package handler

import (
	"bash_go_service/shared/pkg/client"
	"bash_go_service/shared/pkg/constants"
	"bash_go_service/shared/pkg/logger"
	"crypto/md5"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"time"
	"version/api"
)

const (
	updaterExeName = "updater-main"
)

func DoUpdate() {
	logger.Debug("start check updating")
	res, err := api.GetVersion()
	if err != nil {
		logger.Error("Failed to get version: %v", err)
		return
	}
	logger.Debug("res: %v", res)

	if !res.NeedUpdate {
		logger.Info("No update needed.")
		return
	}

	exePath, err := os.Executable()
	if err != nil {
		logger.Error("Failed to get executable path: %v", err)
		return
	}
	exeDir := filepath.Dir(exePath)
	exeBase := filepath.Base(exePath)

	// 备份旧程序
	backupName := fmt.Sprintf("%s.bak.%s", exeBase, time.Now().Format("20060102_150405"))
	backupPath := filepath.Join(exeDir, backupName)
	logger.Debug("backupPath: %v", backupPath)
	err = copyFile(exePath, backupPath)
	if err != nil {
		logger.Error("Failed to backup current executable: %v", err)
		return
	}
	logger.Info("Backup created: %s", backupPath)

	// 下载新程序到临时路径
	newExePath := filepath.Join(exeDir, exeBase+".new")
	cli := client.NewClient()
	query := map[string]string{
		"version": res.Version,
	}
	err = cli.Download(constants.DownloadNewApi, query, newExePath)
	if err != nil {
		logger.Error("Download failed: %v", err)
		_ = os.Rename(backupPath, exePath) // rollback
		return
	}
	logger.Info("New executable downloaded to: %s", newExePath)

	// 🔥 校验 MD5
	if res.MD5 == "" {
		logger.Error("MD5 is empty")
		return
	}
	match, Merr := checkFileMD5(newExePath, res.MD5)
	if Merr != nil {
		logger.Error("Failed to check MD5: %v", Merr)
		_ = os.Rename(backupPath, exePath)
		return
	}
	if !match {
		logger.Error("MD5 mismatch: expected %s", res.MD5)
		_ = os.Rename(backupPath, exePath)
		return
	}
	logger.Info("MD5 checksum verified.")

	// 设置新文件执行权限
	err = os.Chmod(newExePath, 0755)
	if err != nil {
		logger.Error("Failed to set executable permission: %v", err)
		_ = os.Remove(newExePath)
		_ = copyFile(backupPath, exePath)
		return
	}
	logger.Info("Executable permission set for new file.")

	// 启动 updater 进行替换
	updaterPath := filepath.Join(exeDir, updaterExeName)
	cmd := exec.Command(updaterPath, backupPath, newExePath, exePath, "true")
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	err = cmd.Start()
	if err != nil {
		logger.Error("Failed to start updater: %v", err)
		_ = os.Rename(backupPath, exePath)
		return
	}
	logger.Info("Updater started, exiting current process.")
	os.Exit(0)
}

// MD5 校验函数
func checkFileMD5(filePath, expectedMD5 string) (bool, error) {
	f, err := os.Open(filePath)
	if err != nil {
		return false, err
	}
	defer f.Close()

	hash := md5.New()
	if _, err := io.Copy(hash, f); err != nil {
		return false, err
	}
	actualMD5 := fmt.Sprintf("%x", hash.Sum(nil))
	return actualMD5 == expectedMD5, nil
}

// 复制文件函数
func copyFile(src, dst string) error {
	sourceFile, err := os.Open(src)
	if err != nil {
		return err
	}
	defer sourceFile.Close()

	destFile, err := os.Create(dst)
	if err != nil {
		return err
	}
	defer destFile.Close()

	_, err = io.Copy(destFile, sourceFile)
	return err
}