package main

import (
	"bytes"
	"context"
	"encoding/hex"
	"fmt"

	"github.com/charmbracelet/log"
	"github.com/meshnet-gophers/meshtastic-go"
	pb "github.com/meshnet-gophers/meshtastic-go/meshtastic"
	"google.golang.org/protobuf/proto"
)

func (n *Node) RxLoop(ctx context.Context) error {
	for {
		if err := ctx.Err(); err != nil {
			return err
		}
		p, ts, err := n.mesh.ReadMeshPacket()
		if err != nil {
			n.logger.Error("Read mesh packet failed", "err", err)
			return err
		}
		if err := n.rxMessage(ts, p); err != nil {
			n.logger.Error("Processing Radio Message", "error", err)
		}
	}
}

func (n *Node) rxMessage(ts uint64, p *pb.MeshPacket) error {
	pt := PacketTruncated{To: p.To, From: p.From, ID: p.Id}
	info := fmt.Sprintf("ts:%d rssi:%-4d snr:%-5.1f", p.RxTime, p.RxRssi, p.RxSnr)
	header := fmt.Sprintf("from:%08x to:%08x id:%08x ch:%02x next:%02x last:%02x hs:%d hl:%d mq:%d wack:%d", p.From, p.To, p.Id, uint8(p.Channel), p.NextHop, p.RelayNode, p.HopStart, p.HopLimit, bool2Int(p.ViaMqtt), bool2Int(p.WantAck))
	payloadstr := fmt.Sprintf("%x", p.GetEncrypted())
	var dupe bool
	if _, dupe = n.pktLru.Get(pt); dupe {
		n.logger.Debug(")  MeshPacket", "info", info, "header", header, "payload", payloadstr)
	} else {
		n.logger.Debug(")) MeshPacket", "info", info, "header", header, "payload", payloadstr)
		n.pktLru.Add(pt, struct{}{})
	}
	if dupe { // XXX: it would need to be changed for the traceroute
		return nil // skip duplicates
	}
	if p.From == n.nodeID {
		return nil // ourself
	}
	if len(p.GetEncrypted()) == 0 {
		n.logger.Warn(":: Skipping unencrypted or empty packet")
		return nil // we skip unencrypted packets
	}
	var plaintext []byte
	var pubKey []byte
	var channel *pb.ChannelSettings
	if p.To == n.nodeID && p.Channel == 0x00 {
		var err error
		if plaintext, pubKey, err = n.tryDecryptPKC(p); err != nil {
			log.Printf("failed to decrypt PKC message: %s", err)
		}
	}
	if plaintext != nil {
		channel = pkcChan
		p.Channel = 0
	} else {
		plaintext, channel = n.tryDecryptPSK(p)
		if plaintext == nil {
			return nil // failed decrypt
		}
		p.Channel = channel.ChannelNum
	}
	data := &pb.Data{}
	if err := proto.Unmarshal(plaintext, data); err != nil {
		n.logger.Debug(")) MeshPacket.Data", "channel", channel.Name, "mqtt", p.ViaMqtt, "raw", hex.EncodeToString(plaintext))
		return fmt.Errorf("unmarshalling decrypted data: %w", err)
	}

	p.PublicKey = pubKey
	p.PkiEncrypted = channel == pkcChan
	p.PayloadVariant = &pb.MeshPacket_Decoded{Decoded: data}
	msgFromRadio := &pb.FromRadio{PayloadVariant: &pb.FromRadio_Packet{Packet: p}}
	source := data.Source
	if source == 0 {
		source = p.From
	}
	dest := data.Dest
	if dest == 0 {
		dest = p.To
	}
	toUs := dest == n.nodeID
	if dest == broadcastID || toUs {
		n.dispatchMessageToAdmin(msgFromRadio)
	}
	n.db.StoreFromRadio(int64(ts), msgFromRadio)
	n.logger.Debug(")) MeshPacket.Data", "channel", channel.Name, "mqtt", p.ViaMqtt, "raw", hex.EncodeToString(plaintext), "data", data)

	src := n.NodeInfo(source, func(ni *pb.NodeInfo) bool {
		if ni.Num == n.nodeID {
			return false // it's us
		}
		if p.HopLimit > p.HopStart {
			return false // weird hoplimit value
		}
		hopsAway := uint32(p.HopStart - p.HopLimit)
		if ni.HopsAway != nil && *ni.HopsAway <= hopsAway {
			return false // skip update if these hops away are longer
		}
		ni.HopsAway = &hopsAway
		return true
	})
	dst := n.NodeInfo(dest, nil)

	var payload any
	var reply proto.Message
	replyPortNum := data.Portnum
	switch data.Portnum {
	case pb.PortNum_ADMIN_APP:
		admin := &pb.AdminMessage{}
		if err := proto.Unmarshal(data.Payload, admin); err != nil {
			return fmt.Errorf("unmarshalling admin message: %w", err)
		}
		payload = admin
		switch adminPayload := admin.PayloadVariant.(type) {
		case *pb.AdminMessage_GetDeviceMetadataRequest:
			if data.WantResponse && toUs {
				reply = &pb.AdminMessage{
					PayloadVariant: &pb.AdminMessage_GetDeviceMetadataResponse{
						GetDeviceMetadataResponse: n.getDeviceMetadata(),
					},
				}
			}
		default:
			n.logger.Warnf("unhandled admin message type: %T", adminPayload)
		}
	case pb.PortNum_NODEINFO_APP:
		user := &pb.User{}
		if err := proto.Unmarshal(data.Payload, user); err != nil {
			return fmt.Errorf("unmarshalling user: %w", err)
		}
		payload = user
		n.logger.Info(")) NodeInfo", "user", user)
		n.NodeInfo(source, func(nodeInfo *pb.NodeInfo) bool {
			if nodeInfo.User != nil {
				if len(nodeInfo.User.PublicKey) > 0 && !bytes.Equal(nodeInfo.User.PublicKey, user.PublicKey) {
					n.logger.Error("NodeInfo w/ different key", "nodeInfo", nodeInfo, "new", user)
					return false // do not update
				}
			}
			nodeInfo.User = user
			return true
		})
		if data.WantResponse && toUs {
			reply = n.user
		}
	case pb.PortNum_TEXT_MESSAGE_APP:
		n.logger.Info(")) TextMessage", "channel", channel.Name, "source", meshtastic.NodeID(source).String(), "text", string(data.Payload))
	case pb.PortNum_ROUTING_APP:
		routing := &pb.Routing{}
		if err := proto.Unmarshal(data.Payload, routing); err != nil {
			return fmt.Errorf("unmarshalling routingPayload: %w", err)
		}
		payload = routing
		n.logger.Info(")) Routing", "routing", routing)
	case pb.PortNum_TRACEROUTE_APP:
		routeDiscovery := &pb.RouteDiscovery{}
		if err := proto.Unmarshal(data.Payload, routeDiscovery); err != nil {
			return fmt.Errorf("unmarshalling traceroute payload: %w", err)
		}
		payload = routeDiscovery
		n.logger.Info(")) RouteDiscovery", "channel", channel.Name, "source", meshtastic.NodeID(source).String(), "payload", routeDiscovery)
		if !toUs {
			break
		}
		towardsDestination := data.ReplyId == 0
		var route *[]uint32
		var snr *[]int32
		if towardsDestination {
			route = &routeDiscovery.Route
			snr = &routeDiscovery.SnrTowards
		} else {
			route = &routeDiscovery.RouteBack
			snr = &routeDiscovery.SnrBack
		}
		// Only insert unknown hops if hop_start is valid
		if p.HopStart != 0 && p.HopLimit <= p.HopStart {
			var hopsTaken uint8 = uint8(p.HopStart - p.HopLimit)
			diff := int(hopsTaken) - len(*route)
			for i := 0; i < diff; i++ {
				if len(*route) < ROUTE_MAX_SIZE {
					*route = append(*route, broadcastID)
				}
			}
			// Add unknown SNR values if necessary
			diff = len(*route) - len(*snr)
			for i := 0; i < diff; i++ {
				if len(*snr) < ROUTE_MAX_SIZE {
					*snr = append(*snr, 0xFF)
				}
			}
		}

		if len(*snr) < ROUTE_MAX_SIZE {
			*snr = append(*snr, int32(p.RxSnr*4))
		}
		// We don't need to add route, if we are the dest
		// // Length of route array can normally not be exceeded due to the max. hop_limit of 7
		// if *route_count < ROUTE_SIZE {
		// 	route[*route_count] = myNodeInfo.my_node_num
		// 	*route_count += 1
		// } else {
		// 	LOG_WARN("Route exceeded maximum hop limit!") // Are you bridging networks?
		// }
		reply = routeDiscovery
	case pb.PortNum_POSITION_APP:
		position := &pb.Position{}
		if err := proto.Unmarshal(data.Payload, position); err != nil {
			return fmt.Errorf("unmarshalling positionPayload: %w", err)
		}
		payload = position
		n.logger.Info(")) Position", "position", position)
		if data.WantResponse && toUs {
			reply = n.getPosition()
		} else {
			n.NodeInfo(source, func(nodeInfo *pb.NodeInfo) bool {
				nodeInfo.Position = position
				return true
			})
		}
	case pb.PortNum_TELEMETRY_APP:
		telemetry := &pb.Telemetry{}
		if err := proto.Unmarshal(data.Payload, telemetry); err != nil {
			return fmt.Errorf("unmarshalling telemetryPayload: %w", err)
		}
		payload = telemetry
		n.logger.Info(")) Telemetry deviceMetrics", "telemetry", telemetry)
		if data.WantResponse && toUs {
			metrics, err := n.getDeviceMetrics()
			if err != nil {
				break
			}
			reply = metrics
		} else {
			deviceMetrics := telemetry.GetDeviceMetrics()
			if deviceMetrics == nil {
				break
			}
			n.NodeInfo(source, func(nodeInfo *pb.NodeInfo) bool {
				nodeInfo.DeviceMetrics = deviceMetrics
				return true
			})
		}
	default:
		n.logger.Debug(")) !Unhandled app payload", "data", data)
	}
	n.dl.LogPacket(p, channel, src, dst, data, payload)
	if toUs && p.WantAck {
		err := n.txPacket(buildRoutingReply(&pb.MeshPacket{
			From:         p.From,
			To:           p.To,
			HopStart:     uint32(p.HopStart),
			Channel:      channel.ChannelNum,
			Id:           p.Id,
			PkiEncrypted: msgFromRadio.GetPacket().PkiEncrypted,
			PublicKey:    msgFromRadio.GetPacket().PublicKey,
		}, pb.Routing_NONE))
		if err != nil {
			n.logger.Warn("failed to send text ack", "err", err)
		}
	}
	if reply != nil {
		err := n.txPortnumMessage(channel.ChannelNum, source, replyPortNum, reply)
		if err != nil {
			n.logger.Error("Failed to reply", "err", err, "reply", reply)
		} else {
			n.dl.LogPacket(p, channel, dst, src, &pb.Data{Portnum: replyPortNum}, payload)
		}
	}

	return nil
}