Create invitations for closed registrations (#233)

internal/db/db.go

@@ -42,7 +42,7 @@ func Setup(dbPath string, sharedCache bool) error {
 		return err
 	}
 
-	if err = db.AutoMigrate(&User{}, &Gist{}, &SSHKey{}, &AdminSetting{}); err != nil {
+	if err = db.AutoMigrate(&User{}, &Gist{}, &SSHKey{}, &AdminSetting{}, &Invitation{}); err != nil {
 		return err
 	}
 

internal/db/invitation.go

@@ -0,0 +1,87 @@
+package db
+
+import (
+	"math/rand"
+	"time"
+)
+
+type Invitation struct {
+	ID        uint `gorm:"primaryKey"`
+	Code      string
+	ExpiresAt int64
+	NbUsed    uint
+	NbMax     uint
+}
+
+func GetAllInvitations() ([]*Invitation, error) {
+	var invitations []*Invitation
+	err := db.
+		Order("(((expires_at >= strftime('%s', 'now')) AND ((nb_max <= 0) OR (nb_used < nb_max)))) desc").
+		Order("id asc").
+		Find(&invitations).Error
+
+	return invitations, err
+}
+
+func GetInvitationByID(id uint) (*Invitation, error) {
+	invitation := new(Invitation)
+	err := db.
+		Where("id = ?", id).
+		First(&invitation).Error
+	return invitation, err
+}
+
+func GetInvitationByCode(code string) (*Invitation, error) {
+	invitation := new(Invitation)
+	err := db.
+		Where("code = ?", code).
+		First(&invitation).Error
+	return invitation, err
+}
+
+func InvitationCodeExists(code string) (bool, error) {
+	var count int64
+	err := db.Model(&Invitation{}).Where("code = ?", code).Count(&count).Error
+	return count > 0, err
+}
+
+func (i *Invitation) Create() error {
+	i.Code = generateRandomCode()
+	return db.Create(&i).Error
+}
+
+func (i *Invitation) Update() error {
+	return db.Save(&i).Error
+}
+
+func (i *Invitation) Delete() error {
+	return db.Delete(&i).Error
+}
+
+func (i *Invitation) IsExpired() bool {
+	return i.ExpiresAt < time.Now().Unix()
+}
+
+func (i *Invitation) IsMaxedOut() bool {
+	return i.NbMax > 0 && i.NbUsed >= i.NbMax
+}
+
+func (i *Invitation) IsUsable() bool {
+	return !i.IsExpired() && !i.IsMaxedOut()
+}
+
+func (i *Invitation) Use() error {
+	i.NbUsed++
+	return i.Update()
+}
+
+func generateRandomCode() string {
+	const charset = "0123456789ABCDEF"
+	var seededRand = rand.New(rand.NewSource(time.Now().UnixNano()))
+	result := make([]byte, 16)
+
+	for i := range result {
+		result[i] = charset[seededRand.Intn(len(charset))]
+	}
+	return string(result)
+}