How to implement a method for calculating discounts based on a specific user?

To choose a discount calculation method depending on a specific user in PHP, you can use the "Strategy" pattern. The idea is to define different discount calculation classes and select the appropriate one based on the user's properties.

Example:

interface DiscountStrategy {
    public function calculate(float $price): float;
}

class VipDiscount implements DiscountStrategy {
    public function calculate(float $price): float {
        return $price * 0.8; // 20% discount
    }
}

class RegularDiscount implements DiscountStrategy {
    public function calculate(float $price): float {
        return $price * 0.95; // 5% discount
    }
}

class NoDiscount implements DiscountStrategy {
    public function calculate(float $price): float {
        return $price; // no discount
    }
}

class User {
    public string $type; // e.g., 'vip', 'regular', 'guest'

    public function __construct(string $type) {
        $this->type = $type;
    }
}

function getDiscountStrategy(User $user): DiscountStrategy {
    switch ($user->type) {
        case 'vip':
            return new VipDiscount();
        case 'regular':
            return new RegularDiscount();
        default:
            return new NoDiscount();
    }
}

// Usage
$user = new User('vip');
$strategy = getDiscountStrategy($user);
$finalPrice = $strategy->calculate(1000);

echo $finalPrice; // 800

This approach allows easy extension of discount logic and maintenance of the code.