package main

import (
	"bufio"
	"embed"
	"errors"
	"flag"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"strings"
)

// deploymentAssets contains everything needed to register and manage the services.
//
//go:embed .env.example install.sh start.sh stop.sh restart.sh deploy/*.service
var deploymentAssets embed.FS

var validServicePrefix = regexp.MustCompile(`^[A-Za-z0-9][A-Za-z0-9_.-]*$`)

var assetModes = map[string]os.FileMode{
	"install.sh":               0o755,
	"start.sh":                 0o755,
	"stop.sh":                  0o755,
	"restart.sh":               0o755,
	".env.example":             0o644,
	"deploy/server.service":    0o644,
	"deploy/cli.service":       0o644,
	"deploy/scheduler.service": 0o644,
}

func main() {
	prefixFlag := flag.String("prefix", "", "systemd 服务名前缀；未指定时交互输入")
	flag.Parse()

	if runtime.GOOS != "linux" {
		fatalf("初始化工具只能在 Linux 服务器上运行")
	}
	if err := requireRoot(); err != nil {
		fatalf("%v", err)
	}

	appDir, err := executableDir()
	if err != nil {
		fatalf("获取程序目录失败: %v", err)
	}

	prefix, err := resolvePrefix(*prefixFlag, os.Stdin, os.Stdout)
	if err != nil {
		fatalf("读取项目前缀失败: %v", err)
	}

	if err := extractAssets(appDir); err != nil {
		fatalf("释放部署文件失败: %v", err)
	}
	envCreated, err := initializeEnv(appDir)
	if err != nil {
		fatalf("初始化 .env 失败: %v", err)
	}
	if err := os.WriteFile(filepath.Join(appDir, ".service-prefix"), []byte(prefix+"\n"), 0o644); err != nil {
		fatalf("保存项目前缀失败: %v", err)
	}

	fmt.Printf("部署文件已释放到 %s\n", appDir)
	if envCreated {
		fmt.Println("已根据 .env.example 初始化 .env，请按实际环境修改配置")
	} else {
		fmt.Println("检测到已有 .env，已保留现有配置")
	}
	fmt.Printf("正在注册服务: %s-server, %s-cli, %s-scheduler\n", prefix, prefix, prefix)

	install := exec.Command("bash", filepath.Join(appDir, "install.sh"))
	install.Dir = appDir
	install.Stdin = os.Stdin
	install.Stdout = os.Stdout
	install.Stderr = os.Stderr
	if err := install.Run(); err != nil {
		fatalf("install.sh 执行失败: %v", err)
	}
}

func requireRoot() error {
	uid, err := exec.Command("id", "-u").Output()
	if err != nil {
		return fmt.Errorf("无法检查当前用户权限: %w", err)
	}
	if strings.TrimSpace(string(uid)) != "0" {
		return errors.New("请使用 root 权限运行: sudo ./initializer")
	}
	return nil
}

func executableDir() (string, error) {
	filename, err := os.Executable()
	if err != nil {
		return "", err
	}
	filename, err = filepath.Abs(filename)
	if err != nil {
		return "", err
	}
	return filepath.Dir(filename), nil
}

func resolvePrefix(value string, in io.Reader, out io.Writer) (string, error) {
	prefix := strings.TrimSpace(value)
	if prefix == "" {
		if _, err := fmt.Fprint(out, "请输入项目前缀（例如 myapp）: "); err != nil {
			return "", err
		}
		line, err := bufio.NewReader(in).ReadString('\n')
		if err != nil && !errors.Is(err, io.EOF) {
			return "", err
		}
		prefix = strings.TrimSpace(line)
	}

	if !validServicePrefix.MatchString(prefix) {
		return "", fmt.Errorf("%q 不是有效前缀，只允许字母、数字、点、下划线和连字符，且必须以字母或数字开头", prefix)
	}
	return prefix, nil
}

func extractAssets(appDir string) error {
	for name, mode := range assetModes {
		content, err := deploymentAssets.ReadFile(name)
		if err != nil {
			return fmt.Errorf("读取 %s: %w", name, err)
		}
		target := filepath.Join(appDir, filepath.FromSlash(name))
		if err := os.MkdirAll(filepath.Dir(target), 0o755); err != nil {
			return fmt.Errorf("创建 %s: %w", filepath.Dir(target), err)
		}
		if err := os.WriteFile(target, content, mode); err != nil {
			return fmt.Errorf("写入 %s: %w", target, err)
		}
		if err := os.Chmod(target, mode); err != nil {
			return fmt.Errorf("设置 %s 权限: %w", target, err)
		}
	}
	return nil
}

func initializeEnv(appDir string) (bool, error) {
	target := filepath.Join(appDir, ".env")
	if _, err := os.Stat(target); err == nil {
		return false, nil
	} else if !errors.Is(err, os.ErrNotExist) {
		return false, err
	}

	content, err := deploymentAssets.ReadFile(".env.example")
	if err != nil {
		return false, err
	}
	if err := os.WriteFile(target, content, 0o600); err != nil {
		return false, err
	}
	return true, nil
}

func fatalf(format string, args ...any) {
	fmt.Fprintf(os.Stderr, "错误: "+format+"\n", args...)
	os.Exit(1)
}