package main

import (
	log "github.com/sirupsen/logrus"
)

// queue represents a FIFO queue of bounds
type queue struct {
	size     int
	elements []bound
}

// newQueue returns a queue type
// it initializes the queue size and elements
func newQueue(size int, elems []bound) queue {
	return queue{size: size, elements: elems}
}

// enqueue adds an item to the queue
func (q *queue) enqueue(elem bound) {
	if q.size >= 0 && q.getLength() == q.size {
		log.Info("Queue Overflow")
		return
	}
	q.elements = append(q.elements, elem)
}

// dequeue pops an element from the start of the queue
func (q *queue) dequeue() bound {
	if q.isEmpty() {
		log.Info("Queue UnderFlow")
		return bound{}
	}
	element := q.elements[0]
	if q.getLength() == 1 {
		q.elements = nil
		return element
	}
	q.elements = q.elements[1:]
	return element
}

// getLength returns the number of items in the queue
func (q *queue) getLength() int {
	return len(q.elements)
}

// isEmpty returns true if no items are in the queue
func (q *queue) isEmpty() bool {
	return len(q.elements) == 0
}