A fast and simple blog backend.
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mediocre-blog/src/gmi/gemtext.go

73 lines
1.2 KiB

package gmi
import (
"bufio"
"errors"
"fmt"
"io"
"log"
"path"
"regexp"
"strings"
)
func hasImgExt(p string) bool {
switch path.Ext(strings.ToLower(p)) {
case ".jpg", ".jpeg", ".png", ".gif", ".svg":
return true
default:
return false
}
}
// matches `=> dstURL [optional description]`
var linkRegexp = regexp.MustCompile(`^=>\s+(\S+)\s*(.*?)\s*$`)
// GemtextToMarkdown reads a gemtext formatted body from the Reader and writes
// the markdown version of that body to the Writer.
func GemtextToMarkdown(dst io.Writer, src io.Reader) error {
bufSrc := bufio.NewReader(src)
for {
line, err := bufSrc.ReadString('\n')
if err != nil && !errors.Is(err, io.EOF) {
return fmt.Errorf("reading: %w", err)
}
last := err == io.EOF
if match := linkRegexp.FindStringSubmatch(line); len(match) > 0 {
isImg := hasImgExt(match[1])
descr := match[2]
if descr != "" {
// ok
} else if isImg {
descr = "Image"
} else {
descr = "Link"
}
log.Printf("descr:%q", descr)
line = fmt.Sprintf("[%s](%s)\n", descr, match[1])
if isImg {
line = "!" + line
}
}
if _, err := dst.Write([]byte(line)); err != nil {
return fmt.Errorf("writing: %w", err)
}
if last {
return nil
}
}
}