package captcha import ( "crypto/rand" "image" "math/big" "time" "github.com/pkg/errors" ) const ( maxAnswer = 999999 ) var errorNotFound = errors.New("captcha not found") type ID string type Answer string type ICaptcha interface { generateImage() *image.Image GetImage() *image.Image GetAnswer() Answer Solve(answer Answer) bool IsSolved() bool Expiry() time.Time } type Captcha struct { Image image.Image Answer Answer Solved bool ExpireIn time.Time } func (c *Captcha) Solve(answer Answer) bool { c.Solved = c.Answer == answer return c.Solved } func (c *Captcha) GetAnswer() Answer { return c.Answer } func (c *Captcha) IsSolved() bool { return c.Solved } func (c *Captcha) Expiry() time.Time { return c.ExpireIn } func GenerateAnswer() Answer { ans, _ := rand.Int(rand.Reader, big.NewInt(maxAnswer)) return (Answer(ans.String())) } func ExpiryDate(expiry time.Duration) time.Time { return time.Now().Add(expiry) }