inventory console project

inventory console project.kt

file Main.kt:

var productList = mutableListOf<Product>()

fun main(args: Array<String>) {

    val handler = ProductHandler()
    val reader  = ReadFileCoroutine()
    val writer = WriteFileCoroutine()

    reader.read {
        handler.fromJson(it)
    }

    try {
        while (true) {
            when (Menu.getMenu()) {
                1 -> {
                    handler.showAllProducts()
                }

                2 -> {
                    Actions.insertProduct(handler,writer)
                }

                3 -> {
                    Actions.increaseProductCount(handler,writer)
                }

                4 -> {
                    Actions.decreaseProductCount(handler,writer)
                }

                5 -> {
                    Actions.deleteProduct(handler,writer)
                }

                0 -> {
                    println("You are logged out")
                    return
                }
            }
        }
    }
    catch (e:NotFoundExeption){
        println(e.message)
    }
    catch (e:Exception){
        println(e.message)
    }
}

class ReadFileCoroutine:

class ReadFileCoroutine {
    private var fileName = "C:\\\\Users\\PC\\intellij projects\\inventory\\1.txt"
    fun read(callback: (String) -> Unit){
        GlobalScope.launch(Dispatchers.IO) {
            FileUtility.readFile(fileName,callback)
        }
    }
}

class Actions:
r description = readLine()!!
            println("Price : ")
            var price = readLine()?.toInt()!!
            println("Quantity : ")
            var quantity = readLine()?.toInt()!!

            var newProduct = Product(sku, name, description, price, quantity)
            handler.addProduct(newProduct)
            println("Product inserting dose Successfully!")
            writer.write(handler.toJson()!!)
        }

        fun increaseProductCount(handler: ProductHandler, writer: WriteFileCoroutine) {
            println("SKU : ")
            var sku = readLine()!!
            println("Count : ")
            var count = readLine()?.toInt()!!
            if (handler.increaseQuantity(sku, count)) {
                println("increased Product count dose Successfully")
                writer.write(handler.toJson()!!)
            } else {
                println("Error in product increased:0x0000001 ")
            }
        }

        fun decreaseProductCount(handler: ProductHandler, writer: WriteFileCoroutine) {
            println("SKU : ")
            var sku = readLine()!!
            println("Count : ")
            var count = readLine()?.toInt()!!
            if (handler.decreaseQuantity(sku, count)) {
                println("decreased Product count dose Successfully")
                writer.write(handler.toJson()!!)
            } else {
                println("Error in product decreased:0x0000001 ")
            }
        }

        fun deleteProduct(handler: ProductHandler, writer: WriteFileCoroutine) {
            println("SKU : ")
            var sku = readLine()!!
            handler.removeProduct(sku)
            println("Product delete successfully!")
            writer.write(handler.toJson()!!)
        }
    }
}
class ProductHandler:
class ProductHandler {
    companion object {
        private var productList = mutableListOf<Product>()
    }

    fun showAllProducts() {
        if (productList.isEmpty()) println("There are no products")
        productList.forEach { println(it) }
    }

    fun toJson(): String? {
        val gson = Gson()
        return gson.toJson(productList)
    }

    fun fromJson(json: String): List<Product> {
        val gson = Gson()
        val listType: Type = object : TypeToken<MutableList<Product>>() {}.type

        var result = gson.fromJson<List<Product>>(json, listType)
        productList.clear()
        productList.addAll(result)
        return productList
    }

    fun addProduct(product: Product) {
        productList.add(product)
    }

    fun removeProduct(sku: String) {
        productList.removeIf { it.sku == sku }
    }

    fun getProduct(sku: String): Product? {
        return productList.first { it.sku == sku }
    }

    fun increaseQuantity(sku: String, count: Int): Boolean {
        var product = getProduct(sku) ?: throw Exception("There is no product with this SKU")
        product.quantity += count
        return true
    }

    fun decreaseQuantity(sku: String, count: Int): Boolean {
        var product = getProduct(sku) ?: throw NotFoundExeption("There is no product with this SKU")
        if (product.quantity - count < 0) {
            throw Exception("تعداد موجود در انبار از $count کمتر است ")
        }
        product.quantity -= count
        return true
    }
}

data class Product:
data class Product(
    var sku:String,
    var name:String,
    var description:String,
    var price:Int,
    var quantity:Int
){
    fun toJson(): String? {
        var gson = Gson()
        return gson.toJson(this)
    }

    companion object{
        fun fromJson(json: String): Product {
            var gson = Gson()
            return gson.fromJson(json, Product::class.java)
        }
    }
}

class NotFoundExeption:
class NotFoundExeption(messege:String) : Exception(messege) {

}

class WriteFileCoroutine:
class WriteFileCoroutine {
    private var fileName = "C:\\\\Users\\PC\\intellij projects\\inventory\\1.txt"
    fun write(text:String){
        GlobalScope.launch(Dispatchers.IO) {
            FileUtility.write(fileName,text)
        }
    }

    fun append(text:String){
        GlobalScope.launch(Dispatchers.IO) {
            FileUtility.appendToFile(fileName,text)
        }
    }
}

class Menu:
class Menu {
    companion object{
        fun getMenu():Int {
            println("select options")
            println("[1] -> Show Available Products")
            println("[2] -> Add New product")
            println("[3] -> increased inventory Product")
            println("[4] -> decreased inventory Product")
            println("[5] -> delete Product")
            println("[0] -> Exit the Console")
            return readLine()?.toInt()!!
        }
    }
}