Error Handling - HTTP Response

[puuurm]

1. 아직까지는 발견된 http 응답 코드가 200과 404이다. 200일 경우 디코딩한 결과를 반환하고, 이외의 경우 FailureResponse가 적절한 error를 반환한다. 향후 모든 응답 코드에 대해서 대응할 계획.

    private func request<T>(
        _ params: [String: String],
        before object: Storable?,
        baseURL: BaseURL,
        type: T.Type,
        completion: @escaping ((ResponseResult<T>) -> Void)) {

        guard let url = WeatherAPI.url(baseURL: baseURL, parameters: params) else { return }
        NetworkSpinner.on()
        session.dataTask(with: url) { [weak self] (data, response, _) in
            guard let httpResponse = response as? HTTPURLResponse, let `self` = self else { return }
            let result = self.processRequest(type, response: httpResponse, data: data)
            completion(result)
            self.imageCache.deleteImageForkeys(keys: object?.cacheKeys)
            NetworkSpinner.off()
        }.resume()

    }

    private func processRequest<T: Decodable>(
        _ type: T.Type,
        response: HTTPURLResponse,
        data: Data?
        ) -> ResponseResult<T> {

        let status = response.statusCode
        if status == Http.Success,
            let jsonData = data {
            return WeatherAPI.objectFromJSONData(type, data: jsonData)
        } else {
            return .failure(FailureResponse(statusCode: status).error)
        }

    }

struct FailureResponse {
    let statusCode: Int

    var error: HttpError {
        switch statusCode {
        case 404: return HttpError.notFound
        case 300...307: return HttpError.redirection
        case 400...417: return HttpError.clientError
        default: return HttpError.serverError
        }
    }

    enum HttpError: Error, LocalizedError {
        case redirection    // 3xx
        case clientError    // 4xx
        case notFound       // 404
        case serverError    // 5xx

        var errorDescription: String? {
            switch self {
            case .notFound: return "HTTP Not Found"
            case .redirection: return "redirection"
            case .clientError: return "Client Error"
            case .serverError: return "Server Error"
            }
        }
    }
}