Bowling code chanllenge

The app is for the code challenge

Stack

• Ruby version 2.7.1
• Ruby on Rails 6.1
• Redis

Run locally

1. Make sure the required Ruby version is installed.
2. Make sure Redis server is installed and running.
3. Run bundle install to install gems.
4. Run rspec

Functionality

The app's API has three endpoints:

1. GET / - returns the game status
2. POST /start - starts a new game
3. POST /deliveries - adds a delivery to the current frame. The endpoint receives pins number in pins parameter.

Game data storage

The app stores game data in json object. Default storage is Redis, but it is possible to configure any kind of storage and pass it to game as dependency. Example:

{
  "frames": [[5,5],[0,10],[10,0],...],
  "active": true,
  "bonus": [],
  "current_frame": 5
}

Properties:

• frames - stores array of frames with deliveries
• active - shows if game is started
• bonus - stores bonus deliveries in case of last frame is a spare or a strike
• current_frame - current frame index

Main logic

1. When a game is started a new game data object is created and persisted in storage.
2. While new deliveries are being added the app distributes deliveries between frames. If it is the last frame and not a spare or a strike the game is finished and active property bocomes false. If the last frame is a spare or a strike the app puts pins into bonus property.
3. When the game status is requested scores for each frames are calculated and included into game representation. If a frame score is not possible to calculate (for example there are not next deliveries for a strike frame), then the score for the frame is null

Example of a game status response

{
  "status": "success",
  "data": {
    "frames": [[0, 10], [5, 5], [1, 1], [2, 2], [8, 2], [0, 0], [5, 2], [4, 0], [6, 1], [10, 0]],
    "active": false,
    "bonus": [10, 5],
    "score": [15, 26, 28, 32, 42, 42, 49, 53, 60, 85]
  }
}

Having data for each frame and scores allows to display a game details on a frontend.

Features

1. Modular structure.
2. Isolated logic layer with various service objects within game context:

• Commands::BuildGameSchema - build default game schema on start
• Commands::CalculateScore - calculates game scores according to frames
• Commands::CreateDelivery - add delivery to the curren game, distributes deliveries
• Repositories::GameRepository - communicates with storage object
• Presenters::GamePresenter - decorates game status before sending in response.

3. Exchangeable storage to store game data is passed to repository as dependency.
4. Custom exception objects with configurable messages.
5. Self-explanatory code and test coverage with integration and unit tests.