/*
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 secretsmanager

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"strings"

	"github.com/aws/aws-sdk-go/aws/session"
	awssm "github.com/aws/aws-sdk-go/service/secretsmanager"
	"github.com/tidwall/gjson"
	utilpointer "k8s.io/utils/pointer"
	ctrl "sigs.k8s.io/controller-runtime"

	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/provider/aws/util"
	"github.com/external-secrets/external-secrets/pkg/utils"
)

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

// SecretsManager is a provider for AWS SecretsManager.
type SecretsManager struct {
	sess   *session.Session
	client SMInterface
	cache  map[string]*awssm.GetSecretValueOutput
}

// SMInterface is a subset of the smiface api.
// see: https://docs.aws.amazon.com/sdk-for-go/api/service/secretsmanager/secretsmanageriface/
type SMInterface interface {
	GetSecretValue(*awssm.GetSecretValueInput) (*awssm.GetSecretValueOutput, error)
	ListSecrets(*awssm.ListSecretsInput) (*awssm.ListSecretsOutput, error)
}

const (
	errUnexpectedFindOperator = "unexpected find operator"
)

var log = ctrl.Log.WithName("provider").WithName("aws").WithName("secretsmanager")

// New creates a new SecretsManager client.
func New(sess *session.Session) (*SecretsManager, error) {
	return &SecretsManager{
		sess:   sess,
		client: awssm.New(sess),
		cache:  make(map[string]*awssm.GetSecretValueOutput),
	}, nil
}

func (sm *SecretsManager) fetch(_ context.Context, ref esv1beta1.ExternalSecretDataRemoteRef) (*awssm.GetSecretValueOutput, error) {
	ver := "AWSCURRENT"
	if ref.Version != "" {
		ver = ref.Version
	}
	log.Info("fetching secret value", "key", ref.Key, "version", ver)

	cacheKey := fmt.Sprintf("%s#%s", ref.Key, ver)
	if secretOut, found := sm.cache[cacheKey]; found {
		log.Info("found secret in cache", "key", ref.Key, "version", ver)
		return secretOut, nil
	}

	var getSecretValueInput *awssm.GetSecretValueInput
	if strings.HasPrefix(ver, "uuid/") {
		versionID := strings.TrimPrefix(ver, "uuid/")
		getSecretValueInput = &awssm.GetSecretValueInput{
			SecretId:  &ref.Key,
			VersionId: &versionID,
		}
	} else {
		getSecretValueInput = &awssm.GetSecretValueInput{
			SecretId:     &ref.Key,
			VersionStage: &ver,
		}
	}
	secretOut, err := sm.client.GetSecretValue(getSecretValueInput)
	var nf *awssm.ResourceNotFoundException
	if errors.As(err, &nf) {
		return nil, esv1beta1.NoSecretErr
	}
	if err != nil {
		return nil, err
	}
	sm.cache[cacheKey] = secretOut

	return secretOut, nil
}

// GetAllSecrets syncs multiple secrets from aws provider into a single Kubernetes Secret.
func (sm *SecretsManager) GetAllSecrets(ctx context.Context, ref esv1beta1.ExternalSecretFind) (map[string][]byte, error) {
	if ref.Name != nil {
		return sm.findByName(ctx, ref)
	}
	if len(ref.Tags) > 0 {
		return sm.findByTags(ctx, ref)
	}
	return nil, errors.New(errUnexpectedFindOperator)
}

func (sm *SecretsManager) findByName(ctx context.Context, ref esv1beta1.ExternalSecretFind) (map[string][]byte, error) {
	matcher, err := find.New(*ref.Name)
	if err != nil {
		return nil, err
	}

	filters := make([]*awssm.Filter, 0)
	if ref.Path != nil {
		filters = append(filters, &awssm.Filter{
			Key: utilpointer.StringPtr(awssm.FilterNameStringTypeName),
			Values: []*string{
				ref.Path,
			},
		})
	}

	data := make(map[string][]byte)
	var nextToken *string

	for {
		it, err := sm.client.ListSecrets(&awssm.ListSecretsInput{
			Filters:   filters,
			NextToken: nextToken,
		})
		if err != nil {
			return nil, err
		}
		log.V(1).Info("aws sm findByName found", "secrets", len(it.SecretList))
		for _, secret := range it.SecretList {
			if !matcher.MatchName(*secret.Name) {
				continue
			}
			log.V(1).Info("aws sm findByName matches", "name", *secret.Name)
			err = sm.fetchAndSet(ctx, data, *secret.Name)
			if err != nil {
				return nil, err
			}
		}
		nextToken = it.NextToken
		if nextToken == nil {
			break
		}
	}
	return utils.ConvertKeys(ref.ConversionStrategy, data)
}

func (sm *SecretsManager) findByTags(ctx context.Context, ref esv1beta1.ExternalSecretFind) (map[string][]byte, error) {
	filters := make([]*awssm.Filter, 0)
	for k, v := range ref.Tags {
		filters = append(filters, &awssm.Filter{
			Key: utilpointer.StringPtr(awssm.FilterNameStringTypeTagKey),
			Values: []*string{
				utilpointer.StringPtr(k),
			},
		}, &awssm.Filter{
			Key: utilpointer.StringPtr(awssm.FilterNameStringTypeTagValue),
			Values: []*string{
				utilpointer.StringPtr(v),
			},
		})
	}

	if ref.Path != nil {
		filters = append(filters, &awssm.Filter{
			Key: utilpointer.StringPtr(awssm.FilterNameStringTypeName),
			Values: []*string{
				ref.Path,
			},
		})
	}

	data := make(map[string][]byte)
	var nextToken *string
	for {
		log.V(1).Info("aws sm findByTag", "nextToken", nextToken)
		it, err := sm.client.ListSecrets(&awssm.ListSecretsInput{
			Filters:   filters,
			NextToken: nextToken,
		})
		if err != nil {
			return nil, err
		}
		log.V(1).Info("aws sm findByTag found", "secrets", len(it.SecretList))
		for _, secret := range it.SecretList {
			err = sm.fetchAndSet(ctx, data, *secret.Name)
			if err != nil {
				return nil, err
			}
		}
		nextToken = it.NextToken
		if nextToken == nil {
			break
		}
	}
	return utils.ConvertKeys(ref.ConversionStrategy, data)
}

func (sm *SecretsManager) fetchAndSet(ctx context.Context, data map[string][]byte, name string) error {
	sec, err := sm.fetch(ctx, esv1beta1.ExternalSecretDataRemoteRef{
		Key: name,
	})
	if err != nil {
		return err
	}
	if sec.SecretString != nil {
		data[name] = []byte(*sec.SecretString)
	}
	if sec.SecretBinary != nil {
		data[name] = sec.SecretBinary
	}
	return nil
}

// GetSecret returns a single secret from the provider.
func (sm *SecretsManager) GetSecret(ctx context.Context, ref esv1beta1.ExternalSecretDataRemoteRef) ([]byte, error) {
	secretOut, err := sm.fetch(ctx, ref)
	if errors.Is(err, esv1beta1.NoSecretErr) {
		return nil, err
	}
	if err != nil {
		return nil, util.SanitizeErr(err)
	}
	if ref.Property == "" {
		if secretOut.SecretString != nil {
			return []byte(*secretOut.SecretString), nil
		}
		if secretOut.SecretBinary != nil {
			return secretOut.SecretBinary, nil
		}
		return nil, fmt.Errorf("invalid secret received. no secret string nor binary for key: %s", ref.Key)
	}
	var payload string
	if secretOut.SecretString != nil {
		payload = *secretOut.SecretString
	}
	if secretOut.SecretBinary != nil {
		payload = string(secretOut.SecretBinary)
	}
	// We need to search if a given key with a . exists before using gjson operations.
	idx := strings.Index(ref.Property, ".")
	if idx > 0 {
		refProperty := strings.ReplaceAll(ref.Property, ".", "\\.")
		val := gjson.Get(payload, refProperty)
		if val.Exists() {
			return []byte(val.String()), nil
		}
	}
	val := gjson.Get(payload, ref.Property)
	if !val.Exists() {
		return nil, fmt.Errorf("key %s does not exist in secret %s", ref.Property, ref.Key)
	}
	return []byte(val.String()), nil
}

// GetSecretMap returns multiple k/v pairs from the provider.
func (sm *SecretsManager) GetSecretMap(ctx context.Context, ref esv1beta1.ExternalSecretDataRemoteRef) (map[string][]byte, error) {
	log.Info("fetching secret map", "key", ref.Key)
	data, err := sm.GetSecret(ctx, ref)
	if err != nil {
		return nil, err
	}
	kv := make(map[string]json.RawMessage)
	err = json.Unmarshal(data, &kv)
	if err != nil {
		return nil, fmt.Errorf("unable to unmarshal secret %s: %w", ref.Key, err)
	}
	secretData := make(map[string][]byte)
	for k, v := range kv {
		var strVal string
		err = json.Unmarshal(v, &strVal)
		if err == nil {
			secretData[k] = []byte(strVal)
		} else {
			secretData[k] = v
		}
	}
	return secretData, nil
}

func (sm *SecretsManager) Close(ctx context.Context) error {
	return nil
}

func (sm *SecretsManager) Validate() (esv1beta1.ValidationResult, error) {
	_, err := sm.sess.Config.Credentials.Get()
	if err != nil {
		return esv1beta1.ValidationResultError, err
	}
	return esv1beta1.ValidationResultReady, nil
}