package main

import (
	"encoding/json"
	"net/http"
	"strconv"
)

const (
	version = "1.0.1"
)

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

	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("Hello, World page"))
	})
	mux.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
		json.NewEncoder(w).Encode(map[string]string{"message": "hello world json!"})
	})
	mux.HandleFunc("/version", func(w http.ResponseWriter, r *http.Request) {
		json.NewEncoder(w).Encode(map[string]string{"version": version})
	})
	mux.HandleFunc("/sum", func(w http.ResponseWriter, r *http.Request) {
		a, _ := strconv.Atoi(r.URL.Query().Get("a"))
		b, _ := strconv.Atoi(r.URL.Query().Get("b"))
		json.NewEncoder(w).Encode(map[string]int{"result": sum(a, b)})
	})
	mux.HandleFunc("/sub", func(w http.ResponseWriter, r *http.Request) {
		a, _ := strconv.Atoi(r.URL.Query().Get("a"))
		b, _ := strconv.Atoi(r.URL.Query().Get("b"))
		json.NewEncoder(w).Encode(map[string]int{"result": sub(a, b)})
	})

	http.ListenAndServe(":8080", mux)
}

func sum(a, b int) int {
	return a + b
}

func sub(a, b int) int {
	return a - b
}