package wifi

import (
	"bytes"
	"net"
	"time"

	"github.com/bettercap/bettercap/log"
	"github.com/bettercap/bettercap/network"
	"github.com/bettercap/bettercap/packets"

	"github.com/google/gopacket"
	"github.com/google/gopacket/layers"

	"github.com/evilsocket/islazy/tui"
)

var maxStationTTL = 5 * time.Minute

func (w *WiFiModule) stationPruner() {
	w.reads.Add(1)
	defer w.reads.Done()

	log.Debug("wifi stations pruner started.")
	for w.Running() {
		// loop every AP
		for _, ap := range w.Session.WiFi.List() {
			sinceLastSeen := time.Since(ap.LastSeen)
			if sinceLastSeen > maxStationTTL {
				log.Debug("station %s not seen in %s, removing.", ap.BSSID(), sinceLastSeen)
				w.Session.WiFi.Remove(ap.BSSID())
				continue
			}
			// loop every AP client
			for _, c := range ap.Clients() {
				sinceLastSeen := time.Since(c.LastSeen)
				if sinceLastSeen > maxStationTTL {
					log.Debug("client %s of station %s not seen in %s, removing.", c.String(), ap.BSSID(), sinceLastSeen)
					ap.RemoveClient(c.BSSID())

					w.Session.Events.Add("wifi.client.lost", WiFiClientEvent{
						AP:     ap,
						Client: c,
					})
				}
			}
		}
		time.Sleep(1 * time.Second)
	}
}

func (w *WiFiModule) discoverAccessPoints(radiotap *layers.RadioTap, dot11 *layers.Dot11, packet gopacket.Packet) {
	// search for Dot11InformationElementIDSSID
	if ok, ssid := packets.Dot11ParseIDSSID(packet); ok {
		from := dot11.Address3

		// skip stuff we're sending
		if w.apRunning && bytes.Equal(from, w.apConfig.BSSID) {
			return
		}

		if !network.IsZeroMac(from) && !network.IsBroadcastMac(from) {
			if int(radiotap.DBMAntennaSignal) >= w.minRSSI {
				var frequency int
				bssid := from.String()

				if found, channel := packets.Dot11ParseDSSet(packet); found {
					frequency = network.Dot11Chan2Freq(channel)
				} else {
					frequency = int(radiotap.ChannelFrequency)
				}

				if ap, isNew := w.Session.WiFi.AddIfNew(ssid, bssid, frequency, radiotap.DBMAntennaSignal); !isNew {
					ap.EachClient(func(mac string, station *network.Station) {
						station.Handshake.SetBeacon(packet)
					})
				}
			} else {
				log.Debug("skipping %s with %d dBm", from.String(), radiotap.DBMAntennaSignal)
			}
		}
	}
}

func (w *WiFiModule) discoverProbes(radiotap *layers.RadioTap, dot11 *layers.Dot11, packet gopacket.Packet) {
	if dot11.Type != layers.Dot11TypeMgmtProbeReq {
		return
	}

	reqLayer := packet.Layer(layers.LayerTypeDot11MgmtProbeReq)
	if reqLayer == nil {
		return
	}

	req, ok := reqLayer.(*layers.Dot11MgmtProbeReq)
	if !ok {
		return
	}

	tot := len(req.Contents)
	if tot < 3 {
		return
	}

	avail := uint32(tot - 2)
	if avail < 2 {
		return
	}
	size := uint32(req.Contents[1])
	if size == 0 || size > avail {
		return
	}

	w.Session.Events.Add("wifi.client.probe", WiFiProbeEvent{
		FromAddr:   dot11.Address2,
		FromVendor: network.ManufLookup(dot11.Address2.String()),
		FromAlias:  w.Session.Lan.GetAlias(dot11.Address2.String()),
		SSID:       string(req.Contents[2 : 2+size]),
		RSSI:       radiotap.DBMAntennaSignal,
	})
}

func (w *WiFiModule) discoverClients(radiotap *layers.RadioTap, dot11 *layers.Dot11, packet gopacket.Packet) {
	w.Session.WiFi.EachAccessPoint(func(bssid string, ap *network.AccessPoint) {
		// packet going to this specific BSSID?
		if packets.Dot11IsDataFor(dot11, ap.HW) {
			bssid := dot11.Address2.String()
			freq := int(radiotap.ChannelFrequency)
			rssi := radiotap.DBMAntennaSignal

			if station, isNew := ap.AddClientIfNew(bssid, freq, rssi); isNew {
				w.Session.Events.Add("wifi.client.new", WiFiClientEvent{
					AP:     ap,
					Client: station,
				})
			}
		}
	})
}

func allZeros(s []byte) bool {
	for _, v := range s {
		if v != 0 {
			return false
		}
	}
	return true
}

func (w *WiFiModule) discoverHandshakes(radiotap *layers.RadioTap, dot11 *layers.Dot11, packet gopacket.Packet) {
	// ref. https://wlan1nde.wordpress.com/2014/10/27/4-way-handshake/
	if keyLayer := packet.Layer(layers.LayerTypeEAPOLKey); keyLayer != nil {
		if key := keyLayer.(*layers.EAPOLKey); key.KeyType == layers.EAPOLKeyTypePairwise {
			staMac := net.HardwareAddr{}
			apMac := net.HardwareAddr{}
			if dot11.Flags.FromDS() {
				staMac = dot11.Address1
				apMac = dot11.Address2
			} else if dot11.Flags.ToDS() {
				staMac = dot11.Address2
				apMac = dot11.Address1
			}

			// first, locate the AP in our list by its BSSID
			ap, found := w.Session.WiFi.Get(apMac.String())
			if !found {
				log.Warning("could not find AP with BSSID %s", apMac.String())
				return
			}

			// locate the client station, if its BSSID is ours, it means we sent
			// an association request via wifi.assoc because we're trying to capture
			// the PMKID from the first EAPOL sent by the AP.
			// (Reference about PMKID https://hashcat.net/forum/thread-7717.html)
			// In this case, we need to add ourselves as a client station of the AP
			// in order to have a consistent association of AP, client and handshakes.
			staIsUs := bytes.Equal(staMac, w.Session.Interface.HW)
			station, found := ap.Get(staMac.String())
			if !found {
				station, _ = ap.AddClientIfNew(staMac.String(), ap.Frequency, ap.RSSI)
			}

			rawPMKID := []byte(nil)
			if !key.Install && key.KeyACK && !key.KeyMIC {
				// [1] (ACK) AP is sending ANonce to the client
				rawPMKID = station.Handshake.AddAndGetPMKID(packet)
				PMKID := "without PMKID"
				if rawPMKID != nil {
					PMKID = "with PMKID"
				}

				log.Debug("[%s] got frame 1/4 of the %s <-> %s handshake (%s) (anonce:%x)",
					tui.Green("wifi"),
					apMac,
					staMac,
					PMKID,
					key.Nonce)
			} else if !key.Install && !key.KeyACK && key.KeyMIC && !allZeros(key.Nonce) {
				// [2] (MIC) client is sending SNonce+MIC to the API
				station.Handshake.AddFrame(1, packet)

				log.Debug("[%s] got frame 2/4 of the %s <-> %s handshake (snonce:%x mic:%x)",
					tui.Green("wifi"),
					apMac,
					staMac,
					key.Nonce,
					key.MIC)
			} else if key.Install && key.KeyACK && key.KeyMIC {
				// [3]: (INSTALL+ACK+MIC) AP informs the client that the PTK is installed
				station.Handshake.AddFrame(2, packet)

				log.Debug("[%s] got frame 3/4 of the %s <-> %s handshake (mic:%x)",
					tui.Green("wifi"),
					apMac,
					staMac,
					key.MIC)
			}

			// if we have unsaved packets as part of the handshake, save them.
			numUnsaved := station.Handshake.NumUnsaved()
			doSave := numUnsaved > 0
			if doSave && w.shakesFile != "" {
				log.Debug("saving handshake frames to %s", w.shakesFile)
				if err := w.Session.WiFi.SaveHandshakesTo(w.shakesFile, w.handle.LinkType()); err != nil {
					log.Error("error while saving handshake frames to %s: %s", w.shakesFile, err)
				}
			}

			// if we had unsaved packets and either the handshake is complete
			// or it contains the PMKID, generate a new event.
			if doSave && (rawPMKID != nil || station.Handshake.Complete()) {
				w.Session.Events.Add("wifi.client.handshake", WiFiHandshakeEvent{
					File:       w.shakesFile,
					NewPackets: numUnsaved,
					AP:         apMac,
					Station:    staMac,
					PMKID:      rawPMKID,
				})
			}

			// if we added ourselves as a client station but we didn't get any
			// PMKID, just remove it from the list of clients of this AP.
			if staIsUs && rawPMKID == nil {
				ap.RemoveClient(staMac.String())
			}
		}
	}
}