package lib

import (
	"fmt"
	"net"
	"os"
	"strings"
	"time"
)

// UpdateVPNStatus periodically update status of openvpn daemon.
func (c *MyConfig) UpdateVPNStatus() {
	var (
		vpnCStatus         string
		vpnCheck           string
		b                  strings.Builder
		InitialDelay       = 100 * time.Millisecond
		LoopIterationDelay = 3 * time.Second
		Delay              = InitialDelay
		ticker             = time.NewTicker(Delay)
	)

	for range ticker.C {
		if Delay == InitialDelay {
			Delay = LoopIterationDelay
			ticker.Reset(Delay)
		}

		if c.VPNFileCheck() {
			if c.Vpn.UpColor == "" {
				b.WriteRune('⍋')
			} else {
				b.WriteString("<span foreground=\"")
				b.WriteString(c.Vpn.UpColor)
				b.WriteString("\">⍋</span>")
			}
		} else {
			if c.Vpn.DownColor == "" {
				b.WriteRune('⍒')
			} else {
				b.WriteString("<span foreground=\"")
				b.WriteString(c.Vpn.DownColor)
				b.WriteString("\">⍒</span>")
			}
		}

		vpnCheck = b.String()
		b.Reset()

		if c.Vpn.TCPCheck.Enabled {
			if c.VPNTCPCheck() {
				if c.Vpn.UpColor == "" {
					b.WriteRune('✔')
				} else {
					b.WriteString("<span foreground=\"")
					b.WriteString(c.Vpn.UpColor)
					b.WriteString("\">✔</span>")
				}
			} else {
				if c.Vpn.DownColor == "" {
					b.WriteRune('✘')
				} else {
					b.WriteString("<span foreground=\"")
					b.WriteString(c.Vpn.DownColor)
					b.WriteString("\">✘</span>")
				}
			}

			vpnCStatus = "VPN:" + vpnCheck + ":" + b.String()
		} else {
			vpnCStatus = "VPN:" + vpnCheck
		}

		if c.Values.VPNStatus != vpnCStatus {
			c.Values.VPNStatus = vpnCStatus
			c.Channels.UpdateReady <- true
		}
	}
}

// VPNTCPCheck intended to check arbitrary service inside vpn segment, to indicate that openvpn service not stoned.
func (c *MyConfig) VPNTCPCheck() bool {
	conn, err := net.DialTimeout( //nolint: noctx
		"tcp",
		fmt.Sprintf("%s:%d", c.Vpn.TCPCheck.Host, c.Vpn.TCPCheck.Port), //nolint: hostport
		time.Second*time.Duration(c.Vpn.TCPCheck.Timeout),
	)

	if err == nil {
		_ = conn.Close()

		return true
	}

	return false
}

// VPNFileCheck checks modification time of openvpn-status file.
func (c *MyConfig) VPNFileCheck() bool {
	var (
		fi  os.FileInfo
		err error
	)

	if fi, err = os.Stat(c.Vpn.StatusFile); err != nil {
		return false
	}

	if time.Since(fi.ModTime()).Seconds() > float64(c.Vpn.MtimeThreshold) {
		return false
	}

	return true
}

/* vim: set ft=go noet ai ts=4 sw=4 sts=4: */