package networking

import (
	"bytes"
	"encoding/json"
	"os"
	"os/exec"
	"strings"
	"time"

	"github.com/prometheus-community/pro-bing"
)

const deviceFile = "devices.json"

type Device struct {
	Name      string `json:"name"`
	IP        string `json:"ip"`
	Interface string `json:"interface"`
	Icon      string `json:"icon"`
	Online    bool   `json:"online"`
}

func GetDevices() map[string]Device {
	result := make(map[string]Device)
	devices := make(map[string]Device)
	arpDevices := arpDevices()
	knownDevices := knownDevices()
	for mac, device := range arpDevices {
		if strings.HasPrefix(device.Interface, "br") {
			continue
		}
		if known, ok := knownDevices[mac]; ok {
			devices[mac] = Device{Name: known.Name, IP: device.IP, Icon: known.Icon}
		} else {
			devices[mac] = device
		}
	}
	for mac, device := range knownDevices {
		if _, ok := devices[mac]; !ok {
			devices[mac] = Device{Name: device.Name, IP: device.IP, Icon: device.Icon}
		}
	}
	writeDevices(devices)

	for mac, device := range devices {
		if device.Icon == "" {
			device.Icon = "\U000F0C8A"
		}
		pinger, err := probing.NewPinger(device.IP)
		if err == nil {
			pinger.Count = 1
			pinger.Timeout = 500 * time.Millisecond
			if err := pinger.Run(); err == nil {
				if pinger.Statistics().PacketsRecv > 0 {
					device.Online = true
				}
			}
		}
		result[mac] = device
	}

	return result
}

func writeDevices(devices map[string]Device) {
	marshal, err := json.MarshalIndent(devices, "", "  ")
	if err != nil {
	}
	if err := os.WriteFile(deviceFile, marshal, 0644); err != nil {
		panic(err)
	}
}

func knownDevices() map[string]Device {
	knownDevices := make(map[string]Device)
	file, err := os.ReadFile(deviceFile)
	if err == nil {
		if err := json.Unmarshal(file, &knownDevices); err != nil {
			panic(err)
		}
	}
	return knownDevices
}

func arpDevices() map[string]Device {
	arp := exec.Command("arp", "-a")
	var out bytes.Buffer
	arp.Stdout = &out
	if err := arp.Run(); err != nil {
		panic(err)
	}
	res := out.String()
	lines := strings.Split(res, "\n")
	devices := make(map[string]Device)
	for l := range lines {
		entry := strings.Fields(lines[l])
		if len(entry) > 6 {
			devices[entry[3]] = Device{Name: entry[0], IP: strings.ReplaceAll(strings.ReplaceAll(entry[1], "(", ""), ")", ""), Interface: entry[6]}
		}
	}
	return devices
}