W3911 Sudoku Server

Within these castle walls be forged Mavens of Computer Science ...

— Merlin, The Coder

Background A Sudoku board is made up of nine boxes. Boxes (container for nine cells) are listed from top-to-bottom, left-to-right indexed from zero. Cells are listed from top-to-bottom, left-to-right, indexed from zero. All valid payloads and responses must use well-formed JSON. “cells” is returned as follows: “cells”: [[<nine values from top-left>], [<nine values from top-middle>], …]

End Points

POST /games?difficulty=<difficulty>

   * Action: Creates a new game and associated board
   * Parameters:
     * difficulty: easy|medium|hard|hell
   * Payload: None
   * Response: Id uniquely identifying a game
   * Status code: 201 Created

GET /games/<id>/cells

   * Action: None
   * Payload: None
   * Response: cells
   * Status code: 200 OK

PUT /games/<id>/cells/<boxIndex>/<cellIndex>

   * Action: Place specified value at in game at boxIndex, cellIndex
   * Payload: value (null for removing value)
   * Response: Nothing
   * Status: 204 No Content

import Foundation                                                                                                                                                                                                                           
import FoundationNetworking                                                                                                                                                                                                                 
 
// Form the request                                                                                                                                                                                                                                           
var request = URLRequest(url: URL(string: "https://language-server.codermerlin.com/now")!)                                                                                                                                                  
request.httpMethod = "GET"

// Execute synchronously (uses extension in code below)                                                                                                                                                                                                                 
let (data, response, error) = URLSession.shared.syncRequest(with: request)
if let data = data,                                                                                                                                                                          
   let string = String(data: data, encoding: .utf8) {                                                                                                                                     
   print(string)                                                                                                                                                                            
} else if let error = error {
    print("Error: \(error)")
} else {
    print("An unexpected error occurred.")
}

// Reference: https://stackoverflow.com/questions/26784315/can-i-somehow-do-a-synchronous-http-request-via-nsurlsession-in-swift
extension URLSession {
   func syncRequest(with request: URLRequest) -> (Data?, URLResponse?, Error?) {
      var data: Data?
      var response: URLResponse?
      var error: Error?
      
      let dispatchGroup = DispatchGroup()
      let task = dataTask(with: request) {
         data = $0
         response = $1
         error = $2
         dispatchGroup.leave()
      }
      dispatchGroup.enter()
      task.resume()
      dispatchGroup.wait()
      
      return (data, response, error)
   }  
}