package main

import (
	"fmt"
	"log"
	"os"
	"os/signal"
	"path/filepath"
	"syscall"
	"time"

	"github.com/fsnotify/fsnotify"
)

const (
	utmpDir = "/dev/pts/"

	// ANSI转义序列定义颜色
	colorReset  = "\033[0m"
	colorRed    = "\033[31m"
	colorGreen  = "\033[32m"
	colorYellow = "\033[33m"
	colorBlue   = "\033[34m"
	colorPurple = "\033[35m"
	colorCyan   = "\033[36m"
	colorWhite  = "\033[37m"

	// 样式
	bold      = "\033[1m"
	underline = "\033[4m"
)

func main() {
	logFile, err := os.OpenFile("./welcome-service.log", os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
	if err != nil {
		log.Fatal(err)
	}
	defer logFile.Close()
	log.SetOutput(logFile)

	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		log.Fatal(err)
	}
	defer watcher.Close()

	err = watcher.Add(utmpDir)
	if err != nil {
		log.Fatal(err)
	}

	sigChan := make(chan os.Signal, 1)
	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)

	checkExistingTerminals()

	log.Println("Service started")
	for {
		select {
		case event, ok := <-watcher.Events:
			if !ok {
				return
			}
			if event.Op&fsnotify.Create == fsnotify.Create {
				go handleNewTerminal(event.Name)
			}

		case err, ok := <-watcher.Errors:
			if !ok {
				return
			}
			log.Printf("Watcher error: %v", err)

		case sig := <-sigChan:
			log.Printf("Received signal: %v", sig)
			return
		}
	}
}

func checkExistingTerminals() {
	entries, err := os.ReadDir(utmpDir)
	if err != nil {
		log.Printf("Error reading %s: %v", utmpDir, err)
		return
	}

	for _, entry := range entries {
		if !entry.IsDir() {
			go handleNewTerminal(filepath.Join(utmpDir, entry.Name()))
		}
	}
}

func handleNewTerminal(path string) {
	time.Sleep(time.Second)

	f, err := os.OpenFile(path, os.O_WRONLY, 0)
	if err != nil {
		log.Printf("Error opening terminal %s: %v", path, err)
		return
	}
	defer f.Close()

	// 使用颜色和样式的欢迎信息
	welcomeMsg := fmt.Sprintf(`
%s%s╔════════════════════════════════════════════╗%s
%s%s║             Welcome to the System!          ║%s
%s%s║----------------------------------------    ║%s
%s%s║ Terminal: %s%s%-30s%s    ║%s
%s%s║ Time: %s%s%-35s%s    ║%s
%s%s╚════════════════════════════════════════════╝%s
`,
		bold, colorCyan, colorReset,
		bold, colorCyan, colorReset,
		bold, colorCyan, colorReset,
		bold, colorCyan, colorGreen, underline, path, colorCyan, colorReset,
		bold, colorCyan, colorYellow, underline, time.Now().Format("2006-01-02 15:04:05"), colorCyan, colorReset,
		bold, colorCyan, colorReset,
	)

	// 写入欢迎信息
	_, err = f.WriteString(welcomeMsg)
	if err != nil {
		log.Printf("Error writing to terminal %s: %v", path, err)
		return
	}

	// 模拟按下回车键
	_, err = f.Write([]byte{'\n'})
	if err != nil {
		log.Printf("Error sending newline to terminal %s: %v", path, err)
		return
	}

	log.Printf("Welcome message sent to %s", path)
}