package atom

import (
	"errors"
	"fmt"
	"html"
)

type Category struct {
	*CommonAttributes
	Content string `xml:",chardata"` // undefinedContent in RFC4287
	Term    string `xml:"term,attr"`
	Scheme  IRI    `xml:"scheme,attr,omitempty"`
	Label   string `xml:"label,attr,omitempty"`
}

// NewCategory creates a new Category. It returns a *Category and an error.
func NewCategory(term, content string) (*Category, error) {
	return &Category{Term: term, Content: content}, nil
}

// SetLabel sets the label of the Category.
func (c *Category) SetLabel(label string) {
	c.Label = html.UnescapeString(label)
}

// Check checks the Category for incompatibilities with RFC4287. It returns an
// error.
func (c *Category) Check() error {
	if c.Term == "" {
		return errors.New("term attribute of category empty")
	}

	if c.Scheme != "" {
		if !isValidIRI(c.Scheme) {
			return fmt.Errorf("scheme attribute %v of category not correctly formatted", c.Scheme)
		}
	}

	if !isCorrectlyEscaped(c.Label) {
		return fmt.Errorf("label attribute %v of category not correctly escaped", c.Label)
	}

	if c.Content == "" {
		return errors.New("content element of category empty")
	}

	return nil
}