= UseCase02- Manages Clients
** Initiating actor: Admin **
== Description
The Admin moderates Petify by blocking a client account when the client posts disrespectful/abusive reviews, or when the client receives extremely bad reviews that indicate harmful or unacceptable behavior. The Admin reviews evidence (review comments, ratings) and then blocks the client. The system records the decision (who/when/why), marks the user as blocked, and creates a notification for the blocked user.
== Scenario
1. Admin goes to the reviews page that are grouped by client.
{{{#!comment
SELECT
  u.user_id,
  u.username,
  u.email,
  u.is_blocked,
  u.blocked_reason,
  u.blocked_at,
  u.blocked_by,

  COUNT(ur.review_id) AS received_review_count,
  COALESCE(AVG(r.rating), 0)::numeric(10,2) AS avg_received_rating,

  (SELECT COUNT(*)
   FROM reviews rw
   WHERE rw.reviewer_id = u.user_id) AS written_review_count

FROM users u
JOIN clients c ON c.user_id = u.user_id
LEFT JOIN user_reviews ur ON ur.target_user_id = u.user_id
LEFT JOIN reviews r ON r.review_id = ur.review_id
GROUP BY
  u.user_id, u.username, u.email,
  u.is_blocked, u.blocked_reason, u.blocked_at, u.blocked_by
ORDER BY
  (COUNT(ur.review_id) = 0) ASC,
  avg_received_rating ASC,
  received_review_count DESC,
  u.username;

}}}
2. Admin clicks on a client so he can see all the reviews for them.
{{{#!comment
SELECT
  r.review_id,
  r.reviewer_id,
  ru.username AS reviewer_username,
  r.rating,
  r.comment,
  r.created_at
FROM user_reviews ur
JOIN reviews r ON r.review_id = ur.review_id
JOIN users ru ON ru.user_id = r.reviewer_id
WHERE ur.target_user_id = $1        
ORDER BY r.created_at DESC;
}}} 
3. Admin clicks "Block client" and enters the reason.
{{{#!comment
BEGIN;

SELECT u.user_id, u.email, u.is_blocked
FROM users u
JOIN clients c ON c.user_id = u.user_id
WHERE u.user_id = $1
FOR UPDATE;

UPDATE users
SET
  is_blocked = TRUE,
  blocked_reason = $2,       
  blocked_by     = $4,     
  blocked_at     = NOW()
WHERE user_id = $1;

INSERT INTO notifications (user_id, type, message, is_read, created_at)
VALUES (
  $1,
  'ACCOUNT_BLOCKED',
  CONCAT('Your account has been blocked. Reason: ', $2, '. ', COALESCE($3, '')),
  FALSE,
  NOW()
);

COMMIT;
}}}
4. The system sends and email to the client.
{{{#!comment
SELECT
  email,
  username,
  blocked_reason,
  blocked_at
FROM users
WHERE user_id = $1;
}}}