// tera-hwd is the minimal privileged hardware adapter for TERA board controls.
package main

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

	"tera-clone/services/tera-api/internal/hardware/greenled"
	"tera-clone/services/tera-api/internal/hardware/greenledsocket"
	"tera-clone/services/tera-api/internal/hardware/systemcontrol"
)

func main() {
	greenSocketPath := getenv("TERA_HWD_GREEN_LED_SOCKET", greenledsocket.DefaultSocketPath)
	systemSocketPath := getenv("TERA_HWD_SYSTEM_SOCKET", systemcontrol.DefaultSocketPath)
	sysfsRoot := getenv("TERA_HWD_GREEN_LED_SYSFS_ROOT", greenled.DefaultSysfsRoot)
	resetButtonPath := getenv("TERA_HWD_RESET_BUTTON_VALUE_PATH", "/sys/class/gpio/manual_KeyReset/value")
	greenListener, err := listen(greenSocketPath, "TERA_HWD_GREEN_LED_SOCKET")
	if err != nil {
		log.Fatalf("tera-hwd green LED socket setup failed: %v", err)
	}
	systemListener, err := listen(systemSocketPath, "TERA_HWD_SYSTEM_SOCKET")
	if err != nil {
		_ = greenListener.Close()
		_ = os.Remove(greenSocketPath)
		log.Fatalf("tera-hwd system socket setup failed: %v", err)
	}
	defer func() {
		_ = greenListener.Close()
		_ = systemListener.Close()
		_ = os.Remove(greenSocketPath)
		_ = os.Remove(systemSocketPath)
	}()

	greenServer := greenledsocket.Server{Controller: greenled.NewSysfsController(sysfsRoot)}
	systemServer := systemcontrol.Server{
		Controller:  systemcontrol.CommandController{RebootCommand: "/sbin/reboot"},
		ResetButton: systemcontrol.SysfsResetButton{ValuePath: resetButtonPath, ActiveLow: true},
	}
	done := make(chan error, 2)
	go func() { done <- greenServer.Serve(greenListener) }()
	go func() { done <- systemServer.Serve(systemListener) }()
	log.Printf("tera-hwd serving green LED control on %s and system control on %s", greenSocketPath, systemSocketPath)

	signals := make(chan os.Signal, 1)
	signal.Notify(signals, syscall.SIGINT, syscall.SIGTERM)
	remaining := 2
	select {
	case signal := <-signals:
		log.Printf("tera-hwd stopping after %s", signal)
	case err := <-done:
		remaining--
		if err != nil {
			log.Printf("tera-hwd service failed: %v", err)
		}
	}
	_ = greenListener.Close()
	_ = systemListener.Close()
	for remaining > 0 {
		if err := <-done; err != nil {
			log.Printf("tera-hwd stop error: %v", err)
		}
		remaining--
	}
}

func listen(socketPath, variable string) (net.Listener, error) {
	if socketPath == "" || !filepath.IsAbs(socketPath) {
		return nil, errors.New(variable + " 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 hardware 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
}