package datetime

import (
	"strings"
	"time"

	. "gitea.zaclys.com/bvaudour/gob/option"
)

func isValueZero(e string) bool {
	return e == "" || e == "0" || e == "0000-00-00 00:00:00" || e == "0000-00-00" || e == "00:00:00"
}

func format2layout(f string) string {
	var buffer strings.Builder
	runes := []rune(f)
	for i := 0; i < len(runes); i++ {
		if layout, ok := parsers[runes[i]]; ok {
			buffer.WriteString(layout)
		} else {
			switch runes[i] {
			case '\\': // Indique que le caractère suivant ne doit pas être parsé
				buffer.WriteRune(runes[i+1])
				i++
				continue
			default:
				buffer.WriteRune(runes[i])
			}
		}
	}
	return buffer.String()
}

func parseInLocation(e, f string, tz ...string) (t Option[time.Time]) {
	l := timezone(tz...)
	if tt, err := time.ParseInLocation(f, e, l); err == nil {
		t = Some(tt)
	}
	return
}

func parseFromLayout(e, f string, tz ...string) (t Option[time.Time]) {
	if isValueZero(e) {
		return
	}
	return parseInLocation(e, f, tz...)
}

func guess(e string, tz ...string) (t Option[time.Time]) {
	if isValueZero(e) {
		return
	}
	switch e {
	case "now":
		return Some(now(tz...))
	case "yesterday":
		return Some(yesterday(tz...))
	case "tomorrow":
		return Some(tomorrow(tz...))
	}
	for _, l := range layouts {
		if t = parseInLocation(e, l, tz...); t.IsDefined() {
			break
		}
	}
	return
}
func parse(e, f string, tz ...string) Option[time.Time] {
	return parseFromLayout(e, format2layout(f), tz...)
}