package service

import (
	"bufio"
	"context"
	"fmt"
	"log"
	"os"
	"os/exec"
	"os/signal"
	"syscall"

	"github.com/spf13/viper"
)

func RunService() {

	args := viper.GetStringSlice("java.args")
	args = append(args, "-jar")
	args = append(args, viper.GetString("server.jar"))
	args = append(args, "--nogui")
	log.Println("Java: ", viper.GetString("java.path"), " Args: ", args)

	cmd := exec.Command(viper.GetString("java.path"), args...)

	// Open all three pipes
	stdin, err := cmd.StdinPipe()
	  if err != nil {
      log.Fatal(err)
  }
  stdout, err := cmd.StdoutPipe()
  if err != nil {
      log.Fatal(err)
  }
  stderr, err := cmd.StderrPipe()
  if err != nil {
      log.Fatal(err)
  }

	// Start process
  if err := cmd.Start(); err != nil {
      log.Fatal(err)
  }

	// forward stdout and stderr
	go func() {
      sc := bufio.NewScanner(stdout)
      for sc.Scan() {
					fmt.Fprintln(os.Stdout, sc.Text())
      }
  }()

	go func() {
      sc := bufio.NewScanner(stderr)
      for sc.Scan() {
					fmt.Fprintln(os.Stderr, sc.Text())
      }
  }()

	// Separate Channel for handling SIGHUP
  hupCh := make(chan os.Signal, 1)
  signal.Notify(hupCh, syscall.SIGHUP)

	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()
	<- ctx.Done()

  for {
		select {
    case <-hupCh:
         	log.Println("Sending reload signal to Server Process")
          if _, err := stdin.Write([]byte("reload\n")); err != nil {
            log.Printf("write error: %v", err)
          }
    case <-ctx.Done():
         	log.Println("Sending stop signal to Server Process")
          if _, err := stdin.Write([]byte("stop\n")); err != nil {
            log.Printf("write error: %v", err)
          }
        	if err := cmd.Wait(); err != nil {
                log.Printf("child exit: %v", err)
          }
					log.Println("Shutdown completed")
          return
    }
  }


}