/*
Copyright 2021 The Dapr 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 file

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"os"
	"reflect"
	"strconv"
	"strings"

	"github.com/dapr/components-contrib/metadata"
	"github.com/dapr/components-contrib/secretstores"
	"github.com/dapr/kit/logger"
	kitmd "github.com/dapr/kit/metadata"
)

type localSecretStoreMetaData struct {
	SecretsFile     string
	NestedSeparator string
	MultiValued     bool
}

var _ secretstores.SecretStore = (*localSecretStore)(nil)

type localSecretStore struct {
	secretsFile     string
	nestedSeparator string
	currenContext   []string
	currentPath     string
	secrets         map[string]interface{}
	readLocalFileFn func(secretsFile string) (map[string]interface{}, error)
	features        []secretstores.Feature
	logger          logger.Logger
}

// NewLocalSecretStore returns a new Local secret store.
func NewLocalSecretStore(logger logger.Logger) secretstores.SecretStore {
	return &localSecretStore{
		logger: logger,
	}
}

// Init creates a Local secret store.
func (j *localSecretStore) Init(_ context.Context, metadata secretstores.Metadata) error {
	meta, err := j.getLocalSecretStoreMetadata(metadata)
	if err != nil {
		return err
	}

	if len(meta.NestedSeparator) == 0 {
		j.nestedSeparator = ":"
	} else {
		j.nestedSeparator = meta.NestedSeparator
	}

	if j.readLocalFileFn == nil {
		j.readLocalFileFn = j.readLocalFile
	}

	jsonConfig, err := j.readLocalFileFn(meta.SecretsFile)
	if err != nil {
		return err
	}

	if meta.MultiValued {
		allSecrets := map[string]interface{}{}
		for k, v := range jsonConfig {
			switch v := v.(type) {
			case string:
				allSecrets[k] = v
			case map[string]interface{}:
				j.secrets = make(map[string]interface{})
				j.visitJSONObject(v)
				allSecrets[k] = j.secrets
			}
		}
		j.secrets = allSecrets
		// If MultiValued is set, this secret store supports a multiple
		// key-valyes per secret.
		j.features = []secretstores.Feature{
			secretstores.FeatureMultipleKeyValuesPerSecret,
		}
	} else {
		j.secrets = map[string]interface{}{}
		j.visitJSONObject(jsonConfig)
		// MultiValued is not set: reset to its default single-value per
		// secret (no extra feature) behavior.
		j.features = []secretstores.Feature{}
	}

	return nil
}

// GetSecret retrieves a secret using a key and returns a map of decrypted string/string values.
func (j *localSecretStore) GetSecret(ctx context.Context, req secretstores.GetSecretRequest) (secretstores.GetSecretResponse, error) {
	secretValue, exists := j.secrets[req.Name]
	if !exists {
		return secretstores.GetSecretResponse{}, fmt.Errorf("secret %s not found", req.Name)
	}

	var data map[string]string
	switch v := secretValue.(type) {
	case string:
		data = map[string]string{
			req.Name: v,
		}
	case map[string]interface{}:
		data = make(map[string]string, len(v))
		for key, value := range v {
			data[key] = fmt.Sprint(value)
		}
	case map[string]string:
		data = v
	default:
		return secretstores.GetSecretResponse{}, fmt.Errorf("unexpected type %q for secret value", reflect.TypeOf(v))
	}

	return secretstores.GetSecretResponse{
		Data: data,
	}, nil
}

// BulkGetSecret retrieves all secrets in the store and returns a map of decrypted string/string values.
func (j *localSecretStore) BulkGetSecret(ctx context.Context, req secretstores.BulkGetSecretRequest) (secretstores.BulkGetSecretResponse, error) {
	r := map[string]map[string]string{}

	for k, v := range j.secrets {
		switch v := v.(type) {
		case string:
			r[k] = map[string]string{
				k: v,
			}
		case map[string]interface{}:
			data := make(map[string]string, len(v))
			for key, value := range v {
				data[key] = fmt.Sprint(value)
			}
			r[k] = data
		case map[string]string:
			r[k] = v
		default:
			return secretstores.BulkGetSecretResponse{}, fmt.Errorf("unexpected type %q for secret value", reflect.TypeOf(v))
		}
	}

	return secretstores.BulkGetSecretResponse{
		Data: r,
	}, nil
}

func (j *localSecretStore) visitJSONObject(jsonConfig map[string]interface{}) error {
	for key, element := range jsonConfig {
		j.enterContext(key)
		err := j.visitProperty(element)
		if err != nil {
			return err
		}
		j.exitContext()
	}

	return nil
}

func (j *localSecretStore) enterContext(context string) {
	j.currenContext = append(j.currenContext, context)
	j.currentPath = j.combine(j.currenContext)
}

func (j *localSecretStore) visitPrimitive(context string) error {
	key := j.currentPath
	_, exists := j.secrets[key]

	if exists {
		return errors.New("duplicate key")
	}

	j.secrets[key] = context

	return nil
}

func (j *localSecretStore) visitArray(array []interface{}) error {
	for i := 0; i < len(array); i++ {
		j.enterContext(strconv.Itoa(i))
		err := j.visitProperty(array[i])
		if err != nil {
			return err
		}
		j.exitContext()
	}

	return nil
}

func (j *localSecretStore) visitProperty(property interface{}) error {
	switch v := property.(type) {
	case map[string]interface{}:
		return j.visitJSONObject(v)
	case []interface{}:
		return j.visitArray(v)
	case bool, string, int, float32, float64, byte, nil:
		return j.visitPrimitive(fmt.Sprintf("%s", v))
	default:
		return errors.New("couldn't parse property")
	}
}

func (j *localSecretStore) exitContext() {
	j.pop()
	j.currentPath = j.combine(j.currenContext)
}

func (j *localSecretStore) pop() {
	n := len(j.currenContext) - 1 // Top element
	j.currenContext[n] = ""
	j.currenContext = j.currenContext[:n] // Pop
}

func (j *localSecretStore) combine(values []string) string {
	return strings.Join(values, j.nestedSeparator)
}

func (j *localSecretStore) getLocalSecretStoreMetadata(spec secretstores.Metadata) (*localSecretStoreMetaData, error) {
	var meta localSecretStoreMetaData
	err := kitmd.DecodeMetadata(spec.Properties, &meta)
	if err != nil {
		return nil, err
	}

	if meta.SecretsFile == "" {
		return nil, fmt.Errorf("missing local secrets file in metadata")
	}

	return &meta, nil
}

func (j *localSecretStore) readLocalFile(secretsFile string) (map[string]interface{}, error) {
	j.secretsFile = secretsFile
	jsonFile, err := os.Open(secretsFile)
	if err != nil {
		return nil, err
	}

	defer jsonFile.Close()

	byteValue, err := io.ReadAll(jsonFile)
	if err != nil {
		return nil, err
	}

	var jsonConfig map[string]interface{}
	err = json.Unmarshal(byteValue, &jsonConfig)
	if err != nil {
		return nil, err
	}

	return jsonConfig, nil
}

// Features returns the features available in this secret store.
func (j *localSecretStore) Features() []secretstores.Feature {
	return j.features
}

func (j *localSecretStore) GetComponentMetadata() (metadataInfo metadata.MetadataMap) {
	metadataStruct := localSecretStoreMetaData{}
	metadata.GetMetadataInfoFromStructType(reflect.TypeOf(metadataStruct), &metadataInfo, metadata.SecretStoreType)
	return
}