/*
Copyright 2021 The Kubernetes Authors.

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,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package v1

import (
	"fmt"
	"sort"
	"strings"
	"time"

	"github.com/pkg/errors"

	v1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	bootstrapapi "k8s.io/cluster-bootstrap/token/api"
	bootstraputil "k8s.io/cluster-bootstrap/token/util"
	bootstrapsecretutil "k8s.io/cluster-bootstrap/util/secrets"
)

const (
	// When a token is matched with 'BootstrapTokenPattern', the size of validated substrings returned by
	// regexp functions which contains 'Submatch' in their names will be 3.
	// Submatch 0 is the match of the entire expression, submatch 1 is
	// the match of the first parenthesized subexpression, and so on.
	// e.g.:
	// result := bootstraputil.BootstrapTokenRegexp.FindStringSubmatch("abcdef.1234567890123456")
	// result == []string{"abcdef.1234567890123456","abcdef","1234567890123456"}
	// len(result) == 3
	validatedSubstringsSize = 3
)

// MarshalJSON implements the json.Marshaler interface.
func (bts BootstrapTokenString) MarshalJSON() ([]byte, error) {
	return []byte(fmt.Sprintf(`"%s"`, bts.String())), nil
}

// UnmarshalJSON implements the json.Unmarshaller interface.
func (bts *BootstrapTokenString) UnmarshalJSON(b []byte) error {
	// If the token is represented as "", just return quickly without an error
	if len(b) == 0 {
		return nil
	}

	// Remove unnecessary " characters coming from the JSON parser
	token := strings.Replace(string(b), `"`, ``, -1)
	// Convert the string Token to a BootstrapTokenString object
	newbts, err := NewBootstrapTokenString(token)
	if err != nil {
		return err
	}
	bts.ID = newbts.ID
	bts.Secret = newbts.Secret
	return nil
}

// String returns the string representation of the BootstrapTokenString
func (bts BootstrapTokenString) String() string {
	if len(bts.ID) > 0 && len(bts.Secret) > 0 {
		return bootstraputil.TokenFromIDAndSecret(bts.ID, bts.Secret)
	}
	return ""
}

// NewBootstrapTokenString converts the given Bootstrap Token as a string
// to the BootstrapTokenString object used for serialization/deserialization
// and internal usage. It also automatically validates that the given token
// is of the right format
func NewBootstrapTokenString(token string) (*BootstrapTokenString, error) {
	substrs := bootstraputil.BootstrapTokenRegexp.FindStringSubmatch(token)
	if len(substrs) != validatedSubstringsSize {
		return nil, errors.Errorf("the bootstrap token %q was not of the form %q", token, bootstrapapi.BootstrapTokenPattern)
	}

	return &BootstrapTokenString{ID: substrs[1], Secret: substrs[2]}, nil
}

// NewBootstrapTokenStringFromIDAndSecret is a wrapper around NewBootstrapTokenString
// that allows the caller to specify the ID and Secret separately
func NewBootstrapTokenStringFromIDAndSecret(id, secret string) (*BootstrapTokenString, error) {
	return NewBootstrapTokenString(bootstraputil.TokenFromIDAndSecret(id, secret))
}

// BootstrapTokenToSecret converts the given BootstrapToken object to its Secret representation that
// may be submitted to the API Server in order to be stored.
func BootstrapTokenToSecret(bt *BootstrapToken) *v1.Secret {
	return &v1.Secret{
		ObjectMeta: metav1.ObjectMeta{
			Name:      bootstraputil.BootstrapTokenSecretName(bt.Token.ID),
			Namespace: metav1.NamespaceSystem,
		},
		Type: bootstrapapi.SecretTypeBootstrapToken,
		Data: encodeTokenSecretData(bt, time.Now()),
	}
}

// encodeTokenSecretData takes the token discovery object and an optional duration and returns the .Data for the Secret
// now is passed in order to be able to used in unit testing
func encodeTokenSecretData(token *BootstrapToken, now time.Time) map[string][]byte {
	data := map[string][]byte{
		bootstrapapi.BootstrapTokenIDKey:     []byte(token.Token.ID),
		bootstrapapi.BootstrapTokenSecretKey: []byte(token.Token.Secret),
	}

	if len(token.Description) > 0 {
		data[bootstrapapi.BootstrapTokenDescriptionKey] = []byte(token.Description)
	}

	// If for some strange reason both token.TTL and token.Expires would be set
	// (they are mutually exclusive in validation so this shouldn't be the case),
	// token.Expires has higher priority, as can be seen in the logic here.
	if token.Expires != nil {
		// Format the expiration date accordingly
		// TODO: This maybe should be a helper function in bootstraputil?
		expirationString := token.Expires.Time.UTC().Format(time.RFC3339)
		data[bootstrapapi.BootstrapTokenExpirationKey] = []byte(expirationString)

	} else if token.TTL != nil && token.TTL.Duration > 0 {
		// Only if .Expires is unset, TTL might have an effect
		// Get the current time, add the specified duration, and format it accordingly
		expirationString := now.Add(token.TTL.Duration).UTC().Format(time.RFC3339)
		data[bootstrapapi.BootstrapTokenExpirationKey] = []byte(expirationString)
	}

	for _, usage := range token.Usages {
		data[bootstrapapi.BootstrapTokenUsagePrefix+usage] = []byte("true")
	}

	if len(token.Groups) > 0 {
		data[bootstrapapi.BootstrapTokenExtraGroupsKey] = []byte(strings.Join(token.Groups, ","))
	}
	return data
}

// BootstrapTokenFromSecret returns a BootstrapToken object from the given Secret
func BootstrapTokenFromSecret(secret *v1.Secret) (*BootstrapToken, error) {
	// Get the Token ID field from the Secret data
	tokenID := bootstrapsecretutil.GetData(secret, bootstrapapi.BootstrapTokenIDKey)
	if len(tokenID) == 0 {
		return nil, errors.Errorf("bootstrap Token Secret has no token-id data: %s", secret.Name)
	}

	// Enforce the right naming convention
	if secret.Name != bootstraputil.BootstrapTokenSecretName(tokenID) {
		return nil, errors.Errorf("bootstrap token name is not of the form '%s(token-id)'. Actual: %q. Expected: %q",
			bootstrapapi.BootstrapTokenSecretPrefix, secret.Name, bootstraputil.BootstrapTokenSecretName(tokenID))
	}

	tokenSecret := bootstrapsecretutil.GetData(secret, bootstrapapi.BootstrapTokenSecretKey)
	if len(tokenSecret) == 0 {
		return nil, errors.Errorf("bootstrap Token Secret has no token-secret data: %s", secret.Name)
	}

	// Create the BootstrapTokenString object based on the ID and Secret
	bts, err := NewBootstrapTokenStringFromIDAndSecret(tokenID, tokenSecret)
	if err != nil {
		return nil, errors.Wrap(err, "bootstrap Token Secret is invalid and couldn't be parsed")
	}

	// Get the description (if any) from the Secret
	description := bootstrapsecretutil.GetData(secret, bootstrapapi.BootstrapTokenDescriptionKey)

	// Expiration time is optional, if not specified this implies the token
	// never expires.
	secretExpiration := bootstrapsecretutil.GetData(secret, bootstrapapi.BootstrapTokenExpirationKey)
	var expires *metav1.Time
	if len(secretExpiration) > 0 {
		expTime, err := time.Parse(time.RFC3339, secretExpiration)
		if err != nil {
			return nil, errors.Wrapf(err, "can't parse expiration time of bootstrap token %q", secret.Name)
		}
		expires = &metav1.Time{Time: expTime}
	}

	// Build an usages string slice from the Secret data
	var usages []string
	for k, v := range secret.Data {
		// Skip all fields that don't include this prefix
		if !strings.HasPrefix(k, bootstrapapi.BootstrapTokenUsagePrefix) {
			continue
		}
		// Skip those that don't have this usage set to true
		if string(v) != "true" {
			continue
		}
		usages = append(usages, strings.TrimPrefix(k, bootstrapapi.BootstrapTokenUsagePrefix))
	}
	// Only sort the slice if defined
	if usages != nil {
		sort.Strings(usages)
	}

	// Get the extra groups information from the Secret
	// It's done this way to make .Groups be nil in case there is no items, rather than an
	// empty slice or an empty slice with a "" string only
	var groups []string
	groupsString := bootstrapsecretutil.GetData(secret, bootstrapapi.BootstrapTokenExtraGroupsKey)
	g := strings.Split(groupsString, ",")
	if len(g) > 0 && len(g[0]) > 0 {
		groups = g
	}

	return &BootstrapToken{
		Token:       bts,
		Description: description,
		Expires:     expires,
		Usages:      usages,
		Groups:      groups,
	}, nil
}