First implementation of RSS feed generator

rss.go

@@ -0,0 +1,212 @@
+package rss
+
+import (
+	"encoding/xml"
+	"fmt"
+	"time"
+)
+
+type Image struct {
+	XMLName xml.Name `xml:"image"`
+	Url     string   `xml:"url"`
+	Title   string   `xml:"title"`
+	Link    string   `xml:"link"`
+	Width   int      `xml:"width,omitempty"`  // max: 144, default: 88
+	Height  int      `xml:"height,omitempty"` // max: 400, default: 31
+}
+
+type TextInput struct {
+	XMLName     xml.Name `xml:"textInput"`
+	Title       string   `xml:"title,omitempty"`
+	Description string   `xml:"description,omitempty"`
+	Name        string   `xml:"name,omitempty"`
+	Link        string   `xml:"link,omitempty"`
+}
+
+type Enclosure struct {
+	XMLName xml.Name `xml:"enclosure"`
+	Url     string   `xml:"url,attr"`
+	Lenght  int      `xml:"lenght,attr"`
+	Type    string   `xml:"type,attr"`
+}
+
+type Source struct {
+	XMLName xml.Name `xml:"source"`
+	Url     string   `xml:"url,attr"`
+	Value   string
+}
+
+type Item struct {
+	XMLName     xml.Name `xml:"item"`
+	Title       string   `xml:"title,omitempty"`
+	Link        string   `xml:"link,omitempty"`
+	Description string   `xml:"description,omitempty"`
+	Author      string   `xml:"author,omitempty"`
+	Categories  []string `xml:"category,omitempty"`
+	Comments    string   `xml:"comments,omitempty"`
+	Enclosure   *Enclosure
+	Guid        string    `xml:"guid,omitempty"`
+	PubDate     time.Time `xml:"pubDate,omitempty"`
+	Source      *Source
+}
+
+type Channel struct {
+	XMLName        xml.Name  `xml:"channel"`
+	Title          string    `xml:"title"`
+	Link           string    `xml:"link"`
+	Description    string    `xml:"description"`
+	Language       string    `xml:"language,omitempty"`
+	Copyright      string    `xml:"copyright,omitempty"`
+	ManagingEditor string    `xml:"managingEditor,omitempty"`
+	WebMaster      string    `xml:"webMaster,omitempty"`
+	PubDate        time.Time `xml:"pubDate,omitempty"`
+	LastBuildDate  time.Time `xml:"lastBuildDate,omitempty"`
+	Categories     []string  `xml:"category,omitempty"`
+	Generator      string    `xml:"generator,omitempty"`
+	Docs           string    `xml:"docs,omitempty"`
+	Cloud          string    `xml:"cloud,omitempty"`
+	Ttl            int       `xml:"ttl,omitempty"`
+	Image          *Image
+	Rating         string `xml:"rating,omitempty"`
+	TextInput      *TextInput
+	SkipHours      []int `xml:"skipHours,omitempty"`
+	SkipDays       []int `xml:"skipDays,omitempty"`
+	Items          []*Item
+}
+
+type Feed struct {
+	XMLName          xml.Name `xml:"rss"`
+	Version          string   `xml:"version,attr"`
+	ContentNamespace string   `xml:"xmlns:content,attr"`
+	Channels         []*Channel
+}
+
+func (i *Image) check() error {
+	if len(i.Url) == 0 {
+		return fmt.Errorf("error: url not set")
+	}
+	if len(i.Title) == 0 {
+		return fmt.Errorf("error: title not set")
+	}
+	if len(i.Link) == 0 {
+		return fmt.Errorf("error: link not set")
+	}
+	if i.Width == 0 || i.Width > 144 {
+		i.Width = 88
+	}
+	if i.Height == 0 || i.Height > 400 {
+		i.Height = 31
+	}
+
+	return nil
+}
+
+func (t *TextInput) check() error {
+	if len(t.Title) == 0 &&
+		len(t.Description) == 0 &&
+		len(t.Name) == 0 &&
+		len(t.Link) == 0 {
+		return fmt.Errorf("error: textInput is empty")
+	}
+
+	return nil
+}
+
+func (e *Enclosure) check() error {
+	if len(e.Url) == 0 {
+		return fmt.Errorf("error: url not set")
+	}
+	if e.Lenght == 0 {
+		return fmt.Errorf("error: length not set or 0")
+	}
+	if len(e.Type) == 0 {
+		return fmt.Errorf("error: type not set")
+	}
+
+	return nil
+}
+
+func (s *Source) check() error {
+	if len(s.Url) == 0 {
+		return fmt.Errorf("error: url not set")
+	}
+	if len(s.Value) == 0 {
+		return fmt.Errorf("error: value not set")
+	}
+
+	return nil
+}
+
+func (i *Item) check() error {
+	if len(i.Title) == 0 && len(i.Description) == 0 {
+		return fmt.Errorf("error: neither title nor description set")
+	}
+
+	if err := i.Enclosure.check(); err != nil {
+		return fmt.Errorf("error checking enclosure: %v", err)
+	}
+	if err := i.Source.check(); err != nil {
+		return fmt.Errorf("error checking source: %v", err)
+	}
+
+	return nil
+}
+
+func (c *Channel) check() error {
+	if len(c.Title) == 0 {
+		return fmt.Errorf("error: title not set")
+	}
+	if len(c.Link) == 0 {
+		return fmt.Errorf("error: link not set")
+	}
+	if len(c.Description) == 0 {
+		return fmt.Errorf("error: description not set")
+	}
+
+	if err := c.Image.check(); err != nil {
+		return fmt.Errorf("error checking image: %v", err)
+	}
+	if err := c.TextInput.check(); err != nil {
+		return fmt.Errorf("error checking textInput: %v", err)
+	}
+
+	for _, item := range c.Items {
+		if err := item.check(); err != nil {
+			return fmt.Errorf("error checking item: %v", err)
+		}
+	}
+
+	return nil
+}
+
+func (f *Feed) check() error {
+	f = &Feed{
+		Version:          "2.0",
+		ContentNamespace: "http://purl.org/rss/1.0/modules/content/",
+	}
+
+	if f.Channels == nil {
+		return fmt.Errorf("error: feed has no channels")
+	}
+
+	for _, channel := range f.Channels {
+		if err := channel.check(); err != nil {
+			return fmt.Errorf("error checking channel: %v", err)
+		}
+	}
+
+	return nil
+}
+
+func (f *Feed) ToXML() (string, error) {
+	if err := f.check(); err != nil {
+		return "", fmt.Errorf("error checking RSS feed: %v", err)
+	}
+
+	xml, err := xml.MarshalIndent(f, "", "  ")
+	if err != nil {
+		return "", fmt.Errorf("error XML encoding feed: %v", err)
+	}
+
+	return string(xml), nil
+}