From 41d4965db78414ba53237f791919ae17c0b99e14 Mon Sep 17 00:00:00 2001
From: mihna123 <mihailonvojinovic@gmail.com>
Date: Sat, 29 Aug 2026 23:28:28 +0200
Subject: user: add a service stub with validated register method

---
 internal/user/input.go | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 internal/user/input.go

(limited to 'internal/user/input.go')

diff --git a/internal/user/input.go b/internal/user/input.go
new file mode 100644
index 0000000..38db678
--- /dev/null
+++ b/internal/user/input.go
@@ -0,0 +1,65 @@
+package user
+
+import (
+	"errors"
+	"fmt"
+	"regexp"
+)
+
+type RegisterInput struct {
+	Username string
+	Email    string
+	Phone    string
+	Password string
+}
+
+type CreateInput struct {
+	Username string
+	Email    string
+	Phone    string
+	PwHash   string
+}
+
+var ErrInvalidInput = errors.New("invalid input")
+var ErrUserExists = errors.New("user already exists")
+var ErrUserNotFound = errors.New("user not found")
+
+var usrnameRegExp = regexp.MustCompile(`^[a-zA-Z][a-zA-Z0-9_-]*$`)
+var mailRegExp = regexp.MustCompile(`^[^@\s]+@[^@\s]+\.[^@\s]+$`)
+var phoneRegExp = regexp.MustCompile(`^\+?[0-9][0-9\s-]*$`)
+
+func (in *RegisterInput) validate() error {
+	if len(in.Password) < 8 {
+		return fmt.Errorf("%w: password too short - min is 8", ErrInvalidInput)
+	}
+
+	if len(in.Password) > 72 {
+		return fmt.Errorf("%w: password too long - max is 72", ErrInvalidInput)
+	}
+
+	if in.Username == "" {
+		return fmt.Errorf("%w: username is mandatory", ErrInvalidInput)
+	}
+
+	if !usrnameRegExp.MatchString(in.Username) {
+		return fmt.Errorf("%w: bad username - must start with a letter", ErrInvalidInput)
+	}
+
+	if len(in.Username) < 3 {
+		return fmt.Errorf("%w: username too short - min is 3 chars", ErrInvalidInput)
+	}
+
+	if in.Email == "" {
+		return fmt.Errorf("%w: email is mandatory", ErrInvalidInput)
+	}
+
+	if !mailRegExp.MatchString(in.Email) {
+		return fmt.Errorf("%w: bad email format", ErrInvalidInput)
+	}
+
+	if in.Phone != "" && !phoneRegExp.MatchString(in.Phone) {
+		return fmt.Errorf("%w: bad phone format", ErrInvalidInput)
+	}
+
+	return nil
+}
-- 
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