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improve and fix telegram instant preview for markdown articles.

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This commit is contained in:
fiatjaf
2023-09-14 10:31:38 -03:00
parent 90ec9d92dd
commit b0bda60577
5 changed files with 57 additions and 19 deletions
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54
utils.go
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@@ -4,12 +4,15 @@ import (
"context"
"encoding/json"
"fmt"
"io"
"net/http"
"regexp"
"strings"
"time"
"github.com/gomarkdown/markdown"
"github.com/gomarkdown/markdown/ast"
"github.com/gomarkdown/markdown/html"
mdhtml "github.com/gomarkdown/markdown/html"
"github.com/gomarkdown/markdown/parser"
"github.com/microcosm-cc/bluemonday"
@@ -201,7 +204,7 @@ func getParentNevent(event *nostr.Event) string {
// Rendering functions
// ### ### ### ### ### ### ### ### ### ### ###
func replateImageURLsWithTags(input string, replacement string) string {
func replaceImageURLsWithTags(input string, replacement string) string {
// Match and replace image URLs with a custom replacement
// Usually is html <img> => ` <img src="%s" alt=""> `
// or markdown !()[...] tags for further processing => `![](%s)`
@@ -221,7 +224,7 @@ func replateImageURLsWithTags(input string, replacement string) string {
return input
}
func replateVideoURLsWithTags(input string, replacement string) string {
func replaceVideoURLsWithTags(input string, replacement string) string {
// Match and replace video URLs with a custom replacement
// Usually is html <video> => ` <video controls width="100%%"><source src="%s"></video> `
// or markdown !()[...] tags for further processing => `![](%s)`
@@ -287,12 +290,12 @@ func renderInlineMentions(input string) string {
func replaceURLsWithTags(line string) string {
var rline string
rline = replateImageURLsWithTags(line, ` <img src="%s" alt=""> `)
rline = replaceImageURLsWithTags(line, ` <img src="%s" alt=""> `)
if rline != line {
return rline
}
rline = replateVideoURLsWithTags(line, `<video controls width="100%%"><source src="%s"></video>`)
rline = replaceVideoURLsWithTags(line, `<video controls width="100%%"><source src="%s"></video>`)
if rline != line {
return rline
}
@@ -333,24 +336,51 @@ func basicFormatting(input string) string {
return strings.Join(processedLines, "<br/>")
}
func mdToHTML(md string) string {
func mdToHTML(md string, usingTelegramInstantView bool) string {
md = strings.ReplaceAll(md, "\u00A0", " ")
md = replateImageURLsWithTags(md, `![](%s)`)
md = replateVideoURLsWithTags(md, `<video controls width="100%%"><source src="%s"></video>`)
md = replaceImageURLsWithTags(md, `![](%s)`)
md = replaceVideoURLsWithTags(md, `<video controls width="100%%"><source src="%s"></video>`)
md = replaceNostrURLsWithTags(md)
// create markdown parser with extensions
extensions := parser.CommonExtensions | parser.AutoHeadingIDs | parser.NoEmptyLineBeforeBlock | parser.Footnotes
p := parser.NewWithExtensions(extensions)
p := parser.NewWithExtensions(
parser.CommonExtensions | parser.AutoHeadingIDs | parser.NoEmptyLineBeforeBlock | parser.Footnotes)
doc := p.Parse([]byte(md))
var customNodeHook html.RenderNodeFunc = nil
if usingTelegramInstantView {
// telegram instant view really doesn't like when there is an image inside a paragraph (like <p><img></p>)
// so we use this custom thing to stop all paragraphs before the images, print the images then start a new
// paragraph afterwards.
customNodeHook = func(w io.Writer, node ast.Node, entering bool) (ast.WalkStatus, bool) {
if img, ok := node.(*ast.Image); ok {
if entering {
src := img.Destination
w.Write([]byte(`</p><img src="`))
html.EscLink(w, src)
w.Write([]byte(`" alt="`))
} else {
if img.Title != nil {
w.Write([]byte(`" title="`))
html.EscapeHTML(w, img.Title)
}
w.Write([]byte(`" /><p>`))
}
return ast.GoToNext, true
}
return ast.GoToNext, false
}
}
// create HTML renderer with extensions
htmlFlags := mdhtml.CommonFlags | mdhtml.HrefTargetBlank
opts := mdhtml.RendererOptions{Flags: htmlFlags}
opts := mdhtml.RendererOptions{
Flags: mdhtml.CommonFlags | mdhtml.HrefTargetBlank,
RenderNodeHook: customNodeHook,
}
renderer := mdhtml.NewRenderer(opts)
output := string(markdown.Render(doc, renderer))
// Sanitize content
// sanitize content
output = sanitizeXSS(output)
return output