package com.guatec.timeseries

import java.util.*
import java.util.concurrent.ArrayBlockingQueue
import java.util.concurrent.BlockingQueue

/**
 * A chainable bounded queue.  When a value is evicted from this queue, it will be pushed to the chained queue (if any).
 */
class ChainableEvictingQueue<T: Comparable<T>>(maxCapacity: Int, val chainTo: Queue<T>? = null): BlockingQueue<T> by ArrayBlockingQueue<T>(maxCapacity) {
    var max: T? = null
        private set

    override fun offer(element: T): Boolean {
        if (remainingCapacity() == 0) {
            val evicted = poll()
            if (this.chainTo != null) {
                return this.chainTo.offer(evicted) && offer(element)
            }
        }
        if (max == null || element > max!!)
            max = element
        return offer(element)
    }

    override fun put(element: T) {
        offer(element)
    }
}