package storage

import (
	"sort"
	"sync"

	"git.thisco.de/vbatts/image-storage-interfaces/driver"
)

var (
	storageDriversMu sync.RWMutex
	storageDrivers   = make(map[string]driver.Driver)
)

// Drivers returns a sorted list of the registered drivers
func Drivers() []string {
	storageDriversMu.Lock()
	defer storageDriversMu.Unlock()
	var list []string
	for name, _ := range storageDrivers {
		list = append(list, name)
	}
	sort.Strings(list)
	return list
}

// Register makes a database driver available by the provided name. If Register
// is called twice with the same name or if driver is nil, it panics.
func Register(name string, driver driver.Driver) {
	storageDriversMu.Lock()
	defer storageDriversMu.Unlock()
	if driver == nil {
		panic("storage: Register driver is nil")
	}
	if _, dup := storageDrivers[name]; dup {
		panic("storage: Register called twice for driver " + name)
	}
	storageDrivers[name] = driver

}

// OpenHandle a storage handle using the specified storage driver name and a
// rootPath for that driver to operate in.
func OpenHandle(name string, rootPath string) (*S, error) {
	return nil, nil
}

// S is a storage handle for the storage and management of filesystem trees.
//
// Operations on an handle instance are intended to be safe for concurrent use.
// Though this would likely not be safe for two competing instances to be
// operating on the same rootPath (more thought needed here).
type S struct {
}