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package main
import (
"embed"
"encoding/json"
"html/template"
"log"
"mime"
"net/http"
"sort"
"strings"
"github.com/alecthomas/kong"
konghcl "github.com/alecthomas/kong-hcl"
"github.com/gorilla/csrf"
"github.com/gorilla/handlers"
"github.com/gorilla/mux"
"github.com/alecthomas/chroma/v2"
"github.com/alecthomas/chroma/v2/formatters/html"
"github.com/alecthomas/chroma/v2/lexers"
"github.com/alecthomas/chroma/v2/styles"
)
var (
version = "devel"
//go:embed templates/index.html.tmpl
indexTemplate string
//go:embed static
staticFiles embed.FS
htmlTemplate = template.Must(template.New("html").
Funcs(template.FuncMap{
"JS": func(filename string) template.JS {
if version == "devel" {
return template.JS(`import "./static/` + filename + "\";\n")
}
content, err := staticFiles.ReadFile("static/" + strings.TrimSuffix(filename, ".js") + ".min.js")
if err != nil {
panic(err)
}
return template.JS(content)
},
"CSS": func(filename string) template.CSS {
if version == "devel" {
return template.CSS(`@import url("./static/` + filename + "\");")
}
content, err := staticFiles.ReadFile("static/" + strings.TrimSuffix(filename, ".css") + ".min.css")
if err != nil {
panic(err)
}
return template.CSS(content)
},
}).Parse(indexTemplate))
)
type context struct {
Background template.CSS
SelectedLanguage string
Languages []string
SelectedStyle string
Styles []string
CSRFField template.HTML
Version string
}
func index(w http.ResponseWriter, r *http.Request) {
ctx := newContext(r)
err := htmlTemplate.Execute(w, &ctx)
if err != nil {
panic(err)
}
}
type renderRequest struct {
Language string `json:"language"`
Style string `json:"style"`
Text string `json:"text"`
Classes bool `json:"classes"`
}
type renderResponse struct {
Error string `json:"error,omitempty"`
HTML string `json:"html,omitempty"`
Language string `json:"language,omitempty"`
Background string `json:"background,omitempty"`
}
func renderHandler(w http.ResponseWriter, r *http.Request) {
req := &renderRequest{}
err := json.NewDecoder(r.Body).Decode(&req)
var rep *renderResponse
if err != nil {
rep = &renderResponse{Error: err.Error()}
} else {
rep, err = render(req)
if err != nil {
rep = &renderResponse{Error: err.Error()}
}
}
w.Header().Set("Content-Type", "application/json")
_ = json.NewEncoder(w).Encode(rep)
}
func render(req *renderRequest) (*renderResponse, error) {
language := lexers.Get(req.Language)
if language == nil {
language = lexers.Analyse(req.Text)
if language != nil {
req.Language = language.Config().Name
}
}
if language == nil {
language = lexers.Fallback
}
tokens, err := chroma.Coalesce(language).Tokenise(nil, req.Text)
if err != nil {
return nil, err
}
style := styles.Get(req.Style)
if style == nil {
style = styles.Fallback
}
buf := &strings.Builder{}
options := []html.Option{}
if req.Classes {
options = append(options, html.WithClasses(true), html.Standalone(true))
}
formatter := html.New(options...)
err = formatter.Format(buf, style, tokens)
if err != nil {
return nil, err
}
lang := language.Config().Name
if language == lexers.Fallback {
lang = ""
}
return &renderResponse{
Language: lang,
HTML: buf.String(),
Background: html.StyleEntryToCSS(style.Get(chroma.Background)),
}, nil
}
func newContext(r *http.Request) context {
ctx := context{
SelectedStyle: "monokailight",
CSRFField: csrf.TemplateField(r),
Version: version,
}
style := styles.Get(ctx.SelectedStyle)
if style == nil {
style = styles.Fallback
}
ctx.Background = template.CSS(html.StyleEntryToCSS(style.Get(chroma.Background)))
if ctx.SelectedStyle == "" {
ctx.SelectedStyle = "monokailight"
}
for _, lexer := range lexers.GlobalLexerRegistry.Lexers {
ctx.Languages = append(ctx.Languages, lexer.Config().Name)
}
sort.Strings(ctx.Languages)
for _, style := range styles.Registry {
ctx.Styles = append(ctx.Styles, style.Name)
}
sort.Strings(ctx.Styles)
return ctx
}
func main() {
var cli struct {
Version kong.VersionFlag `help:"Show version."`
Config kong.ConfigFlag `help:"Load configuration." placeholder:"FILE"`
Bind string `help:"HTTP bind address." default:"127.0.0.1:8080"`
CSRFKey string `help:"CSRF key." default:""`
}
ctx := kong.Parse(&cli, kong.Configuration(konghcl.Loader), kong.Vars{"version": version})
log.Printf("Starting chromad %s on http://%s\n", version, cli.Bind)
mime.AddExtensionType(".js", "application/javascript")
router := mux.NewRouter()
router.Handle("/", http.HandlerFunc(index)).Methods("GET")
router.Handle("/api/render", http.HandlerFunc(renderHandler)).Methods("POST")
router.Handle("/static/{file:.*}", http.FileServer(http.FS(staticFiles))).Methods("GET")
options := []csrf.Option{}
if cli.CSRFKey == "" {
options = append(options, csrf.Secure(false))
}
root := handlers.CORS()(csrf.Protect([]byte(cli.CSRFKey), options...)(router))
err := http.ListenAndServe(cli.Bind, root)
ctx.FatalIfErrorf(err)
}
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