mstore/app/storage/storage.go

/*
 * Copyright 2026 Oleg Borodin <onborodin@gmail.com>
 *
 * This work is published and licensed under a Creative Commons
 * Attribution-NonCommercial-NoDerivatives 4.0 International License.
 *
 * Distribution of this work is permitted, but commercial use and
 * modifications are strictly prohibited.
 */
package storage

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"os"
	"path/filepath"

	"mstore/app/logger"
	"mstore/pkg/auxuuid"
)

const (
	sha256prefix = "sha256:"
	fileSubdir   = "files"
	tmpSubdir    = "tmps"
)

type Storage struct {
	basepath string
	logg     *logger.Logger
}

func NewStorage(basepath string) *Storage {
	res := &Storage{
		basepath: basepath,
	}
	res.logg = logger.NewLoggerWithSubject("storage")
	return res
}

func (store *Storage) makeCollecionpath(collection string) string {
	return filepath.Join(store.basepath, fileSubdir, collection)
}

func (store *Storage) makeFilepath(collection, filename string) string {
	return filepath.Join(store.basepath, fileSubdir, collection, filename)
}

func (store *Storage) makeTmppath(tmpName string) string {
	return filepath.Join(store.basepath, tmpSubdir, tmpName)
}

func (store *Storage) makeTmpsubdir() string {
	return filepath.Join(store.basepath, tmpSubdir)
}

func (store *Storage) makeFilesubdir(collection, filename string) string {
	return filepath.Join(store.basepath, fileSubdir)
}

func (store *Storage) GetFileReader(collection, filename string) (io.ReadCloser, error) {
	var err error
	var res io.ReadCloser

	filename = store.makeFilepath(collection, filename)
	file, err := os.OpenFile(filename, os.O_RDONLY, 0)
	if err != nil {
		return res, err
	}
	res = file
	return res, err
}

func (store *Storage) WriteTempFile(source io.Reader) (string, int64, string, error) {
	var err error
	var size int64
	var csum string

	tmpName := fmt.Sprintf("%d.tmp", auxuuid.NewUUID())
	tmpPath := store.makeTmppath(tmpName)

	tmpdirpath := store.makeTmpsubdir()
	err = os.MkdirAll(tmpdirpath, 0750)
	if err != nil {
		return tmpName, size, csum, err
	}

	file, err := os.OpenFile(tmpPath, os.O_WRONLY|os.O_CREATE, 0640)
	if err != nil {
		return tmpName, size, csum, err
	}
	defer file.Close()

	hasher := NewHasher()
	mWriter := io.MultiWriter(file, hasher.Writer())
	size, err = io.Copy(mWriter, source)
	if err != nil {
		return tmpName, size, csum, err
	}
	csum = hasher.Hex()

	return tmpName, size, csum, err
}

func (store *Storage) HardlinkFile(tmpName, collection, filename string) error {
	var err error

	dirname := store.makeCollecionpath(collection)
	_, err = os.Stat(dirname)
	if os.IsNotExist(err) {
		err = os.MkdirAll(dirname, 0750)
		if err != nil {
			return err
		}
	}
	if err != nil {
		return err
	}
	filename = store.makeFilepath(collection, filename)
	_, err = os.Stat(dirname)
	if os.IsExist(err) {
		os.Remove(filename) // TODO: safe removing
	}
	tmpName = store.makeTmppath(tmpName)
	err = os.Link(tmpName, filename)
	if err != nil {
		return err
	}
	err = os.Remove(tmpName)
	if err != nil {
		return err
	}
	return err
}

func (store *Storage) DeleteFile(collection, filename string) error {
	var err error
	filename = store.makeFilepath(collection, filename)
	err = os.Remove(filename)
	if err != nil {
		return err
	}
	// TODO: clean removing
	dirname := store.makeCollecionpath(collection)
	os.RemoveAll(dirname)
	return err
}

const (
	upsubdir   = "uploads"
	blobsubdir = "blobs"
)

func (store *Storage) makeUppath(upname string) string {
	return filepath.Join(store.basepath, upsubdir, upname) + ".bin"
}

func (store *Storage) makeUpsubdir() string {
	return filepath.Join(store.basepath, upsubdir)
}

func (store *Storage) makeBlobpath(upname string) string {
	return filepath.Join(store.basepath, blobsubdir, upname) + ".bin"
}

func (store *Storage) makeBlobsubdir() string {
	return filepath.Join(store.basepath, blobsubdir)
}

func (store *Storage) WriteUpload(upID string, source io.Reader) (int64, error) {
	var err error
	var recsize int64

	uploadDir := store.makeUpsubdir()
	_, err = os.Stat(uploadDir)
	if os.IsNotExist(err) {
		err = os.MkdirAll(uploadDir, 0750)
		if err != nil {
			return recsize, err
		}
	}
	if err != nil {
		return recsize, err
	}
	upPath := store.makeUppath(upID)
	upFile, err := os.OpenFile(upPath, os.O_WRONLY|os.O_CREATE, 0644)
	if err != nil {
		return recsize, err
	}
	defer upFile.Close()
	recsize, err = io.Copy(upFile, source)
	if err != nil {
		return recsize, err
	}
	return recsize, err
}

func (store *Storage) LinkUpload(reference, digest string) error {
	var err error
	upPath := store.makeUppath(reference)

	blobdir := store.makeBlobsubdir()
	_, err = os.Stat(blobdir)
	if errors.Is(err, os.ErrNotExist) {
		err = os.MkdirAll(blobdir, 0750)
		if err != nil {
			return err
		}
	}
	if err != nil {
		return err
	}
	blobPath := store.makeBlobpath(digest)
	_, err = os.Stat(blobPath)
	if err == nil {
		err = os.Remove(blobPath)
		if err != nil {
			return err
		}
	}
	if os.IsNotExist(err) {
		err = nil
	}
	if err != nil {
		return err
	}
	err = os.Link(upPath, blobPath)
	if err != nil {
		return err
	}
	err = os.Remove(upPath)
	if err != nil {
		return err
	}
	return err
}

func (store *Storage) RemoveUpload(digest string) error {
	var err error
	upPath := store.makeUppath(digest)
	err = os.Remove(upPath)
	if err != nil {
		return err
	}
	return err
}

func (st *Storage) UploadExists(name, reference string) (bool, int64, error) {
	var err error
	var size int64
	upPath := st.makeUppath(reference)
	fileStat, err := os.Stat(upPath)
	if errors.Is(err, os.ErrNotExist) {
		return false, 0, nil
	}
	if err != nil {
		return false, 0, err
	}
	size = fileStat.Size()
	return true, size, err
}

func (store *Storage) WriteBlob(digstr string, source io.Reader) (int64, error) {
	var err error
	var size int64
	blobDir := store.makeBlobsubdir()
	_, err = os.Stat(blobDir)
	if os.IsNotExist(err) {
		err = os.MkdirAll(blobDir, 0750)
		if err != nil {
			return size, err
		}
	}
	if err != nil {
		return size, err
	}
	blobPath := store.makeBlobpath(digstr)
	blobFile, err := os.OpenFile(blobPath, os.O_WRONLY|os.O_CREATE, 0644)
	if err != nil {
		return size, err
	}
	defer blobFile.Close()
	size, err = io.Copy(blobFile, source)
	if err != nil {
		return size, err
	}
	return size, err
}

func (st *Storage) BlobExists(digest string) (bool, int64, error) {
	var err error
	var size int64

	blobPath := st.makeBlobpath(digest)
	fileStat, err := os.Stat(blobPath)
	if os.IsNotExist(err) {
		return false, 0, nil
	}
	if err != nil {
		return false, 0, err
	}
	size = fileStat.Size()
	return true, size, err
}

func (store *Storage) BlobReader(digest string) (int64, io.ReadCloser, error) {
	var err error
	var size int64
	blobPath := store.makeBlobpath(digest)
	nop := io.NopCloser(bytes.NewReader(nil))
	file, err := os.OpenFile(blobPath, os.O_RDONLY, 0)
	if err != nil {
		return size, nop, err
	}
	defer func() {
		if err != nil {
			file.Close()
		}
	}()
	filestat, err := file.Stat()
	if err != nil {
		return size, nop, err
	}
	size = filestat.Size()
	return size, file, err
}

func (store *Storage) DeleteBlob(digest string) error {
	var err error
	blobPath := store.makeBlobpath(digest)
	err = os.Remove(blobPath)
	if os.IsNotExist(err) {
		err = nil
	}
	if err != nil {
		return err
	}
	return err
}