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// gomuks - A terminal Matrix client written in Go.
// Copyright (C) 2020 Tulir Asokan
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
package ui
import (
"bytes"
"fmt"
"html"
"io"
"math/rand"
"unicode"
"github.com/rivo/uniseg"
"github.com/russross/blackfriday/v2"
)
type RainbowRenderer struct {
*blackfriday.HTMLRenderer
sr *blackfriday.SPRenderer
ColorID string
}
func Rand(n int) (str string) {
b := make([]byte, n)
rand.Read(b)
str = fmt.Sprintf("%x", b)
return
}
func NewRainbowRenderer(html *blackfriday.HTMLRenderer) *RainbowRenderer {
return &RainbowRenderer{
HTMLRenderer: html,
sr: blackfriday.NewSmartypantsRenderer(html.Flags),
ColorID: Rand(16),
}
}
func (r *RainbowRenderer) RenderNode(w io.Writer, node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
if node.Type == blackfriday.Text {
var buf bytes.Buffer
if r.Flags&blackfriday.Smartypants != 0 {
var tmp bytes.Buffer
escapeHTML(&tmp, node.Literal)
r.sr.Process(&buf, tmp.Bytes())
} else {
if node.Parent.Type == blackfriday.Link {
escLink(&buf, node.Literal)
} else {
escapeHTML(&buf, node.Literal)
}
}
graphemes := uniseg.NewGraphemes(buf.String())
buf.Reset()
for graphemes.Next() {
runes := graphemes.Runes()
if len(runes) == 1 && unicode.IsSpace(runes[0]) {
buf.WriteRune(runes[0])
continue
}
_, _ = fmt.Fprintf(&buf, "<font color=\"%s\">%s</font>", r.ColorID, graphemes.Str())
}
_, _ = w.Write(buf.Bytes())
return blackfriday.GoToNext
}
return r.HTMLRenderer.RenderNode(w, node, entering)
}
// This stuff is copied directly from blackfriday
var htmlEscaper = [256][]byte{
'&': []byte("&"),
'<': []byte("<"),
'>': []byte(">"),
'"': []byte("""),
}
func escapeHTML(w io.Writer, s []byte) {
var start, end int
for end < len(s) {
escSeq := htmlEscaper[s[end]]
if escSeq != nil {
w.Write(s[start:end])
w.Write(escSeq)
start = end + 1
}
end++
}
if start < len(s) && end <= len(s) {
w.Write(s[start:end])
}
}
func escLink(w io.Writer, text []byte) {
unesc := html.UnescapeString(string(text))
escapeHTML(w, []byte(unesc))
}
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