Heap, heapsort, heapify with PHP

Heap.php

<?php
function heapSort( $arr ) {
	$arr       = createHeap( $arr );
	$sorted    = [];
	$arrLength = count( $arr );

	for ( $i = 1; $i <= $arrLength; $i ++ ) {
		$last = count( $arr );
		array_unshift( $sorted, $arr[1] );
		$arr[1] = $arr[ $last ];
		unset( $arr[ $last ] );

		if ( ! $arr ) {
			return $sorted;
		}

		$current = 1;

		while ( true ) {
			$leftIndex  = $current * 2;
			$rightIndex = $current * 2 + 1;
			$max        = null;

			if ( isset( $arr[ $leftIndex ], $arr[ $rightIndex ] ) ) {
				if ( $arr[ $leftIndex ] > $arr[ $rightIndex ] && $arr[ $leftIndex ] > $arr[ $current ] ) {
					$max = $leftIndex;
				} elseif ( $arr[ $leftIndex ] < $arr[ $rightIndex ] && $arr[ $rightIndex ] > $arr[ $current ] ) {
					$max = $rightIndex;
				}
			} elseif ( isset( $arr[ $leftIndex ] ) && $arr[ $leftIndex ] > $arr[ $current ] ) {
				$max = $arr[ $leftIndex ];
			} elseif ( isset( $arr[ $rightIndex ] ) && $arr[ $rightIndex ] > $arr[ $current ] ) {
				$max = $arr[ $rightIndex ];
			}

			if ( ! $max ) {
				break;
			}

			$temp            = $arr[ $max ];
			$arr[ $max ]     = $arr[ $current ];
			$arr[ $current ] = $temp;
			$current         = $max;
		}
	}

	return $sorted;
}

function createHeap( $arr ) {
	array_unshift( $arr, 'value' );
	unset( $arr[0] );

	$arrLength = count( $arr );

	for ( $i = 1; $i <= $arrLength; $i ++ ) {
		$current = $i;
		while ( true ) {
			$updated = false;
			$parent  = ( int ) ( $current / 2 );

			if ( ! isset( $arr[ $parent ] ) ) {
				break;
			}

			if ( $arr[ $current ] > $arr[ $parent ] ) {
				$temp            = $arr[ $current ];
				$arr[ $current ] = $arr[ $parent ];
				$arr[ $parent ]  = $temp;
				$updated         = true;
			}

			$current = $parent;

			if ( ! $parent || ! $updated ) {
				break;
			}
		}
	}

	return $arr;
}

function heapify( $arr ) {
	array_unshift( $arr, '1' );
	unset( $arr[0] );

	for ( $i = count( $arr ); $i > 0; $i -- ) {
		$current = $i;
		while( true ) {
			$left  = $current * 2;
			$right = $current * 2 + 1;
			$max = null;

			if ( isset( $arr[ $left ], $arr[ $right ] ) ) {
				if ( $arr[ $left ] > $arr[ $right ] && $arr[ $left ] > $arr[ $current ] ) {
					$max = $left;
				} elseif ( $arr[ $left ] < $arr[ $right ] && $arr[ $right ] > $arr[ $current ] ) {
					$max = $right;
				}
			} elseif ( isset( $arr[ $left ] ) && $arr[ $left ] > $arr[ $current ] ) {
				$max = $left;
			} elseif ( isset( $arr[ $right ] ) && $arr[ $right ] > $arr[ $current ] ) {
				$max = $right;
			}

			if ( ! $max ) {
				break;
			}

			$temp = $arr[ $current ];
			$arr[ $current  ] = $arr[ $max ];
			$arr[ $max ] = $temp;
			$current = $max;
		}
	}

	return $arr;
}

echo implode( ',', heapify( [ 10, 20, 15, 12, 40, 25, 18 ] ) );


//echo implode( ',', heapSort( [ 10, 20, 15, 30, 40 ] ) );