package main

import (
	"bufio"
	"fmt"
	"os"
	"strings"
)

type product struct {
	id   int
	name string
	stock int
}

type order struct {
	id int
	name string
	idProduct int
	quantity int
}

type user struct {
	username string
	password string
}

func main() {
	var products []product
	var users []user
	var orders []order

	var isLogin = false

	var input, idOrder, idProduct, quantity, action, id int
	var username, password, name string

	for !isLogin {

		displayGuestMenu()

		_, _ = fmt.Scanf("%d", &action)

		if action == 1 {
			isLogin = login(users)
		} else if action == 2 {
			fmt.Println("Masukkan username:")
			_, _ = fmt.Scanf("%s", &username)
			fmt.Println("Masukkan password:")
			_, _ = fmt.Scanf("%s", &password)

			register(username, password, &users)
		} else if action == 0 {
			fmt.Println("Thank you for using i-Shope! :)")
			break
		}
	}

	for isLogin {
		displayMenu()

		_, _ = fmt.Scanf("%d", &input)

		switch input {
		case 0:
			fmt.Println("Thank you for using i-Shope! :)")
			isLogin = false
			break
		case 1:
			showListProduct(products)
			break
		case 2:
			fmt.Println("Masukkan id product:")
			_, _ = fmt.Scanf("%d", &id)
			showProductById(id, products)
			break
		case 3:
			addProduct(&products)
			break
		case 4:
			fmt.Println("Masukkan id product:")
			_, _ = fmt.Scanf("%d", &id)
			updateProductById(id, &products)
			break
		case 5:
			fmt.Println("Masukkan id product:")
			_, _ = fmt.Scanf("%d", &id)
			deleteProductById(id, &products)
			break
		case 6:
			fmt.Println("Masukkan order sesuai format: idOrder userName idProduct Quantity")
			_, _ = fmt.Scanf("%d %s %d %d", &idOrder, &name, &idProduct, &quantity)
			orderProduct(order{idOrder, name, idProduct, quantity}, &products, &orders)
			break
		default:
			fmt.Println("Menu tidak dikenali, coba cek lagi!")
			break
		}
	}
}

func displayGuestMenu() {
	fmt.Println("Welcome to i-Shope :)")
	fmt.Println("Guest menu:")
	fmt.Println("1. Login")
	fmt.Println("2. Register")
	fmt.Println("0. Cancel")
}

func displayMenu() {
	fmt.Println("[======================]")
	fmt.Println("List menu: ")
	fmt.Println("1.] -> Show list product")
	fmt.Println("2.] -> Show product by id")
	fmt.Println("3.] -> Add product")
	fmt.Println("4.] -> Update product")
	fmt.Println("5.] -> Delete product")
	fmt.Println("6.] -> Order product")
	fmt.Println("0.] -> [[ Exit Program ]]")
	fmt.Println("[======================]")
}

func orderProduct(order order, products *[]product, orders *[]order) {
	for i, p := range *products {
		if p.id == order.idProduct {
			if p.stock >= 1 &&  p.stock >= order.quantity {
				(*products)[i] = product{p.id, p.name, p.stock - order.quantity}
				*orders = append(*orders, order)
				printOrders(orders)
				fmt.Println("Terimakasih, anda sudah berhasil melakukan pemesanan terhadap product kami :)")
			} else {
				fmt.Println("Maaf, stock sudah habis atau tidak mencukupi!")
			}
			return
		}
	}
}

func printOrders(orders *[]order) {
	fmt.Println("Berhasil di order:")
	for _, o := range *orders {
		fmt.Println("ID: ", o.id)
		fmt.Println("Username: ", o.name)
		fmt.Println("ID Product: ", o.idProduct)
		fmt.Println("Quantity: ", o.quantity)
		fmt.Println("=======================")
	}
}

func deleteProductById(id int, products *[]product) {
	for i, p := range *products {
		if p.id == id {
			*products = append((*products)[:i], (*products)[i+1:]...)
			showListProduct(*products)
			return
		}

		if i == len(*products) - 1 {
			fmt.Println("Product not found!")
		}
	}
}

func updateProductById(id int, products *[]product) {
	newName := ""
	newStock := 0

	fmt.Println("Masukkan nama terbaru product")
	consoleReader := bufio.NewReader(os.Stdin)
	newName, _ = consoleReader.ReadString('\n')

	fmt.Println("Masukkan jumlah stock")
	_, _ = fmt.Scanf("%d", &newStock)

	for i, p := range *products {
		if p.id == id {
			(*products)[i] = product{id, newName, newStock}
			showListProduct(*products)
			return
		}

		if i == len(*products) - 1 {
			fmt.Println("Product not found!")
		}
	}
}

func addProduct(products *[]product) {
	var id, stock int
	name := ""

	fmt.Println("Masukkan id product")
	_, _ = fmt.Scanf("%d", &id)
	fmt.Println("Masukkan nama product")

	consoleReader := bufio.NewReader(os.Stdin)
	name, _ = consoleReader.ReadString('\n')

	fmt.Println("Masukkan jumlah stock")
	_, _ = fmt.Scanf("%d", &stock)

	*products = append(*products, product{id, name, stock})
	showListProduct(*products)
}

func showProductById(id int, products []product) {
	if len(products) == 0 {
		fmt.Println("There's no product yet!")
	}

	for i, p := range products {
		if p.id == id {
			fmt.Println("ID: ", p.id)
			fmt.Println("Stock: ", p.stock)
			fmt.Println("Name: ", p.name)
			return
		}

		if i == len(products) - 1 {
			fmt.Println("Product not found!")
		}
	}
}

func showListProduct(products []product) {
	if len(products) == 0 {
		fmt.Println("There's no product yet, please add a product before")
		return
	}

	fmt.Println("List products:")
	for _, p := range products {
		fmt.Println("ID: ", p.id)
		fmt.Println("Stock: ", p.stock)
		fmt.Println("Name: ", p.name)
	}
}

func checkCredential(username string, password string, users []user) bool {
	for _, u := range users {
		if strings.Compare(username, u.username) == 0 && strings.Compare(password, u.password) == 0 {
			return true
		}
	}

	return false
}

func login(users []user) bool {
	var username, password string

	fmt.Println("You must login to access this program.")

	fmt.Println("Username: ")
	_, _ = fmt.Scanf("%s", &username)
	fmt.Println("Password: ")
	_, _ = fmt.Scanf("%s", &password)

	if checkCredential(username, password, users) {
		return true
	}

	return false
}

func register(username string, password string, users *[]user) {
	*users = append(*users, user{username, password})
}