package com.coreoz.wisp.schedule;

/**

* Provide the time of the next executions of a job.

* The implementations should be thread-safe.

* Moreover the same instance of a schedule should be usable on multiple jobs.

*/

public interface Schedule {

/**

* If the {@link #nextExecutionInMillis(long, int, Long)} returned value is {@code -1},

* then the corresponding job will not be executed again.

*/

static final long WILL_NOT_BE_EXECUTED_AGAIN = -1L;

/**

* A schedule that will always return {@link #WILL_NOT_BE_EXECUTED_AGAIN}.

*/

static final Schedule willNeverBeExecuted = (c, e, l) -> Schedule.WILL_NOT_BE_EXECUTED_AGAIN;

/**

* Compute the next execution time for a job.

* This method should be thread-safe.

*

* @param currentTimeInMillis The current time in milliseconds. This time must be used if

* a next execution is planned for the job

* @param executionsCount The number of times a job has already been executed

* @param lastExecutionEndedTimeInMillis The time at which the job has last been executed; will be null

* if the job has never been executed

* @return The time in milliseconds at which the job should execute next.

* This time must be relative to {@code currentTimeInMillis}.

* If the returned value is negative, the job will not be executed again.

*/

long nextExecutionInMillis(long currentTimeInMillis, int executionsCount, Long lastExecutionEndedTimeInMillis);

}