Sprechstunden hinzufügen und durch einen E-Mail-Link bestätigen lassen

repositories/request.go

@@ -0,0 +1,141 @@
+// request
+package repositories
+
+import (
+	"bytes"
+	"crypto/rand"
+	"database/sql"
+	"html/template"
+	"math/big"
+	"net/smtp"
+	"sprechstundentool/models"
+)
+
+type RequestRepo struct {
+	db             *sql.DB
+	officeHourRepo models.OfficeHourRepository
+}
+
+func NewRequestRepo(db *sql.DB, officeHourRepo models.OfficeHourRepository) *RequestRepo {
+	return &RequestRepo{
+		db:             db,
+		officeHourRepo: officeHourRepo,
+	}
+}
+
+func (r *RequestRepo) FindBySecret(secret string) (models.Request, error) {
+	// This query is not safe against timing sidechannel attacks – I don't care.
+	row := r.db.QueryRow("SELECT * FROM request WHERE secret=?", secret)
+	var request models.Request
+	var officeHourId int
+	err := row.Scan(&request.Id, &officeHourId, &request.Action, &request.Secret)
+	if err != nil {
+		return models.Request{}, err
+	}
+	request.OfficeHour, err = r.officeHourRepo.FindById(officeHourId)
+	return request, err
+}
+
+func (r *RequestRepo) FindByOfficeHour(officeHour models.OfficeHour) ([]models.Request, error) {
+	rows, err := r.db.Query("SELECT * FROM request WHERE officeHour=?", officeHour.Id)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var requests []models.Request
+	for rows.Next() {
+		var request models.Request
+		var officeHourId int
+		if err := rows.Scan(&request.Id, &officeHourId, &request.Action, &request.Secret); err != nil {
+			return requests, err
+		}
+		requests = append(requests, request)
+	}
+	return requests, nil
+}
+
+func (r *RequestRepo) Add(officeHour models.OfficeHour, action int) (int, error) {
+	existents, err := r.FindByOfficeHour(officeHour)
+	if err != nil && err != sql.ErrNoRows {
+		return 0, err
+	}
+	/* Resend confirmation mail if identical request exists,
+	 * but don't insert new request into database.
+	 */
+	for _, request := range existents {
+		if request.Action == action { // already covered by selection && request.OfficeHour == officeHour {
+			return request.Id, sendConfirmationMail(request)
+		}
+	}
+	secret, err := r.newSecret()
+	if err != nil {
+		return 0, err
+	}
+	request := models.Request{0, officeHour, action, secret}
+	_, err = r.db.Exec("INSERT INTO `request` (officeHour, action, secret) VALUES (?,?,?)", officeHour.Id, action, secret)
+	if err != nil {
+		return 0, err
+	}
+
+	request, err = r.FindBySecret(secret)
+	if err != nil {
+		return request.Id, err
+	}
+	return request.Id, sendConfirmationMail(request)
+}
+
+func (r *RequestRepo) Execute(request models.Request) error {
+	var err error
+	switch request.Action {
+	case models.RequestActivate:
+		_, err = r.db.Exec("UPDATE officeHour SET active=true WHERE id=?", request.OfficeHour.Id)
+		r.db.Exec("DELETE FROM request WHERE id=?", request.Id)
+	case models.RequestDelete:
+		_, err = r.db.Exec("DELETE FROM officeHour WHERE id=?", request.OfficeHour.Id)
+		r.db.Exec("DELETE FROM request WHERE id=?", request.Id)
+	default:
+		r.db.Exec("DELETE FROM request WHERE id=?", request.Id)
+	}
+	return err
+}
+
+func (r *RequestRepo) newSecret() (string, error) {
+	secret := randomString(models.SecretLength)
+
+	_, err := r.FindBySecret(secret)
+	if err != nil && err != sql.ErrNoRows {
+		return "", err
+	}
+	// find unused secret
+	for err != sql.ErrNoRows {
+		secret = randomString(models.SecretLength)
+		_, err = r.FindBySecret(secret)
+	}
+	return secret, nil
+}
+
+func sendConfirmationMail(request models.Request) error {
+	to := []string{request.OfficeHour.Tutor.Email}
+	tmpl, err := template.New("confirmationMail").Funcs(template.FuncMap{"DayName": models.DayName}).ParseFiles("templates/confirmationMail")
+	var message bytes.Buffer
+	err = tmpl.Execute(&message, request)
+	if err != nil {
+		return err
+	}
+	err = smtp.SendMail("192.168.0.24:25", nil, "Mathebau Sprechstunden <sprechstunden@mathebau.de>", to, message.Bytes())
+	return err
+}
+
+func randomString(n int) string {
+	// []byte would be faster and also work, but []rune keeps working for UTF8 characters
+	// if someone would like them.
+	var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
+
+	s := make([]rune, n)
+	for i := range s {
+		position, _ := rand.Int(rand.Reader, big.NewInt(int64(len(letters))))
+		s[i] = letters[position.Int64()]
+	}
+	return string(s)
+}