/*
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 fake

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

	"github.com/tidwall/gjson"
	corev1 "k8s.io/api/core/v1"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"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"
)

var (
	errMissingStore        = errors.New("missing store provider")
	errMissingFakeProvider = errors.New("missing store provider fake")
	errMissingKeyField     = "key must be set in data %v"
	errMissingValueField   = "at least one value must be set in data %v"
)

type SourceOrigin string

const (
	FakeSecretStore SourceOrigin = "SecretStore"
	FakeSetSecret   SourceOrigin = "SetSecret"
)

type Data struct {
	Value   string
	Version string
	Origin  SourceOrigin
}
type Config map[string]*Data
type Provider struct {
	config           Config
	database         map[string]Config
	validationResult *esv1.ValidationResult
}

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

func (p *Provider) NewClient(_ context.Context, store esv1.GenericStore, _ client.Client, _ string) (esv1.SecretsClient, error) {
	if p.database == nil {
		p.database = make(map[string]Config)
	}
	c, err := getProvider(store)
	if err != nil {
		return nil, err
	}
	cfg := p.database[store.GetName()]
	if cfg == nil {
		cfg = Config{}
	}
	// We want to remove any FakeSecretStore entry from memory
	// this will ensure SecretStores can delete from memory.
	for key, data := range cfg {
		if data.Origin == FakeSecretStore {
			delete(cfg, key)
		}
	}
	for _, data := range c.Data {
		key := mapKey(data.Key, data.Version)
		cfg[key] = &Data{
			Value:   data.Value,
			Version: data.Version,
			Origin:  FakeSecretStore,
		}
	}
	p.database[store.GetName()] = cfg
	return &Provider{
		config:           cfg,
		validationResult: c.ValidationResult,
	}, nil
}

func getProvider(store esv1.GenericStore) (*esv1.FakeProvider, error) {
	if store == nil {
		return nil, errMissingStore
	}
	spc := store.GetSpec()
	if spc == nil || spc.Provider == nil || spc.Provider.Fake == nil {
		return nil, errMissingFakeProvider
	}
	return spc.Provider.Fake, nil
}

func (p *Provider) DeleteSecret(_ context.Context, _ esv1.PushSecretRemoteRef) error {
	return nil
}

func (p *Provider) SecretExists(_ context.Context, ref esv1.PushSecretRemoteRef) (bool, error) {
	_, ok := p.config[ref.GetRemoteKey()]
	return ok, nil
}

func (p *Provider) PushSecret(_ context.Context, secret *corev1.Secret, data esv1.PushSecretData) error {
	value := secret.Data[data.GetSecretKey()]
	currentData, ok := p.config[data.GetRemoteKey()]
	if !ok {
		p.config[data.GetRemoteKey()] = &Data{
			Value:  string(value),
			Origin: FakeSetSecret,
		}
		return nil
	}

	if currentData.Origin != FakeSetSecret {
		return errors.New("key already exists")
	}
	currentData.Value = string(value)

	return nil
}

// GetAllSecrets returns multiple secrets from the given ExternalSecretFind
// Currently, only the Name operator is supported.
func (p *Provider) GetAllSecrets(_ context.Context, ref esv1.ExternalSecretFind) (map[string][]byte, error) {
	if ref.Name == nil {
		return nil, fmt.Errorf("unsupported find operator: %#v", ref)
	}

	matcher, err := find.New(*ref.Name)
	if err != nil {
		return nil, err
	}

	dataMap := p.collectMatchingSecrets(matcher)
	return esutils.ConvertKeys(ref.ConversionStrategy, dataMap)
}

func (p *Provider) collectMatchingSecrets(matcher *find.Matcher) map[string][]byte {
	latestVersionMap := make(map[string]string)
	dataMap := make(map[string][]byte)

	for key, data := range p.config {
		originalKey := strings.TrimSuffix(key, data.Version)
		if !matcher.MatchName(originalKey) {
			continue
		}

		p.updateLatestVersion(originalKey, data, latestVersionMap, dataMap)
	}
	return dataMap
}

func (p *Provider) updateLatestVersion(originalKey string, data *Data, latestVersionMap map[string]string, dataMap map[string][]byte) {
	version, exists := latestVersionMap[originalKey]
	if !exists || version < data.Version {
		latestVersionMap[originalKey] = data.Version
		dataMap[originalKey] = []byte(data.Value)
	}
}

// GetSecret returns a single secret from the provider.
func (p *Provider) GetSecret(_ context.Context, ref esv1.ExternalSecretDataRemoteRef) ([]byte, error) {
	data, ok := p.config[mapKey(ref.Key, ref.Version)]
	if !ok || data.Version != ref.Version {
		return nil, esv1.NoSecretErr
	}

	if ref.Property != "" {
		val := gjson.Get(data.Value, ref.Property)
		if !val.Exists() {
			return nil, esv1.NoSecretErr
		}

		return []byte(val.String()), nil
	}

	return []byte(data.Value), nil
}

// GetSecretMap returns multiple k/v pairs from the provider.
func (p *Provider) GetSecretMap(ctx context.Context, ref esv1.ExternalSecretDataRemoteRef) (map[string][]byte, error) {
	ddata, ok := p.config[mapKey(ref.Key, ref.Version)]
	if !ok || ddata.Version != ref.Version {
		return nil, esv1.NoSecretErr
	}

	data, err := p.GetSecret(ctx, ref)
	if err != nil {
		return nil, err
	}

	secretData := make(map[string][]byte)
	kv := make(map[string]json.RawMessage)
	err = json.Unmarshal(data, &kv)
	if err != nil {
		return nil, fmt.Errorf("unable to unmarshal secret: %w", err)
	}

	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 (p *Provider) Close(_ context.Context) error {
	return nil
}

func (p *Provider) Validate() (esv1.ValidationResult, error) {
	if p.validationResult != nil && *p.validationResult != esv1.ValidationResultReady {
		return *p.validationResult, errors.New("unable to validate")
	}
	return esv1.ValidationResultReady, nil
}

func (p *Provider) ValidateStore(store esv1.GenericStore) (admission.Warnings, error) {
	prov := store.GetSpec().Provider.Fake
	if prov == nil {
		return nil, nil
	}
	for pos, data := range prov.Data {
		if data.Key == "" {
			return nil, fmt.Errorf(errMissingKeyField, pos)
		}
		if data.Value == "" {
			return nil, fmt.Errorf(errMissingValueField, pos)
		}
	}
	return nil, nil
}

func mapKey(key, version string) string {
	// Add the version suffix to preserve entries with the old versions as well.
	return fmt.Sprintf("%v%v", key, version)
}

// 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{
		Fake: &esv1.FakeProvider{},
	}
}

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