package main

import (
	"crypto/rand"
	"html/template"
	"log"
	"net/http"
)

const (
	passwordLength = 32
	chars          = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
)

var templates = make(map[string]*template.Template)
var AppVersion = "development"

func loadTemplates() {
    // 1. FuncMap definieren
    funcMap := template.FuncMap{
        "getAppVersion": func() string {
            return AppVersion
        },
    }

    // 2. Templates mit FuncMap laden
    // Wir nutzen New("base.html"), da base.html meist das Haupt-Layout definiert
    templates["index.html"] = template.Must(template.New("base.html").Funcs(funcMap).ParseFiles(
        "templates/base.html", 
        "templates/index.html",
    ))

    templates["help.html"] = template.Must(template.New("base.html").Funcs(funcMap).ParseFiles(
        "templates/base.html", 
        "templates/help.html",
    ))

    log.Printf("Alle Templates erfolgreich geladen")
}

func generatePassword() string {
	password := make([]byte, passwordLength)
	_, err := rand.Read(password)
	if err != nil {
		log.Fatal(err)
	}
	for i := 0; i < passwordLength; i++ {
		password[i] = chars[int(password[i])%len(chars)]
	}
	return string(password)
}

func passwordHandler(w http.ResponseWriter, r *http.Request) {
	password := generatePassword()
	w.Header().Set("Content-Type", "text/plain")
	w.Write([]byte(password))
}

func indexHandler(w http.ResponseWriter, r *http.Request) {
	log.Printf("call indexHandler: Request %s %s\n", r.Method, r.URL)
	password := generatePassword()
	data := struct {
		Password string
	}{
		Password: password,
	}
	err := templates["index.html"].ExecuteTemplate(w, "base.html", data)
	if err != nil {
		log.Printf("Fehler beim Rendern des Templates: %v", err)
		http.Error(w, "Interner Serverfehler", http.StatusInternalServerError)
	}
}

func helpHandler(w http.ResponseWriter, r *http.Request) {
	log.Printf("call helpHandler\n")
	err := templates["help.html"].ExecuteTemplate(w, "base.html", nil)
	if err != nil {
		log.Printf("Fehler beim Rendern des Templates: %v", err)
		http.Error(w, "Interner Serverfehler", http.StatusInternalServerError)
	}
}

func main() {
	loadTemplates()
	fs := http.FileServer(http.Dir("static"))
	http.Handle("/static/", http.StripPrefix("/static/", fs))

	http.HandleFunc("/", indexHandler)
	http.HandleFunc("/api/password", passwordHandler)
	http.HandleFunc("/help", helpHandler)

	log.Println("Server läuft auf http://localhost:8080")
	log.Fatal(http.ListenAndServe(":8080", nil))
}