package main

import (
	"fmt"
	"github.com/go-git/go-git/v5"
	"golang.org/x/crypto/ssh"
	"golang.org/x/crypto/ssh/knownhosts"
	"io/ioutil"
	"os"
)

const (
	PublicKeysName = "ssh-public-keys"
)

// PublicKeys implements AuthMethod by using the given key pairs.
type PublicKeys struct {
	User      string
	KnownHost string
	Signer    ssh.Signer
}

func NewPublicKeys(user string, pemBytes []byte, knownHost, password string) (*PublicKeys, error) {
	signer, err := ssh.ParsePrivateKey(pemBytes)
	if _, ok := err.(*ssh.PassphraseMissingError); ok {
		signer, err = ssh.ParsePrivateKeyWithPassphrase(pemBytes, []byte(password))
	}
	if err != nil {
		return nil, err
	}
	return &PublicKeys{User: user, KnownHost: knownHost, Signer: signer}, nil
}

func (a *PublicKeys) Name() string {
	return PublicKeysName
}

func (a *PublicKeys) String() string {
	return fmt.Sprintf("user: %s, name: %s", a.User, a.Name())
}

func (a *PublicKeys) ClientConfig() (*ssh.ClientConfig, error) {
	hostKeyCallback, err := knownhosts.New(a.KnownHost)
	if err != nil {
		return nil, fmt.Errorf("client config %+v", err)
	}

	return &ssh.ClientConfig{
		User:            a.User,
		Auth:            []ssh.AuthMethod{ssh.PublicKeys(a.Signer)},
		HostKeyCallback: hostKeyCallback,
	}, nil
}

// CheckIfError should be used to naively panics if an error is not nil.
func CheckIfError(err error, track string) {
	if err == nil {
		return
	}

	fmt.Printf("\x1b[31;1m%s\x1b[0m\n", fmt.Sprintf("track:%s error: %s", track, err))
	os.Exit(1)
}

func GetAuth() (*PublicKeys, error) {
	sshKey, _ := ioutil.ReadFile("/home/demo1/.deploy/9CaCEM6QhP4jdP3DyhWYzbYCrJVFkhLC0B3Nwki59Nod45r6OmVZMVASnww9")
	publicKeys, err := NewPublicKeys("git", sshKey, "/home/demo1/.deploy/known_hosts", "")

	if err != nil {
		return nil, fmt.Errorf("NewPublicKeys failed %+v", err)
	}

	return publicKeys, nil
}

func pull(path string, auth *PublicKeys) {
	// We instantiate a new repository targeting the given path (the .git folder)
	r, err := git.PlainOpen(path)
	CheckIfError(err, "2")

	// Get the working directory for the repository
	w, err := r.Worktree()
	CheckIfError(err, "3")

	err = w.Pull(&git.PullOptions{
		// RemoteName: "origin",
		SingleBranch: true,
		Auth:         auth,
		Progress:     os.Stdout,
	})
	CheckIfError(err, "5")

	// Print the latest commit that was just pulled
	ref, err := r.Head()
	CheckIfError(err, "6")
	commit, err := r.CommitObject(ref.Hash())
	CheckIfError(err, "7")

	fmt.Println(commit)
}

// Pull changes from a remote repository
func main() {
	path := "/home/demo1/.deploy/repos/json"

       // ssh-keyscan -H github.com >> /home/demo1/.deploy/known_hosts
	err := os.Setenv("SSH_KNOWN_HOSTS", "/home/demo1/.deploy/known_hosts")

	auth, err := GetAuth()
	CheckIfError(err, "4")

	// clone is working

	/*	r, err := git.PlainClone(path, false, &git.CloneOptions{
			Auth:     auth,
			URL:      "git@github.com:surjit/json.git",
			Progress: os.Stdout,
			Depth:    1,
		})

		CheckIfError(err, "1")
		fmt.Printf("r %+v\n", r)
	*/

	// not working
	pull(path, auth)
}