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package org.scijava.task;

import java.util.concurrent.ExecutionException;

import org.scijava.Cancelable;
import org.scijava.Named;

/**
 * A self-aware job which reports its status and progress as it runs.
 *
 * @author Curtis Rueden
 */
public interface Task extends Cancelable, Named {

	/**
	 * Starts running the task.
	 *
	 * @throws IllegalStateException if the task was already started.
	 */
	void run(Runnable r);

	/**
	 * Waits for the task to complete.
	 *
	 * @throws IllegalStateException if {@link #run} has not been called yet.
	 * @throws InterruptedException if the task is interrupted.
	 * @throws ExecutionException if the task throws an exception while running.
	 */
	void waitFor() throws InterruptedException, ExecutionException;

	/** Checks whether the task has completed. */
	boolean isDone();

	/** Gets a status message describing what the task is currently doing. */
	String getStatusMessage();

	/**
	 * Gets the step the task is currently performing.
	 *
	 * @return A value between 0 and {@link #getProgressMaximum()} inclusive.
	 * @see #getProgressMaximum()
	 */
	long getProgressValue();

	/**
	 * Gets the number of steps the task performs in total.
	 *
	 * @return Total number of steps the task will perform, or 0 if unknown.
	 * @see #getProgressValue()
	 */
	long getProgressMaximum();

	/**
	 * Sets the status message. Called by task implementors.
	 *
	 * @param status The message to set.
	 * @see #getStatusMessage()
	 */
	void setStatusMessage(String status);

	/**
	 * Sets the current step. Called by task implementors.
	 *
	 * @param step The step vaule to set.
	 * @see #getProgressValue()
	 */
	void setProgressValue(long step);

	/**
	 * Sets the total number of steps. Called by task implementors.
	 *
	 * @param max The step count to set.
	 * @see #getProgressMaximum()
	 */
	void setProgressMaximum(long max);
}