Move some files into models' sub packages (#20262)

* Move some files into models' sub packages

* Move functions

* merge main branch

* Fix check

* fix check

* Fix some tests

* Fix lint

* Fix lint

* Revert lint changes

* Fix error comments

* Fix lint

Co-authored-by: 6543 <6543@obermui.de>

models/repo/wiki.go

@@ -6,6 +6,7 @@
 package repo
 
 import (
+	"fmt"
 	"path/filepath"
 	"strings"
 
@@ -14,6 +15,51 @@ import (
 	"code.gitea.io/gitea/modules/util"
 )
 
+// ErrWikiAlreadyExist represents a "WikiAlreadyExist" kind of error.
+type ErrWikiAlreadyExist struct {
+	Title string
+}
+
+// IsErrWikiAlreadyExist checks if an error is an ErrWikiAlreadyExist.
+func IsErrWikiAlreadyExist(err error) bool {
+	_, ok := err.(ErrWikiAlreadyExist)
+	return ok
+}
+
+func (err ErrWikiAlreadyExist) Error() string {
+	return fmt.Sprintf("wiki page already exists [title: %s]", err.Title)
+}
+
+// ErrWikiReservedName represents a reserved name error.
+type ErrWikiReservedName struct {
+	Title string
+}
+
+// IsErrWikiReservedName checks if an error is an ErrWikiReservedName.
+func IsErrWikiReservedName(err error) bool {
+	_, ok := err.(ErrWikiReservedName)
+	return ok
+}
+
+func (err ErrWikiReservedName) Error() string {
+	return fmt.Sprintf("wiki title is reserved: %s", err.Title)
+}
+
+// ErrWikiInvalidFileName represents an invalid wiki file name.
+type ErrWikiInvalidFileName struct {
+	FileName string
+}
+
+// IsErrWikiInvalidFileName checks if an error is an ErrWikiInvalidFileName.
+func IsErrWikiInvalidFileName(err error) bool {
+	_, ok := err.(ErrWikiInvalidFileName)
+	return ok
+}
+
+func (err ErrWikiInvalidFileName) Error() string {
+	return fmt.Sprintf("Invalid wiki filename: %s", err.FileName)
+}
+
 // WikiCloneLink returns clone URLs of repository wiki.
 func (repo *Repository) WikiCloneLink() *CloneLink {
 	return repo.cloneLink(true)