/*
Copyright © The ESO 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

    https://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 akeyless provides integration with Akeyless Vault for secrets management.
package akeyless

import (
	"bytes"
	"context"
	"crypto/tls"
	"crypto/x509"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"slices"
	"strconv"
	"strings"
	"time"

	"github.com/akeylesslabs/akeyless-go/v4"
	"github.com/tidwall/gjson"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/client-go/kubernetes"
	typedcorev1 "k8s.io/client-go/kubernetes/typed/core/v1"
	"sigs.k8s.io/controller-runtime/pkg/client"
	ctrlcfg "sigs.k8s.io/controller-runtime/pkg/client/config"
	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"

	esv1 "github.com/external-secrets/external-secrets/apis/externalsecrets/v1"
	"github.com/external-secrets/external-secrets/runtime/esutils"
	"github.com/external-secrets/external-secrets/runtime/find"
)

// Ctx is a type used for context keys in Akeyless provider implementations.
type Ctx string

const (
	defaultAPIUrl           = "https://api.akeyless.io"
	extSecretManagedTag     = "k8s-external-secrets"
	aKeylessToken       Ctx = "AKEYLESS_TOKEN"
)

// https://github.com/external-secrets/external-secrets/issues/644
var _ esv1.SecretsClient = &Akeyless{}
var _ esv1.Provider = &Provider{}

// Provider satisfies the provider interface.
type Provider struct{}

// akeylessBase satisfies the provider.SecretsClient interface.
type akeylessBase struct {
	kube      client.Client
	store     esv1.GenericStore
	storeKind string
	corev1    typedcorev1.CoreV1Interface
	namespace string

	akeylessGwAPIURL string
	RestAPI          *akeyless.V2ApiService
}

// Akeyless represents a client for the Akeyless Vault service.
type Akeyless struct {
	Client akeylessVaultInterface
	url    string
}

// Item represents an item in the Akeyless Vault.
type Item struct {
	ItemName    string `json:"item_name"`
	ItemType    string `json:"item_type"`
	LastVersion int32  `json:"last_version"`
}

type akeylessVaultInterface interface {
	GetSecretByType(ctx context.Context, secretName string, version int32) (string, error)
	TokenFromSecretRef(ctx context.Context) (string, error)
	ListSecrets(ctx context.Context, path, tag string) ([]string, error)
	DescribeItem(ctx context.Context, itemName string) (*akeyless.Item, error)
	CreateSecret(ctx context.Context, remoteKey, data string) error
	UpdateSecret(ctx context.Context, remoteKey, data string) error
	DeleteSecret(ctx context.Context, remoteKey string) error
}

// Capabilities return the provider supported capabilities (ReadOnly, WriteOnly, ReadWrite).
func (p *Provider) Capabilities() esv1.SecretStoreCapabilities {
	return esv1.SecretStoreReadOnly
}

// NewClient constructs a new secrets client based on the provided store.
func (p *Provider) NewClient(ctx context.Context, store esv1.GenericStore, kube client.Client, namespace string) (esv1.SecretsClient, error) {
	// controller-runtime/client does not support TokenRequest or other subresource APIs
	// so we need to construct our own client and use it to fetch tokens
	// (for Kubernetes service account token auth)
	restCfg, err := ctrlcfg.GetConfig()
	if err != nil {
		return nil, err
	}
	clientset, err := kubernetes.NewForConfig(restCfg)
	if err != nil {
		return nil, err
	}

	return newClient(ctx, store, kube, clientset.CoreV1(), namespace)
}

// ValidateStore validates the configuration of the Akeyless provider in the store.
func (p *Provider) ValidateStore(store esv1.GenericStore) (admission.Warnings, error) {
	storeSpec := store.GetSpec()
	akeylessSpec := storeSpec.Provider.Akeyless

	akeylessGWApiURL := akeylessSpec.AkeylessGWApiURL

	if akeylessGWApiURL != nil && *akeylessGWApiURL != "" {
		parsedURL, err := url.Parse(*akeylessGWApiURL)
		if err != nil {
			return nil, errors.New(errInvalidAkeylessURL)
		}

		if parsedURL.Host == "" {
			return nil, errors.New(errInvalidAkeylessURL)
		}
	}
	if akeylessSpec.Auth.KubernetesAuth != nil {
		if akeylessSpec.Auth.KubernetesAuth.ServiceAccountRef != nil {
			if err := esutils.ValidateReferentServiceAccountSelector(store, *akeylessSpec.Auth.KubernetesAuth.ServiceAccountRef); err != nil {
				return nil, fmt.Errorf(errInvalidKubeSA, err)
			}
		}
		if akeylessSpec.Auth.KubernetesAuth.SecretRef != nil {
			err := esutils.ValidateSecretSelector(store, *akeylessSpec.Auth.KubernetesAuth.SecretRef)
			if err != nil {
				return nil, err
			}
		}

		if akeylessSpec.Auth.KubernetesAuth.AccessID == "" {
			return nil, errors.New("missing kubernetes auth-method access-id")
		}

		if akeylessSpec.Auth.KubernetesAuth.K8sConfName == "" {
			return nil, errors.New("missing kubernetes config name")
		}
		return nil, nil
	}

	accessID := akeylessSpec.Auth.SecretRef.AccessID
	err := esutils.ValidateSecretSelector(store, accessID)
	if err != nil {
		return nil, err
	}

	if accessID.Name == "" {
		return nil, errors.New(errInvalidAkeylessAccessIDName)
	}

	if accessID.Key == "" {
		return nil, errors.New(errInvalidAkeylessAccessIDKey)
	}

	accessType := akeylessSpec.Auth.SecretRef.AccessType
	err = esutils.ValidateSecretSelector(store, accessType)
	if err != nil {
		return nil, err
	}

	accessTypeParam := akeylessSpec.Auth.SecretRef.AccessTypeParam
	err = esutils.ValidateSecretSelector(store, accessTypeParam)
	if err != nil {
		return nil, err
	}

	return nil, nil
}

func newClient(ctx context.Context, store esv1.GenericStore, kube client.Client, corev1 typedcorev1.CoreV1Interface, namespace string) (esv1.SecretsClient, error) {
	akl := &akeylessBase{
		kube:      kube,
		store:     store,
		namespace: namespace,
		corev1:    corev1,
		storeKind: store.GetObjectKind().GroupVersionKind().Kind,
	}

	spec, err := GetAKeylessProvider(store)
	if err != nil {
		return nil, err
	}
	akeylessGwAPIURL := defaultAPIUrl
	if spec != nil && spec.AkeylessGWApiURL != nil && *spec.AkeylessGWApiURL != "" {
		akeylessGwAPIURL = getV2Url(*spec.AkeylessGWApiURL)
	}

	if spec.Auth == nil {
		return nil, errors.New("missing Auth in store config")
	}

	client, err := akl.getAkeylessHTTPClient(ctx, spec)
	if err != nil {
		return nil, err
	}

	RestAPIClient := akeyless.NewAPIClient(&akeyless.Configuration{
		HTTPClient: client,
		Servers: []akeyless.ServerConfiguration{
			{
				URL: akeylessGwAPIURL,
			},
		},
	}).V2Api

	akl.akeylessGwAPIURL = akeylessGwAPIURL
	akl.RestAPI = RestAPIClient
	return &Akeyless{Client: akl, url: akeylessGwAPIURL}, nil
}

func (a *Akeyless) contextWithToken(ctx context.Context) (context.Context, error) {
	if v := ctx.Value(aKeylessToken); v != nil {
		return ctx, nil
	}
	token, err := a.Client.TokenFromSecretRef(ctx)
	if err != nil {
		return nil, err
	}
	return context.WithValue(ctx, aKeylessToken, token), nil
}

// Close closes the Akeyless client connection.
func (a *Akeyless) Close(_ context.Context) error {
	return nil
}

// Validate validates the Akeyless connection by testing network connectivity.
func (a *Akeyless) Validate() (esv1.ValidationResult, error) {
	timeout := 15 * time.Second
	serviceURL := a.url

	if err := esutils.NetworkValidate(serviceURL, timeout); err != nil {
		return esv1.ValidationResultError, err
	}

	return esv1.ValidationResultReady, nil
}

// GetSecret retrieves a secret with the secret name defined in ref.Name.
// Implements store.Client.GetSecret Interface.
func (a *Akeyless) GetSecret(ctx context.Context, ref esv1.ExternalSecretDataRemoteRef) ([]byte, error) {
	if esutils.IsNil(a.Client) {
		return nil, errors.New(errUninitalizedAkeylessProvider)
	}
	ctx, err := a.contextWithToken(ctx)
	if err != nil {
		return nil, err
	}
	version := int32(0)
	if ref.Version != "" {
		i, err := strconv.ParseInt(ref.Version, 10, 32)
		if err == nil {
			version = int32(i)
		}
	}
	value, err := a.Client.GetSecretByType(ctx, ref.Key, version)
	if err != nil {
		return nil, err
	}

	if ref.Property == "" {
		if value != "" {
			return []byte(value), nil
		}
		return nil, fmt.Errorf("invalid value received, found no value string : %s", ref.Key)
	}
	// We need to search if a given key with a . exists before using gjson operations.
	idx := strings.Index(ref.Property, ".")
	if idx > -1 {
		refProperty := strings.ReplaceAll(ref.Property, ".", "\\.")
		val := gjson.Get(value, refProperty)
		if val.Exists() {
			return []byte(val.String()), nil
		}
	}
	val := gjson.Get(value, ref.Property)
	if !val.Exists() {
		return nil, fmt.Errorf("key %s does not exist in value %s", ref.Property, ref.Key)
	}
	return []byte(val.String()), nil
}

// GetAllSecrets Implements store.Client.GetAllSecrets Interface.
// Retrieves all secrets with defined in ref.Name or tags.
func (a *Akeyless) GetAllSecrets(ctx context.Context, ref esv1.ExternalSecretFind) (map[string][]byte, error) {
	if esutils.IsNil(a.Client) {
		return nil, errors.New(errUninitalizedAkeylessProvider)
	}
	ctx, err := a.contextWithToken(ctx)
	if err != nil {
		return nil, err
	}

	searchPath := ""
	if ref.Path != nil {
		searchPath = *ref.Path
		if !strings.HasPrefix(searchPath, "/") {
			searchPath = "/" + searchPath
		}
		if !strings.HasSuffix(searchPath, "/") {
			searchPath += "/"
		}
	}
	if ref.Name != nil {
		return a.findSecretsFromName(ctx, searchPath, *ref.Name)
	}
	if len(ref.Tags) > 0 {
		return a.getSecrets(ctx, searchPath, ref.Tags)
	}

	return nil, errors.New("unexpected find operator")
}

func (a *Akeyless) getSecrets(ctx context.Context, searchPath string, tags map[string]string) (map[string][]byte, error) {
	var potentialSecretsName []string
	for _, v := range tags {
		potentialSecrets, err := a.Client.ListSecrets(ctx, searchPath, v)
		if err != nil {
			return nil, err
		}
		if len(potentialSecrets) > 0 {
			potentialSecretsName = append(potentialSecretsName, potentialSecrets...)
		}
	}
	if len(potentialSecretsName) == 0 {
		return nil, nil
	}

	secrets := make(map[string][]byte)
	for _, name := range potentialSecretsName {
		secretValue, err := a.Client.GetSecretByType(ctx, name, 0)
		if err != nil {
			return nil, err
		}
		if secretValue != "" {
			secrets[name] = []byte(secretValue)
		}
	}
	return secrets, nil
}

func (a *Akeyless) findSecretsFromName(ctx context.Context, searchPath string, ref esv1.FindName) (map[string][]byte, error) {
	potentialSecrets, err := a.Client.ListSecrets(ctx, searchPath, "")
	if err != nil {
		return nil, err
	}
	if len(potentialSecrets) == 0 {
		return nil, nil
	}

	secrets := make(map[string][]byte)
	matcher, err := find.New(ref)
	if err != nil {
		return nil, err
	}
	for _, name := range potentialSecrets {
		ok := matcher.MatchName(name)
		if ok {
			secretValue, err := a.Client.GetSecretByType(ctx, name, 0)
			if err != nil {
				return nil, err
			}
			if secretValue != "" {
				secrets[name] = []byte(secretValue)
			}
		}
	}
	return secrets, nil
}

// GetSecretMap implements store.Client.GetSecretMap Interface.
// New version of GetSecretMap.
func (a *Akeyless) GetSecretMap(ctx context.Context, ref esv1.ExternalSecretDataRemoteRef) (map[string][]byte, error) {
	if esutils.IsNil(a.Client) {
		return nil, errors.New(errUninitalizedAkeylessProvider)
	}
	val, err := a.GetSecret(ctx, ref)
	if err != nil {
		return nil, err
	}
	// Maps the json data to a string:string map
	kv := make(map[string]string)
	err = json.Unmarshal(val, &kv)
	if err != nil {
		return nil, fmt.Errorf(errJSONSecretUnmarshal, err)
	}

	// Converts values in K:V pairs into bytes, while leaving keys as strings
	secretData := make(map[string][]byte)
	for k, v := range kv {
		secretData[k] = []byte(v)
	}
	return secretData, nil
}

// SecretExists checks if a secret exists in Akeyless Vault at the specified remote reference.
func (a *Akeyless) SecretExists(ctx context.Context, ref esv1.PushSecretRemoteRef) (bool, error) {
	if esutils.IsNil(a.Client) {
		return false, errors.New(errUninitalizedAkeylessProvider)
	}
	secret, err := a.GetSecret(ctx, esv1.ExternalSecretDataRemoteRef{Key: ref.GetRemoteKey()})
	if errors.Is(err, ErrItemNotExists) {
		return false, nil
	}
	if err != nil {
		return false, err
	}
	if ref.GetProperty() == "" {
		return true, nil
	}
	var secretMap map[string]any
	err = json.Unmarshal(secret, &secretMap)
	if err != nil {
		// Do not return the raw error as json.Unmarshal errors may contain
		// sensitive secret data in the error message
		return false, errors.New("failed to unmarshal secret: invalid JSON format")
	}
	_, ok := secretMap[ref.GetProperty()]
	return ok, nil
}

func initMapIfNotExist(psd esv1.PushSecretData, secretMapSize int) map[string]any {
	mapSize := 1
	if psd.GetProperty() == "" {
		mapSize = secretMapSize
	}
	return make(map[string]any, mapSize)
}

// PushSecret pushes a Kubernetes secret to Akeyless Vault using the provided data.
func (a *Akeyless) PushSecret(ctx context.Context, secret *corev1.Secret, psd esv1.PushSecretData) error {
	if esutils.IsNil(a.Client) {
		return errors.New(errUninitalizedAkeylessProvider)
	}
	ctx, err := a.contextWithToken(ctx)
	if err != nil {
		return err
	}
	secretRemote, err := a.GetSecret(ctx, esv1.ExternalSecretDataRemoteRef{Key: psd.GetRemoteKey()})
	isNotExists := errors.Is(err, ErrItemNotExists)
	if err != nil && !isNotExists {
		return err
	}
	var data map[string]any
	if isNotExists {
		data = initMapIfNotExist(psd, len(secret.Data))
		err = nil
	} else {
		err = json.Unmarshal(secretRemote, &data)
	}
	if err != nil {
		// Do not return the raw error as json.Unmarshal errors may contain
		// sensitive secret data in the error message
		return errors.New("failed to unmarshal remote secret: invalid JSON format")
	}
	if psd.GetProperty() == "" {
		for k, v := range secret.Data {
			data[k] = string(v)
		}
	} else if v, ok := secret.Data[psd.GetSecretKey()]; ok {
		data[psd.GetProperty()] = string(v)
	}
	dataByte, err := json.Marshal(data)
	if err != nil {
		return err
	}
	if bytes.Equal(dataByte, secretRemote) {
		return nil
	}
	if isNotExists {
		return a.Client.CreateSecret(ctx, psd.GetRemoteKey(), string(dataByte))
	}
	return a.Client.UpdateSecret(ctx, psd.GetRemoteKey(), string(dataByte))
}

// DeleteSecret deletes a secret from Akeyless Vault at the specified remote reference.
func (a *Akeyless) DeleteSecret(ctx context.Context, psr esv1.PushSecretRemoteRef) error {
	if esutils.IsNil(a.Client) {
		return errors.New(errUninitalizedAkeylessProvider)
	}
	ctx, err := a.contextWithToken(ctx)
	if err != nil {
		return err
	}
	item, err := a.Client.DescribeItem(ctx, psr.GetRemoteKey())
	if err != nil {
		return err
	}
	if item == nil || item.ItemTags == nil || !slices.Contains(*item.ItemTags, extSecretManagedTag) {
		return nil
	}
	if psr.GetProperty() == "" {
		err = a.Client.DeleteSecret(ctx, psr.GetRemoteKey())
		return err
	}
	secret, err := a.GetSecret(ctx, esv1.ExternalSecretDataRemoteRef{Key: psr.GetRemoteKey()})
	if err != nil {
		return err
	}
	var secretMap map[string]any
	err = json.Unmarshal(secret, &secretMap)
	if err != nil {
		// Do not return the raw error as json.Unmarshal errors may contain
		// sensitive secret data in the error message
		return errors.New("failed to unmarshal secret for deletion: invalid JSON format")
	}
	delete(secretMap, psr.GetProperty())
	if len(secretMap) == 0 {
		err = a.Client.DeleteSecret(ctx, psr.GetRemoteKey())
		return err
	}
	byteSecretMap, err := json.Marshal(secretMap)
	if err != nil {
		return err
	}
	err = a.Client.UpdateSecret(ctx, psr.GetRemoteKey(), string(byteSecretMap))
	return err
}

func (a *akeylessBase) getAkeylessHTTPClient(ctx context.Context, provider *esv1.AkeylessProvider) (*http.Client, error) {
	client := &http.Client{Timeout: 30 * time.Second}
	if len(provider.CABundle) == 0 && provider.CAProvider == nil {
		return client, nil
	}

	cert, err := esutils.FetchCACertFromSource(ctx, esutils.CreateCertOpts{
		StoreKind:  a.storeKind,
		Client:     a.kube,
		Namespace:  a.namespace,
		CABundle:   provider.CABundle,
		CAProvider: provider.CAProvider,
	})
	if err != nil {
		return nil, err
	}

	caCertPool := x509.NewCertPool()
	ok := caCertPool.AppendCertsFromPEM(cert)
	if !ok {
		return nil, errors.New("failed to append caBundle")
	}

	tlsConf := &tls.Config{
		RootCAs:    caCertPool,
		MinVersion: tls.VersionTLS12,
	}
	client.Transport = &http.Transport{TLSClientConfig: tlsConf}
	return client, nil
}

// NewProvider creates a new Provider instance.
func NewProvider() esv1.Provider {
	return &Provider{}
}

// ProviderSpec returns the provider specification for registration.
func ProviderSpec() *esv1.SecretStoreProvider {
	return &esv1.SecretStoreProvider{
		Akeyless: &esv1.AkeylessProvider{},
	}
}

// MaintenanceStatus returns the maintenance status of the provider.
func MaintenanceStatus() esv1.MaintenanceStatus {
	return esv1.MaintenanceStatusMaintained
}