//
//  NetworkInterface.swift
//  Tun
//
//  Created by 安礼成 on 2024/1/19.
//

import Foundation

struct NetworkInterface {
    let name: String
    let ip: String
    let netmask: String
}

struct NetworkInterfaceManager {
    /**
    获取网卡信息, (let name: String let ip: String let netmask: String)
     */
    public static func getInterfaces() -> [NetworkInterface] {
        var interfaces: [NetworkInterface] = []
        
        // Get list of all interfaces on the local machine:
        var ifaddr : UnsafeMutablePointer<ifaddrs>? = nil
        if getifaddrs(&ifaddr) == 0 {
            
            // For each interface ...
            var ptr = ifaddr
            while( ptr != nil) {
                
                let flags = Int32(ptr!.pointee.ifa_flags)
                var addr = ptr!.pointee.ifa_addr.pointee
                
                // Check for running IPv4, IPv6 interfaces. Skip the loopback interface.
                if (flags & (IFF_UP|IFF_RUNNING|IFF_LOOPBACK)) == (IFF_UP|IFF_RUNNING) {
                    if addr.sa_family == UInt8(AF_INET) || addr.sa_family == UInt8(AF_INET6) {
                        
                        var mask = ptr!.pointee.ifa_netmask.pointee
                        
                        // Convert interface address to a human readable string:
                        let zero  = CChar(0)
                        var hostname = [CChar](repeating: zero, count: Int(NI_MAXHOST))
                        var netmask =  [CChar](repeating: zero, count: Int(NI_MAXHOST))
                        if (getnameinfo(&addr, socklen_t(addr.sa_len), &hostname, socklen_t(hostname.count),
                                        nil, socklen_t(0), NI_NUMERICHOST) == 0) {
                            let address = String(cString: hostname)
                            let name = ptr!.pointee.ifa_name!
                            let ifname = String(cString: name)
                            
                            if (getnameinfo(&mask, socklen_t(mask.sa_len), &netmask, socklen_t(netmask.count), nil, socklen_t(0), NI_NUMERICHOST) == 0) {
                                let netmaskIP = String(cString: netmask)
                                
                                interfaces.append(NetworkInterface(name: ifname, ip: address, netmask: netmaskIP))
                            }
                        }
                    }
                }
                ptr = ptr!.pointee.ifa_next
            }
            freeifaddrs(ifaddr)
        }
        
        return interfaces
    }
    
}