As API, I provide the possibility to fetch the jackpot rounds data

[melpadden]

The API should be a simple https://expressjs.com/ application. For this task, the following endpoint should be added:

GET /rounds

That returns a paginated list of Round entities with the following properties:

• round_id
• plays_num
• jackpot_amount
• winner_account_hash
• winner_public_key
• ended_at

The jackpot data should be calculated over the plays table using a query like the following one which should be provided as getRounds(offset, limit) function in the Round repository:

select 
    p.round_id, 
    w.plays_num, 
    p.prize_amount as jackpot_amount, 
    p.player_account_hash as winner_account_hash, 
    p.timestamp as ended_at 
from plays p
join (
    select max(play_id) as play_id, count(*) as plays_num
    from plays 
    group by round_id
) w on w.play_id = p.play_id
order by p.round_id desc;

The winner_public_key should be deanonimized from the winner_account_hash in the API handler using CSPR.cloud Account API. Let’s implement it as a utility addPublicKeys(data, accountHashProperty, publicKeyProperty) because we’ll reuse it for three endpoints.