package main

import (
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"strconv"
	"time"
)

var portToListenOn int = 9100
var defaultTZ string = "Europe/Berlin"

type DateTimeResponse struct {
	Year         int    `json:"year,omitempty"`
	Month        int    `json:"month,omitempty"`
	Day          int    `json:"day,omitempty"`
	Hour         int    `json:"hour,omitempty"`
	Minute       int    `json:"minute,omitempty"`
	Seconds      int    `json:"seconds,omitempty"`
	MilliSeconds int    `json:"milliSeconds,omitempty"`
	DateTime     string `json:"dateTime,omitempty"`
	Date         string `json:"date,omitempty"`
	Time         string `json:"time,omitempty"`
	TimeZone     string `json:"timeZone,omitempty"`
	DayOfWeek    string `json:"dayOfWeek,omitempty"`
	DstActive    bool   `json:"dstActive,omitempty"`
}

func main() {
	fmt.Println("********************************************")
	fmt.Println("*                                          *")
	fmt.Println("*  git.0x0001f346.de/andreas/Datetime-API  *")
	fmt.Println("*                                          *")
	fmt.Println("********************************************")
	fmt.Println("")
	fmt.Printf("Listening: http://localhost:%d\n", portToListenOn)
	fmt.Println("")

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		loc, _ := time.LoadLocation(defaultTZ)
		if r.URL.String() != "/" {
			newloc, err := time.LoadLocation(r.URL.String()[1:])
			if err == nil {
				loc = newloc
			}
		}

		log.Printf(
			"%q %q\n",
			loc.String(),
			r.RemoteAddr,
		)

		w.Header().Add("Content-Language", "en")
		w.Header().Add("Content-Type", "application/json; charset=utf-8")
		w.Header().Add("Server", "git.0x0001f346.de/andreas/Datetime-API")
		fmt.Fprint(w, GetDateTimeResponseAsJSONString(loc))
	})

	log.Fatal(http.ListenAndServe(fmt.Sprintf(":%d", portToListenOn), nil))
}

func GetDateTimeResponse(loc *time.Location) DateTimeResponse {
	t := time.Now().In(loc)
	return DateTimeResponse{
		Year:         t.Year(),
		Month:        int(t.Month()),
		Day:          t.Day(),
		Hour:         t.Hour(),
		Minute:       t.Minute(),
		Seconds:      t.Second(),
		MilliSeconds: func(i int64, err error) int { return int(i) }(strconv.ParseInt(strconv.Itoa(t.Nanosecond())[:3], 10, 0)),
		DateTime:     t.Format(time.RFC3339),
		Date:         fmt.Sprintf("%02d/%02d/%04d", t.Month(), t.Day(), t.Year()),
		Time:         fmt.Sprintf("%02d:%02d", t.Hour(), t.Minute()),
		TimeZone:     loc.String(),
		DayOfWeek:    t.Weekday().String(),
		DstActive:    t.IsDST(),
	}
}

func GetDateTimeResponseAsJSONString(loc *time.Location) string {
	r, _ := json.Marshal(GetDateTimeResponse(loc))
	return string(r)
}