DVDoug\BoxPacker\OrientatedItemFactory

Complexity

Total Complexity

25

Size/Duplication

Total Lines	201
Duplicated Lines	0 %

Coupling/Cohesion

Components	1
Dependencies	5

Test Coverage

Coverage

98.73%

Importance

Changes	1
Bugs	0	Features	0

4 Methods

Rating	Name	Duplication	Size	Complexity
C	getBestOrientation()	0	50	11
B	getPossibleOrientations()	0	24	5
B	getPossibleOrientationsInEmptyBox()	0	29	2
C	getUsableOrientations()	0	46	7

<?php
/**
 * Box packing (3D bin packing, knapsack problem).
 *
 * @author Doug Wright
 */

namespace DVDoug\BoxPacker;

use Psr\Log\LoggerAwareInterface;
use Psr\Log\LoggerAwareTrait;

/**
 * Figure out orientations for an item and a given set of dimensions.
 *
 * @author Doug Wright
 */
class OrientatedItemFactory implements LoggerAwareInterface
{
    use LoggerAwareTrait;

    /**
     * @var OrientatedItem[]
     */
    protected static $emptyBoxCache = [];

    /**
     * Get the best orientation for an item.
     *
     * @param Box                 $box
     * @param Item                $item
     * @param OrientatedItem|null $prevItem
     * @param Item|null           $nextItem
     * @param bool                $isLastItem
     * @param int                 $widthLeft
     * @param int                 $lengthLeft
     * @param int                 $depthLeft
     *
     * @return OrientatedItem|null
     */
    public function getBestOrientation(
        Box $box,
        Item $item,
        $prevItem,
        $nextItem,
        $isLastItem,
        $widthLeft,
        $lengthLeft,
        $depthLeft
    ) {
        $possibleOrientations = $this->getPossibleOrientations($item, $prevItem, $widthLeft, $lengthLeft, $depthLeft);
        $usableOrientations = $this->getUsableOrientations($possibleOrientations, $box, $item, $isLastItem);

        if (empty($usableOrientations)) {
            return;
        }

        usort($usableOrientations, function (OrientatedItem $a, OrientatedItem $b) use ($widthLeft, $lengthLeft, $depthLeft, $nextItem) {
            $orientationAWidthLeft = $widthLeft - $a->getWidth();
            $orientationALengthLeft = $lengthLeft - $a->getLength();
            $orientationBWidthLeft = $widthLeft - $b->getWidth();
            $orientationBLengthLeft = $lengthLeft - $b->getLength();

            $orientationAMinGap = min($orientationAWidthLeft, $orientationALengthLeft);
            $orientationBMinGap = min($orientationBWidthLeft, $orientationBLengthLeft);

            if ($orientationAMinGap === 0) { // prefer A if it leaves no gap
                return -1;
            } elseif ($orientationBMinGap === 0) { // prefer B if it leaves no gap
                return 1;
            } else { // prefer leaving room for next item in current row
                if ($nextItem) {
                    $nextItemFitA = count($this->getPossibleOrientations($nextItem, $a, $orientationAWidthLeft, $orientationALengthLeft, $depthLeft));
                    $nextItemFitB = count($this->getPossibleOrientations($nextItem, $b, $orientationBWidthLeft, $orientationBLengthLeft, $depthLeft));
                    if ($nextItem && $nextItemFitA && !$nextItemFitB) {
                        return -1;
                    } elseif ($nextItem && $nextItemFitB && !$nextItemFitA) {
                        return 1;
                    }
                }
                // otherwise prefer leaving minimum possible gap
                return min($orientationAWidthLeft, $orientationALengthLeft) - min($orientationBWidthLeft, $orientationBLengthLeft);
            }
        });

        $bestFit = reset($usableOrientations);
        $this->logger->debug('Selected best fit orientation', ['orientation' => $bestFit]);

        return $bestFit;
    }

    /**
     * Find all possible orientations for an item.
     *
     * @param Item                $item
     * @param OrientatedItem|null $prevItem
     * @param int                 $widthLeft
     * @param int                 $lengthLeft
     * @param int                 $depthLeft
     *
     * @return OrientatedItem[]
     */
    public function getPossibleOrientations(
        Item $item,
        $prevItem,
        $widthLeft,
        $lengthLeft,
        $depthLeft
    ) {
        $orientations = [];

        //Special case items that are the same as what we just packed - keep orientation
        /* @noinspection PhpNonStrictObjectEqualityInspection */
        if ($prevItem && $prevItem->getItem() == $item) {
            $orientations[] = new OrientatedItem($item, $prevItem->getWidth(), $prevItem->getLength(), $prevItem->getDepth());
        } else {
            //simple 2D rotation
            $orientations[] = new OrientatedItem($item, $item->getWidth(), $item->getLength(), $item->getDepth());
            $orientations[] = new OrientatedItem($item, $item->getLength(), $item->getWidth(), $item->getDepth());
        }

        //remove any that simply don't fit
        return array_filter($orientations, function (OrientatedItem $i) use ($widthLeft, $lengthLeft, $depthLeft) {
            return $i->getWidth() <= $widthLeft && $i->getLength() <= $lengthLeft && $i->getDepth() <= $depthLeft;
        });
    }

    /**
     * @param Item $item
     * @param Box  $box
     *
     * @return OrientatedItem[]
     */
    public function getPossibleOrientationsInEmptyBox(Item $item, Box $box)
    {
        $cacheKey = $item->getWidth().
            '|'.
            $item->getLength().
            '|'.
            $item->getDepth().
            '|'.
            $box->getInnerWidth().
            '|'.
            $box->getInnerLength().
            '|'.
            $box->getInnerDepth();

        if (isset(static::$emptyBoxCache[$cacheKey])) {
            $orientations = static::$emptyBoxCache[$cacheKey];
        } else {
            $orientations = $this->getPossibleOrientations(
                $item,
                null,
                $box->getInnerWidth(),
                $box->getInnerLength(),
                $box->getInnerDepth()
            );
            static::$emptyBoxCache[$cacheKey] = $orientations;
        }

        return $orientations;
    }

    /**
     * @param OrientatedItem[] $possibleOrientations
     * @param Box              $box
     * @param Item             $item
     * @param bool             $isLastItem
     *
     * @return OrientatedItem[]
     */
    protected function getUsableOrientations(
        $possibleOrientations,
        Box $box,
        Item $item,
        $isLastItem
    ) {
        /*
         * Divide possible orientations into stable (low centre of gravity) and unstable (high centre of gravity)
         */
        $stableOrientations = [];
        $unstableOrientations = [];

        foreach ($possibleOrientations as $o => $orientation) {
            if ($orientation->isStable()) {
                $stableOrientations[] = $orientation;
            } else {
                $unstableOrientations[] = $orientation;
            }
        }

        $orientationsToUse = [];

        /*
         * We prefer to use stable orientations only, but allow unstable ones if either
         * the item is the last one left to pack OR
         * the item doesn't fit in the box any other way
         */
        if (count($stableOrientations) > 0) {
            $orientationsToUse = $stableOrientations;
        } elseif (count($unstableOrientations) > 0) {
            $orientationsInEmptyBox = $this->getPossibleOrientationsInEmptyBox($item, $box);

            $stableOrientationsInEmptyBox = array_filter(
                $orientationsInEmptyBox,
                function (OrientatedItem $orientation) {
                    return $orientation->isStable();
                }
            );

            if ($isLastItem || count($stableOrientationsInEmptyBox) == 0) {
                $orientationsToUse = $unstableOrientations;
            }
        }

        return $orientationsToUse;
    }
}