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

class GatewayClient {
    let ws: URLSessionWebSocketTask
    var sequenceNum: Int? = nil

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

    func openConnection() async throws {
        ws.resume()
        guard case .hello(let helloMessage) = try await getMessage().d else { throw GatewayError.mismatchedOpcode }
        dump(helloMessage)
        Timer.scheduledTimer(withTimeInterval: (helloMessage.heartbeat_interval / 1000.0), repeats: true) {
            
        }
    }

    func getMessage() async throws -> GatewayMessage {
        let wsMessage = try await ws.receive()
        guard case .string(let str) = wsMessage else { throw GatewayError.invalidMessage }
        let json = JSONDecoder()
        let gwMessage = try json.decode(GatewayMessage.self, from: Data(str.utf8))
        sequenceNum = gwMessage.s ?? sequenceNum
        return gwMessage
    }

}

public enum GatewayError: Error {
    case invalidMessage
    case invalidOpcode
    case mismatchedOpcode
}