package ssh

import (
	"bytes"
	"fmt"
	"io"
	"log"
	"net"
	"os"
	"os/user"
	"path"
	"strings"

	"gitea.meta-tech.academy/go/core/echo"
	"gitea.meta-tech.academy/go/core/sys"
	"gitea.meta-tech.academy/go/core/util"
	"github.com/pkg/sftp"
	"golang.org/x/crypto/ssh"
	"golang.org/x/crypto/ssh/agent"
	"golang.org/x/crypto/ssh/knownhosts"
)

type SshAuth struct {
	Host string `yaml:"host"`
	Type string `yaml:"type"`
	Port int    `yaml:"port"`
	User string `yaml:"user"`
}

type Ssh struct {
	Config  *SshAuth
	Client  *ssh.Client
	Session *ssh.Session
	bar     *io.Writer
	withBar bool
}

func NewSsh(config *SshAuth) *Ssh {
	s := &Ssh{Config: config, withBar: false}
	s.InitDial()
	return s
}

func (s *Ssh) initSession() {
	var err error
	s.Session, err = s.Client.NewSession()
	if err != nil {
		log.Fatal(err)
	}
}

func (s *Ssh) AddBar(bar io.Writer) {
	s.bar = &bar
	s.withBar = true
}

func (s *Ssh) Exec(cmd string, close bool) *bytes.Buffer {
	if close {
		defer s.Client.Close()
	}
	s.initSession()
	defer s.Session.Close()

	var buff bytes.Buffer
	s.Session.Stdout = &buff
	if err := s.Session.Run(cmd); err != nil {
		log.Fatal(err)
	}
	return &buff
}

func (s *Ssh) getHostKeyCB() ssh.HostKeyCallback {
	user, err := user.Current()
	if err != nil {
		log.Fatalf(err.Error())
	}
	hkcb, err := knownhosts.New(fmt.Sprintf("/home/%s/.ssh/known_hosts", user.Username))
	if err != nil {
		panic(err)
	}
	//  return ssh.InsecureIgnoreHostKey()
	return hkcb
}

func (s *Ssh) getSigners() []ssh.Signer {
	sock, err := net.Dial("unix", os.Getenv("SSH_AUTH_SOCK"))
	if err != nil {
		log.Fatal(err)
	}
	agent := agent.NewClient(sock)
	signers, err := agent.Signers()
	if err != nil {
		log.Fatal(err)
	}
	return signers
}

func (s *Ssh) InitDial() {
	auths := []ssh.AuthMethod{ssh.PublicKeys(s.getSigners()...)}
	cfg := &ssh.ClientConfig{
		User:            s.Config.User,
		Auth:            auths,
		HostKeyCallback: s.getHostKeyCB(), // ssh.InsecureIgnoreHostKey(),
	}
	cfg.SetDefaults()
	var err error
	s.Client, err = ssh.Dial(s.Config.Type, fmt.Sprintf("%s:%d", s.Config.Host, s.Config.Port), cfg)
	if err != nil {
		log.Fatal(err)
	}
}

func (s *Ssh) Scp() *sftp.Client {
	scp, err := sftp.NewClient(s.Client)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Unable to start SFTP subsystem: %v\n", err)
		os.Exit(1)
	}
	return scp
}

type ApplyOnSize func(s *Ssh, size int64)

func (s *Ssh) DownloadFile(remoteFile string, localFile string, display bool, close bool, fn ...ApplyOnSize) bool {
	if display {
		echo.Action("Downloading remote file", path.Base(remoteFile))
	}
	done := false
	alreadyDownload := false
	checksum := ""
	buf := s.Exec(fmt.Sprintf("du --apparent-size --block-size=1  \"%s\" | awk '{ print $1}'", remoteFile), false)
	size := util.Str2int64(buf.String(), 10, -1)
	buf.Reset()
	if len(fn) > 0 {
		fn[0](s, size)
	}
	buf = s.Exec(fmt.Sprintf("sha256sum \"%s\" | cut -d' ' -f1", remoteFile), false)
	checksum = strings.TrimSuffix(buf.String(), "\n")
	buf.Reset()
	if sys.CheckFileSize(size, localFile) {
		if display {
			echo.Cstyle("usageCom").Echo("    already downloaded\n")
		}
		alreadyDownload = sys.CheckSumFile(checksum, localFile)
		if display {
			if alreadyDownload {
				echo.Cstyle("usageCom").Echo("    file integrity confirmed\n")
				echo.State(alreadyDownload)
				done = alreadyDownload
			} else {
				echo.Cstyle("podFullName").Echo("    file seems corrupt, retry download\n")
			}
		}
	} else if display {
		echo.Cstyle("podFullName").Echo("    file seems corrupt, retry download\n")
	}
	if !alreadyDownload {
		scp := s.Scp()
		if close {
			defer scp.Close()
		}
		if err := s.downloadFile(size, scp, remoteFile, localFile); err == nil {
			done = sys.CheckSumFile(checksum, localFile)
			if display {
				echo.Cstyle("usageCom").Echo("    file downloaded !\n")
				if done {
					echo.Cstyle("usageCom").Echo("    file integrity confirmed\n")
				} else {
					echo.Cstyle("usageCom").Echo("    file seems corrupt, abort\n")
				}
				echo.State(done)
			}
		} else {
			log.Fatal(err)
		}
	}
	return done
}

func (s *Ssh) ScpDownload(size int64, remoteFile string, localFile string, close bool) bool {
	var done bool = false
	scp := s.Scp()
	if close {
		defer scp.Close()
	}
	if err := s.downloadFile(size, scp, remoteFile, localFile); err == nil {
		done = true
	} else {
		log.Fatal(err)
	}
	return done
}

func (s *Ssh) downloadFile(size int64, sc *sftp.Client, remoteFile string, localFile string) (err error) {

	// Note: SFTP To Go doesn't support O_RDWR mode
	srcFile, err := sc.OpenFile(remoteFile, (os.O_RDONLY))
	if err != nil {
		fmt.Fprintf(os.Stderr, "Unable to open remote file: %v\n", err)
		return
	}
	defer srcFile.Close()
	fmt.Println()

	dstFile, err := os.Create(localFile)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Unable to open local file: %v\n", err)
		return
	}
	defer dstFile.Close()

	if s.withBar {
		_, err = io.Copy(io.MultiWriter(dstFile, *s.bar), srcFile)
	} else {
		_, err = io.Copy(dstFile, srcFile)
	}

	// s.bar.Clear()
	// s.bar.Finish()
	echo.LineUp(1)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Unable to download remote file: %v\n", err)
		os.Exit(1)
	}
	// fmt.Fprintf(os.Stdout, "%d bytes copied\n", bytes)

	return
}