// Chapter 33 example: reading values from the query string.
// Run with: go run exercises/33/01-query-string.go

package main

import (
	"fmt"
	"net/http"
	"strconv"
)

func handleHello(w http.ResponseWriter, r *http.Request) {
	name := r.URL.Query().Get("name")
	if name == "" {
		http.Error(w, "Please give a name, as in /hello?name=Keiko", http.StatusBadRequest)
		return
	}

	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	fmt.Fprintf(w, "Hello, %s!\n", name)
}

func handleAdd(w http.ResponseWriter, r *http.Request) {
	query := r.URL.Query()

	a, err := strconv.Atoi(query.Get("a"))
	if err != nil {
		http.Error(w, "a must be a whole number.", http.StatusBadRequest)
		return
	}

	b, err := strconv.Atoi(query.Get("b"))
	if err != nil {
		http.Error(w, "b must be a whole number.", http.StatusBadRequest)
		return
	}

	fmt.Fprintf(w, "%d + %d = %d\n", a, b, a+b)
}

func main() {
	http.HandleFunc("GET /hello", handleHello)
	http.HandleFunc("GET /add", handleAdd)

	fmt.Println("Server running at http://localhost:8080")
	fmt.Println("Press Ctrl+C to stop it.")

	err := http.ListenAndServe("localhost:8080", nil)
	if err != nil {
		fmt.Println("Server stopped:", err)
	}
}