package atom

import (
	"encoding/xml"
	"fmt"

	"github.com/google/uuid"
)

type CommonAttributes struct {
	UndefinedAttributes map[uuid.UUID]*xml.Attr `xml:",attr,omitempty"`
	Base                string                  `xml:"base,attr,omitempty"` // IRI
	Lang                string                  `xml:"lang,attr,omitempty"` // LanguageTag
}

// NewCommonAttributes creates a new set of CommonAttributes. It returns a
// *CommonAttributes.
func newCommonAttributes() *CommonAttributes {
	return new(CommonAttributes)
}

// AddAttribute adds the Attribute to the CommonAttributes.
func (c *CommonAttributes) AddAttribute(name, value string) {
	if c.UndefinedAttributes == nil {
		c.UndefinedAttributes = make(map[uuid.UUID]*xml.Attr, 1)
	}
	c.UndefinedAttributes[uuid.New()] = &xml.Attr{Name: xml.Name{Local: name}, Value: value}
}

// DeleteAttribute deletes the Attribute from the CommonAttributes.
func (c *CommonAttributes) DeleteAttribute(id uuid.UUID) {
	delete(c.UndefinedAttributes, id)
}

// Check checks the CommonAttributes for incompatibilities with RFC4287. It
// returns an error.
func (c *CommonAttributes) Check() error {
	for i, u := range c.UndefinedAttributes {
		if u.Name.Local == "" {
			return fmt.Errorf("xml name of undefined attribute %v empty", i)
		}
		if u.Value == "" {
			return fmt.Errorf("value of undefined attribute %v empty", i)
		}
	}

	return nil
}