package sshutil

import (
	"fmt"
	"io/ioutil"
	"net"
	"time"

	"golang.org/x/crypto/ssh"
)

func Connect(user, password, host, key, passphrase string, port int) (*ssh.Client, error) {
	var (
		auth         []ssh.AuthMethod
		addr         string
		clientConfig *ssh.ClientConfig
		config       ssh.Config
		pemBytes     []byte
		err          error
	)

	// Determine if the key value is filled in. If you fill it out, use key authentication.
	// If not filled in, use the username and password to authenticate.
	auth = make([]ssh.AuthMethod, 0)
	if key == "" {
		auth = append(auth, ssh.Password(password))
	} else {
		pemBytes, err = ioutil.ReadFile(key)
		if err != nil {
			return nil, err
		}

		var signer ssh.Signer
		if passphrase == "" {
			signer, err = ssh.ParsePrivateKey(pemBytes)
		} else {
			signer, err = ssh.ParsePrivateKeyWithPassphrase(pemBytes, []byte(passphrase))
		}
		if err != nil {
			return nil, err
		}
		auth = append(auth, ssh.PublicKeys(signer))
	}

	// provide a full cipher list instead of specify a cipher list
	config = ssh.Config{
		Ciphers: []string{
			"aes128-ctr",
			"aes192-ctr",
			"aes256-ctr",
			"aes128-gcm@openssh.com",
			"arcfour256",
			"arcfour128",
			"aes128-cbc",
			"3des-cbc",
			"aes192-cbc",
			"aes256-cbc",
		},
	}

	clientConfig = &ssh.ClientConfig{
		User:    user,
		Auth:    auth,
		Timeout: 30 * time.Second,
		Config:  config,
		HostKeyCallback: func(hostname string, remote net.Addr, key ssh.PublicKey) error {
			return nil
		},
	}

	addr = fmt.Sprintf("%s:%d", host, port)

	return ssh.Dial("tcp", addr, clientConfig)
}