Move code rendering to the backend & frontend improvements (#176)

Added Chroma & Goldmark

Added Mermaidjs

More languages supported

Add default values for gist links input

Added copy code from markdown blocks

internal/render/highlight.go

@@ -0,0 +1,134 @@
+package render
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"github.com/alecthomas/chroma/v2"
+	"github.com/alecthomas/chroma/v2/formatters/html"
+	"github.com/alecthomas/chroma/v2/lexers"
+	"github.com/alecthomas/chroma/v2/styles"
+	"github.com/thomiceli/opengist/internal/db"
+	"github.com/thomiceli/opengist/internal/git"
+)
+
+type RenderedFile struct {
+	*git.File
+	Type  string
+	Lines []string
+	HTML  string
+}
+
+type RenderedGist struct {
+	*db.Gist
+	Lines []string
+	HTML  string
+}
+
+func HighlightFile(file *git.File) (RenderedFile, error) {
+	rendered := RenderedFile{
+		File: file,
+	}
+
+	style := newStyle()
+	lexer := newLexer(file.Filename)
+	if lexer.Config().Name == "markdown" {
+		return MarkdownFile(file)
+	}
+
+	formatter := html.New(html.WithClasses(true), html.PreventSurroundingPre(true))
+
+	iterator, err := lexer.Tokenise(nil, file.Content)
+	if err != nil {
+		return rendered, err
+	}
+
+	htmlbuf := bytes.Buffer{}
+	w := bufio.NewWriter(&htmlbuf)
+
+	tokensLines := chroma.SplitTokensIntoLines(iterator.Tokens())
+	lines := make([]string, 0, len(tokensLines))
+	for _, tokens := range tokensLines {
+		iterator = chroma.Literator(tokens...)
+		err = formatter.Format(&htmlbuf, style, iterator)
+		if err != nil {
+			return rendered, fmt.Errorf("unable to format code: %w", err)
+		}
+		lines = append(lines, htmlbuf.String())
+		htmlbuf.Reset()
+	}
+
+	_ = w.Flush()
+
+	rendered.Lines = lines
+	rendered.Type = parseFileTypeName(*lexer.Config())
+
+	return rendered, err
+}
+
+func HighlightGistPreview(gist *db.Gist) (RenderedGist, error) {
+	rendered := RenderedGist{
+		Gist: gist,
+	}
+
+	style := newStyle()
+	lexer := newLexer(gist.PreviewFilename)
+	if lexer.Config().Name == "markdown" {
+		return MarkdownGistPreview(gist)
+	}
+
+	formatter := html.New(html.WithClasses(true), html.PreventSurroundingPre(true))
+
+	iterator, err := lexer.Tokenise(nil, gist.Preview)
+	if err != nil {
+		return rendered, err
+	}
+
+	htmlbuf := bytes.Buffer{}
+	w := bufio.NewWriter(&htmlbuf)
+
+	tokensLines := chroma.SplitTokensIntoLines(iterator.Tokens())
+	lines := make([]string, 0, len(tokensLines))
+	for _, tokens := range tokensLines {
+		iterator = chroma.Literator(tokens...)
+		err = formatter.Format(&htmlbuf, style, iterator)
+		if err != nil {
+			return rendered, fmt.Errorf("unable to format code: %w", err)
+		}
+		lines = append(lines, htmlbuf.String())
+		htmlbuf.Reset()
+	}
+
+	_ = w.Flush()
+
+	rendered.Lines = lines
+
+	return rendered, err
+}
+
+func parseFileTypeName(config chroma.Config) string {
+	fileType := config.Name
+	if fileType == "fallback" || fileType == "plaintext" {
+		return "Text"
+	}
+
+	return fileType
+}
+
+func newLexer(filename string) chroma.Lexer {
+	var lexer chroma.Lexer
+	if lexer = lexers.Get(filename); lexer == nil {
+		lexer = lexers.Fallback
+	}
+
+	return lexer
+}
+
+func newStyle() *chroma.Style {
+	var style *chroma.Style
+	if style = styles.Get("catppuccin-latte"); style == nil {
+		style = styles.Fallback
+	}
+
+	return style
+}