package network

import (
	"bytes"
	"encoding/json"
	"fmt"
	"os/exec"
	"strconv"
	"strings"

	"kattila-agent/models"
)

type ipAddrInfo struct {
	Local     string `json:"local"`
	PrefixLen int    `json:"prefixlen"`
}

type ipInterface struct {
	Ifname   string       `json:"ifname"`
	Address  string       `json:"address"` // MAC address in newer iproute2
	AddrInfo []ipAddrInfo `json:"addr_info"`
}

func getInterfaces() ([]models.Interface, error) {
	cmd := exec.Command("ip", "-j", "a")
	out, err := cmd.Output()
	if err != nil {
		return nil, err
	}

	var parsed []ipInterface
	if err := json.Unmarshal(out, &parsed); err != nil {
		return nil, err
	}

	var results []models.Interface
	for _, itf := range parsed {
		mac := itf.Address
		var addrs []string
		for _, info := range itf.AddrInfo {
			addrs = append(addrs, fmt.Sprintf("%s/%d", info.Local, info.PrefixLen))
		}
		
		isVirtual := false
		var vpnType *string
		if strings.HasPrefix(itf.Ifname, "wg") || strings.HasPrefix(itf.Ifname, "tun") || strings.HasPrefix(itf.Ifname, "parvpn") || strings.HasPrefix(itf.Ifname, "home") || strings.HasPrefix(itf.Ifname, "tailscale") {
			isVirtual = true
		}

		results = append(results, models.Interface{
			Name:      itf.Ifname,
			MAC:       mac,
			Addresses: addrs,
			IsVirtual: isVirtual,
			VPNType:   vpnType,
		})
	}
	return results, nil
}

type ipRoute struct {
	Dst     string `json:"dst"`
	Gateway string `json:"gateway"`
	Via     string `json:"via"` // Sometimes present instead of gateway
	Dev     string `json:"dev"`
}

func getRoutes() ([]models.Route, error) {
	cmd := exec.Command("ip", "-j", "-4", "r")
	out, err := cmd.Output()
	if err != nil {
		return nil, err
	}

	var parsed []ipRoute
	if err := json.Unmarshal(out, &parsed); err != nil {
		return nil, err
	}

	var results []models.Route
	for _, r := range parsed {
		via := r.Gateway
		if via == "" {
			via = r.Via
		}
		results = append(results, models.Route{
			Dst: r.Dst,
			Via: via,
			Dev: r.Dev,
		})
	}
	return results, nil
}

func getWgPeers() ([]models.WGPeer, error) {
	cmd := exec.Command("wg", "show", "all", "dump")
	out, err := cmd.Output()
	if err != nil { // wg might fail or not be installed, ignore and return empty
		return nil, nil
	}

	var peers []models.WGPeer
	lines := bytes.Split(out, []byte("\n"))
	for _, line := range lines {
		line = bytes.TrimSpace(line)
		if len(line) == 0 {
			continue
		}
		
		cols := strings.Split(string(line), "\t")
		// wg interface line: itf, privkey, pubkey, port, fwmark (5 cols)
		// wg peer line: itf, pubkey, psk, endpoint, allowed-ips, handshake, rx, tx, keepalive (9 cols)
		if len(cols) >= 8 {
			itf := cols[0]
			pubkey := cols[1]
			endpoint := cols[3]
			if endpoint == "(none)" {
				endpoint = ""
			}
			allowedIpsRaw := cols[4]
			if allowedIpsRaw == "(none)" {
				allowedIpsRaw = ""
			}
			allowedIps := strings.Split(allowedIpsRaw, ",")
			
			handshake, _ := strconv.ParseInt(cols[5], 10, 64)
			rx, _ := strconv.ParseInt(cols[6], 10, 64)
			tx, _ := strconv.ParseInt(cols[7], 10, 64)

			peers = append(peers, models.WGPeer{
				Interface:       itf,
				PublicKey:       pubkey,
				Endpoint:        endpoint,
				AllowedIPs:      allowedIps,
				LatestHandshake: handshake,
				TransferRx:      rx,
				TransferTx:      tx,
			})
		}
	}
	return peers, nil
}

func GatherSystemData() (models.SystemData, error) {
	hostname, _ := exec.Command("hostname").Output()
	
	// Simplified uptime extraction
	uptimeBytes, _ := exec.Command("cat", "/proc/uptime").Output()
	var uptimeSec int64
	if len(uptimeBytes) > 0 {
		parts := strings.Fields(string(uptimeBytes))
		if len(parts) > 0 {
			uptimeFloat, _ := strconv.ParseFloat(parts[0], 64)
			uptimeSec = int64(uptimeFloat)
		}
	}

	loadavgBytes, _ := exec.Command("cat", "/proc/loadavg").Output()
	var loadavg []float64
	if len(loadavgBytes) > 0 {
		parts := strings.Fields(string(loadavgBytes))
		if len(parts) >= 3 {
			l1, _ := strconv.ParseFloat(parts[0], 64)
			l2, _ := strconv.ParseFloat(parts[1], 64)
			l3, _ := strconv.ParseFloat(parts[2], 64)
			loadavg = []float64{l1, l2, l3}
		}
	}

	intfs, err := getInterfaces()
	if err != nil {
		intfs = []models.Interface{}
	}

	routes, err := getRoutes()
	if err != nil {
		routes = []models.Route{}
	}

	wgPeers, err := getWgPeers()
	if err != nil {
		wgPeers = []models.WGPeer{}
	}

	return models.SystemData{
		Hostname:      strings.TrimSpace(string(hostname)),
		UptimeSeconds: uptimeSec,
		LoadAvg:       loadavg,
		Interfaces:    intfs,
		Routes:        routes,
		WGPeers:       wgPeers,
	}, nil
}