add users logic

users/internal/domain/user.go

@@ -0,0 +1,80 @@
+package domain
+
+import (
+	"net/mail"
+	"strings"
+	"time"
+
+	"github.com/google/uuid"
+)
+
+type Role string
+
+const (
+	RoleAdmin Role = "admin"
+	RoleUser  Role = "user"
+)
+
+func (r Role) Valid() bool {
+	switch r {
+	case RoleAdmin, RoleUser:
+		return true
+	default:
+		return false
+	}
+}
+
+type User struct {
+	ID           uuid.UUID
+	Email        string
+	PasswordHash string
+	Role         Role
+	CreatedAt    time.Time
+	UpdatedAt    time.Time
+}
+
+// NewUser builds a freshly registered account. It normalises the email and
+// enforces every invariant a row must satisfy, so an invalid User cannot be
+// constructed. The caller supplies the already-hashed password — hashing is an
+// adapter's job, not the domain's.
+//
+// Registration always produces a plain user; promotion to admin is a manual,
+// out-of-band operation, never something a request can trigger.
+func NewUser(email, passwordHash string, now time.Time) (*User, error) {
+	email = NormalizeEmail(email)
+	if err := validateEmail(email); err != nil {
+		return nil, err
+	}
+	if passwordHash == "" {
+		return nil, ErrEmptyPasswordHash
+	}
+	return &User{
+		ID:           uuid.New(),
+		Email:        email,
+		PasswordHash: passwordHash,
+		Role:         RoleUser,
+		CreatedAt:    now,
+		UpdatedAt:    now,
+	}, nil
+}
+
+// NormalizeEmail lower-cases and trims an address so that "Bob@X.com " and
+// "bob@x.com" resolve to the same account. Every lookup and every insert must
+// pass through here, matching the ck_users_email_lower database constraint.
+func NormalizeEmail(email string) string {
+	return strings.ToLower(strings.TrimSpace(email))
+}
+
+func validateEmail(email string) error {
+	if email == "" {
+		return ErrEmptyEmail
+	}
+	// A minimal shape check, not full RFC 5322: real deliverability is proven by
+	// sending mail, not by a regex. mail.ParseAddress also accepts the
+	// "Name <addr>" form, so we insist the parsed address equals the input.
+	addr, err := mail.ParseAddress(email)
+	if err != nil || addr.Address != email {
+		return ErrInvalidEmail
+	}
+	return nil
+}