-- name: is-user-following-for-another^
SELECT CASE
           WHEN following_id IS NULL THEN
               FALSE
           ELSE
               TRUE
           END AS is_following
FROM users u
         LEFT OUTER JOIN followers_to_followings f ON u.id = f.follower_id
    AND f.following_id = (
        SELECT id
        FROM users
        WHERE username = :following_username)
WHERE u.username = :follower_username
LIMIT 1;


-- name: subscribe-user-to-another!
INSERT INTO followers_to_followings (follower_id, following_id)
VALUES ((
            SELECT id
            FROM users
            WHERE username = :follower_username), (
            SELECT id
            FROM users
            WHERE username = :following_username));

-- name: unsubscribe-user-from-another!
DELETE
FROM followers_to_followings
WHERE follower_id = (
    SELECT id
    FROM users
    WHERE username = :follower_username)
  AND following_id = (
    SELECT id
    FROM users
    WHERE username = :following_username);