//
//  PacketTunnelProvider.swift
//  punchnet
//
//  Created by 安礼成 on 2025/8/3.
//

import Foundation
import NetworkExtension

enum TunnelError: Error {
    case invalidConfiguration
    case invalidContext
}

class PacketTunnelProvider: NEPacketTunnelProvider {
    private lazy var contextBootstrap = SDLContextBootstrap(provider: self)
    
    override func startTunnel(options: [String: NSObject]?, completionHandler: @escaping (Error?) -> Void) {
        guard let options, let config = SDLConfiguration.parse(options: options) else {
            SDLLogger.fatal("[PacketTunnelProvider] startTunnel failed: invalid configuration", category: .app)
            completionHandler(TunnelError.invalidConfiguration)
            return
        }

        do {
            let rsaCipher = try CCRSACipher(keySize: 1024)
            self.contextBootstrap.start(config: config, rsaCipher: rsaCipher, completionHandler: completionHandler)
        } catch {
            SDLLogger.fatal("[PacketTunnelProvider] startTunnel failed: rsa cipher initialization failed: \(error)", category: .app)
            completionHandler(error)
        }
    }

    override func stopTunnel(with reason: NEProviderStopReason, completionHandler: @escaping () -> Void) {
        SDLLogger.fatal("[PacketTunnelProvider] stopTunnel requested, reason: \(reason.rawValue)", category: .app)
        self.contextBootstrap.stop(clearRuntimeConfiguration: true, completionHandler: completionHandler)
    }

    override func handleAppMessage(_ messageData: Data, completionHandler: ((Data?) -> Void)?) {
        // Add code here to handle the message.
        Task {
            do {
                let message = try AppRequest(serializedBytes: messageData)
                let replyData = try await self.handleAppRequest(message: message)
                completionHandler?(replyData)
            } catch let err {
                var reply = TunnelResponse()
                reply.code = 1
                reply.message = err.localizedDescription

                let errorReplyData = try? reply.serializedData()
                completionHandler?(errorReplyData)
            }
        }
    }

    override func sleep(completionHandler: @escaping () -> Void) {
        SDLLogger.fatal("[PacketTunnelProvider] sleep requested, will stop current context", category: .app)
        self.contextBootstrap.stop(clearRuntimeConfiguration: false) {
            SDLLogger.log("[PacketTunnelProvider] sleep", category: .app)
            completionHandler()
        }
    }

    override func wake() {
        SDLLogger.log("[PacketTunnelProvider] wake up!!!!!!!", category: .app)
        self.contextBootstrap.startCached { err in
            if let err {
                SDLLogger.fatal("[PacketTunnelProvider] wakeup start failed: \(err)", category: .app)
                SDLLogger.log("[PacketTunnelProvider] wakeup start failed: \(err.localizedDescription)", category: .app)
            } else {
                SDLLogger.log("[PacketTunnelProvider] wakeup and try start", category: .app)
            }
        }
    }

    private func handleAppRequest(message: AppRequest) async throws -> Data? {
        guard let contextActor = self.contextBootstrap.currentContextActor() else {
            throw TunnelError.invalidContext
        }
        
        switch message.command {
        case .changeExitNode(let changeExitNode):
            let exitNodeIp = changeExitNode.ip
            do {
                try await contextActor.updateExitNode(exitNodeIp: exitNodeIp)
                var reply = TunnelResponse()
                reply.code = 0
                reply.message = "操作成功"
                return try reply.serializedData()
                
            } catch let err {
                var reply = TunnelResponse()
                reply.code = 1
                reply.message = err.localizedDescription
                
                return try reply.serializedData()
            }
        case .none:
            var reply = TunnelResponse()
            reply.code = 1
            reply.message = "无效请求"
            return try reply.serializedData()
        }
    }

}