// Copyright 2020 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.

package cliutil

import (
	"io/ioutil"

	"github.com/ScaleFT/sshkeys"
	"github.com/pingcap-incubator/tiup-cluster/pkg/errutil"
	"golang.org/x/crypto/ssh"
)

var (
	// ErrIdentityFileReadFiled is ErrIdentityFileReadFiled
	ErrIdentityFileReadFiled = errNS.NewType("id_read_failed", errutil.ErrTraitPreCheck)
)

// SSHConnectionProps is SSHConnectionProps
type SSHConnectionProps struct {
	Password               string
	IdentityFile           string
	IdentityFilePassphrase string
}

// ReadIdentityFileOrPassword is ReadIdentityFileOrPassword
func ReadIdentityFileOrPassword(identityFilePath string, usePass bool) (*SSHConnectionProps, error) {
	// If identity file is not specified, prompt to read password
	if usePass {
		password := PromptForPassword("Input SSH password: ")
		return &SSHConnectionProps{
			Password: password,
		}, nil
	}

	// Identity file is specified, check identity file
	buf, err := ioutil.ReadFile(identityFilePath)
	if err != nil {
		return nil, ErrIdentityFileReadFiled.
			Wrap(err, "Failed to read SSH identity file '%s'", identityFilePath).
			WithProperty(SuggestionFromTemplate(`
Please check whether your SSH identity file {{ColorKeyword}}{{.File}}{{ColorReset}} exists and have access permission.
`, map[string]string{
				"File": identityFilePath,
			}))
	}

	// Try to decode as not encrypted
	_, err = ssh.ParsePrivateKey(buf)
	if err == nil {
		return &SSHConnectionProps{
			IdentityFile: identityFilePath,
		}, nil
	}

	// Other kind of error.. e.g. not a valid SSH key
	if _, ok := err.(*ssh.PassphraseMissingError); !ok {
		return nil, ErrIdentityFileReadFiled.
			Wrap(err, "Failed to read SSH identity file '%s'", identityFilePath).
			WithProperty(SuggestionFromTemplate(`
Looks like your SSH private key {{ColorKeyword}}{{.File}}{{ColorReset}} is invalid.
`, map[string]string{
				"File": identityFilePath,
			}))
	}

	// SSH key is passphrase protected
	passphrase := PromptForPassword("The SSH identity key is encrypted. Input its passphrase: ")
	if _, err := sshkeys.ParseEncryptedPrivateKey(buf, []byte(passphrase)); err != nil {
		return nil, ErrIdentityFileReadFiled.
			Wrap(err, "Failed to decrypt SSH identity file '%s'", identityFilePath)
	}

	return &SSHConnectionProps{
		IdentityFile:           identityFilePath,
		IdentityFilePassphrase: passphrase,
	}, nil
}