package atomfeed

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

type Generator struct {
	*CommonAttributes
	URI     IRI    `xml:"uri,attr,omitempty"`
	Version string `xml:"version,attr,omitempty"`
	Text    string `xml:"text"`
}

// NewGenerator creates a new Generator. It returns a *Generator.
func NewGenerator(text string) *Generator {
	return &Generator{Text: html.UnescapeString(text)}
}

// Check checks the Generator for incompatibilities with RFC4287. It returns an
// error.
func (g *Generator) Check() error {
	if g.URI != "" {
		if !isValidIRI(g.URI) {
			return fmt.Errorf("uri attribute %v of generator not correctly formatted", g.URI)
		}
	}

	if g.Text == "" {
		return errors.New("text element of generator empty")
	}

	if !isCorrectlyEscaped(g.Text) {
		return fmt.Errorf("text element %v of generator not correctly escaped", g.Text)
	}

	return nil
}