/*
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 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/v3"
	"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"

	esv1beta1 "github.com/external-secrets/external-secrets/apis/externalsecrets/v1beta1"
	"github.com/external-secrets/external-secrets/pkg/find"
	"github.com/external-secrets/external-secrets/pkg/utils"
)

type AkeylessCtx string

const (
	defaultAPIUrl                   = "https://api.akeyless.io"
	errNotImplemented               = "not implemented"
	ExtSecretManagedTag             = "k8s-external-secrets"
	AkeylessToken       AkeylessCtx = "AKEYLESS_TOKEN"
)

// https://github.com/external-secrets/external-secrets/issues/644
var _ esv1beta1.SecretsClient = &Akeyless{}
var _ esv1beta1.Provider = &Provider{}

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

// akeylessBase satisfies the provider.SecretsClient interface.
type akeylessBase struct {
	kube      client.Client
	store     esv1beta1.GenericStore
	storeKind string
	corev1    typedcorev1.CoreV1Interface
	namespace string

	akeylessGwAPIURL string
	RestAPI          *akeyless.V2ApiService
}

type Akeyless struct {
	Client akeylessVaultInterface
	url    string
}

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
}

func init() {
	esv1beta1.Register(&Provider{}, &esv1beta1.SecretStoreProvider{
		Akeyless: &esv1beta1.AkeylessProvider{},
	})
}

// Capabilities return the provider supported capabilities (ReadOnly, WriteOnly, ReadWrite).
func (p *Provider) Capabilities() esv1beta1.SecretStoreCapabilities {
	return esv1beta1.SecretStoreReadOnly
}

// NewClient constructs a new secrets client based on the provided store.
func (p *Provider) NewClient(ctx context.Context, store esv1beta1.GenericStore, kube client.Client, namespace string) (esv1beta1.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)
}

func (p *Provider) ValidateStore(store esv1beta1.GenericStore) (admission.Warnings, error) {
	storeSpec := store.GetSpec()
	akeylessSpec := storeSpec.Provider.Akeyless

	akeylessGWApiURL := akeylessSpec.AkeylessGWApiURL

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

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

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

	return nil, nil
}

func newClient(ctx context.Context, store esv1beta1.GenericStore, kube client.Client, corev1 typedcorev1.CoreV1Interface, namespace string) (esv1beta1.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
}

func (a *Akeyless) Close(_ context.Context) error {
	return nil
}

func (a *Akeyless) Validate() (esv1beta1.ValidationResult, error) {
	timeout := 15 * time.Second
	url := a.url

	if err := utils.NetworkValidate(url, timeout); err != nil {
		return esv1beta1.ValidationResultError, err
	}

	return esv1beta1.ValidationResultReady, nil
}

// Implements store.Client.GetSecret Interface.
// Retrieves a secret with the secret name defined in ref.Name.
func (a *Akeyless) GetSecret(ctx context.Context, ref esv1beta1.ExternalSecretDataRemoteRef) ([]byte, error) {
	if utils.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
}

// Implements store.Client.GetAllSecrets Interface.
// Retrieves a all secrets with defined in ref.Name or tags.
func (a *Akeyless) GetAllSecrets(ctx context.Context, ref esv1beta1.ExternalSecretFind) (map[string][]byte, error) {
	if utils.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 {
		potentialSecrets, err := a.Client.ListSecrets(ctx, searchPath, "")
		if err != nil {
			return nil, err
		}
		if len(potentialSecrets) == 0 {
			return nil, nil
		}
		return a.findSecretsFromName(ctx, potentialSecrets, *ref.Name)
	}
	if len(ref.Tags) > 0 {
		var potentialSecretsName []string
		for _, v := range ref.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
		}
		return a.getSecrets(ctx, potentialSecretsName)
	}
	return nil, errors.New("unexpected find operator")
}

func (a *Akeyless) getSecrets(ctx context.Context, candidates []string) (map[string][]byte, error) {
	secrets := make(map[string][]byte)
	for _, name := range candidates {
		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, candidates []string, ref esv1beta1.FindName) (map[string][]byte, error) {
	secrets := make(map[string][]byte)
	matcher, err := find.New(ref)
	if err != nil {
		return nil, err
	}
	for _, name := range candidates {
		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
}

// Implements store.Client.GetSecretMap Interface.
// New version of GetSecretMap.
func (a *Akeyless) GetSecretMap(ctx context.Context, ref esv1beta1.ExternalSecretDataRemoteRef) (map[string][]byte, error) {
	if utils.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
}

func (a *Akeyless) SecretExists(ctx context.Context, ref esv1beta1.PushSecretRemoteRef) (bool, error) {
	if utils.IsNil(a.Client) {
		return false, errors.New(errUninitalizedAkeylessProvider)
	}
	secret, err := a.GetSecret(ctx, esv1beta1.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 {
		return false, err
	}
	_, ok := secretMap[ref.GetProperty()]
	return ok, nil
}

func initMapIfNotExist(psd esv1beta1.PushSecretData, secretMapSize int) map[string]any {
	mapSize := 1
	if psd.GetProperty() == "" {
		mapSize = secretMapSize
	}
	return make(map[string]any, mapSize)
}

func (a *Akeyless) PushSecret(ctx context.Context, secret *corev1.Secret, psd esv1beta1.PushSecretData) error {
	if utils.IsNil(a.Client) {
		return errors.New(errUninitalizedAkeylessProvider)
	}
	ctx, err := a.contextWithToken(ctx)
	if err != nil {
		return err
	}
	secretRemote, err := a.GetSecret(ctx, esv1beta1.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 {
		return err
	}
	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))
}

func (a *Akeyless) DeleteSecret(ctx context.Context, psr esv1beta1.PushSecretRemoteRef) error {
	if utils.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, esv1beta1.ExternalSecretDataRemoteRef{Key: psr.GetRemoteKey()})
	if err != nil {
		return err
	}
	var secretMap map[string]any
	err = json.Unmarshal(secret, &secretMap)
	if err != nil {
		return err
	}
	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 *esv1beta1.AkeylessProvider) (*http.Client, error) {
	client := &http.Client{Timeout: 30 * time.Second}
	if len(provider.CABundle) == 0 && provider.CAProvider == nil {
		return client, nil
	}

	cert, err := utils.FetchCACertFromSource(ctx, utils.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
}