package edgeos

import (
	"fmt"
	"os"
	"os/exec"

	"github.com/nextdns/nextdns/config"
	"github.com/nextdns/nextdns/router/internal"
)

type Router struct {
	DNSMasqPath     string
	ListenPort      string
	ClientReporting bool
	CacheEnabled    bool
}

func New() (*Router, bool) {
	if st, err := os.Stat("/config/scripts/post-config.d"); err != nil || !st.IsDir() {
		if _, err = os.Stat("/etc/ubnt/init/vyatta-router"); err != nil {
			return nil, false
		}
	}
	return &Router{
		DNSMasqPath: "/etc/dnsmasq.d/nextdns.conf",
		ListenPort:  "5342",
	}, true
}

func (r *Router) Configure(c *config.Config) error {
	c.Listens = []string{"127.0.0.1:" + r.ListenPort}
	r.ClientReporting = c.ReportClientInfo
	if cs, _ := config.ParseBytes(c.CacheSize); cs > 0 {
		r.CacheEnabled = true
		c.Listens = []string{":53"}
		return r.setupDNSMasq() // Make dnsmasq stop listening on 53 before we do.
	}
	return nil
}

func (r *Router) Setup() error {
	if !r.CacheEnabled {
		return r.setupDNSMasq()
	}
	return nil
}

func (r *Router) setupDNSMasq() error {
	if err := internal.WriteTemplate(r.DNSMasqPath, tmpl, r, 0644); err != nil {
		return err
	}

	return restartDNSMasq()
}

func (r *Router) Restore() error {
	if err := os.Remove(r.DNSMasqPath); err != nil {
		return err
	}
	return restartDNSMasq()
}

func restartDNSMasq() error {
	if err := exec.Command("sudo", "/etc/init.d/dnsmasq", "restart").Run(); err != nil {
		return fmt.Errorf("dnsmasq restart: %v", err)
	}
	return nil
}

var tmpl = `# Configuration generated by NextDNS
{{- if .CacheEnabled}}
# DNS is handled by NextDNS
port=0
{{- else}}
no-resolv
server=127.0.0.1#{{.ListenPort}}
{{- if .ClientReporting}}
add-mac
add-subnet=32,128
{{- end}}
{{- end}}
`
