package config

import (
	"context"
	"sync"

	awsconfig "github.com/aws/aws-sdk-go-v2/config"
	"github.com/aws/aws-sdk-go-v2/service/secretsmanager"
	"github.com/creasty/defaults"
	"github.com/go-playground/validator/v10"
	"github.com/imdario/mergo"
	"github.com/mitchellh/mapstructure"
	"github.com/pingcap/errors"
	"github.com/spf13/viper"
	"gopkg.in/yaml.v2"
	"k8s.io/utils/pointer"
)

// use defaults <- pulumi config (config file) <- remote config <- secrets
// defaults for tag default in the config struct.

var (
	secretsmanagerOnce sync.Once
	secretsmanagerCli  *secretsmanager.Client
	// use a single instance of Validate, it caches struct info
	validate = validator.New()
)

// InitConfig parse the central configuration file and init the global config var
func InitConfig(path string) error {
	viper.SetConfigFile(path)
	err := viper.ReadInConfig()
	if err != nil {
		return err
	}

	err = NormalizeConfig()
	if err != nil {
		return err
	}

	return nil
}

func NormalizeConfig() error {
	config := &ChaosConfig{}

	err := NormalizeConfigDefaults(config)
	if err != nil {
		return err
	}
	err = NormalizeConfigSetup(config)
	if err != nil {
		return err
	}
	err = NormalizeConfigValidate(config)
	if err != nil {
		return err
	}
	globalConf = config
	return nil
}

func NormalizeConfigDefaults(config *ChaosConfig) error {
	return defaults.Set(config)
}

func NormalizeConfigSetup(config *ChaosConfig) error {
	err := viper.Unmarshal(config)
	if err != nil {
		return errors.Annotate(err, "failed unmarshal from viper")
	}

	// let's load some secret from aws and merge it
	if config.ServerConfig.SecretStore != nil {
		secretConfig, err := GetSecretFromAwsSecretManager(config.ServerConfig.SecretStore.SecretKey, config.ServerConfig.SecretStore.Region)
		if err != nil {
			return errors.Annotate(err, "failed to load secret config from aws")
		}
		m := make(map[interface{}]interface{})
		if err := yaml.Unmarshal([]byte(secretConfig), &m); err != nil {
			return errors.Annotate(err, "failed to unmarshal secret config")
		}

		var s ChaosConfig

		if err := mapstructure.Decode(m, &s); err != nil {
			return errors.Annotate(err, "failed to mapsturcture secret config")
		}

		if err := mergo.Merge(config, s, mergo.WithOverride); err != nil {
			return errors.Annotate(err, "failed to merge secret config")
		}
	}
	return nil
}

func NormalizeConfigValidate(config *ChaosConfig) error {
	// validate the values
	if err := validate.Struct(config); err != nil {
		return errors.Annotate(err, "failed to validate the config values")
	}

	return nil
}

func GetSecretFromAwsSecretManager(secretName, region string) (string, error) {
	secretsmanagerOnce.Do(func() {
		awsConfig, err := awsconfig.LoadDefaultConfig(context.TODO())
		if err != nil {
			panic("AWS configuration error, " + err.Error())
		}
		awsConfig.RetryMaxAttempts = 3
		secretsmanagerCli = secretsmanager.NewFromConfig(awsConfig)
	})

	input := &secretsmanager.GetSecretValueInput{
		SecretId:     pointer.String(secretName),
		VersionStage: pointer.String("AWSCURRENT"), // VersionStage defaults to AWSCURRENT if unspecified
	}
	result, err := secretsmanagerCli.GetSecretValue(context.TODO(), input)
	if err != nil {
		return "", err
	}
	return *result.SecretString, nil
}