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store.go
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store.go
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package main
import (
"bytes"
"crypto/sha1"
"encoding/hex"
"errors"
"fmt"
"io"
"log"
"os"
"strings"
)
var defaultRootFolderName = "GloxDefaultFolder"
func CASPathTransformFunc(key string) PathKey {
hash := sha1.Sum([]byte(key))
hashedString := hex.EncodeToString(hash[:]) //[:] converts it to a byte slice
blockSize := 5
sliceLength := len(hashedString) / blockSize
paths := make([]string, sliceLength)
for i := 0; i < sliceLength; i++ {
paths[i] = hashedString[i*blockSize : (i+1)*blockSize]
}
return PathKey{
Pathname: strings.Join(paths, "/"),
Filename: hashedString,
}
}
type PathKey struct {
Pathname string
Filename string
}
func (p PathKey) FirstPathName() string {
paths := strings.Split(p.Pathname, "/")
if len(paths) == 0 {
return ""
}
return paths[0]
}
func (p PathKey) Fullpath() string {
return fmt.Sprintf("%s/%s", p.Pathname, p.Filename)
}
type PathTransformFunc func(string) PathKey
//INFO: root is the folder name of the root directory, containing all files and folders of the system
type StoreOpts struct {
Root string
PathTransformFunc PathTransformFunc
}
func DefaultPathTransformFunc(key string) PathKey {
return PathKey{
Filename: key,
Pathname: key,
}
}
type Store struct {
StoreOpts
}
func NewStore(opts StoreOpts) *Store {
if opts.PathTransformFunc == nil {
opts.PathTransformFunc = DefaultPathTransformFunc
}
if opts.Root == "" {
opts.Root = defaultRootFolderName
}
return &Store{
StoreOpts: opts,
}
}
func (store *Store) Has(key string) bool {
pathkey := store.PathTransformFunc(key)
fullPathwithRoot := fmt.Sprintf("%s/%s", store.Root, pathkey.Fullpath())
_, err := os.Stat(fullPathwithRoot)
if errors.Is(err, os.ErrNotExist) {
return false
}
return true
}
func (store *Store) Clear() error {
return os.RemoveAll(store.Root)
}
func (store *Store) Delete(key string) error {
pathkey := store.PathTransformFunc(key)
firstPathNamewithRoot := fmt.Sprintf("%s/%s", store.Root, pathkey.FirstPathName())
defer func() {
log.Printf("deleted [%s] from disk", firstPathNamewithRoot)
}()
return os.RemoveAll(firstPathNamewithRoot)
}
func (store *Store) Read(key string) (io.Reader, error) {
f, err := store.readStream(key)
if err != nil {
return nil, err
}
defer f.Close()
buf := new(bytes.Buffer)
_, err = io.Copy(buf, f)
if err != nil {
return nil, err
}
return buf, nil
}
func (store *Store) readStream(key string) (io.ReadCloser, error) {
pathKey := store.PathTransformFunc(key)
fullPathwithRoot := fmt.Sprintf("%s/%s", store.Root, pathKey.Fullpath())
return os.Open(fullPathwithRoot)
}
func (store *Store) Write(key string, r io.Reader) error {
return store.writeStream(key, r)
}
func (store *Store) writeStream(key string, r io.Reader) error {
pathKey := store.PathTransformFunc(key)
pathNamewithRoot := fmt.Sprintf("%s/%s", store.Root, pathKey.Pathname)
if err := os.MkdirAll(pathNamewithRoot, os.ModePerm); err != nil {
return err
}
fullPathwithRoot := fmt.Sprintf("%s/%s", store.Root, pathKey.Fullpath())
file, err := os.Create(fullPathwithRoot)
if err != nil {
return err
}
n, err := io.Copy(file, r)
if err != nil {
return err
}
log.Printf("written (%d) to disk: %s", n, fullPathwithRoot)
return nil
}