epee-service/main.go

package main

import (
	"embed"
	"encoding/json"
	"fmt"
	"html/template"
	"net/http"

	log "github.com/sirupsen/logrus"
)

//go:embed static
var staticFS embed.FS

//go:embed templates
var templatesFS embed.FS

// Error model
type Error struct {
	Title   string `json:"title"`
	Message string `json:"message"`
}

func main() {
	port := "5900"

	http.Handle("/cdn-cgi/static/", http.StripPrefix("/cdn-cgi/", http.FileServer(http.FS(staticFS))))
	http.HandleFunc("/cdn-cgi/trace", headersHandler)
	http.HandleFunc("/", errorHandler)

	log.WithFields(log.Fields{
		"port": port,
	}).Info("Started webserver listening")

	err := http.ListenAndServe(fmt.Sprintf(":%s", port), nil)
	if err != nil {
		log.Fatal(err)
	}
}

func errorHandler(w http.ResponseWriter, r *http.Request) {
	errorCode := r.URL.Query().Get("error")

	// Load error messages from JSON file
	jsonData, err := templatesFS.ReadFile("templates/errors.json")
	if err != nil {
		generateInternalServerError(w, err)
		return
	}
	errors := make(map[string]Error)
	err = json.Unmarshal(jsonData, &errors)
	if err != nil {
		generateInternalServerError(w, err)
		return
	}
	errorData := errors[errorCode]
	if errorData.Title == "" {
		errorData.Title = "Oops 🤓"
		errorData.Message = "It seems like something went wrong. Please try again later."
	}

	// Render error page
	tmpl, err := templatesFS.ReadFile("templates/error.html")
	if err != nil {
		generateInternalServerError(w, err)
		return
	}
	t, err := template.New("error").Parse(string(tmpl))
	if err != nil {
		generateInternalServerError(w, err)
		return
	}
	t.Execute(w, errorData)
}

func generateInternalServerError(w http.ResponseWriter, err error) {
	log.Println(err)
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(http.StatusInternalServerError)
	w.Write([]byte(`{"error": "Internal Server Error"}`))
}

func headersHandler(w http.ResponseWriter, r *http.Request) {
	for name, headers := range r.Header {
		for _, h := range headers {
			fmt.Fprintf(w, "%v: %v\n", name, h)
		}
	}
}