I have 3 levels of permission to see the product:

• Brand -> Allow/Deny

• Category -> Allow/Deny

• Product -> Allow/Deny

For example, product A has:

• Category: Allow
• Product: Deny

=> product A cannot be seen because product A isn't allowed in Product level.

if(allowForCategory == true) {
    if(allowForProduct == false) return false;
    if(allowForProduct == true) return true;
} else {
    ...
}

This is not a good choice because it will become more complex if we add brand level.

if() {
    if() {
        if() {}
    }
}

So is there any general algorithm to deal with the permission problem just like 777 solution in Linux?