package main

import (
	"flag"
	"fmt"
	"os"
	"strings"
	"sync"
	"time"
	"text/template"
)

/*

	%H:%M:%S
	H{%:}M{%:}%S

	{{if .Hour}}{{.Hours}}h {{end}}{{if .Minute}}{{.Minutes}}m {{end}}{{.Seconds}}s

*/

func main() {

	var filename string
	var untilStr string
	var targetTimeStr string
	var doneStr string
	var format string

	flag.StringVar(&filename, "o", "/tmp/countdown.txt", "Output file to write the countdown to.")
	flag.StringVar(&untilStr, "u", "", "Countdown duration")
	flag.StringVar(&targetTimeStr, "t", "", "Countdown to time")
	flag.StringVar(&doneStr, "d", "00:00:00", "String to display when done")
	//flag.StringVar(&format, "f", "%H:%M:%S", "Format for the countdown")
	flag.StringVar(&format, "f", "{{if .Hours}}{{.Hours}}h {{end}}{{if or .Minutes .Hours}}{{.Minutes}}m {{end}}{{.Seconds}}s", "Format for the countdown")

	var targetYear int
	var targetDay int
	var targetMonth int

	flag.IntVar(&targetYear, "target-year", -1, "")
	flag.IntVar(&targetDay, "target-day", -1, "")
	flag.IntVar(&targetMonth, "target-month", -1, "")

	var targetHour int
	var targetMinute int
	var targetSecond int

	flag.IntVar(&targetHour, "target-hour", -1, "")
	flag.IntVar(&targetMinute, "target-minute", 0, "")
	flag.IntVar(&targetSecond, "target-second", 0, "")

	flag.Parse()

	var until time.Time
	now := time.Now()

	if untilStr != "" {
		untilDuration, err := time.ParseDuration(untilStr)
		if err != nil {
			fmt.Println(err)
			os.Exit(1)
		}
		until = time.Now().Add(untilDuration)
	} else {
		if targetYear == -1 {
			targetYear = now.Year()
		}
		if targetMonth == -1 {
			targetMonth = int(now.Month())
		}
		if targetDay == -1 {
			targetDay = now.Day()
		}

		if targetHour == -1 {
			targetHour = now.Hour()
		}
		if targetMinute == -1 {
			targetMinute = now.Minute()
		}
		if targetSecond == -1 {
			targetSecond = now.Second()
		}

		until = time.Date(
			targetYear, time.Month(targetMonth), targetDay,
			targetHour, targetMinute, targetSecond,
			0, time.Local,
		)
	}

	fmt.Printf("Output file: %s\nCountdown to: %s\n", filename, until)

	var err error
	tp := template.New("time")
	tp, err = tp.Parse(format)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}

	wg := sync.WaitGroup{}
	wg.Add(1)
	ticker := time.NewTicker(time.Second)

	go func(c <-chan time.Time) {
		count := time.Until(until)
		fmt.Println(count)
		for ; count >= 0; count = time.Until(until) {
			h := int(count.Hours())
			m := int(int(count.Minutes()) % 60)
			s := int(int(count.Seconds()) % 60)
			data := struct {
				Hours int
				Minutes int
				Seconds int
			}{
				Hours: h,
				Minutes: m,
				Seconds: s,
			}

			// Do I want to use this format as well as the complicated AF one?I want to use this format as well as the complicated AF template one?
			//str := format
			//if hide && h == 0 {
			//	str = strings.ReplaceAll(str, "%H", "")
			//	str = strings.ReplaceAll(str, "%h", "")
			//} else {
			//	str = strings.ReplaceAll(str, "%H", fmt.Sprintf("%02d", h))
			//	str = strings.ReplaceAll(str, "%h", fmt.Sprintf("%d", h))
			//}
			//if !(hide && h == 0 && m == 0) {
			//	str = strings.ReplaceAll(str, "%M", fmt.Sprintf("%02d", m))
			//	str = strings.ReplaceAll(str, "%m", fmt.Sprintf("%d", m))
			//}
			//str = strings.ReplaceAll(str, "%S", fmt.Sprintf("%02d", s))
			//str = strings.ReplaceAll(str, "%s", fmt.Sprintf("%d", s))

			sb := strings.Builder{}
			err = tp.Execute(&sb, &data)
			if err != nil {
				fmt.Println(err)
				continue
			}

			err = os.WriteFile(filename, []byte(sb.String()), 0644)
			if err != nil {
				fmt.Println("unable to write file: %v\n", err)
			}
			_ = <-c
		}
		wg.Done()
	}(ticker.C)

	wg.Wait()

	err = os.WriteFile(filename, []byte(doneStr), 0644)
	if err != nil {
		fmt.Println("unable to write file: %v\n", err)
	}

	fmt.Println("\nDONE")
}