Code Decoupling and Modularization in Kotlin

// Coupled code
class AreaCalculator {
    fun calculateArea(length: Double, width: Double, shape: String): Double {
        return when (shape) {
            "rectangle" -> length * width // calculate area for rectangle
            "triangle" -> (length * width) / 2 // calculate area for triangle
            else -> 0.0
        }
    }
}

// Decoupled code
class RectangleAreaCalculator {
    fun calculateRectangleArea(length: Double, width: Double): Double {
        return length * width // function to calculate rectangle area
    }
}

class TriangleAreaCalculator {
    fun calculateTriangleArea(length: Double, width: Double): Double {
        return (length * width) / 2 // function to calculate triangle area
    }
}

// Monolithic code with high dependencies
class Order(
    private val items: Array<String>,
    private val prices: DoubleArray,
    private val discountRate: Double,
    private val taxRate: Double
) {

    fun calculateTotal(): Double {
        var total = prices.sum()
        total -= total * discountRate
        total += total * taxRate
        return total
    }

    fun printOrderSummary() {
        val total = calculateTotal()
        println("Order Summary: Items: ${items.joinToString(", ")}, Total after tax and discount: $%.2f".format(total))
    }
}

// Decoupled and modularized code
object DiscountCalculator {
    fun applyDiscount(price: Double, discountRate: Double): Double {
        return price - (price * discountRate)
    }
}

object TaxCalculator {
    fun applyTax(price: Double, taxRate: Double): Double {
        return price + (price * taxRate)
    }
}

class Order(
    private val items: Array<String>,
    private val prices: DoubleArray,
    private val discountRate: Double,
    private val taxRate: Double
) {

    fun calculateTotal(): Double {
        var total = prices.sum()
        total = DiscountCalculator.applyDiscount(total, discountRate)
        total = TaxCalculator.applyTax(total, taxRate)
        return total
    }

    fun printOrderSummary() {
        val total = calculateTotal()
        println("Order Summary: Items: ${items.joinToString(", ")}, Total after tax and discount: $%.2f".format(total))
    }
}