bin/utils/highlight_text.go

package utils

import (
	"bytes"
	"context"
	"fmt"
	"io"

	"github.com/alecthomas/chroma/formatters/html"
	"github.com/alecthomas/chroma/lexers"
	"github.com/alecthomas/chroma/styles"
	"github.com/sirupsen/logrus"
)

type HighlightedText struct {
	text string
}

func (ht HighlightedText) Render(ctx context.Context, w io.Writer) error {
	_, err := w.Write([]byte(ht.text))
	return err
}

func NewPreText(text string) HighlightedText {
	return HighlightedText{
		text: fmt.Sprintf("<pre>%s</pre>", text),
	}
}

func HighlightText(text, lang, style_name string) HighlightedText {
	if style_name == "" {
		style_name = "solarized-light"
	}
	style := styles.Get(style_name)
	if style == nil {
		logrus.WithField("style", style_name).Warnln("Cannot find style")
		return NewPreText(text)
	}

	lexer := lexers.Get(lang)
	if lexer == nil {
		return NewPreText(text)
	}

	formatter := html.New(html.WithLineNumbers(true))
	if formatter == nil {
		return NewPreText(text)
	}

	tokens, err := lexer.Tokenise(nil, text)
	if err != nil {
		return NewPreText(text)
	}

	buf := new(bytes.Buffer)

	err = formatter.Format(buf, style, tokens)
	if err != nil {
		return NewPreText(text)
	}

	b, err := io.ReadAll(buf)
	if err != nil {
		return NewPreText(text)
	}

	return HighlightedText{
		text: "<style>pre { width: fit-content; }</style>\n" + string(b),
	}
}