Scontrini-Web-Client/main.go

package main

import (
	"errors"
	"fmt"
	"html/template"
	"net/http"
	"os"
	"strconv"
)

var (
	templates = template.Must(template.ParseFiles("templates/index.html", "templates/pizza.html", "templates/ordered.html"))
)

type Pizza struct {
	Name     string `json:"name"`
	Price    int    `json:"price"`
	Quantity int    `json:"quantity"`
}

/**
* Handler function for "/"
 */
func indexHandler(w http.ResponseWriter, r *http.Request) {
	templates.ExecuteTemplate(w, "index.html", nil)
}

/**
* Handler function for "/print", only accepts POST requests
*
* Tells the API to print the text specified in its Form
 */
func printHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	text := r.PostFormValue("text")

	json_command := PrintCommand{Command: "print", Text: text}
	_, err := sendJSONToServer(nil, json_command)

	if err != nil {
		fmt.Fprintf(w, "Error while connecting to the printer server")
		return
	}

	http.Redirect(w, r, "/", http.StatusSeeOther)
}

/**
* Handler function for "/pizza", only accepts POST requests
*
* Tells the API to print the pizza order specified in its Form, then receive
* back the correct price and return a formatted HTML page
 */
func pizzaHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	pizzas := make([]Pizza, 0)

	r.ParseForm()
	for key, _ := range r.Form {
		// only put in the pizzas that have a quantity bigger than 0
		if key != "submit" && r.Form[key][0] != "0" {
			quantity, _ := strconv.ParseInt(r.Form[key][0], 10, 0)
			pizzas = append(pizzas, Pizza{key, 0, int(quantity)})
		}
	}

	json_command := PizzaCommand{Command: "pizza", Pizzas: pizzas}
	socket, err := sendJSONToServer(nil, json_command)

	if err != nil {
		fmt.Fprintf(w, "Error while connecting to the printer server")
		return
	}

	price := ReceivePrice{}
	_, err = receiveJSONFromServer(socket, &price)

	if err != nil {
		fmt.Fprintf(w, "Error while connecting to the printer server")
		return
	}

	// pass the order data to the HTML
	order := struct {
		Pizzas     []Pizza
		TotalPrice int
	}{
		pizzas,
		price.TotalPrice,
	}

	templates.ExecuteTemplate(w, "ordered.html", order)
}

/**
* Handler function for "/order_pizzas"
*
* Asks the API for the list of all pizzas then returns a formatted HTML page
 */
func orderPizzasHandler(w http.ResponseWriter, r *http.Request) {
	json_command := GetPizzasCommand{Command: "get-pizzas"}
	socket, err := sendJSONToServer(nil, json_command)

	if err != nil {
		fmt.Fprintf(w, "Error while connecting to the printer server")
		return
	}

	pizzas := ReceivePizzas{}
	_, err = receiveJSONFromServer(socket, &pizzas)

	if err != nil {
		fmt.Fprintf(w, "Error while connecting to the printer server")
		return
	}

	templates.ExecuteTemplate(w, "pizza.html", pizzas.Pizzas)
}

func main() {
	mux := http.NewServeMux()

	mux.HandleFunc("/", indexHandler)
	mux.HandleFunc("/print", printHandler)
	mux.HandleFunc("/pizza", pizzaHandler)
	mux.HandleFunc("/order_pizzas", orderPizzasHandler)

	err := http.ListenAndServe(":8080", mux)
	if errors.Is(err, http.ErrServerClosed) {
		fmt.Println("Server closed")
	} else if err != nil {
		fmt.Printf("Error starting server: %s\n", err)
		os.Exit(1)
	}
}