import Foundation

actor SDLSuperService {
    typealias MessageHandler = @Sendable (SDLQUICInboundMessage) async -> Void

    private let serverEndpoint: SDLConfiguration.ResolvedServerEndpoint
    private let port: UInt16
    private let onMessage: MessageHandler

    private var superClient: SDLSuperClient?
    private var monitorTask: Task<Void, Never>?

    init(serverEndpoint: SDLConfiguration.ResolvedServerEndpoint, port: UInt16 = 1443, onMessage: @escaping MessageHandler) {
        self.serverEndpoint = serverEndpoint
        self.port = port
        self.onMessage = onMessage
    }

    func start() {
        guard self.monitorTask == nil else {
            return
        }

        self.monitorTask = startMonitorTask(name: "superServiceMonitor") { [weak self] in
            guard let self else {
                throw CancellationError()
            }
            try await self.runOnce()
        }
    }

    func stop() async {
        let monitorTask = self.monitorTask
        self.monitorTask = nil

        let superClient = self.superClient
        self.superClient = nil

        monitorTask?.cancel()
        await superClient?.stop()

        if let monitorTask {
            await monitorTask.value
        }
    }

    func send(type: SDLPacketType, data: Data) async {
        await self.superClient?.send(type: type, data: data)
    }

    private func runOnce() async throws {
        let superClient = SDLSuperClient(serverEndpoint: self.serverEndpoint, port: self.port)
        self.superClient = superClient
        await superClient.start()

        do {
            try await withTaskCancellationHandler {
                try await self.run(superClient)
            } onCancel: {
                Task {
                    await superClient.stop()
                }
            }
            
            await self.cleanup(superClient)
        } catch {
            await self.cleanup(superClient)
            throw error
        }
    }

    private func run(_ superClient: SDLSuperClient) async throws {
        try await Task.sleep(for: .seconds(0.5))
        try Task.checkCancellation()

        SDLLogger.log("[SDLSuperService] start super client: \(self.serverEndpoint.ip)")

        try await withThrowingTaskGroup(of: Void.self) { group in
            defer {
                group.cancelAll()
            }

            let onMessage = self.onMessage
            group.addTask {
                for try await message in superClient.messageStream {
                    try Task.checkCancellation()
                    await onMessage(message)
                }
            }

            group.addTask {
                while true {
                    try await Task.sleep(for: .seconds(5))
                    try Task.checkCancellation()
                    await superClient.send(type: .ping, data: Data())
                }
            }

            _ = try await group.next()
        }
    }

    private func cleanup(_ superClient: SDLSuperClient) async {
        await superClient.stop()

        if self.superClient === superClient {
            self.superClient = nil
        }

        SDLLogger.log("[SDLSuperService] cleanup")
    }
}