Move user follow and openid into models/user/ (#17613)

* Move UserRedirect into models/user/

* Fix lint & test

* Fix lint

* Fix lint

* remove nolint comment

* Fix lint

* Move user follow and openid into models/user

* Ignore the lint

* Ignore the lint

* Fix test

* ignore stutters lint on UserOpenID

models/user/follow.go

@@ -0,0 +1,80 @@
+// Copyright 2017 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 user
+
+import (
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/timeutil"
+)
+
+// Follow represents relations of user and his/her followers.
+type Follow struct {
+	ID          int64              `xorm:"pk autoincr"`
+	UserID      int64              `xorm:"UNIQUE(follow)"`
+	FollowID    int64              `xorm:"UNIQUE(follow)"`
+	CreatedUnix timeutil.TimeStamp `xorm:"INDEX created"`
+}
+
+func init() {
+	db.RegisterModel(new(Follow))
+}
+
+// IsFollowing returns true if user is following followID.
+func IsFollowing(userID, followID int64) bool {
+	has, _ := db.GetEngine(db.DefaultContext).Get(&Follow{UserID: userID, FollowID: followID})
+	return has
+}
+
+// FollowUser marks someone be another's follower.
+func FollowUser(userID, followID int64) (err error) {
+	if userID == followID || IsFollowing(userID, followID) {
+		return nil
+	}
+
+	sess := db.NewSession(db.DefaultContext)
+	defer sess.Close()
+	if err = sess.Begin(); err != nil {
+		return err
+	}
+
+	if _, err = sess.Insert(&Follow{UserID: userID, FollowID: followID}); err != nil {
+		return err
+	}
+
+	if _, err = sess.Exec("UPDATE `user` SET num_followers = num_followers + 1 WHERE id = ?", followID); err != nil {
+		return err
+	}
+
+	if _, err = sess.Exec("UPDATE `user` SET num_following = num_following + 1 WHERE id = ?", userID); err != nil {
+		return err
+	}
+	return sess.Commit()
+}
+
+// UnfollowUser unmarks someone as another's follower.
+func UnfollowUser(userID, followID int64) (err error) {
+	if userID == followID || !IsFollowing(userID, followID) {
+		return nil
+	}
+
+	sess := db.NewSession(db.DefaultContext)
+	defer sess.Close()
+	if err = sess.Begin(); err != nil {
+		return err
+	}
+
+	if _, err = sess.Delete(&Follow{UserID: userID, FollowID: followID}); err != nil {
+		return err
+	}
+
+	if _, err = sess.Exec("UPDATE `user` SET num_followers = num_followers - 1 WHERE id = ?", followID); err != nil {
+		return err
+	}
+
+	if _, err = sess.Exec("UPDATE `user` SET num_following = num_following - 1 WHERE id = ?", userID); err != nil {
+		return err
+	}
+	return sess.Commit()
+}