probo/server/main.go

package main

import (
	"encoding/json"
	"log"
	"math/rand"
	"net/http"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"text/template"

	"git.andreafazzi.eu/andrea/probo/models"
	"git.andreafazzi.eu/andrea/probo/store/file"
)

var (
	DefaultDataDir     = "data"
	DefaultSessionDir  = "sessions"
	DefaultTemplateDir = "templates"
	DefaultStaticDir   = "static"
)

type Config struct {
	SessionDir  string
	TemplateDir string
	StaticDir   string
}

type ExamSession []*models.Exam

type ExamTemplateData struct {
	*models.Exam

	SessionID string
}

type Server struct {
	config        *Config
	mux           *http.ServeMux
	responseStore *file.ResponseFileStore
}

func GetDefaultSessionDir() string {
	return filepath.Join(DefaultDataDir, DefaultSessionDir)
}

func GetDefaultTemplateDir() string {
	return DefaultTemplateDir
}

func GetDefaultStaticDir() string {
	return DefaultStaticDir
}

func NewServer(config *Config) (*Server, error) {

	_, err := os.Stat(config.SessionDir)
	if err != nil {
		return nil, err
	}

	_, err = os.Stat(config.TemplateDir)
	if err != nil {
		return nil, err
	}

	_, err = os.Stat(config.StaticDir)
	if err != nil {
		return nil, err
	}

	s := &Server{
		config,
		http.NewServeMux(),
		nil,
	}

	s.mux.Handle("/static/", http.StripPrefix("/static", http.FileServer(http.Dir(config.StaticDir))))
	s.mux.HandleFunc("/create", s.createExamSessionHandler)
	s.mux.HandleFunc("/", s.getExamHandler)

	return s, nil
}

func NewDefaultServer() (*Server, error) {
	return NewServer(&Config{
		SessionDir:  GetDefaultSessionDir(),
		TemplateDir: GetDefaultTemplateDir(),
		StaticDir:   GetDefaultStaticDir(),
	})
}

func (s *Server) createExamSessionHandler(w http.ResponseWriter, r *http.Request) {
	var p ExamSession
	err := json.NewDecoder(r.Body).Decode(&p)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	id := generateRandomID()
	path := filepath.Join(s.config.SessionDir, id)

	err = os.MkdirAll(path, os.ModePerm)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	for _, exam := range p {
		file, err := os.Create(filepath.Join(path, strconv.Itoa(exam.Participant.Token)) + ".json")
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		defer file.Close()

		err = json.NewEncoder(file).Encode(exam)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
	}
	response := map[string]string{"id": id}
	json.NewEncoder(w).Encode(response)
}

func (s *Server) getExamHandler(w http.ResponseWriter, r *http.Request) {
	urlParts := strings.Split(r.URL.Path, "/")

	examID := urlParts[1]
	token := urlParts[2]

	filePath := filepath.Join(s.config.SessionDir, examID, token+".json")

	data, err := os.ReadFile(filePath)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	exam := new(models.Exam)
	err = json.Unmarshal(data, &exam)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	if r.Method == "GET" {

		w.Header().Set("Content-Type", "text/html")

		tplData, err := os.ReadFile(filepath.Join(GetDefaultTemplateDir(), "exam.tpl"))
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return

		}
		tmpl := template.Must(template.New("exam").Parse(string(tplData)))

		err = tmpl.Execute(w, ExamTemplateData{exam, examID})
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
	}

	if r.Method == "POST" {
		err := r.ParseForm()
		if err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		w.Header().Set("Content-Type", "text/html")
		if r.FormValue("answer") == exam.Quizzes[0].Correct.ID {
			w.Write([]byte("<p>Corretto!</p>"))
			return
		}
		w.Write([]byte("<p>Errato!</p>"))
		return
	}

}

func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	s.mux.ServeHTTP(w, r)
}

func generateRandomID() string {
	id := ""
	for i := 0; i < 6; i++ {
		id += strconv.Itoa(rand.Intn(9) + 1)
	}
	return id
}

func main() {
	server, err := NewDefaultServer()
	if err != nil {
		panic(err)
	}

	log.Println("Probo server started.", "Config", server.config)
	http.ListenAndServe(":8080", server)
}