//
//  SDLUDPHoleActor 2.swift
//  punchnet
//
//  Created by 安礼成 on 2026/1/28.
//


//
//  SDLanServer.swift
//  Tun
//
//  Created by 安礼成 on 2024/1/31.
//

import Foundation
import NIOCore
import NIOPosix
import SwiftProtobuf

// 处理和sn-server服务器之间的通讯
final class SDLUDPHole: ChannelInboundHandler {
    typealias InboundIn = AddressedEnvelope<ByteBuffer>
    
    private let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
    private var channel: Channel?
    
    public let signalStream: AsyncStream<(SocketAddress, SDLHoleSignal)>
    private let signalContinuation: AsyncStream<(SocketAddress, SDLHoleSignal)>.Continuation
    
    public let dataStream: AsyncStream<SDLData>
    private let dataContinuation: AsyncStream<SDLData>.Continuation
    
    public let eventStream: AsyncStream<HoleEvent>
    private let eventContinuation: AsyncStream<HoleEvent>.Continuation

    private let logger: SDLLogger
    
    enum HoleEvent {
        case ready
        case closed
    }
    
    // 启动函数
    init(logger: SDLLogger) throws {
        self.logger = logger
        (self.signalStream, self.signalContinuation) = AsyncStream.makeStream(of: (SocketAddress, SDLHoleSignal).self, bufferingPolicy: .unbounded)
        (self.dataStream, self.dataContinuation) = AsyncStream.makeStream(of: SDLData.self, bufferingPolicy: .unbounded)
        (self.eventStream, self.eventContinuation) = AsyncStream.makeStream(of: HoleEvent.self, bufferingPolicy: .unbounded)
    }
    
    func start() throws {
        let bootstrap = DatagramBootstrap(group: group)
            .channelOption(ChannelOptions.socketOption(.so_reuseaddr), value: 1)
            .channelInitializer { channel in
                channel.pipeline.addHandler(self)
            }
        
        self.channel = try bootstrap.bind(host: "0.0.0.0", port: 0).wait()
        self.logger.log("[UDPHole] started", level: .debug)
    }
    
    // --MARK: ChannelInboundHandler delegate
    
    func channelActive(context: ChannelHandlerContext) {
        self.eventContinuation.yield(.ready)
    }
    
    func channelRead(context: ChannelHandlerContext, data: NIOAny) {
        let envelope = unwrapInboundIn(data)
        
        var buffer = envelope.data
        let remoteAddress = envelope.remoteAddress
        do {
            if let message = try decode(buffer: &buffer) {
                switch message {
                case .data(let data):
                    self.dataContinuation.yield(data)
                case .signal(let signal):
                    self.signalContinuation.yield((remoteAddress, signal))
                }
            } else {
                self.logger.log("[SDLUDPHole] decode message, get null", level: .warning)
            }
        } catch let err {
            self.logger.log("[SDLUDPHole] decode message, get error: \(err)", level: .warning)
        }
    }
    
    func channelInactive(context: ChannelHandlerContext) {
        self.signalContinuation.finish()
        self.dataContinuation.finish()
        self.eventContinuation.yield(.closed)
        self.eventContinuation.finish()
        
        context.close(promise: nil)
    }
    
    func errorCaught(context: ChannelHandlerContext, error: any Error) {
        context.close(promise: nil)
    }
    
    func getLocalAddress() -> SocketAddress? {
        return self.channel?.localAddress
    }
    
    // MARK: 处理写入逻辑
    func send(type: SDLPacketType, data: Data, remoteAddress: SocketAddress) {
        guard let channel = self.channel else {
            return
        }
        
        var buffer = channel.allocator.buffer(capacity: data.count + 1)
        buffer.writeBytes([type.rawValue])
        buffer.writeBytes(data)
        
        let envelope = AddressedEnvelope<ByteBuffer>(remoteAddress: remoteAddress, data: buffer)
        channel.eventLoop.execute {
            channel.writeAndFlush(envelope, promise: nil)
        }
    }
    
    // --MARK: 编解码器
    private func decode(buffer: inout ByteBuffer) throws -> SDLHoleMessage? {
        guard let type = buffer.readInteger(as: UInt8.self),
              let packetType = SDLPacketType(rawValue: type),
              let bytes = buffer.readBytes(length: buffer.readableBytes) else {
            return nil
        }
        
        switch packetType {
        case .data:
            let dataPacket = try SDLData(serializedBytes: bytes)
            return .data(dataPacket)
        case .register:
            let registerPacket = try SDLRegister(serializedBytes: bytes)
            return .signal(.register(registerPacket))
        case .registerAck:
            let registerAck = try SDLRegisterAck(serializedBytes: bytes)
            return .signal(.registerAck(registerAck))
        case .stunProbeReply:
            let stunProbeReply = try SDLStunProbeReply(serializedBytes: bytes)
            return .signal(.stunProbeReply(stunProbeReply))
        case .registerSuperAck:
            guard let bytes = buffer.readBytes(length: buffer.readableBytes),
                  let registerSuperAck = try? SDLRegisterSuperAck(serializedBytes: bytes) else {
                return nil
            }
            return .signal(.registerSuperAck(registerSuperAck))
        case .registerSuperNak:
            guard let bytes = buffer.readBytes(length: buffer.readableBytes),
                  let registerSuperNak = try? SDLRegisterSuperNak(serializedBytes: bytes) else {
                return nil
            }
            return .signal(.registerSuperNak(registerSuperNak))
            
        case .peerInfo:
            guard let bytes = buffer.readBytes(length: buffer.readableBytes),
                  let peerInfo = try? SDLPeerInfo(serializedBytes: bytes) else {
                return nil
            }
            
            return .signal(.peerInfo(peerInfo))
        case .event:
            guard let eventVal = buffer.readInteger(as: UInt8.self),
                  let event = SDLEventType(rawValue: eventVal),
                  let bytes = buffer.readBytes(length: buffer.readableBytes) else {
                return nil
            }
            
            switch event {
            case .natChanged:
                guard let natChangedEvent = try? SDLNatChangedEvent(serializedBytes: bytes) else {
                    return nil
                }
                return .signal(.event(.natChanged(natChangedEvent)))
            case .sendRegister:
                guard let sendRegisterEvent = try? SDLSendRegisterEvent(serializedBytes: bytes) else {
                    return nil
                }
                return .signal(.event(.sendRegister(sendRegisterEvent)))
            case .networkShutdown:
                guard let networkShutdownEvent = try? SDLNetworkShutdownEvent(serializedBytes: bytes) else {
                    return nil
                }
                return .signal(.event(.networkShutdown(networkShutdownEvent)))
            }
            
        default:
            return nil
        }
    }
    
    deinit {
        try? self.group.syncShutdownGracefully()
        self.eventContinuation.finish()
        self.channel?.close(promise: nil)
    }
    
}