Best practice for looping through a nested array php - php

Question

I am writing in PHP.
What I am trying to do is something like a configurable product in Magento2 or variable product in Woocommerce. I am asking the user to enter attributes to the product, like color, size, etc'.
Think of each attribute as a attribute category which contains attributes inside it, e.g 'color' will have attributes like 'red', 'green', 'blue' and so on. Size will have attributes like 'large', 'small', 'medium' and so on.
Now, I need to make a loop which takes all sizes, colors and other chosen attributes and returns all the possible configurations. At the same time the amount of attributes to loop through isn't predefined since the user can add or remove attributes.
For example if I have this:
Color - - - - - - - - Size - - - - - - - - Shape
Red - - - - - - - - - Large - - - - - - - Square
Green - - - - - - - - Medium - - - - - - - Rounded
Blue - - - - - - - - Small - - - - - - - -
So I will have to have every color with every size and shape:
Red - Large - Square
Red - Large - Rounded
Red - Medium - Square
Red - Medium - Rounded
Red - Small - Square
Red - Small - Rounded
And the same with the other attributes.
What is the best practice to achive it?

Answer 1

You will need recursion for this.
function getCombinations($attributes){
$combinations = [];
buildCombinationChain($attributes,0,[],$combinations);
// encode combinations to desired string format
$result = [];
foreach ($combinations as $combination) {
$result[] = implode(' - ', $combination);
}
return $result;
}
function buildCombinationChain($attributes,$index,$chain,&$output){
if($index>=count($attributes)){
// we have reached the last attribute, stop recursion and push the current chain to the output array
$output[] = $chain;
return;
}
foreach ($attributes[$index] as $attribute) {
$new_chain = $chain; // create a copy of the current chain
$new_chain[] = $attribute; // and add the current attribute to it
buildCombinationChain($attributes,$index+1,$new_chain,$output); // continue recursively on the next attribute group
}
}
$attributes = [
['Red', 'Green', 'Blue'],
['Large', 'Medium', 'Small'],
['Square', 'Rounded']
];
echo json_encode(getCombinations($attributes));