142 lines
4.0 KiB
Go
142 lines
4.0 KiB
Go
package store
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import (
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"net/url"
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"strings"
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"github.com/Depado/bfchroma/v2"
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"github.com/PuerkitoBio/goquery"
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"github.com/alecthomas/chroma/v2/formatters/html"
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bf "github.com/russross/blackfriday/v2"
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)
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// CommentFormatter implements all generic formatting ops on comment
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type CommentFormatter struct {
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converters []CommentConverter
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}
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// CommentConverter defines interface to convert some parts of commentHTML
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// Passed at creation time and does client-defined conversions, like image proxy link change
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type CommentConverter interface {
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Convert(text string) string
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}
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// CommentConverterFunc functional struct implementing CommentConverter
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type CommentConverterFunc func(text string) string
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// Convert calls func for given text
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func (f CommentConverterFunc) Convert(text string) string {
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return f(text)
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}
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// NewCommentFormatter makes CommentFormatter
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func NewCommentFormatter(converters ...CommentConverter) *CommentFormatter {
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return &CommentFormatter{converters: converters}
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}
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// Format comment fields
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func (f *CommentFormatter) Format(c Comment, raw bool) Comment {
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c.Text = f.FormatText(c.Text, raw)
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return c
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}
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// FormatText converts text with markdown processor, applies external converters and shortens links
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//
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// raw=true disables SmartyPants for HTML rendering (replacement of quotes, dashes, fractions, etc).
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func (f *CommentFormatter) FormatText(txt string, raw bool) (res string) {
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mdExt, rend := GetMdExtensionsAndRenderer(raw)
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res = string(bf.Run([]byte(txt), bf.WithExtensions(mdExt), bf.WithRenderer(rend)))
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res = f.unEscape(res)
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for _, conv := range f.converters {
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res = conv.Convert(res)
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}
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res = f.shortenAutoLinks(res, shortURLLen)
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res = f.lazyImage(res)
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return res
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}
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// Shortens all the automatic links in HTML: auto link has equal "href" and "text" attributes.
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func (f *CommentFormatter) shortenAutoLinks(commentHTML string, maximum int) (resHTML string) {
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doc, err := goquery.NewDocumentFromReader(strings.NewReader(commentHTML))
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if err != nil {
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return commentHTML
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}
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doc.Find("a").Each(func(_ int, s *goquery.Selection) {
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if href, ok := s.Attr("href"); ok {
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if href != s.Text() || len(href) < maximum+3 || maximum < 3 {
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return
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}
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commentURL, e := url.Parse(href)
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if e != nil {
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return
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}
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commentURL.Path, commentURL.RawQuery, commentURL.Fragment = "", "", ""
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host := commentURL.String()
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if host == "" {
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return
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}
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short := string([]rune(href)[:maximum-3])
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if len(short) < len(host) {
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short = host
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}
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s.SetText(short + "...")
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}
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})
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resHTML, err = doc.Find("body").Html()
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if err != nil {
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return commentHTML
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}
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return resHTML
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}
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func (f *CommentFormatter) unEscape(txt string) (res string) {
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elems := []struct {
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from, to string
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}{
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{`&mdash;`, "—"},
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}
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res = txt
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for _, e := range elems {
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res = strings.ReplaceAll(res, e.from, e.to)
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}
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return res
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}
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// lazyImage adds loading=“lazy” attribute to all images
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func (f *CommentFormatter) lazyImage(commentHTML string) (resHTML string) {
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doc, err := goquery.NewDocumentFromReader(strings.NewReader(commentHTML))
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if err != nil {
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return commentHTML
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}
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doc.Find("img").Each(func(_ int, s *goquery.Selection) {
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s.SetAttr("loading", "lazy")
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})
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resHTML, err = doc.Find("body").Html()
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if err != nil {
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return commentHTML
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}
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return resHTML
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}
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// GetMdExtensionsAndRenderer returns blackfriday extensions and renderer used for rendering markdown
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// within store module.
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//
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// raw=true disables SmartyPants for HTML rendering (replacement of quotes, dashes, fractions, etc).
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func GetMdExtensionsAndRenderer(raw bool) (bf.Extensions, *bfchroma.Renderer) {
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mdExt := bf.NoIntraEmphasis | bf.Tables | bf.FencedCode |
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bf.Strikethrough | bf.SpaceHeadings | bf.HardLineBreak |
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bf.BackslashLineBreak | bf.Autolink
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flags := bf.HTMLFlags(0)
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if !raw {
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flags = bf.Smartypants | bf.SmartypantsFractions | bf.SmartypantsDashes | bf.SmartypantsAngledQuotes
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}
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rend := bf.NewHTMLRenderer(bf.HTMLRendererParameters{Flags: flags})
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extRend := bfchroma.NewRenderer(bfchroma.Extend(rend), bfchroma.ChromaOptions(html.WithClasses(true)))
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return mdExt, extRend
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}
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