verifies apple app store receipt using vapor

ReceiptController.swift

//
//  ReceiptController.swift
//  App
//
//  Created by Justin Anderson on 3/2/19.
//

import Foundation
import Vapor

fileprivate enum Website: String {
    case reciptSandbox = "https://sandbox.itunes.apple.com/verifyReceipt"
    case recipt = "https://buy.itunes.apple.com/verifyReceipt"
    
    var url: URL {
        return URL(string: self.rawValue)!
    }
}

final class ReceiptController {
    
    private static var appleJsonDecoder: JSONDecoder = {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss 'Etc/'zzz"
        let jsonDecoder = JSONDecoder()
        jsonDecoder.dataDecodingStrategy = .base64
        jsonDecoder.dateDecodingStrategy = .formatted(dateFormatter)
        return jsonDecoder
    }()
    
    func verify(request: Request, receipt: ReceiptData) throws -> Future<AppleReceiptResponse> {
        
        let website: Website = receipt.environment == .production ? .recipt : .reciptSandbox
        let userAgent = UserAgentUtilites.userAgent(from: request)

        let httpHeaders = HTTPHeaders([.contentType : "application/json"])
        
        return try request.client().post(website.url, headers: httpHeaders) { (request) in
            let appleRequest = ReceiptRequest(data: receipt.data)
            try request.content.encode(json: appleRequest)
        }.map { (receiptResponse) in
            guard let body = receiptResponse.http.body.data else {
                throw Abort(.failedDependency)
            }
            return try ReceiptController.appleJsonDecoder.decode(AppleReceiptResponse.self, from: body)
        }
    }
}