package main

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

	"github.com/alexflint/go-arg"
)

/*

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

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

*/

type Arguments struct {
	Hour int   `arg:"--hour,-h" help:"Target hour" default:"-1"`
	Minute int `arg:"--minute,-m" help:"Target minute" default:"-1"`
	Year int   `arg:"--year" help:"Target year" default:"-1"`
	Day int    `arg:"--day" help:"Target day" default:"-1"`
	Month int  `arg:"--month" help:"Target month" default:"-1"`

	Output string `arg:"--output,-o" help:"Output filename" default:"/tmp/countdown.txt"`
	Done string   `arg:"--done,-d" help:"String to display when done" default:"MOVIE SIGN"`
	Format string `arg:"--format,-f" help:"Format string for the countdown" default:"{{if .Hours}}{{.Hours}}h {{end}}{{if or .Minutes .Hours}}{{.Minutes}}m {{end}}{{.Seconds}}s"`
}

func main() {
	args := &Arguments{}
	arg.MustParse(args)

	now := time.Now()

	if args.Hour == -1 {
		args.Hour = now.Hour()
	}

	if args.Minute == -1 {
		args.Minute = now.Minute()
	}

	if args.Year == -1 {
		args.Year = now.Year()
	}

	if args.Month == -1 {
		args.Month = int(now.Month())
	}

	if args.Day == -1 {
		args.Day = now.Day()
	}

	until := time.Date(
		args.Year, time.Month(args.Month), args.Day,
		args.Hour, args.Minute, 0, 0, time.Local,
	)

	if now.After(until) {
		fmt.Println("time is in the past!")
		return
	}

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

	var err error
	tp := template.New("time")
	tp, err = tp.Parse(args.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?
			//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(args.Output, []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(args.Output, []byte(args.Done), 0644)
	if err != nil {
		fmt.Println("unable to write file: %v\n", err)
	}

	fmt.Println("\nDONE")
}