Move user related model into models/user (#17781)

* Move user related model into models/user

* Fix lint for windows

* Fix windows lint

* Fix windows lint

* Move some tests in models

* Merge

models/db/name.go

@@ -0,0 +1,91 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package db
+
+import (
+	"errors"
+	"fmt"
+	"regexp"
+	"strings"
+	"unicode/utf8"
+)
+
+var (
+	// ErrNameEmpty name is empty error
+	ErrNameEmpty = errors.New("Name is empty")
+
+	// AlphaDashDotPattern characters prohibited in a user name (anything except A-Za-z0-9_.-)
+	AlphaDashDotPattern = regexp.MustCompile(`[^\w-\.]`)
+)
+
+// ErrNameReserved represents a "reserved name" error.
+type ErrNameReserved struct {
+	Name string
+}
+
+// IsErrNameReserved checks if an error is a ErrNameReserved.
+func IsErrNameReserved(err error) bool {
+	_, ok := err.(ErrNameReserved)
+	return ok
+}
+
+func (err ErrNameReserved) Error() string {
+	return fmt.Sprintf("name is reserved [name: %s]", err.Name)
+}
+
+// ErrNamePatternNotAllowed represents a "pattern not allowed" error.
+type ErrNamePatternNotAllowed struct {
+	Pattern string
+}
+
+// IsErrNamePatternNotAllowed checks if an error is an ErrNamePatternNotAllowed.
+func IsErrNamePatternNotAllowed(err error) bool {
+	_, ok := err.(ErrNamePatternNotAllowed)
+	return ok
+}
+
+func (err ErrNamePatternNotAllowed) Error() string {
+	return fmt.Sprintf("name pattern is not allowed [pattern: %s]", err.Pattern)
+}
+
+// ErrNameCharsNotAllowed represents a "character not allowed in name" error.
+type ErrNameCharsNotAllowed struct {
+	Name string
+}
+
+// IsErrNameCharsNotAllowed checks if an error is an ErrNameCharsNotAllowed.
+func IsErrNameCharsNotAllowed(err error) bool {
+	_, ok := err.(ErrNameCharsNotAllowed)
+	return ok
+}
+
+func (err ErrNameCharsNotAllowed) Error() string {
+	return fmt.Sprintf("User name is invalid [%s]: must be valid alpha or numeric or dash(-_) or dot characters", err.Name)
+}
+
+// IsUsableName checks if name is reserved or pattern of name is not allowed
+// based on given reserved names and patterns.
+// Names are exact match, patterns can be prefix or suffix match with placeholder '*'.
+func IsUsableName(names, patterns []string, name string) error {
+	name = strings.TrimSpace(strings.ToLower(name))
+	if utf8.RuneCountInString(name) == 0 {
+		return ErrNameEmpty
+	}
+
+	for i := range names {
+		if name == names[i] {
+			return ErrNameReserved{name}
+		}
+	}
+
+	for _, pat := range patterns {
+		if pat[0] == '*' && strings.HasSuffix(name, pat[1:]) ||
+			(pat[len(pat)-1] == '*' && strings.HasPrefix(name, pat[:len(pat)-1])) {
+			return ErrNamePatternNotAllowed{pat}
+		}
+	}
+
+	return nil
+}