response.swift

class Response {
    
    typealias Headers = [String : String]
    
    enum ResponseError: Error {
        case badInput
        case noData
        case noResponseReceived
        case unacceptableResponse(Int)
    }
    
    enum Result<T> {
        case success(T)
        case error(Error)
    }
    
    let response: HTTPURLResponse?
    let error: Error?
    let data: Data?
    
    init(data: Data?, response: HTTPURLResponse?, error: Error?) {
        self.data = data
        self.error = error
        self.response = response
    }
    
    var jsonResult: Result<Any> {
        let e = errorOccurred()
        guard e == nil else { return .error(e!) }
        guard let _data = data else { return .error(ResponseError.noData) }
        do {
            let json = try JSONSerialization.jsonObject(with: _data, options: [])
            return Result<Any>.success(json)
        } catch let parsingError {
            return .error(parsingError)
        }
    }
    
    var dataResult: Result<Data> {
        if let e = errorOccurred() { return .error(e) }
        guard let _data = data else { return .error(ResponseError.noData) }
        return Result<Data>.success(_data)
    }
    
    var headersResult: Result<Headers> {
        if let e = errorOccurred() { return .error(e) }
        var headers = Headers()
        for (key, value) in response!.allHeaderFields {
            headers["\(key)"] = "\(value)"
        }
        return Result<Headers>.success(headers)
    }
    
    private func errorOccurred() -> Error? {
        guard error == nil else { return error! }
        guard let r = response else { return ResponseError.noResponseReceived }
        let statusCode = r.statusCode
        guard Array(200...220).contains(statusCode) else { return ResponseError.unacceptableResponse(statusCode) }
        return nil
    }
}