import Foundation
#if canImport(FoundationNetworking)
import FoundationNetworking
#endif

struct GatewayClient {
    let gatewayURL: URL
    let ws: URLSessionWebSocketTask

    init(gatewayURL: URL) {
        self.gatewayURL = gatewayURL
        ws = URLSession.shared.webSocketTask(with: gatewayURL.appending(component: "?v=10&encoding=json"))
    }

    func openConnection() {
        listen()
        ws.resume()
        RunLoop.current.run()
    }

    func listen() {
        ws.receive { result in
            defer { listen() }
            do {
                if case .failure(let err) = result { throw err }
                guard case .success(let message) = result else { return }
                guard case .string(let str) = message else { throw GatewayError.invalidMessage }
                let json = JSONDecoder()
                let gwMessage = try json.decode(GatewayMessage.self, from: Data(str.utf8))
                switch gwMessage.d {
                    case .hello(let hello):
                        dump(hello)
                    case .none:
                        return
                }
            } catch {
                print(error)
            }
        }
    }

}

public enum GatewayError: Error {
    case invalidMessage
    case invalidOpcode
}