STOPPED;
         }
     }
 
     /**
      * Calculate the hidden time.
      *
      * @return the hidden time
      */
     private OceanusDecimal calculateHidden() {
         /* Initialise hidden value */
         final OceanusDecimal myHidden = new OceanusDecimal(theElapsed);
 
         /* Loop through the subTasks */
         for (OceanusProfile myProfile : theSubTasks) {
             /* Subtract child time */
             myHidden.subtractValue(myProfile.theElapsed);
         }
 
         /* Return calculated value */
         return myHidden;
     }
 
     /**
      * is the task running?
      *
      * @return true/false.
      */
     public boolean isRunning() {
         /* return status */
         return theStatus.isRunning();
     }
 
     /**
      * Obtain the currently active task.
      *
      * @return the task
      */
     public OceanusProfile getActiveTask() {
         /* If we are not currently running */
         if (!isRunning()) {
             return null;
         }
 
         /* Return self is no active and running subTask else ask subTask */
         return theCurrentTask == null
                 || !theCurrentTask.isRunning()
                 ? this
                 : theCurrentTask.getActiveTask();
     }
 
     /**
      * Status of timer.
      */
     public enum OceanusProfileStatus {
         /**
          * Running.
          */
         RUNNING,
 
         /**
          * Stopped.
          */
         STOPPED;
 
         /**
          * is the timer running?
          *
          * @return true/false
          */
         private boolean isRunning() {
             return this == RUNNING;
         }
     }
 }