// tera-netd is the minimal privileged dual-Ethernet configuration adapter.
package main

import (
	"context"
	"errors"
	"log"
	"net"
	"os"
	"os/signal"
	"path/filepath"
	"syscall"
	"time"

	"tera-clone/services/tera-api/internal/networkconfig"
	"tera-clone/services/tera-api/internal/networkconfig/netsocket"
)

func main() {
	controller, err := networkconfig.NewOSController(networkconfig.OSOptions{
		InterfacesPath:      getenv("TERA_NETD_INTERFACES", networkconfig.DefaultInterfacesPath),
		RoutingPath:         getenv("TERA_NETD_ROUTING_SCRIPT", networkconfig.DefaultRoutingPath),
		ConfigPath:          getenv("TERA_NETD_CONFIG", networkconfig.DefaultConfigPath),
		PendingPath:         getenv("TERA_NETD_PENDING", networkconfig.DefaultPendingPath),
		HostnamePath:        getenv("TERA_NETD_HOSTNAME_FILE", networkconfig.DefaultHostnamePath),
		HostnameCommandPath: getenv("TERA_NETD_HOSTNAME_COMMAND", "/bin/hostname"),
		IfdownPath:          getenv("TERA_NETD_IFDOWN", "/sbin/ifdown"),
		IfupPath:            getenv("TERA_NETD_IFUP", "/sbin/ifup"),
		IPPath:              getenv("TERA_NETD_IP", "/sbin/ip"),
		PingPath:            getenv("TERA_NETD_PING", "/bin/ping"),
		ShellPath:           getenv("TERA_NETD_SHELL", "/bin/sh"),
		SysClassRoot:        getenv("TERA_NETD_SYS_CLASS_ROOT", "/sys/class/net"),
	})
	if err != nil {
		log.Fatalf("tera-netd setup failed: %v", err)
	}
	recoveryContext, cancelRecovery := context.WithTimeout(context.Background(), 30*time.Second)
	if err := controller.Recover(recoveryContext); err != nil {
		log.Printf("tera-netd recovery incomplete; starting control socket for operator retry: %v", err)
	}
	cancelRecovery()
	monitorContext, stopMonitor := context.WithCancel(context.Background())
	defer stopMonitor()
	go controller.RunOOBMonitor(monitorContext)

	socketPath := getenv("TERA_NETD_SOCKET", netsocket.DefaultSocketPath)
	listener, err := listen(socketPath)
	if err != nil {
		log.Fatalf("tera-netd socket setup failed: %v", err)
	}
	defer func() {
		_ = listener.Close()
		_ = os.Remove(socketPath)
	}()

	server := netsocket.Server{Controller: controller}
	done := make(chan error, 1)
	go func() { done <- server.Serve(listener) }()
	log.Printf("tera-netd serving network control on %s", socketPath)

	signals := make(chan os.Signal, 1)
	signal.Notify(signals, syscall.SIGINT, syscall.SIGTERM)
	select {
	case signal := <-signals:
		log.Printf("tera-netd stopping after %s", signal)
		_ = listener.Close()
		if err := <-done; err != nil {
			log.Printf("tera-netd stop error: %v", err)
		}
	case err := <-done:
		if err != nil {
			log.Fatalf("tera-netd failed: %v", err)
		}
	}
}

func listen(socketPath string) (net.Listener, error) {
	if socketPath == "" || !filepath.IsAbs(socketPath) {
		return nil, errors.New("TERA_NETD_SOCKET must be an absolute path")
	}
	if err := os.MkdirAll(filepath.Dir(socketPath), 0o750); err != nil {
		return nil, err
	}
	if info, err := os.Lstat(socketPath); err == nil {
		if info.Mode()&os.ModeSocket == 0 {
			return nil, errors.New("refusing to replace non-socket network control path")
		}
		if err := os.Remove(socketPath); err != nil {
			return nil, err
		}
	} else if !os.IsNotExist(err) {
		return nil, err
	}
	listener, err := net.Listen("unix", socketPath)
	if err != nil {
		return nil, err
	}
	if err := os.Chmod(socketPath, 0o660); err != nil {
		_ = listener.Close()
		return nil, err
	}
	return listener, nil
}

func getenv(key, fallback string) string {
	if value := os.Getenv(key); value != "" {
		return value
	}
	return fallback
}