Podcast-focused library
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package podcast
import (
"bytes"
"encoding/xml"
"fmt"
"io"
"strconv"
"time"
"unicode/utf8"
"github.com/pkg/errors"
)
const (
pVersion = "1.3.1"
)
// Podcast represents a podcast.
type Podcast struct {
XMLName xml.Name `xml:"channel"`
Title string `xml:"title"`
Link string `xml:"link"`
Description string `xml:"description"`
Category string `xml:"category,omitempty"`
Cloud string `xml:"cloud,omitempty"`
Copyright string `xml:"copyright,omitempty"`
Docs string `xml:"docs,omitempty"`
Generator string `xml:"generator,omitempty"`
Language string `xml:"language,omitempty"`
LastBuildDate string `xml:"lastBuildDate,omitempty"`
ManagingEditor string `xml:"managingEditor,omitempty"`
PubDate string `xml:"pubDate,omitempty"`
Rating string `xml:"rating,omitempty"`
SkipHours string `xml:"skipHours,omitempty"`
SkipDays string `xml:"skipDays,omitempty"`
TTL int `xml:"ttl,omitempty"`
WebMaster string `xml:"webMaster,omitempty"`
Email string `xml:"email,omitempty"`
Image *Image
TextInput *TextInput
AtomLink *AtomLink
// https://help.apple.com/itc/podcasts_connect/#/itcb54353390
IAuthor string `xml:"itunes:author,omitempty"`
ISubtitle string `xml:"itunes:subtitle,omitempty"`
ISummary *ISummary
IBlock string `xml:"itunes:block,omitempty"`
IImage *IImage
IDuration string `xml:"itunes:duration,omitempty"`
IExplicit string `xml:"itunes:explicit,omitempty"`
IComplete string `xml:"itunes:complete,omitempty"`
INewFeedURL string `xml:"itunes:new-feed-url,omitempty"`
IOwner *Author // Author is formatted for itunes as-is
ICategories []*ICategory
IType string `xml:"itunes:type,omitempty"`
Items []*Item
encode func(w io.Writer, o interface{}) error
}
// New instantiates a Podcast with required parameters.
//
// Nil-able fields are optional but recommended as they are formatted
// to the expected proper formats.
func New(title, link, description string,
pubDate, lastBuildDate *time.Time) Podcast {
return Podcast{
Title: title,
Link: link,
Description: description,
Generator: fmt.Sprintf("feeder v%s (gitlab.com/iarenzana/feeder)", pVersion),
PubDate: parseDateRFC1123Z(pubDate),
LastBuildDate: parseDateRFC1123Z(lastBuildDate),
Language: "es-es",
IType: "episodic",
// setup dependency (could inject later)
encode: encoder,
}
}
// AddAuthor adds the specified Author to the podcast.
func (p *Podcast) AddAuthor(name, email string) {
if len(email) == 0 {
return
}
p.ManagingEditor = parseAuthorNameEmail(&Author{
Name: name,
Email: email,
})
p.IAuthor = p.ManagingEditor
}
// AddAtomLink adds a FQDN reference to an atom feed.
func (p *Podcast) AddAtomLink(href string) {
if len(href) == 0 {
return
}
p.AtomLink = &AtomLink{
HREF: href,
Rel: "self",
Type: "application/rss+xml",
}
}
// AddCategory adds the category to the Podcast.
//
// ICategory can be listed multiple times.
//
// Calling this method multiple times will APPEND the category to the existing
// list, if any, including ICategory.
//
// Note that Apple iTunes has a specific list of categories that only can be
// used and will invalidate the feed if deviated from the list. That list is
// as follows.
//
// * Arts
// * Design
// * Fashion & Beauty
// * Food
// * Literature
// * Performing Arts
// * Visual Arts
// * Business
// * Business News
// * Careers
// * Investing
// * Management & Marketing
// * Shopping
// * Comedy
// * Education
// * Education Technology
// * Higher Education
// * K-12
// * Language Courses
// * Training
// * Games & Hobbies
// * Automotive
// * Aviation
// * Hobbies
// * Other Games
// * Video Games
// * Government & Organizations
// * Local
// * National
// * Non-Profit
// * Regional
// * Health
// * Alternative Health
// * Fitness & Nutrition
// * Self-Help
// * Sexuality
// * Kids & Family
// * Music
// * News & Politics
// * Religion & Spirituality
// * Buddhism
// * Christianity
// * Hinduism
// * Islam
// * Judaism
// * Other
// * Spirituality
// * Science & Medicine
// * Medicine
// * Natural Sciences
// * Social Sciences
// * Society & Culture
// * History
// * Personal Journals
// * Philosophy
// * Places & Travel
// * Sports & Recreation
// * Amateur
// * College & High School
// * Outdoor
// * Professional
// * Technology
// * Gadgets
// * Podcasting
// * Software How-To
// * Tech News
// * TV & Film
func (p *Podcast) AddCategory(category string, subCategories []string) {
if len(category) == 0 {
return
}
// RSS 2.0 Category only supports 1-tier
if len(p.Category) > 0 {
p.Category = p.Category + "," + category
} else {
p.Category = category
}
icat := ICategory{Text: category}
for _, c := range subCategories {
if len(c) == 0 {
continue
}
icat2 := ICategory{Text: c}
icat.ICategories = append(icat.ICategories, &icat2)
}
p.ICategories = append(p.ICategories, &icat)
}
// AddImage adds the specified Image to the Podcast.
//
// Podcast feeds contain artwork that is a minimum size of
// 1400 x 1400 pixels and a maximum size of 3000 x 3000 pixels,
// 72 dpi, in JPEG or PNG format with appropriate file
// extensions (.jpg, .png), and in the RGB colorspace. To optimize
// images for mobile devices, Apple recommends compressing your
// image files.
func (p *Podcast) AddImage(url string) {
if len(url) == 0 {
return
}
p.Image = &Image{
URL: url,
Title: p.Title,
Link: p.Link,
}
p.IImage = &IImage{HREF: url}
}
// AddItem adds the podcast episode. It returns a count of Items added or any
// errors in validation that may have occurred.
//
// This method takes the "itunes overrides" approach to populating
// itunes tags according to the overrides rules in the specification.
// This not only complies completely with iTunes parsing rules; but, it also
// displays what is possible to be set on an individual episode level – if you
// wish to have more fine grain control over your content.
//
// This method imposes strict validation of the Item being added to confirm
// to Podcast and iTunes specifications.
//
// Article minimal requirements are:
//
// * Title
// * Description
// * Link
//
// Audio, Video and Downloads minimal requirements are:
//
// * Title
// * Description
// * Enclosure (HREF, Type and Length all required)
//
// The following fields are always overwritten (don't set them):
//
// * GUID
// * PubDateFormatted
// * AuthorFormatted
// * Enclosure.TypeFormatted
// * Enclosure.LengthFormatted
//
// Recommendations:
//
// * Just set the minimal fields: the rest get set for you.
// * Always set an Enclosure.Length, to be nice to your downloaders.
// * Follow Apple's best practices to enrich your podcasts:
// https://help.apple.com/itc/podcasts_connect/#/itc2b3780e76
// * For specifications of itunes tags, see:
// https://help.apple.com/itc/podcasts_connect/#/itcb54353390
//
func (p *Podcast) AddItem(i Item) (int, error) {
// initial guards for required fields
if len(i.Title) == 0 || len(i.Description) == 0 {
return len(p.Items), errors.New("Title and Description are required")
}
if i.Enclosure != nil {
if len(i.Enclosure.URL) == 0 {
return len(p.Items),
errors.New(i.Title + ": Enclosure.URL is required")
}
if i.Enclosure.Type.String() == enclosureDefault {
return len(p.Items),
errors.New(i.Title + ": Enclosure.Type is required")
}
} else if len(i.Link) == 0 {
return len(p.Items),
errors.New(i.Title + ": Link is required when not using Enclosure")
}
// corrective actions and overrides
//
i.PubDateFormatted = parseDateRFC1123Z(i.PubDate)
i.AuthorFormatted = parseAuthorNameEmail(i.Author)
if i.Enclosure != nil {
if len(i.GUID) == 0 {
i.GUID = i.Enclosure.URL // yep, GUID is the Permlink URL
}
if i.Enclosure.Length < 0 {
i.Enclosure.Length = 0
}
i.Enclosure.LengthFormatted = strconv.FormatInt(i.Enclosure.Length, 10)
i.Enclosure.TypeFormatted = i.Enclosure.Type.String()
// allow Link to be set for article references to Downloads,
// otherwise set it to the enclosurer's URL.
if len(i.Link) == 0 {
i.Link = i.Enclosure.URL
}
} else {
i.GUID = i.Link // yep, GUID is the Permlink URL
}
// iTunes it
//
if len(i.IAuthor) == 0 {
switch {
case i.Author != nil:
i.IAuthor = i.Author.Email
case len(p.IAuthor) != 0:
i.Author = &Author{Email: p.IAuthor}
i.IAuthor = p.IAuthor
case len(p.ManagingEditor) != 0:
i.Author = &Author{Email: p.ManagingEditor}
i.IAuthor = p.ManagingEditor
}
}
if i.IImage == nil {
if p.Image != nil {
i.IImage = &IImage{HREF: p.Image.URL}
}
}
p.Items = append(p.Items, &i)
//if episode number is not passed; we will just increase the items by one
if i.IEpisode == 0 && p.IType == "episodic" {
i.IEpisode = len(p.Items) + 1
}
return len(p.Items), nil
}
// AddPubDate adds the datetime as a parsed PubDate.
//
// UTC time is used by default.
func (p *Podcast) AddPubDate(datetime *time.Time) {
p.PubDate = parseDateRFC1123Z(datetime)
}
// AddLastBuildDate adds the datetime as a parsed PubDate.
//
// UTC time is used by default.
func (p *Podcast) AddLastBuildDate(datetime *time.Time) {
p.LastBuildDate = parseDateRFC1123Z(datetime)
}
// AddSubTitle adds the iTunes subtitle that is displayed with the title
// in iTunes.
//
// Note that this field should be just a few words long according to Apple.
// This method will truncate the string to 64 chars if too long with "..."
func (p *Podcast) AddSubTitle(subTitle string) {
count := utf8.RuneCountInString(subTitle)
if count == 0 {
return
}
if count > 64 {
s := []rune(subTitle)
subTitle = string(s[0:61]) + "..."
}
p.ISubtitle = subTitle
}
// AddSummary adds the iTunes summary.
//
// Limit: 4000 characters
//
// Note that this field is a CDATA encoded field which allows for rich text
// such as html links: `<a href="http://www.apple.com">Apple</a>`.
func (p *Podcast) AddSummary(summary string) {
count := utf8.RuneCountInString(summary)
if count == 0 {
return
}
if count > 4000 {
s := []rune(summary)
summary = string(s[0:4000])
}
p.ISummary = &ISummary{
Text: summary,
}
}
// AddIType adds the specified type to the podcast to the podcast.
func (p *Podcast) AddIType(iType string) {
if len(iType) == 0 {
return
}
if iType == "serial" {
p.IType = "serial"
return
}
p.IType = "episodic"
}
// Bytes returns an encoded []byte slice.
func (p *Podcast) Bytes() []byte {
return []byte(p.String())
}
// Encode writes the bytes to the io.Writer stream in RSS 2.0 specification.
func (p *Podcast) Encode(w io.Writer) error {
if _, err := w.Write([]byte("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n")); err != nil {
return errors.Wrap(err, "podcast.Encode: w.Write return error")
}
atomLink := ""
if p.AtomLink != nil {
atomLink = "http://www.w3.org/2005/Atom"
}
wrapped := podcastWrapper{
ITUNESNS: "http://www.itunes.com/dtds/podcast-1.0.dtd",
ATOMNS: atomLink,
Version: "2.0",
Channel: p,
}
return p.encode(w, wrapped)
}
// String encodes the Podcast state to a string.
func (p *Podcast) String() string {
b := new(bytes.Buffer)
if err := p.Encode(b); err != nil {
return "String: podcast.write returned the error: " + err.Error()
}
return b.String()
}
// // Write implements the io.Writer interface to write an RSS 2.0 stream
// // that is compliant to the RSS 2.0 specification.
// func (p *Podcast) Write(b []byte) (n int, err error) {
// buf := bytes.NewBuffer(b)
// if err := p.Encode(buf); err != nil {
// return 0, errors.Wrap(err, "Write: podcast.encode returned error")
// }
// return buf.Len(), nil
// }
type podcastWrapper struct {
XMLName xml.Name `xml:"rss"`
Version string `xml:"version,attr"`
ATOMNS string `xml:"xmlns:atom,attr,omitempty"`
ITUNESNS string `xml:"xmlns:itunes,attr"`
Channel *Podcast
}
var encoder = func(w io.Writer, o interface{}) error {
e := xml.NewEncoder(w)
e.Indent("", " ")
if err := e.Encode(o); err != nil {
return errors.Wrap(err, "podcast.encoder: e.Encode returned error")
}
return nil
}
var parseAuthorNameEmail = func(a *Author) string {
var author string
if a != nil {
author = a.Email
if len(a.Name) > 0 {
author = fmt.Sprintf("%s", a.Name)
}
}
return author
}