Minesweeper-API

Minesweeper game written as a simple REST API using Golang.

It uses Redis as database although it is designed to easily swap out to other database vendors (e.g., postgresql, sqllite)

It provides the ability to easily change underlying http routing framework (e.g., switch from Chi to Mux or viceversa)

The game engine has been written by adapting the classical Flood Fill algorithm.

Technical highlights

• Follows clean architecture principles
• Independent of http framework and data repository technology
• Use Docker
• Deployed in Kubernetes AKS (deployment/k8s-deployment.yaml)

Running the application locally

There are two ways to run the API server locally.

1. Running the app using docker-compose (recommended).
2. Build and running locally.

Option 1. Running using docker-compose

Starting the server

docker-compose up

Stopping the server

docker-compose down --remove-orphans

Option 2. Building and running locally

Pre-requisites:

• If Golang is not installed, click here for installation instructions
• Provision a local Redis instance.

Build

go build -o minesweeper-api

Run

go run .

API Endpoints

Create User

Creates a user for playing. The user should be created before starting a new game.

POST http://localhost:8080/users

Code	Description
201	User created
400	Bad request
500	Server error

Body

{
	"username": "player1"
}

Example Request

curl --location --request POST 'http://localhost:8080/users' \
--data-raw '{
	"username": "player1"
}'

Example Response

{
    "username": "player1",
    "createdAt": "2020-06-11T13:03:30.917771715-03:00"
}

Start/Restart Game

Starts a new game or restart a game

PUT http://localhost:8080/games

Code	Description
201	Game created/restarted
400	Bad request
500	Server error

Body

{
	"name": "game1",
	"username": "player1",
	"rows": 4,
	"cols": 4,
	"mines": 5
}

Example Request

curl --location --request PUT 'http://localhost:8080/games' \
--data-raw '{
	"name": "game1",
	"username": "player1",
	"rows": 4,
	"cols": 4,
	"mines": 5
}'

Example Response

{
    "name": "game1",
    "username": "player1",
    "rows": 4,
    "cols": 4,
    "mines": 5,
    "status": "ready",
    "board": [
        "RU1FRUVNRQ==",
        "RUVFRUVFRQ==",
        "RUVFRUVFRQ==",
        "RUVFRUVFTQ=="
    ],
    "clicks": 0,
    "created_at": "2020-06-11T13:05:54.943472481-03:00",
    "started_at": "0001-01-01T00:00:00Z",
    "time_spent": 0
}

Click

Click or flag a cell in the game board. Use the kind field to indicate either click or flag

POST http://localhost:8080/games/game1/player1/click

Code	Description
200	Successfully applied click on cell
400	Bad request (wrong click kind, already won / lost)
404	Cell not found
500	Server error

Body

{
	"row": 1,
	"col": 0,
	"kind": "click"
}

Example Request

curl --location --request POST 'http://localhost:8080/games/game1/player1/click' \ --data-raw '{ "row": 1, "col": 0, "kind": "click" }'

Example Response

{
    "name": "game1",
    "username": "player1",
    "rows": 7,
    "cols": 7,
    "mines": 5,
    "status": "in_progress",
    "board": [
        "RU1FRUVNRQ==",
        "MUVFRUVFRQ==",
        "RUVFRUVFRQ==",
        "RUVFRUVFTQ=="
    ],
    "clicks": 1,
    "created_at": "2020-06-11T13:05:54.943472481-03:00",
    "started_at": "2020-06-11T13:06:30.513938447-03:00",
    "time_spent": 700
}

Get the Game Board

Get the board in JSON format.

GET http://localhost:8080/games/game1/player1/board

Code	Description
200	OK
404	User / Game not found
500	Server error

Example Request

curl --location --request GET 'http://localhost:8080/games/game1/player1/board'

Example Response

[
    [
        "E",
        "M",
        "E",
        "E"
    ],
	... omitted some data to shorten
    [
        "E",
        "E",
        "E",
        "E"
    ]
]

Note! Using Postman? You can pretty render the response using the Postman Visualize feature. Follow this steps to render the game board in Postman:

1. Add this code to the Tests script for the request.
2. Click Send to run the request.
3. Click the Visualize tab to render the game board.

Game engine logic and how to interpret the board

The game board is part of the Game structure types/game.go. This board is a 2-Dimensional array of bytes an its data is coded as follows:

Unrevealed values

* M -----> Veiled mine 
* E -----> Veiled Empty 

By clicking on a cell (using the click endpoint) it will reveal the corresponding cell.

Revealed values

* X -----> Exploded mine
* B -----> Revealed Blank
* Digit -> Revealed with adjacent mine count

Logic

• When a mine ('M') is clicked, it changes to ('X') and the game is over.
• When a Veiled Empty ('E') cell is clicked, it can either, transition to Revealed blank ('B') or to a digit (1 to 8) indicating the number of adjacent mines.
• When a cell transition to 'B' it triggers a recursive reveal of adjacent cells.
• Flagging a cell will change any unrevealed value to its corresponding lowercase letter value.