package main

import (
	"fmt"
	"io"
	"os/exec"
	"runtime"
	"strings"

	"github.com/andlabs/ui"
)

const ConfigBody = `[NetDev]
Name=%s
Kind=wireguard
Description=%s

[WireGuard]
ListenPort=12345
PrivateKey=%s

`
const ConfigPeer = `[WireGuardPeer]
PublicKey=%s
PresharedKey=%s
AllowedIPs=%s
`

var win *ui.Window
var (
	private, public, psk string
	devname              string = "wg0"
	desc                 string = "WireGuard tunnel/listener ()"

	peerpublic  string
	peerip      string
	peerallowed string = "0.0.0.0/0"
)
var wgexe string

func init() {
	if runtime.GOOS == "windows" {
		wgexe = "wg.exe"
	} else {
		wgexe = "wg"
	}
}

func readStringFromCommands(stdin io.Reader, cmd string, args ...string) (string, error) {
	runner := exec.Command(cmd, args...)
	runner.Stdin = stdin
	genkey_out, err := runner.Output()
	if err != nil {
		return "", err
	}

	// Remove unprintable chars at the end
	str := string(genkey_out)
	for str[len(str)-1] == '\n' {
		str = str[:len(str)-1]
	}

	return str, nil
}

func resetKeys() {

	var err error
	private, err = readStringFromCommands(nil, wgexe, "genkey")
	if err != nil {
		ui.MsgBox(win, "wg genkey error", err.Error())
		return
	}

	public, err = readStringFromCommands(strings.NewReader(private), wgexe, "pubkey")
	if err != nil {
		ui.MsgBox(win, "wg pubkey error", err.Error())
		return
	}
}

func resetPsk() {
	var err error
	psk, err = readStringFromCommands(strings.NewReader(private), wgexe, "genpsk")
	if err != nil {
		ui.MsgBox(win, "wg genpsk error", err.Error())
		return
	}
}

func resetConfig() string {
	buf := &strings.Builder{}

	fmt.Fprintf(buf, ConfigBody, devname, desc, private)
	fmt.Fprintf(buf, ConfigPeer, peerpublic, psk, peerallowed)
	if len(peerip) > 0 {
		fmt.Fprintf(buf, "Endpoint=%s\n", peerip)
	}

	return buf.String()
}

func setup() {
	resetKeys()
	resetPsk()

	win = ui.NewWindow("WireGuard Generator", 500, 700, false)
	win.OnClosing(func(*ui.Window) bool {
		ui.Quit()
		return true
	})
	ui.OnShouldQuit(func() bool {
		win.Destroy()
		return true
	})

	muti := ui.NewMultilineEntry()

	vbox := ui.NewVerticalBox()
	vbox.SetPadded(true)

	form := ui.NewForm()
	form.SetPadded(true)

	entry1 := ui.NewEntry()
	entry1.SetReadOnly(true)
	entry1.SetText(private)
	entry2 := ui.NewEntry()
	entry2.SetText(public)
	entry2.SetReadOnly(true)
	entry3 := ui.NewEntry()
	entry3.SetText(psk)
	entry3.OnChanged(func(e *ui.Entry) {
		psk = e.Text()
		muti.SetText(resetConfig())
	})

	form.Append("Private", entry1, false)
	form.Append("Public", entry2, false)
	form.Append("PSK", entry3, false)
	vbox.Append(form, false)

	hbox_buttons := ui.NewHorizontalBox()
	hbox_buttons.SetPadded(true)

	button1 := ui.NewButton("Generate Keys")
	button1.OnClicked(func(*ui.Button) {
		resetKeys()
		entry1.SetText(private)
		entry2.SetText(public)
		muti.SetText(resetConfig())
	})
	button2 := ui.NewButton("Generate PSK")
	button2.OnClicked(func(*ui.Button) {
		resetPsk()
		entry3.SetText(psk)
		muti.SetText(resetConfig())
	})
	hbox_buttons.Append(button1, true)
	hbox_buttons.Append(button2, true)
	vbox.Append(hbox_buttons, false)

	// Device  Name
	vbox.Append(ui.NewHorizontalSeparator(), false)
	form_dev := ui.NewForm()
	form_dev.SetPadded(true)

	dev_entry1 := ui.NewEntry()
	dev_entry1.SetText(devname)
	dev_entry2 := ui.NewEntry()
	dev_entry2.SetText(desc)
	dev_entry1.OnChanged(func(e *ui.Entry) {
		devname = e.Text()
		muti.SetText(resetConfig())
	})
	dev_entry2.OnChanged(func(e *ui.Entry) {
		desc = e.Text()
		muti.SetText(resetConfig())
	})

	form_dev.Append("Device name", dev_entry1, false)
	form_dev.Append("Description", dev_entry2, false)
	vbox.Append(form_dev, false)

	// Peer
	vbox.Append(ui.NewHorizontalSeparator(), false)

	form2 := ui.NewForm()
	form2.SetPadded(true)

	peer_entry1 := ui.NewEntry()
	peer_entry1.SetText(peerpublic)
	peer_entry2 := ui.NewEntry()
	peer_entry2.SetText(peerip)
	peer_entry3 := ui.NewEntry()
	peer_entry3.SetText(peerallowed)
	peer_entry1.OnChanged(func(e *ui.Entry) {
		peerpublic = e.Text()
		muti.SetText(resetConfig())
	})
	peer_entry2.OnChanged(func(e *ui.Entry) {
		peerip = e.Text()
		muti.SetText(resetConfig())
	})
	peer_entry3.OnChanged(func(e *ui.Entry) {
		peerallowed = e.Text()
		muti.SetText(resetConfig())
	})

	form2.Append("Peer public", peer_entry1, false)
	form2.Append("Endpoint", peer_entry2, false)
	form2.Append("Allowed IPs", peer_entry3, false)
	vbox.Append(form2, false)

	muti.SetText(resetConfig())
	vbox.Append(muti, true)

	win.SetChild(vbox)
	win.SetMargined(true)
	win.Show()
}

func main() {
	ui.Main(setup)
}