package backend

import (
	"io"
	"os"
	"strings"
	"time"

	"github.com/seaweedfs/seaweedfs/weed/glog"
	"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
	"github.com/seaweedfs/seaweedfs/weed/pb/volume_server_pb"
	"github.com/seaweedfs/seaweedfs/weed/util"
)

type BackendStorageFile interface {
	io.ReaderAt
	io.WriterAt
	Truncate(off int64) error
	io.Closer
	GetStat() (datSize int64, modTime time.Time, err error)
	Name() string
	Sync() error
}

type BackendStorage interface {
	ToProperties() map[string]string
	NewStorageFile(key string, tierInfo *volume_server_pb.VolumeInfo) BackendStorageFile
	// concurrency > 0 caps concurrent network transfers; <= 0 uses the backend default.
	CopyFile(f *os.File, fn func(progressed int64, percentage float32) error, concurrency int) (key string, size int64, err error)
	DownloadFile(fileName string, key string, fn func(progressed int64, percentage float32) error, concurrency int) (size int64, err error)
	DeleteFile(key string) (err error)
}

type StringProperties interface {
	GetString(key string) string
}
type StorageType string
type BackendStorageFactory interface {
	StorageType() StorageType
	BuildStorage(configuration StringProperties, configPrefix string, id string) (BackendStorage, error)
}

var (
	BackendStorageFactories = make(map[StorageType]BackendStorageFactory)
	BackendStorages         = make(map[string]BackendStorage)
)

// used by master to load remote storage configurations
func LoadConfiguration(config *util.ViperProxy) {

	StorageBackendPrefix := "storage.backend"

	for backendTypeName := range config.GetStringMap(StorageBackendPrefix) {
		backendStorageFactory, found := BackendStorageFactories[StorageType(backendTypeName)]
		if !found {
			glog.Fatalf("backend storage type %s not found", backendTypeName)
		}
		for backendStorageId := range config.GetStringMap(StorageBackendPrefix + "." + backendTypeName) {
			if !config.GetBool(StorageBackendPrefix + "." + backendTypeName + "." + backendStorageId + ".enabled") {
				continue
			}
			if _, found := BackendStorages[backendTypeName+"."+backendStorageId]; found {
				continue
			}
			backendStorage, buildErr := backendStorageFactory.BuildStorage(config,
				StorageBackendPrefix+"."+backendTypeName+"."+backendStorageId+".", backendStorageId)
			if buildErr != nil {
				glog.Fatalf("fail to create backend storage %s.%s", backendTypeName, backendStorageId)
			}
			BackendStorages[backendTypeName+"."+backendStorageId] = backendStorage
			if backendStorageId == "default" {
				BackendStorages[backendTypeName] = backendStorage
			}
		}
	}

}

// used by volume server to receive remote storage configurations from master
func LoadFromPbStorageBackends(storageBackends []*master_pb.StorageBackend) {

	for _, storageBackend := range storageBackends {
		backendStorageFactory, found := BackendStorageFactories[StorageType(storageBackend.Type)]
		if !found {
			glog.Warningf("storage type %s not found", storageBackend.Type)
			continue
		}
		if _, found := BackendStorages[storageBackend.Type+"."+storageBackend.Id]; found {
			continue
		}
		backendStorage, buildErr := backendStorageFactory.BuildStorage(newProperties(storageBackend.Properties), "", storageBackend.Id)
		if buildErr != nil {
			glog.Fatalf("fail to create backend storage %s.%s", storageBackend.Type, storageBackend.Id)
		}
		BackendStorages[storageBackend.Type+"."+storageBackend.Id] = backendStorage
		if storageBackend.Id == "default" {
			BackendStorages[storageBackend.Type] = backendStorage
		}
	}
}

type Properties struct {
	m map[string]string
}

func newProperties(m map[string]string) *Properties {
	return &Properties{m: m}
}

func (p *Properties) GetString(key string) string {
	if v, found := p.m[key]; found {
		return v
	}
	return ""
}

func ToPbStorageBackends() (backends []*master_pb.StorageBackend) {
	for sName, s := range BackendStorages {
		sType, sId := BackendNameToTypeId(sName)
		if sType == "" {
			continue
		}
		backends = append(backends, &master_pb.StorageBackend{
			Type:       sType,
			Id:         sId,
			Properties: s.ToProperties(),
		})
	}
	return
}

func BackendNameToTypeId(backendName string) (backendType, backendId string) {
	parts := strings.Split(backendName, ".")
	if len(parts) == 1 {
		return backendName, "default"
	}
	if len(parts) != 2 {
		return
	}

	backendType, backendId = parts[0], parts[1]
	return
}