package service

import (
	"fmt"
	"io"
	"io/fs"
	"io/ioutil"
	"log"
	"net"
	"os"
	"path"
	"path/filepath"
	"runtime"
	"sync"
	"time"

	"github.com/pkg/errors"
	"github.com/pkg/sftp"
	"github.com/sirupsen/logrus"
	"golang.org/x/crypto/ssh"
)

var sftpCli *sftp.Client
var sftpOne sync.Once

type SSHService struct {
	Client     *ssh.Client
	LastResult string //执行结果
}

func NewSSHService() *SSHService {
	ss := &SSHService{}
	return ss
}

func (ss *SSHService) Connect(user, password, host, key string, port int, cipherList []string) error {
	var (
		auth         []ssh.AuthMethod //认证方式
		addr         string
		clientConfig *ssh.ClientConfig
		config       ssh.Config
		err          error
	)
	auth = make([]ssh.AuthMethod, 0)
	if key == "" {
		// 密码认证
		auth = append(auth, ssh.Password(password))
	} else {
		// 秘钥认证
		pemBytes, err := ioutil.ReadFile(key)
		if err != nil {
			return err
		}

		var signer ssh.Signer
		if password == "" {
			signer, err = ssh.ParsePrivateKey(pemBytes)
		} else {
			signer, err = ssh.ParsePrivateKeyWithPassphrase(pemBytes, []byte(password))
		}

		if err != nil {
			return err
		}
		// 加载秘钥
		auth = append(auth, ssh.PublicKeys(signer))
	}

	// 设置ssh 的配置参数
	if len(cipherList) == 0 {
		config = ssh.Config{
			// 连接所允许的加密算法， go的SSH包允许的算法
			Ciphers: []string{"aes128-ctr", "aes192-ctr", "aes256-ctr", "aes128-gcm@openssh.com", "arcfour256", "arcfour128", "aes128-cbc", "3des-cbc", "aes192-cbc", "aes256-cbc"},
		}
	} else {
		config = ssh.Config{
			Ciphers: cipherList,
		}
	}

	clientConfig = &ssh.ClientConfig{
		User:    user,
		Auth:    auth,
		Timeout: time.Second * 30,
		Config:  config,
		// 默认密钥不受信任时，Go 的 ssh 包会在 HostKeyCallback 里把连接干掉（1.8 之后加的应该）。但是我们使用用户名密码连接的时候，这个太正常了，所以让他 return nil 就好了
		HostKeyCallback: func(hostname string, remote net.Addr, key ssh.PublicKey) error {
			return nil
		},
	}
	addr = fmt.Sprintf("%s:%d", host, port)

	if ss.Client, err = ssh.Dial("tcp", addr, clientConfig); err != nil {
		return err
	}

	sftpCli, err = sftp.NewClient(ss.Client)
	return nil
}

func (ss *SSHService) getSftp() (*sftp.Client, error) {
	if ss.Client == nil {
		return nil, errors.New("ssh client is nil")
	}
	var err error
	sftpOne.Do(func() {
		if sftpCli, err = sftp.NewClient(ss.Client); err != nil {
			return
		}
	})
	return sftpCli, nil
}

func (ss *SSHService) Close() {
	if ss.Client != nil {
		if err := ss.Client.Close(); err != nil {
			logrus.WithField("err", err).Error("close ssh err")
		}
	}
	// if sftpCli != nil {
	// 	if err := sftpCli.Close(); err != nil {
	// 		logrus.WithField("err", err).Error("close sftp err")
	// 	}
	// }
}

func (ss *SSHService) RunShell(shell string) {
	var (
		session *ssh.Session
		err     error
	)

	//获取session，这个session是用来远程执行操作的
	if session, err = ss.Client.NewSession(); err != nil {
		logrus.Errorf("error newsession:%v", err)
	}
	// 使用 session.Shell() 模拟终端时，所建立的终端参数
	modes := ssh.TerminalModes{
		ssh.ECHO:          0,     //disable echoing
		ssh.TTY_OP_ISPEED: 14400, //input speed=14.4kbaud
		ssh.TTY_OP_OSPEED: 14400,
	}

	if err := session.RequestPty("xterm", 80, 40, modes); err != nil {
		logrus.Error(err)
	}

	//执行shell
	if output, err := session.CombinedOutput(shell); err != nil {
		logrus.Errorf("error CombinedOutput:%v", err)
	} else {
		ss.LastResult = string(output)
	}
}

//单个copy
func (ss *SSHService) ScpCopy(localFilePath, remoteDir string) error {
	var (
		err error
	)

	fi, err := os.Stat(localFilePath)
	if err != nil {
		return err
	}
	if fi.IsDir() {
		return errors.New(localFilePath + " is not file")
	}

	sftpCli, err = ss.getSftp()
	if err != nil {
		return fmt.Errorf("new sftp client error: %w", err)
	}

	// defer sftpCli.Close()

	srcFile, err := os.Open(localFilePath)
	if err != nil {
		log.Println("scpCopy:", err)
		return err
	}
	defer srcFile.Close()

	var remoteFileName string
	sysTyep := runtime.GOOS
	if sysTyep == "windows" {
		remoteFileName = path.Base(filepath.ToSlash(localFilePath))
	} else {
		remoteFileName = path.Base(localFilePath)
	}

	dstFile, err := sftpCli.Create(path.Join(remoteDir, remoteFileName))
	if err != nil {
		log.Println("scpCopy:", err)
		return err
	}
	defer dstFile.Close()

	fileByte, err := ioutil.ReadAll(srcFile)
	if nil != err {
		return fmt.Errorf("read local file failed: %w", err)
	}

	if _, err := dstFile.Write(fileByte); err != nil {
		return err
	}

	return nil
}

//批量copy
func (ss *SSHService) BatchScpCoy(cfs []CopyFiles, remoteDir string) error {
	var err error
	sftpCli, err = ss.getSftp()
	if err != nil {
		return fmt.Errorf("new sftp client error: %w", err)
	}

	for _, f := range cfs {
		srcFile, err := os.Open(path.Join(f.Dir, f.FileName))
		if err != nil {
			return err
		}
		defer srcFile.Close()

		dstFile, err := sftpCli.Create(path.Join(remoteDir, f.FileName))
		if err != nil {
			logrus.Error("scpCopy:", err)
			return err
		}
		defer dstFile.Close()

		fileByte, err := ioutil.ReadAll(srcFile)
		if nil != err {
			return fmt.Errorf("read local file failed: %w", err)
		}

		if _, err := dstFile.Write(fileByte); err != nil {
			return err
		}
	}

	return nil
}

//Deprecated Scp
func (ss *SSHService) Scp(targetDir, srcFileName string) (int, error) {
	sftpClient, err := sftp.NewClient(ss.Client)
	if err != nil {
		return 0, fmt.Errorf("new sftp client error: %w", err)
	}
	defer sftpClient.Close()
	// source, err := sftpClient.Open(srcFileName)
	// if err != nil {
	// 	return 0, fmt.Errorf("sftp client open src file error: %w", err)
	// }
	// defer source.Close()
	srcFile, err := os.Open(srcFileName)
	if err != nil {
		return 0, fmt.Errorf("open local file error: %w", err)
	}
	defer srcFile.Close()

	var remoteFileName = path.Base(srcFileName)
	dstFile, err := sftpClient.Create(path.Join(targetDir, remoteFileName))
	if err != nil {
		fmt.Errorf("scpCopy:%v", err)
		return 0, err
	}
	// n, err := io.Copy(target, source)
	if err != nil {
		return 0, fmt.Errorf("copy file error: %w", err)
	}
	defer dstFile.Close()

	buf := make([]byte, 1024)
	n := 0
	for {
		n, _ = srcFile.Read(buf)
		if n == 0 {
			break
		}
		dstFile.Write(buf[0:n])
	}
	return n, nil
}

//Download
func (ss *SSHService) ScpDownload(localDir, remoteFilePath string) error {
	var err error
	sftpCli, err = ss.getSftp()
	if err != nil {
		return fmt.Errorf("new sftp client error: %w", err)
	}

	remoteFile, err := sftpCli.Open(remoteFilePath)
	if err != nil {
		log.Println("scpCopy:", err)
		return err
	}
	defer remoteFile.Close()

	fileName := path.Base(remoteFile.Name())

	if err := os.MkdirAll(localDir, fs.ModePerm); err != nil {
		logrus.Error(err)
		return err
	}

	target, err := os.OpenFile(localDir+fileName, os.O_RDWR|os.O_CREATE|os.O_TRUNC, fs.ModePerm)
	if err != nil {
		return fmt.Errorf("open local file error: %w", err)
	}
	defer target.Close()

	_, err = io.Copy(target, remoteFile)
	if err != nil {
		return fmt.Errorf("write file error: %w", err)
	}
	return nil
}

func (ss *SSHService) GetRemoteDir(remoteDir string) (files []File, err error) {
	sftpCli, err = ss.getSftp()
	if err != nil {
		return nil, fmt.Errorf("new sftp client error: %w", err)
	}

	remoteFiles, err := sftpCli.ReadDir(remoteDir)
	if err != nil {
		log.Println("read remote Dir:", err)
		return nil, err
	}

	for _, f := range remoteFiles {
		fi := File{
			FileName: f.Name(),
			FilePath: filepath.Join(remoteDir, f.Name()),
			Size:     f.Size(),
		}
		files = append(files, fi)
		// logrus.WithFields(logrus.Fields{"name": f.Name(), "size": f.Size()}).Debug("远程日志文件")
	}
	return
}

func (ss *SSHService) BatchScpDownload(localDir, remoteDir string) error {
	var err error
	sftpCli, err = ss.getSftp()
	if err != nil {
		return fmt.Errorf("new sftp client error: %w", err)
	}

	remoteFiles, err := sftpCli.ReadDir(remoteDir)
	if err != nil {
		log.Println("read remote Dir:", err)
		return err
	}

	for _, f := range remoteFiles {
		if err := ss.ScpDownload(localDir, filepath.Join(remoteDir, f.Name())); err != nil {
			return err
		}
	}

	return nil
}

type CopyFiles struct {
	Dir      string
	FileName string
}

type File struct {
	FileName string
	FilePath string
	Size     int64
}