package kyoketsu

import (
	"fmt"
	"log"
	"net"
	"os"
	"sync"
	"time"

	"github.com/go-ping/ping"
	"golang.org/x/net/icmp"
	"golang.org/x/net/ipv4"
)

var PORT_MAP = map[int]string{
	22: "ssh", 23: "telnet", 53: "dns", 80: "http", 25: "smtp", 443: "https", 8080: "unknown", 8081: "unknown",
	//8082: "unknown", 8085: "unknown", 8090: "unknown", 8091: "unknown", 9010: "unknown", 9012: "unknown", 10000: "unknown", 1433: "microsoft_sql",
	3306: "mysql", 3050: "firebird", 5432: "postgres", 27017: "mongo", 6379: "redis", 8005: "tomcat", 6443: "kubernetes", 853: "dns-tls", 143: "imap",
	389: "ldap", 445: "smb", 543: "kerberos", 544: "kerberos", 749: "kerberos", 760: "kerberos",
}

/*
Need to work with with a database schema in mind, and revolve functionality around that
*/

type Host struct {
	Fqdn           string           // The FQDN of the address targeted as per the systems default resolver
	IpAddress      string           // the IPv4 address (no ipv6 support yet)
	PingResponse   bool             // boolean value representing if the host responded to ICMP
	ListeningPorts []map[int]string // list of maps depicting a port number -> service name
}

/*
Perform a concurrent TCP port dial on a host, either by domain name or IP.

	:param addr: the address of fqdn to scan
	:param portmap: a key/value pair of port numbers to service names to dial the host with
*/
func PortWalk(addr string, portmap map[int]string) *Host {
	wg := &sync.WaitGroup{}
	out := []*PortScanResult{}

	ports := RetrieveScanDirectives()
	for p, s := range ports.Pairs {
		wg.Add(1)
		go func(target string, p int, s string) {
			defer wg.Done()
			out = append(out, singlePortScan(target, p, s))
		}(addr, p, s)
	}
	wg.Wait()
	host := &Host{IpAddress: addr, ListeningPorts: []map[int]string{}}
	for i := range out {
		if out[i].Listening {
			host.ListeningPorts = append(host.ListeningPorts, map[int]string{
				out[i].PortNumber: out[i].Service,
			})
		}
	}
	return host

}

type PortScanResult struct {
	// This is used to represent the results of a port scan against one host
	PortNumber int    `json:"port_number"` // The port number that was scanned
	Service    string `json:"service"`     // the name of the service that the port was identified/mapped to
	Protocol   string `json:"protocol"`    // The IP protocol (TCP/UDP)
	Listening  bool   `json:"listening"`   // A boolean value that depicts if the service is listening or not
}

type PortScanDirective struct {
	// Struct for dependency injecting the dynamic port map used for scans
	Pairs map[int]string
}

/*
Wrapper function to dependency inject the resource for a port -> service name mapping.
May move to a database, or something.
*/
func RetrieveScanDirectives() PortScanDirective {
	return PortScanDirective{Pairs: PORT_MAP}
}

/*
Scans a single host on a single port

	:param addr: the address to dial
	:param port: the port number to dial
	:param svcs: the name of the service that the port is associate with
*/
func singlePortScan(addr string, port int, svcs string) *PortScanResult {
	address := fmt.Sprintf("%v:%d", addr, port)
	conn, err := net.DialTimeout("tcp", address, 5*time.Second)
	if err != nil {
		return &PortScanResult{PortNumber: port, Protocol: "tcp", Service: svcs, Listening: false}
	}
	conn.Close()
	return &PortScanResult{PortNumber: port, Protocol: "tcp", Service: svcs, Listening: true}
}

/*
This function makes use of an external dependency, may or may not keep. It still needs to be implemented

	    :param addr: the ip address to send an ICMP request to
		:param pinger: a pointer to a ping.Pinger struct to reuse
*/
func PingTarget(addr string, pinger *ping.Pinger) bool {
	err := pinger.SetAddr(addr)
	if err != nil {
		log.Println(err)
		return false
	}
	err = pinger.Run()
	if err != nil {
		log.Println(err)
		return false
	}
	stats := pinger.Statistics()
	if stats.PacketsRecv > 0 {
		return true
	}
	return false

}

/*
Listen for ICMP responses on a specific address

	:param listening: the address of your server
*/
func IcmpListen(listening string) *icmp.PacketConn {
	icmpSrv, err := icmp.ListenPacket("udp4", listening)
	icmpSrv.SetDeadline(time.Now().Add(5 * time.Second))
	if err != nil {
		log.Println(err)
	}
	return icmpSrv

}

/*
Send an ICMP request to an address and listen for a response (UNFINISHED/NON-FUNCTIONAL)

	    :param icmpSrv: a pointer to an ICMP PacketConn struct, for reading and sending ICMP requests.
		:param addr: the address to send the request to
*/
func icmpAsk(icmpSrv *icmp.PacketConn, addr string) bool {
	icmpReq := icmp.Message{
		Type: ipv4.ICMPTypeEcho, Code: 0,
		Body: &icmp.Echo{
			ID: os.Getpid() & 0xffff, Seq: 1,
			Data: []byte("DIALING FROM KYOKETSU"),
		},
	}
	icmpB, err := icmpReq.Marshal(nil)
	if err != nil {
		log.Println(err)
		return false
	}
	if _, err := icmpSrv.WriteTo(icmpB, &net.UDPAddr{IP: net.ParseIP(addr)}); err != nil {
		log.Println(err)
		return false
	}
	respB := make([]byte, 1500)
	n, peer, err := icmpSrv.ReadFrom(respB)
	if err != nil {
		log.Println(err)
		return false
	}
	rm, err := icmp.ParseMessage(ipv4.ICMPTypeEcho.Protocol(), respB[:n])
	if err != nil {
		log.Println(err)
		return false
	}
	switch rm.Type {
	case ipv4.ICMPTypeEchoReply:
		echo, ok := rm.Body.(*icmp.Echo)
		if !ok {
			return false
		}
		if peer.(*net.UDPAddr).IP.String() == addr && echo.Seq == 1 {
			return true
		}
	default:
		return false

	}
	return false

}