Add initial implementation of the UserStore
diff --git a/core/kg/model/user.go b/core/kg/model/user.go
new file mode 100644
index 0000000..4ed6cc8
--- /dev/null
+++ b/core/kg/model/user.go
@@ -0,0 +1,112 @@
+package model
+
+import (
+ "net/mail"
+ "regexp"
+ "strings"
+ "unicode"
+
+ "github.com/pkg/errors"
+)
+
+const (
+ userNameMaxLength = 64
+ userNameMinLength = 1
+ userEmailMaxLength = 128
+)
+
+// User contains the details about the user.
+// This struct's serializer methods are auto-generated. If a new field is added/removed,
+// please run make gen-serialized.
+type User struct {
+ ID string `json:"id"`
+ CreateAt int64 `json:"create_at,omitempty"`
+ UpdateAt int64 `json:"update_at,omitempty"`
+ DeleteAt int64 `json:"delete_at"`
+ Username string `json:"username"`
+ Password string `json:"password,omitempty"`
+ Email string `json:"email"`
+ EmailVerified bool `json:"email_verified,omitempty"`
+ FirstName string `json:"first_name"`
+ LastName string `json:"last_name"`
+ LastPasswordUpdate int64 `json:"last_password_update,omitempty"`
+}
+
+// IsValid validates the user and returns an error if it isn't configured
+// correctly.
+func (u *User) IsValid() error {
+ if !isValidID(u.ID) {
+ return invalidUserError("id", "")
+ }
+
+ if u.CreateAt == 0 {
+ return invalidUserError("create_at", u.ID)
+ }
+
+ if u.UpdateAt == 0 {
+ return invalidUserError("update_at", u.ID)
+ }
+
+ if !isValidUsername(u.Username) {
+ return invalidUserError("username", u.ID)
+ }
+
+ if !isValidEmail(u.Email) {
+ return invalidUserError("email", u.ID)
+ }
+
+ return nil
+}
+
+func isValidID(value string) bool {
+ if len(value) != 26 {
+ return false
+ }
+
+ for _, r := range value {
+ if !unicode.IsLetter(r) && !unicode.IsNumber(r) {
+ return false
+ }
+ }
+
+ return true
+}
+
+func invalidUserError(fieldName string, userID string) error {
+ return errors.Errorf("Invalid User field: %s; id: %s", fieldName, userID)
+}
+
+func isValidUsername(s string) bool {
+ if len(s) < userNameMinLength || len(s) > userNameMaxLength {
+ return false
+ }
+
+ validUsernameChars := regexp.MustCompile(`^[a-z0-9\.\-_]+$`)
+ if !validUsernameChars.MatchString(s) {
+ return false
+ }
+
+ return true
+}
+
+func isValidEmail(email string) bool {
+ if len(email) > userEmailMaxLength || email == "" {
+ return false
+ }
+ if !isLower(email) {
+ return false
+ }
+
+ if addr, err := mail.ParseAddress(email); err != nil {
+ return false
+ } else if addr.Name != "" {
+ // mail.ParseAddress accepts input of the form "Billy Bob <billy@example.com>" which we don't allow
+ return false
+ }
+
+ return true
+}
+
+func isLower(s string) bool {
+ return strings.ToLower(s) == s
+}