/*
    * Copyright 2013 The Netty Project
    *
    * The Netty Project licenses this file to you 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:
    *
    *   https://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.netty.util.concurrent;
  
  import io.netty.util.internal.DefaultPriorityQueue;
  import io.netty.util.internal.PriorityQueueNode;
  
  import java.util.concurrent.Callable;
  import java.util.concurrent.Delayed;
  import java.util.concurrent.TimeUnit;
  
  @SuppressWarnings("ComparableImplementedButEqualsNotOverridden")
  final class ScheduledFutureTask<V> extends PromiseTask<V> implements ScheduledFuture<V>, PriorityQueueNode {
      // set once when added to priority queue
      private long id;
  
      private long deadlineNanos;
      /* 0 - no repeat, >0 - repeat at fixed rate, <0 - repeat with fixed delay */
      private final long periodNanos;
  
      private int queueIndex = INDEX_NOT_IN_QUEUE;
  
      ScheduledFutureTask(AbstractScheduledEventExecutor executor,
              Runnable runnable, long nanoTime) {
  
          super(executor, runnable);
          deadlineNanos = nanoTime;
          periodNanos = 0;
      }
  
      ScheduledFutureTask(AbstractScheduledEventExecutor executor,
              Runnable runnable, long nanoTime, long period) {
  
          super(executor, runnable);
          deadlineNanos = nanoTime;
          periodNanos = validatePeriod(period);
      }
  
      ScheduledFutureTask(AbstractScheduledEventExecutor executor,
              Callable<V> callable, long nanoTime, long period) {
  
          super(executor, callable);
          deadlineNanos = nanoTime;
          periodNanos = validatePeriod(period);
      }
  
      ScheduledFutureTask(AbstractScheduledEventExecutor executor,
              Callable<V> callable, long nanoTime) {
  
          super(executor, callable);
          deadlineNanos = nanoTime;
          periodNanos = 0;
      }
  
      private static long validatePeriod(long period) {
          if (period == 0) {
              throw new IllegalArgumentException("period: 0 (expected: != 0)");
          }
          return period;
      }
  
      ScheduledFutureTask<V> setId(long id) {
          if (this.id == 0L) {
              this.id = id;
          }
          return this;
      }
  
      long getId() {
          return id;
      }
  
      @Override
      protected EventExecutor executor() {
          return super.executor();
      }
  
      public long deadlineNanos() {
          return deadlineNanos;
      }
  
      void setConsumed() {
          // Optimization to avoid checking system clock again
          // after deadline has passed and task has been dequeued
          if (periodNanos == 0) {
             assert scheduledExecutor().getCurrentTimeNanos() >= deadlineNanos;
             deadlineNanos = 0L;
         }
     }
 
     public long delayNanos() {
         if (deadlineNanos == 0L) {
             return 0L;
         }
         return delayNanos(scheduledExecutor().getCurrentTimeNanos());
     }
 
     static long deadlineToDelayNanos(long currentTimeNanos, long deadlineNanos) {
         return deadlineNanos == 0L ? 0L : Math.max(0L, deadlineNanos - currentTimeNanos);
     }
 
     public long delayNanos(long currentTimeNanos) {
         return deadlineToDelayNanos(currentTimeNanos, deadlineNanos);
     }
 
     @Override
     public long getDelay(TimeUnit unit) {
         return unit.convert(delayNanos(), TimeUnit.NANOSECONDS);
     }
 
     @Override
     public int compareTo(Delayed o) {
         if (this == o) {
             return 0;
         }
 
         ScheduledFutureTask<?> that = (ScheduledFutureTask<?>) o;
         long d = deadlineNanos() - that.deadlineNanos();
         if (d < 0) {
             return -1;
         } else if (d > 0) {
             return 1;
         } else if (id < that.id) {
             return -1;
         } else {
             assert id != that.id;
             return 1;
         }
     }
 
     @Override
     public void run() {
         assert executor().inEventLoop();
         try {
             if (delayNanos() > 0L) {
                 // Not yet expired, need to add or remove from queue
                 if (isCancelled()) {
                     scheduledExecutor().scheduledTaskQueue().removeTyped(this);
                 } else {
                     scheduledExecutor().scheduleFromEventLoop(this);
                 }
                 return;
             }
             if (periodNanos == 0) {
                 if (setUncancellableInternal()) {
                     V result = runTask();
                     setSuccessInternal(result);
                 }
             } else {
                 // check if is done as it may was cancelled
                 if (!isCancelled()) {
                     runTask();
                     if (!executor().isShutdown()) {
                         if (periodNanos > 0) {
                             deadlineNanos += periodNanos;
                         } else {
                             deadlineNanos = scheduledExecutor().getCurrentTimeNanos() - periodNanos;
                         }
                         if (!isCancelled()) {
                             scheduledExecutor().scheduleFromEventLoop(this);
                         }
                     }
                 }
             }
         } catch (Throwable cause) {
             setFailureInternal(cause);
         }
     }
 
     private AbstractScheduledEventExecutor scheduledExecutor() {
         return (AbstractScheduledEventExecutor) executor();
     }
 
     /**
      * {@inheritDoc}
      *
      * @param mayInterruptIfRunning this value has no effect in this implementation.
      */
     @Override
     public boolean cancel(boolean mayInterruptIfRunning) {
         boolean canceled = super.cancel(mayInterruptIfRunning);
         if (canceled) {
             scheduledExecutor().removeScheduled(this);
         }
         return canceled;
     }
 
     boolean cancelWithoutRemove(boolean mayInterruptIfRunning) {
         return super.cancel(mayInterruptIfRunning);
     }
 
     @Override
     protected StringBuilder toStringBuilder() {
         StringBuilder buf = super.toStringBuilder();
         buf.setCharAt(buf.length() - 1, ',');
 
         return buf.append(" deadline: ")
                   .append(deadlineNanos)
                   .append(", period: ")
                   .append(periodNanos)
                   .append(')');
     }
 
     @Override
     public int priorityQueueIndex(DefaultPriorityQueue<?> queue) {
         return queueIndex;
     }
 
     @Override
     public void priorityQueueIndex(DefaultPriorityQueue<?> queue, int i) {
         queueIndex = i;
     }
 }