package main

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

	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"`
	Description string        `json:"description"`
	Message     template.HTML `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")

	// Set status code based on error code
	errorCodeInt, err := strconv.Atoi(errorCode)
	if err != nil || errorCodeInt < 400 || errorCodeInt > 599 {
		errorCodeInt = http.StatusInternalServerError
	}
	w.WriteHeader(errorCodeInt)

	// 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 = errors["500"] // Fallback to 500 error if specific error not found
	}

	// 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
	}

	if err := t.Execute(w, errorData); err != nil {
		log.Error(err)
	}
}

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

func headersHandler(w http.ResponseWriter, r *http.Request) {
	headersName := make([]string, 0, len(r.Header))
	for hName := range r.Header {
		headersName = append(headersName, hName)
	}
	sort.Strings(headersName)

	for _, hName := range headersName {
		fmt.Fprintf(w, "%v: %v\n", hName, r.Header.Get(hName))
	}
}