Sibyx/phpGPX

<?php
/**
 * DistanceCalculator.php
 *
 * @author Jens Hassler
 * @author Jakub Dubec
 * @since  07/2018
 * @version 2.0
 */

namespace phpGPX\Helpers;

use phpGPX\Models\Point;
use phpGPX\phpGPX;

class DistanceCalculator
{
    /**
     * @var Point[]
     */
    private $points;

    /**
     * DistanceCalculator constructor.
     * @param Point[] $points
     */
    public function __construct(array $points)
    {
        $this->points = $points;
    }

    public function getRawDistance()
    {
        return $this->calculate([GeoHelper::class, 'getRawDistance']);
    }

    public function getRealDistance()
    {
        return $this->calculate([GeoHelper::class, 'getRealDistance']);
    }

    /**
     * @param Point[]|array $points
     * @return float
     */
    private function calculate($strategy)
    {
        $distance = 0;

        $pointCount = count($this->points);

        $lastConsideredPoint = null;

        for ($p = 0; $p < $pointCount; $p++) {
            $curPoint = $this->points[$p];

            // skip the first point
            if ($p === 0) {
                $lastConsideredPoint = $curPoint;
                continue;
            }

            // calculate the delta from current point to last considered point
            $curPoint->difference = call_user_func($strategy, $lastConsideredPoint, $curPoint);

            // if smoothing is applied we only consider points with a delta above the threshold (e.g. 2 meters)
            if (phpGPX::$APPLY_DISTANCE_SMOOTHING) {
                $differenceFromLastConsideredPoint = call_user_func($strategy, $curPoint, $lastConsideredPoint);

                if ($differenceFromLastConsideredPoint > phpGPX::$DISTANCE_SMOOTHING_THRESHOLD) {
                    $distance += $differenceFromLastConsideredPoint;
                    $lastConsideredPoint = $curPoint;
                }
            }

            // if smoothing is not applied we consider every point
            else {
                $distance += $curPoint->difference;
                $lastConsideredPoint = $curPoint;
            }

            $curPoint->distance = $distance;
        }

        return $distance;
    }
}