package timeutil

import (
	"fmt"
	"strings"
	"time"
)

const DateLayout = "2006-01-02"
const LocalDateTimeLayout = "2006-01-02T15:04"

func LoadLocation(name string) (*time.Location, error) {
	location, err := time.LoadLocation(name)
	if err == nil {
		return location, nil
	}
	if strings.Contains(name, "/") {
		return nil, fmt.Errorf("load timezone %q: %w", name, err)
	}
	location, chicagoErr := time.LoadLocation("America/" + name)
	if chicagoErr == nil {
		return location, nil
	}
	return nil, fmt.Errorf("load timezone %q: %w", name, err)
}

func LocalDate(now time.Time, location *time.Location) time.Time {
	local := now.In(location)
	return time.Date(local.Year(), local.Month(), local.Day(), 0, 0, 0, 0, location)
}

func ParseLocalDate(value string, location *time.Location) (time.Time, error) {
	parsed, err := time.ParseInLocation(DateLayout, value, location)
	if err != nil {
		return time.Time{}, fmt.Errorf("parse date %q as YYYY-MM-DD: %w", value, err)
	}
	return parsed, nil
}

func ParseStormTime(value string, location *time.Location) (time.Time, error) {
	if parsed, err := time.Parse(time.RFC3339, value); err == nil {
		return parsed, nil
	}
	parsed, err := time.ParseInLocation(LocalDateTimeLayout, value, location)
	if err != nil {
		return time.Time{}, fmt.Errorf("parse storm time %q as YYYY-MM-DDTHH:MM or RFC3339: %w", value, err)
	}
	return parsed, nil
}