LeadKit/Sources/Extensions/Alamofire/DataRequest+Extensions.swift

//
//  Copyright (c) 2017 Touch Instinct
//
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//
//  The above copyright notice and this permission notice shall be included in
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//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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//  THE SOFTWARE.
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import Alamofire
import RxSwift
import RxAlamofire

typealias ServerResponse = (HTTPURLResponse, Data)

public extension Reactive where Base: DataRequest {

    /// Method that serializes response into target object
    ///
    /// - Parameter mappingQueue: The dispatch queue to use for mapping
    /// - Parameter decoder: JSONDecoder used to decode a decodable type
    /// - Returns: Observable with HTTP URL Response and target object
    func apiResponse<T: Decodable>(mappingQueue: DispatchQueue = .global(), decoder: JSONDecoder)
        -> Observable<SessionManager.ModelResponse<T>> {

            response(onQueue: mappingQueue)
                .tryMapResult { response, data in
                    (response, try decoder.decode(T.self, from: data))
                }
                .catchAsRequestError(with: self.base)
    }

    /// Method that serializes response into target object
    ///
    /// - Parameter mappingQueue: The dispatch queue to use for mapping
    /// - Returns: Observable with HTTP URL Response and target object
    func observableApiResponse<T: ObservableMappable>(mappingQueue: DispatchQueue = .global(), decoder: JSONDecoder)
        -> Observable<SessionManager.ModelResponse<T>> {

            response(onQueue: mappingQueue)
                .tryMapObservableResult { response, value in
                    let json = try JSONSerialization.jsonObject(with: value, options: [])
                    return T.create(from: json, with: decoder)
                        .map { (response, $0) }
                }
                .catchAsRequestError(with: self.base)
    }

    /// Method that serializes response into data
    ///
    /// - Parameter mappingQueue: The dispatch queue to use for mapping
    /// - Returns: Observable with HTTP URL Response and data
    func dataApiResponse(mappingQueue: DispatchQueue) -> Observable<SessionManager.DataResponse> {
        response(onQueue: mappingQueue)
            .map { $0 as SessionManager.DataResponse }
            .catchAsRequestError(with: self.base)
    }

    private func response(onQueue queue: DispatchQueue) -> Observable<(HTTPURLResponse, Data)> {
        responseResult(queue: queue, responseSerializer: DataResponseSerializer())
    }
}

public extension ObservableType where Element == DataRequest {

    /// Method that validates status codes and catch network errors
    ///
    /// - Parameter statusCodes: set of status codes to validate
    /// - Returns: Observable on self
    func validate(statusCodes: Set<Int>, url: String? = nil) -> Observable<Element> {
        map { $0.validate(statusCode: statusCodes) }
            .catchAsRequestError(url: url)
    }
}

private extension ObservableType where Element == ServerResponse {

    func tryMapResult<R>(_ transform: @escaping (Element) throws -> R) -> Observable<R> {
        map {
            do {
                return try transform($0)
            } catch {
                throw RequestError.mapping(error: error,
                                           response: $0.1,
                                           url: $0.0.url?.absoluteString)
            }
        }
    }

    func tryMapObservableResult<R>(_ transform: @escaping (Element) throws -> Observable<R>) -> Observable<R> {
        flatMap { response, result -> Observable<R> in
            do {
                return try transform((response, result))
                    .catch {
                        throw RequestError.mapping(error: $0,
                                                   response: result,
                                                   url: response.url?.absoluteString)
                    }
            } catch {
                throw RequestError.mapping(error: error,
                                           response: result,
                                           url: response.url?.absoluteString)
            }
        }
    }
}

private extension ObservableType {

    func catchAsRequestError(with request: DataRequest? = nil,
                             url: String? = nil) -> Observable<Element> {
        self.catch { error in
            let resultError: RequestError
            let response = request?.data

            switch error {
            case let requestError as RequestError:
                resultError = requestError

            case let urlError as URLError:
                switch urlError.code {
                case .notConnectedToInternet:
                    resultError = .noConnection(url: url)

                default:
                    resultError = .network(error: urlError, response: response, url: url)
                }

            case let afError as AFError:
                switch afError {
                case let .sessionTaskFailed(error):
                    switch error {
                    case let urlError as URLError where urlError.code == .notConnectedToInternet:
                        resultError = .noConnection(url: url)

                    default:
                        resultError = .network(error: error, response: response, url: url)
                    }

                case .responseSerializationFailed, .responseValidationFailed:
                    resultError = .invalidResponse(error: afError, response: response, url: url)

                default:
                    resultError = .network(error: afError, response: response, url: url)
                }

            default:
                resultError = .network(error: error, response: response, url: url)
            }

            throw resultError
        }
    }
}