Time Left Estimator

class-estimator.php

<?php
/**
 * Estimator class to get estimated time left.
 */

class Estimator {

	public $total      = 0;
	public $count      = 0;
	public $start_time = 0;

	/**
	 * Creates a new Estimator class.
	 *
	 * @param int $total The total number of items for estimating.
	 */
	public function __construct( $total ) {
		$this->total      = $total;
		$this->count      = 0;
		$this->start_time = time();
	}

	/**
	 * Increments the total number of items processed.
	 *
	 * @return void
	 */
	public function tick() {
		$this->count++;
	}

	/**
	 * Gets the estimated number of seconds left.
	 *
	 * @return int
	 */
	public function seconds_left() {
		$per_second = $this->per_second();
		$items_left = $this->total - $this->count;
		return intval( ceil( $items_left * $per_second ) );
	}

	/**
	 * Gets the elapsed number of seconds since the class was created.
	 *
	 * @return int
	 */
	public function elapsed_seconds() {
		return time() - $this->start_time;
	}

	/**
	 * Gets the number of items processed per second.
	 *
	 * @return float
	 */
	public function per_second() {
		$per_second = floatval( 0 );
		$elapsed = $this->elapsed_seconds();
		if ( $elapsed > 0 && $this->count > 0 ) {
			$per_second = round( $this->count / $elapsed, 1 );
		}

		return $per_second;
	}

	/**
	 * Takes a time span given in seconds and formats it for display. The
	 * returned string will be in MM:SS form.
	 *
	 * @param int  $time The time span in seconds to format.
	 * @return string  The formatted time span.
	 */
	public function format_time( $time ) {
		// From https://github.com/wp-cli/php-cli-tools/blob/master/lib/cli/Notify.php
		return floor( $time / 60 ) . ':' . str_pad( $time % 60, 2, 0, STR_PAD_LEFT );
	}
}