Проверка на совпадение значений и сортировка массива

Исходный массив:

Array
(
[0] => Array
    (
        [product_id] => 353534543
        [offer_id] => 23424234
        [stock] => 50
        [warehouse_id] => 31558867618000
    )

[1] => Array
    (
        [product_id] => 353534543
        [offer_id] => 23424234
        [stock] => 12
        [warehouse_id] => 31558867618000
    )
[2] => Array
    (
        [product_id] => 123456
        [offer_id] => 3333333
        [stock] => 6
        [warehouse_id] => 21558867618010
    )
[3] => Array
    (
        [product_id] => 123456
        [offer_id] => 3333333
        [stock] => 6
        [warehouse_id] => 21558867618010
    )
[4] => Array
    (
        [product_id] => 44444
        [offer_id] => 12314
        [stock] => 5
        [warehouse_id] => 21558867618010
    )

)

Если значения offer_id и warehouse_id равны, тогда stock нужно сложить. Как реализовать это условие на PHP?

В результате должен получиться массив:

Array
(
[0] => Array
    (
        [product_id] => 353534543
        [offer_id] => 23424234
        [stock] => 62
        [warehouse_id] => 31558867618000
    )

[1] => Array
    (
        [product_id] => 123456
        [offer_id] => 3333333
        [stock] => 12
        [warehouse_id] => 21558867618010
    )
[2] => Array
    (
        [product_id] => 44444
        [offer_id] => 12314
        [stock] => 5
        [warehouse_id] => 21558867618010
    )

)