1 files changed, 85 insertions, 0 deletions
diff --git a/models/user/follow.go b/models/user/follow.go
new file mode 100644
index 0000000..9c3283b
--- /dev/null
+++ b/models/user/follow.go
@@ -0,0 +1,85 @@
+// Copyright 2017 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package user
+
+import (
+	"context"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/timeutil"
+)
+
+// Follow represents relations of user and their 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(ctx context.Context, userID, followID int64) bool {
+	has, _ := db.GetEngine(ctx).Get(&Follow{UserID: userID, FollowID: followID})
+	return has
+}
+
+// FollowUser marks someone be another's follower.
+func FollowUser(ctx context.Context, userID, followID int64) (err error) {
+	if userID == followID || IsFollowing(ctx, userID, followID) {
+		return nil
+	}
+
+	if IsBlocked(ctx, userID, followID) || IsBlocked(ctx, followID, userID) {
+		return ErrBlockedByUser
+	}
+
+	ctx, committer, err := db.TxContext(ctx)
+	if err != nil {
+		return err
+	}
+	defer committer.Close()
+
+	if err = db.Insert(ctx, &Follow{UserID: userID, FollowID: followID}); err != nil {
+		return err
+	}
+
+	if _, err = db.Exec(ctx, "UPDATE `user` SET num_followers = num_followers + 1 WHERE id = ?", followID); err != nil {
+		return err
+	}
+
+	if _, err = db.Exec(ctx, "UPDATE `user` SET num_following = num_following + 1 WHERE id = ?", userID); err != nil {
+		return err
+	}
+	return committer.Commit()
+}
+
+// UnfollowUser unmarks someone as another's follower.
+func UnfollowUser(ctx context.Context, userID, followID int64) (err error) {
+	if userID == followID || !IsFollowing(ctx, userID, followID) {
+		return nil
+	}
+
+	ctx, committer, err := db.TxContext(ctx)
+	if err != nil {
+		return err
+	}
+	defer committer.Close()
+
+	if _, err = db.DeleteByBean(ctx, &Follow{UserID: userID, FollowID: followID}); err != nil {
+		return err
+	}
+
+	if _, err = db.Exec(ctx, "UPDATE `user` SET num_followers = num_followers - 1 WHERE id = ?", followID); err != nil {
+		return err
+	}
+
+	if _, err = db.Exec(ctx, "UPDATE `user` SET num_following = num_following - 1 WHERE id = ?", userID); err != nil {
+		return err
+	}
+	return committer.Commit()
+}