package atom

import (
	"errors"
	"time"
)

type Date struct {
	*CommonAttributes
	DateTime string `xml:",chardata"`
}

// DateTime formats a time.Time to string formated as defined by RFC3339. It
// returns a string.
func DateTime(t time.Time) string {
	return t.Format(time.RFC3339)
}

// NewDate creates a new Date. It returns a *Date.
func NewDate(t time.Time) *Date {
	return &Date{
		CommonAttributes: newCommonAttributes(),
		DateTime:         DateTime(t),
	}
}

// Update updates the Date.
func (d *Date) Update() {
	if d == nil {
		d = NewDate(time.Now())
	} else {
		d.DateTime = DateTime(time.Now())
	}
}

// Check checks the Date for incompatibilities with RFC4287. It returns an
// error.
func (d *Date) Check() error {
	if d.DateTime == "" {
		return errors.New("date time element of date is empty")
	}

	return nil
}