package config

import (
	"fmt"
	"time"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/secretsmanager"
	"github.com/creasty/defaults"
	"github.com/fsnotify/fsnotify"
	"github.com/go-playground/validator/v10"
	"github.com/imdario/mergo"
	"github.com/mitchellh/mapstructure"
	"github.com/pingcap/errors"
	"github.com/pingcap/log"
	"github.com/spf13/viper"
	ov "github.com/tidbcloud/config-service/oneconfig/viper"
	"go.uber.org/zap"
	"gopkg.in/yaml.v2"
)

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

// use a single instance of Validate, it caches struct info
var validate = validator.New()

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

func mergeConfigWithSecretStore(config *CentralConfig, secretName, region string) error {
	secretConfig, err := GetSecretFromAwsSecretManager(secretName, 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")
	}

	s := CentralConfig{}
	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 NormalizeConfigSetup(config *CentralConfig) 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 {
		err := mergeConfigWithSecretStore(config, config.ServerConfig.SecretStore.SecretKey, config.ServerConfig.SecretStore.Region)
		if err != nil {
			return err
		}

		err = mergeConfigWithSecretStore(config, config.ServerConfig.SecretStore.ExtraSecretKey, config.ServerConfig.SecretStore.Region)
		if err != nil {
			return err
		}
	}
	return nil
}

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

	return nil
}

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

	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
}

// 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
	}
	// metrics-server and metrics-pipeline do not rely on the remote configs.
	//err = LoadRemote()
	//if err != nil {
	//	log.Warn("load remote config failed, just ignore it in persnonal project", zap.Error(err))
	//}

	// register config change watcher
	viper.WatchConfig()
	viper.OnConfigChange(func(e fsnotify.Event) {
		log.Info("config file changed", zap.String("path", e.Name))
	})
	err = NormalizeConfig()
	if err != nil {
		return err
	}

	return nil
}

func LoadRemote() error {
	remote := fmt.Sprintf("%s/oneconfig-central/config.yaml", viper.Get("server.project"))
	log.Info("Read From Remote", zap.String("remote", remote))
	err := viper.AddRemoteProvider(ov.Provider, ov.Endpoint, remote)
	if err != nil {
		return errors.Annotate(err, "failed to load remote config")
	}

	err = viper.ReadRemoteConfig()
	if err != nil {
		return errors.Annotate(err, "failed to load remote config")
	}

	// open a goroutine to watch remote changes forever
	go func() {
		for {
			time.Sleep(time.Second * 5) // delay after each request

			// currently, only tested with etcd support
			err := viper.WatchRemoteConfig()
			if err != nil {
				log.Error("unable to read remote config", zap.Error(err))
				continue
			}

			err = NormalizeConfig()
			if err != nil {
				log.Error("failed to normalize config", zap.Error(err))
				continue
			}
		}
	}()
	return nil
}

func Global() *CentralConfig {
	return globalConf
}

func LoadTopSQLTLS() *TLSConfig {
	conf := topSQLTLSConf.Load().(TLSConfig)
	return &conf
}

func StoreTopSQLTLS(conf TLSConfig) {
	topSQLTLSConf.Store(conf)
}

func GetSecretFromAwsSecretManager(secretName, region string) (string, error) {
	awsConfig := aws.NewConfig().WithMaxRetries(3).WithRegion(region)
	opts := session.Options{Config: *awsConfig}
	sess, err := session.NewSessionWithOptions(opts)
	if err != nil {
		return "", err
	}
	svc := secretsmanager.New(sess)
	input := &secretsmanager.GetSecretValueInput{
		SecretId:     aws.String(secretName),
		VersionStage: aws.String("AWSCURRENT"), // VersionStage defaults to AWSCURRENT if unspecified
	}
	result, err := svc.GetSecretValue(input)
	if err != nil {
		return "", err
	}
	return *result.SecretString, nil
}