oath-exchange.swift

public func exchange(code: String, handler: TraktOAuthCompletionHandler) -> Void
{
    guard let exchangeURL = URL(string: "https://api.trakt.tv/oauth/token") else
    {
        return
    }

    let message = OAuthCodeMessageRequest(code: code)

    guard let bodyData = try? self.encoder.encode(message) else
    {
        return
    }

    var request = URLRequest(url: exchangeURL)

    request.addValue("application/json", forHTTPHeaderField: "Content-Type")
    request.httpMethod = "POST"
    request.httpBody = bodyData

    self.processTokenRequest(request, handler: handler)
}

private func processTokenRequest(_ request: URLRequest, handler: TraktOAuthCompletionHandler) -> Void
{
    self.processRequest(request) { (result: HttpResult) -> Void in
        switch result
        {
            case .success(let data, _):
                if let tokenResponse = try? self.decoder.decode(OAuthTokenResponse.self, from: data)
                {
                    self.accessToken = tokenResponse.accessToken
                    self.refreshToken = tokenResponse.refreshToken

                    handler(true, nil)
                }
                else
                {
                    handler(false, TraktError.preconditionFailed)
                }

            case .requestError(let code, let message):
                #if targetEnvironment(simulator)
                    print(message)
                #endif

                let error = TraktError(httpCode: code)
                handler(false, error)

            case .connectionError:
                handler(false, TraktError.serverIsDown)
        }
    }
}