fs storage

2026-03-13 21:07:23 +02:00
parent 43039a79bf
commit 9ade76e21d
117 changed files with 1734 additions and 176 deletions
@@ -1,75 +1,704 @@
-// fs implements galaxy/storage.Storage with filesystem
+// Package fs implements galaxy/storage.Storage using the filesystem.
 package fs

-/*
-
-Общие правила:
-
-1. Все хранимые объекты сериализуются / десериализуются как JSON.
-
-2. Структура хранения файлов:
-
- storageRoot \
-			  |
-			  +-- state.dat
-			  |
-			  +-- {GameID} \
-			  |	           |
-			  |			   +-- {Turn}.dat (client.GameData)
-			  |			   +-- {Turn}.dat (client.GameData)
-			  |			   +-- ...
-			  |
-			  +-- {GameID} \
-			  			   |
-						   +-- ...
-
-*/
-
 import (
+	"encoding/json"
+	"errors"
 	"fmt"
-	"galaxy/util"
+	"os"
 	"path/filepath"
+	"slices"
+	"strconv"
+	"strings"
+	"sync"
+
+	"galaxy/model/client"
+	"galaxy/model/order"
+	"galaxy/model/report"
+	"galaxy/util"
 )

 const (
-	// Name of the file under the storage's root where [model.State] is stored.
+	// stateFileName is the file name under the storage root where [client.State] is stored.
 	stateFileName = "state.dat"

-	// Suffix of a Game's file inder the storage's root where [model.GameData] is stored.
+	// gameDataFileSuffix is the extension for per-turn [client.GameData] files.
 	gameDataFileSuffix = ".dat"
+
+	defaultFilePerm = 0o644
+	oldFileSuffix   = ".old"
+	newFileSuffix   = ".new"
 )

-// StateFilePath returns client's state file path relative to the root,
-// file name and extension are pre-defined constant.
+// StateFilePath returns the path to the persisted [client.State] file under root.
 func StateFilePath(root string) string {
 	return filepath.Join(root, stateFileName)
 }

-// GameDataPath returns game's data file path relative to the root,
-// data file name is GameID string representation and extension is a pre-defined constant.
+// GameDataFilePath returns the legacy per-game data file path under root.
+//
+// The storage implementation keeps turn data in per-turn files under a game directory
+// and does not use this helper internally.
 func GameDataFilePath(root string, id fmt.Stringer) string {
 	return filepath.Join(root, id.String()) + gameDataFileSuffix
 }

-type fsStorage struct {
-	storageRoot string
+type pathLock struct {
+	mu   sync.Mutex
+	refs int
 }

-// NewFS returns on-filesystem implementation of the "galaxy/storage.Storage" with root located at storageRoot.
-// storageRoot must me a directory and has write access to the current user. If initial checks failed, return nil and non-nil error.
-func NewStorage(storageRoot string) (*fsStorage, error) {
-	if ok, err := util.PathExists(storageRoot, true); err != nil {
-		return nil, fmt.Errorf("new storage: check path %q exists: %w", storageRoot, err)
-	} else if !ok {
-		return nil, fmt.Errorf("new storage: path %q does not exists", storageRoot)
-	}
-	if ok, err := util.Writable(storageRoot); err != nil {
-		return nil, fmt.Errorf("new storage: check path %q writable: %w", storageRoot, err)
-	} else if !ok {
-		return nil, fmt.Errorf("new storage: path %q is not writable", storageRoot)
-	}
-	s := &fsStorage{
-		storageRoot: storageRoot,
-	}
-	return s, nil
+type fsStorage struct {
+	storageRoot string
+
+	locksMu sync.Mutex
+	locks   map[string]*pathLock
+
+	readFileFn   func(string) ([]byte, error)
+	writeFileFn  func(string, []byte, os.FileMode) error
+	renameFileFn func(string, string) error
+	removeFileFn func(string) error
+}
+
+type storedOrder struct {
+	UpdatedAt int               `json:"updatedAt"`
+	Commands  []json.RawMessage `json:"cmd"`
+}
+
+type storedGameData struct {
+	Turn   uint          `json:"turn"`
+	Report report.Report `json:"report"`
+	Order  *storedOrder  `json:"order,omitempty"`
+}
+
+// NewFS returns a filesystem-backed implementation of galaxy/storage.Storage rooted at storageRoot.
+// storageRoot must already exist, be a directory, and be writable by the current user.
+func NewFS(storageRoot string) (*fsStorage, error) {
+	fmt.Println("using fs root:", storageRoot)
+	absRoot, err := filepath.Abs(storageRoot)
+	if err != nil {
+		return nil, fmt.Errorf("new fs storage: resolve absolute path for %q: %w", storageRoot, err)
+	}
+	if ok, err := util.PathExists(absRoot, true); err != nil {
+		return nil, fmt.Errorf("new fs storage: check path %q exists: %w", absRoot, err)
+	} else if !ok {
+		return nil, fmt.Errorf("new fs storage: path %q does not exist", absRoot)
+	}
+	if ok, err := util.Writable(absRoot); err != nil {
+		return nil, fmt.Errorf("new fs storage: check path %q writable: %w", absRoot, err)
+	} else if !ok {
+		return nil, fmt.Errorf("new fs storage: path %q is not writable", absRoot)
+	}
+
+	return &fsStorage{
+		storageRoot:  absRoot,
+		locks:        make(map[string]*pathLock),
+		readFileFn:   os.ReadFile,
+		writeFileFn:  os.WriteFile,
+		renameFileFn: os.Rename,
+		removeFileFn: os.Remove,
+	}, nil
+}
+
+func (s *fsStorage) StateExists(callback func(bool, error)) {
+	go func() {
+		exists, err := s.FileExists(stateFileName)
+		if callback != nil {
+			callback(exists, err)
+		}
+	}()
+}
+
+func (s *fsStorage) LoadState(callback func(client.State, error)) {
+	go func() {
+		state, err := s.loadStateSync()
+		if callback != nil {
+			callback(state, err)
+		}
+	}()
+}
+
+func (s *fsStorage) SaveState(state client.State, callback func(error)) {
+	go func() {
+		err := s.saveStateSync(state)
+		if callback != nil {
+			callback(err)
+		}
+	}()
+}
+
+func (s *fsStorage) LoadReport(id client.GameID, turn uint, callback func(report.Report, error)) {
+	go func() {
+		rep, err := s.loadReportSync(id, turn)
+		if callback != nil {
+			callback(rep, err)
+		}
+	}()
+}
+
+func (s *fsStorage) SaveReport(id client.GameID, turn uint, rep report.Report, callback func(error)) {
+	go func() {
+		err := s.saveReportSync(id, turn, rep)
+		if callback != nil {
+			callback(err)
+		}
+	}()
+}
+
+func (s *fsStorage) LoadOrder(id client.GameID, turn uint, callback func(order.Order, error)) {
+	go func() {
+		o, err := s.loadOrderSync(id, turn)
+		if callback != nil {
+			callback(o, err)
+		}
+	}()
+}
+
+func (s *fsStorage) SaveOrder(id client.GameID, turn uint, o order.Order, callback func(error)) {
+	go func() {
+		err := s.saveOrderSync(id, turn, o)
+		if callback != nil {
+			callback(err)
+		}
+	}()
+}
+
+func (s *fsStorage) FileExists(path string) (bool, error) {
+	absPath, err := s.resolvePath(path)
+	if err != nil {
+		return false, err
+	}
+
+	var exists bool
+	err = s.withPathLock(absPath, func() error {
+		var opErr error
+		exists, opErr = s.fileExistsUnlocked(absPath)
+		return opErr
+	})
+	return exists, err
+}
+
+func (s *fsStorage) ReadFile(path string) ([]byte, error) {
+	absPath, err := s.resolvePath(path)
+	if err != nil {
+		return nil, err
+	}
+
+	var data []byte
+	err = s.withPathLock(absPath, func() error {
+		var opErr error
+		data, opErr = s.readFileUnlocked(absPath)
+		return opErr
+	})
+	return data, err
+}
+
+func (s *fsStorage) WriteFile(path string, data []byte) error {
+	absPath, err := s.resolvePath(path)
+	if err != nil {
+		return err
+	}
+
+	return s.withPathLock(absPath, func() error {
+		return s.writeFileUnlocked(absPath, data)
+	})
+}
+
+func (s *fsStorage) DeleteFile(path string) error {
+	absPath, err := s.resolvePath(path)
+	if err != nil {
+		return err
+	}
+
+	return s.withPathLock(absPath, func() error {
+		exists, err := s.fileExistsUnlocked(absPath)
+		if err != nil {
+			return err
+		}
+		if !exists {
+			return fmt.Errorf("delete file %q: %w", absPath, os.ErrNotExist)
+		}
+		if err := s.removeFileFn(absPath); err != nil {
+			return fmt.Errorf("delete file %q: %w", absPath, err)
+		}
+		return nil
+	})
+}
+
+func (s *fsStorage) ListFiles() ([]string, error) {
+	files := make([]string, 0)
+	err := filepath.WalkDir(s.storageRoot, func(path string, d os.DirEntry, walkErr error) error {
+		if walkErr != nil {
+			return walkErr
+		}
+		if d.IsDir() {
+			return nil
+		}
+		if strings.HasSuffix(d.Name(), newFileSuffix) || strings.HasSuffix(d.Name(), oldFileSuffix) {
+			return nil
+		}
+
+		relPath, err := filepath.Rel(s.storageRoot, path)
+		if err != nil {
+			return fmt.Errorf("resolve relative path for %q: %w", path, err)
+		}
+		files = append(files, filepath.Clean(relPath))
+		return nil
+	})
+	if err != nil {
+		return nil, fmt.Errorf("list files under %q: %w", s.storageRoot, err)
+	}
+
+	slices.Sort(files)
+	return files, nil
+}
+
+func (s *fsStorage) loadStateSync() (client.State, error) {
+	data, err := s.ReadFile(stateFileName)
+	if err != nil {
+		return client.State{}, err
+	}
+	return unmarshalState(data)
+}
+
+func (s *fsStorage) saveStateSync(state client.State) error {
+	data, err := marshalState(state)
+	if err != nil {
+		return err
+	}
+	return s.WriteFile(stateFileName, data)
+}
+
+func (s *fsStorage) loadReportSync(id client.GameID, turn uint) (report.Report, error) {
+	gameData, err := s.loadGameDataSync(id, turn)
+	if err != nil {
+		return report.Report{}, err
+	}
+	return gameData.Report, nil
+}
+
+func (s *fsStorage) saveReportSync(id client.GameID, turn uint, rep report.Report) error {
+	absPath, err := s.resolvePath(gameTurnFilePath(id, turn))
+	if err != nil {
+		return err
+	}
+
+	return s.withPathLock(absPath, func() error {
+		gameData, err := s.loadGameDataUnlocked(absPath)
+		if err != nil {
+			if !errors.Is(err, os.ErrNotExist) {
+				return err
+			}
+			gameData = client.GameData{Turn: turn}
+		}
+
+		gameData.Turn = turn
+		gameData.Report = rep
+		return s.writeGameDataUnlocked(absPath, gameData)
+	})
+}
+
+func (s *fsStorage) loadOrderSync(id client.GameID, turn uint) (order.Order, error) {
+	gameData, err := s.loadGameDataSync(id, turn)
+	if err != nil {
+		return order.Order{}, err
+	}
+	if gameData.Order == nil {
+		return order.Order{}, fmt.Errorf("load order for game %q turn %d: %w", id, turn, os.ErrNotExist)
+	}
+	return *gameData.Order, nil
+}
+
+func (s *fsStorage) saveOrderSync(id client.GameID, turn uint, o order.Order) error {
+	absPath, err := s.resolvePath(gameTurnFilePath(id, turn))
+	if err != nil {
+		return err
+	}
+
+	return s.withPathLock(absPath, func() error {
+		gameData, err := s.loadGameDataUnlocked(absPath)
+		if err != nil {
+			if errors.Is(err, os.ErrNotExist) {
+				return fmt.Errorf("save order for game %q turn %d: %w", id, turn, os.ErrNotExist)
+			}
+			return err
+		}
+
+		gameData.Turn = turn
+		gameData.Order = &o
+		return s.writeGameDataUnlocked(absPath, gameData)
+	})
+}
+
+func (s *fsStorage) loadGameDataSync(id client.GameID, turn uint) (client.GameData, error) {
+	absPath, err := s.resolvePath(gameTurnFilePath(id, turn))
+	if err != nil {
+		return client.GameData{}, err
+	}
+
+	var gameData client.GameData
+	err = s.withPathLock(absPath, func() error {
+		var opErr error
+		gameData, opErr = s.loadGameDataUnlocked(absPath)
+		return opErr
+	})
+	return gameData, err
+}
+
+func (s *fsStorage) loadGameDataUnlocked(absPath string) (client.GameData, error) {
+	data, err := s.readFileUnlocked(absPath)
+	if err != nil {
+		return client.GameData{}, err
+	}
+	return unmarshalGameData(data)
+}
+
+func (s *fsStorage) writeGameDataUnlocked(absPath string, gameData client.GameData) error {
+	data, err := marshalGameData(gameData)
+	if err != nil {
+		return err
+	}
+	return s.writeFileUnlocked(absPath, data)
+}
+
+func marshalState(state client.State) ([]byte, error) {
+	return marshalJSON(state)
+}
+
+func unmarshalState(data []byte) (client.State, error) {
+	var state client.State
+	if err := unmarshalJSON(data, &state); err != nil {
+		return client.State{}, err
+	}
+	return state, nil
+}
+
+func marshalGameData(gameData client.GameData) ([]byte, error) {
+	stored, err := makeStoredGameData(gameData)
+	if err != nil {
+		return nil, err
+	}
+	return marshalJSON(stored)
+}
+
+func unmarshalGameData(data []byte) (client.GameData, error) {
+	var stored storedGameData
+	if err := unmarshalJSON(data, &stored); err != nil {
+		return client.GameData{}, err
+	}
+	return stored.toGameData()
+}
+
+func marshalJSON(value any) ([]byte, error) {
+	data, err := json.Marshal(value)
+	if err != nil {
+		return nil, fmt.Errorf("marshal json: %w", err)
+	}
+	return data, nil
+}
+
+func unmarshalJSON(data []byte, target any) error {
+	if err := json.Unmarshal(data, target); err != nil {
+		return fmt.Errorf("unmarshal json: %w", err)
+	}
+	return nil
+}
+
+func makeStoredGameData(gameData client.GameData) (storedGameData, error) {
+	stored := storedGameData{
+		Turn:   gameData.Turn,
+		Report: gameData.Report,
+	}
+	if gameData.Order == nil {
+		return stored, nil
+	}
+
+	storedOrder, err := makeStoredOrder(*gameData.Order)
+	if err != nil {
+		return storedGameData{}, err
+	}
+	stored.Order = &storedOrder
+	return stored, nil
+}
+
+func (d storedGameData) toGameData() (client.GameData, error) {
+	gameData := client.GameData{
+		Turn:   d.Turn,
+		Report: d.Report,
+	}
+	if d.Order == nil {
+		return gameData, nil
+	}
+
+	o, err := d.Order.toOrder()
+	if err != nil {
+		return client.GameData{}, err
+	}
+	gameData.Order = o
+	return gameData, nil
+}
+
+func makeStoredOrder(o order.Order) (storedOrder, error) {
+	result := storedOrder{
+		UpdatedAt: o.UpdatedAt,
+		Commands:  make([]json.RawMessage, len(o.Commands)),
+	}
+	for i := range o.Commands {
+		data, err := marshalJSON(o.Commands[i])
+		if err != nil {
+			return storedOrder{}, fmt.Errorf("marshal order command %d: %w", i, err)
+		}
+		result.Commands[i] = data
+	}
+	return result, nil
+}
+
+func (o *storedOrder) toOrder() (*order.Order, error) {
+	if o == nil {
+		return nil, nil
+	}
+
+	result := &order.Order{
+		UpdatedAt: o.UpdatedAt,
+		Commands:  make([]order.DecodableCommand, len(o.Commands)),
+	}
+	for i := range o.Commands {
+		cmd, err := parseOrderCommand(o.Commands[i])
+		if err != nil {
+			return nil, fmt.Errorf("decode order command %d: %w", i, err)
+		}
+		result.Commands[i] = cmd
+	}
+	return result, nil
+}
+
+func parseOrderCommand(data json.RawMessage) (order.DecodableCommand, error) {
+	meta := new(order.CommandMeta)
+	if err := json.Unmarshal(data, meta); err != nil {
+		return nil, fmt.Errorf("decode order command metadata: %w", err)
+	}
+
+	switch meta.CmdType {
+	case order.CommandTypeRaceQuit:
+		return decodeOrderCommand(data, new(order.CommandRaceQuit))
+	case order.CommandTypeRaceVote:
+		return decodeOrderCommand(data, new(order.CommandRaceVote))
+	case order.CommandTypeRaceRelation:
+		return decodeOrderCommand(data, new(order.CommandRaceRelation))
+	case order.CommandTypeShipClassCreate:
+		return decodeOrderCommand(data, new(order.CommandShipClassCreate))
+	case order.CommandTypeShipClassMerge:
+		return decodeOrderCommand(data, new(order.CommandShipClassMerge))
+	case order.CommandTypeShipClassRemove:
+		return decodeOrderCommand(data, new(order.CommandShipClassRemove))
+	case order.CommandTypeShipGroupBreak:
+		return decodeOrderCommand(data, new(order.CommandShipGroupBreak))
+	case order.CommandTypeShipGroupLoad:
+		return decodeOrderCommand(data, new(order.CommandShipGroupLoad))
+	case order.CommandTypeShipGroupUnload:
+		return decodeOrderCommand(data, new(order.CommandShipGroupUnload))
+	case order.CommandTypeShipGroupSend:
+		return decodeOrderCommand(data, new(order.CommandShipGroupSend))
+	case order.CommandTypeShipGroupUpgrade:
+		return decodeOrderCommand(data, new(order.CommandShipGroupUpgrade))
+	case order.CommandTypeShipGroupMerge:
+		return decodeOrderCommand(data, new(order.CommandShipGroupMerge))
+	case order.CommandTypeShipGroupDismantle:
+		return decodeOrderCommand(data, new(order.CommandShipGroupDismantle))
+	case order.CommandTypeShipGroupTransfer:
+		return decodeOrderCommand(data, new(order.CommandShipGroupTransfer))
+	case order.CommandTypeShipGroupJoinFleet:
+		return decodeOrderCommand(data, new(order.CommandShipGroupJoinFleet))
+	case order.CommandTypeFleetMerge:
+		return decodeOrderCommand(data, new(order.CommandFleetMerge))
+	case order.CommandTypeFleetSend:
+		return decodeOrderCommand(data, new(order.CommandFleetSend))
+	case order.CommandTypeScienceCreate:
+		return decodeOrderCommand(data, new(order.CommandScienceCreate))
+	case order.CommandTypeScienceRemove:
+		return decodeOrderCommand(data, new(order.CommandScienceRemove))
+	case order.CommandTypePlanetRename:
+		return decodeOrderCommand(data, new(order.CommandPlanetRename))
+	case order.CommandTypePlanetProduce:
+		return decodeOrderCommand(data, new(order.CommandPlanetProduce))
+	case order.CommandTypePlanetRouteSet:
+		return decodeOrderCommand(data, new(order.CommandPlanetRouteSet))
+	case order.CommandTypePlanetRouteRemove:
+		return decodeOrderCommand(data, new(order.CommandPlanetRouteRemove))
+	default:
+		return nil, fmt.Errorf("unknown order command type %q", meta.CmdType)
+	}
+}
+
+func decodeOrderCommand[T order.DecodableCommand](data json.RawMessage, target T) (T, error) {
+	if err := json.Unmarshal(data, target); err != nil {
+		return target, err
+	}
+	return target, nil
+}
+
+func (s *fsStorage) resolvePath(path string) (string, error) {
+	relPath, err := normalizeRelativePath(path)
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(s.storageRoot, relPath), nil
+}
+
+func normalizeRelativePath(path string) (string, error) {
+	path = strings.ReplaceAll(path, "\\", string(filepath.Separator))
+	path = strings.TrimLeft(path, string(filepath.Separator))
+	path = filepath.Clean(path)
+
+	switch {
+	case path == "." || path == "":
+		return "", errors.New("path must not be empty")
+	case filepath.IsAbs(path):
+		return "", fmt.Errorf("path %q must be relative", path)
+	case filepath.VolumeName(path) != "":
+		return "", fmt.Errorf("path %q must not include a volume name", path)
+	case path == "..":
+		return "", fmt.Errorf("path %q escapes storage root", path)
+	case strings.HasPrefix(path, ".."+string(filepath.Separator)):
+		return "", fmt.Errorf("path %q escapes storage root", path)
+	}
+
+	return path, nil
+}
+
+func gameTurnFilePath(id fmt.Stringer, turn uint) string {
+	return filepath.Join(id.String(), strconv.FormatUint(uint64(turn), 10)+gameDataFileSuffix)
+}
+
+func (s *fsStorage) withPathLock(absPath string, fn func() error) error {
+	lock := s.acquirePathLock(absPath)
+	defer s.releasePathLock(absPath)
+
+	lock.mu.Lock()
+	defer lock.mu.Unlock()
+
+	return fn()
+}
+
+func (s *fsStorage) acquirePathLock(absPath string) *pathLock {
+	s.locksMu.Lock()
+	defer s.locksMu.Unlock()
+
+	lock, ok := s.locks[absPath]
+	if !ok {
+		lock = &pathLock{}
+		s.locks[absPath] = lock
+	}
+	lock.refs++
+	return lock
+}
+
+func (s *fsStorage) releasePathLock(absPath string) {
+	s.locksMu.Lock()
+	defer s.locksMu.Unlock()
+
+	lock, ok := s.locks[absPath]
+	if !ok {
+		return
+	}
+	lock.refs--
+	if lock.refs == 0 {
+		delete(s.locks, absPath)
+	}
+}
+
+func (s *fsStorage) fileExistsUnlocked(absPath string) (bool, error) {
+	ok, err := util.FileExists(absPath)
+	if err != nil {
+		return false, fmt.Errorf("check file %q exists: %w", absPath, err)
+	}
+	return ok, nil
+}
+
+func (s *fsStorage) readFileUnlocked(absPath string) ([]byte, error) {
+	data, err := s.readFileFn(absPath)
+	if err != nil {
+		return nil, fmt.Errorf("read file %q: %w", absPath, err)
+	}
+	return data, nil
+}
+
+func (s *fsStorage) writeFileUnlocked(absPath string, data []byte) error {
+	if err := s.ensureParentDir(absPath); err != nil {
+		return err
+	}
+
+	targetExists, err := s.fileExistsUnlocked(absPath)
+	if err != nil {
+		return err
+	}
+
+	oldPath := absPath + oldFileSuffix
+	oldExists, err := s.fileExistsUnlocked(oldPath)
+	if err != nil {
+		return err
+	}
+	if oldExists {
+		return fmt.Errorf("write file %q: old file already exists at %q", absPath, oldPath)
+	}
+
+	newPath := absPath + newFileSuffix
+	newExists, err := s.fileExistsUnlocked(newPath)
+	if err != nil {
+		return err
+	}
+	if newExists {
+		return fmt.Errorf("write file %q: new file already exists at %q", absPath, newPath)
+	}
+
+	if err := s.writeFileFn(newPath, data, defaultFilePerm); err != nil {
+		return fmt.Errorf("write new file %q: %w", newPath, err)
+	}
+
+	if targetExists {
+		if err := s.renameFileFn(absPath, oldPath); err != nil {
+			return errors.Join(
+				fmt.Errorf("rename file %q to %q: %w", absPath, oldPath, err),
+				s.cleanupTempFile(newPath),
+			)
+		}
+	}
+
+	if err := s.renameFileFn(newPath, absPath); err != nil {
+		var restoreErr error
+		if targetExists {
+			restoreErr = s.renameFileFn(oldPath, absPath)
+			if restoreErr != nil {
+				restoreErr = fmt.Errorf("restore file %q from %q: %w", absPath, oldPath, restoreErr)
+			}
+		}
+		return errors.Join(
+			fmt.Errorf("rename new file %q to %q: %w", newPath, absPath, err),
+			restoreErr,
+			s.cleanupTempFile(newPath),
+		)
+	}
+
+	if !targetExists {
+		return nil
+	}
+	if err := s.removeFileFn(oldPath); err != nil {
+		return fmt.Errorf("remove old file %q: %w", oldPath, err)
+	}
+	return nil
+}
+
+func (s *fsStorage) cleanupTempFile(path string) error {
+	if err := s.removeFileFn(path); err != nil && !errors.Is(err, os.ErrNotExist) {
+		return fmt.Errorf("remove temp file %q: %w", path, err)
+	}
+	return nil
+}
+
+func (s *fsStorage) ensureParentDir(absPath string) error {
+	parentDir := filepath.Dir(absPath)
+	if err := os.MkdirAll(parentDir, os.ModePerm); err != nil {
+		return fmt.Errorf("create parent directory %q: %w", parentDir, err)
+	}
+	return nil
 }
@@ -0,0 +1,529 @@
+package fs
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"galaxy/model/client"
+	"galaxy/model/order"
+	"galaxy/model/report"
+)
+
+const testTimeout = time.Second
+
+type callbackResult[T any] struct {
+	value T
+	err   error
+}
+
+func TestStateRoundTripAsync(t *testing.T) {
+	s := newTestStorage(t)
+	want := sampleState()
+
+	saveDone := make(chan error, 1)
+	s.SaveState(want, func(err error) {
+		saveDone <- err
+	})
+	if err := waitError(t, saveDone); err != nil {
+		t.Fatalf("save state: %v", err)
+	}
+
+	existsDone := make(chan callbackResult[bool], 1)
+	s.StateExists(func(ok bool, err error) {
+		existsDone <- callbackResult[bool]{value: ok, err: err}
+	})
+	exists := waitResult(t, existsDone)
+	if exists.err != nil {
+		t.Fatalf("state exists: %v", exists.err)
+	}
+	if !exists.value {
+		t.Fatal("state file should exist after save")
+	}
+
+	loadDone := make(chan callbackResult[client.State], 1)
+	s.LoadState(func(state client.State, err error) {
+		loadDone <- callbackResult[client.State]{value: state, err: err}
+	})
+	got := waitResult(t, loadDone)
+	if got.err != nil {
+		t.Fatalf("load state: %v", got.err)
+	}
+	if !reflect.DeepEqual(got.value, want) {
+		t.Fatalf("loaded state mismatch\nwant: %#v\ngot:  %#v", want, got.value)
+	}
+}
+
+func TestReportAndOrderRoundTripAsync(t *testing.T) {
+	s := newTestStorage(t)
+	id := client.GameID("game-1")
+	turn := uint(7)
+	initialReport := sampleReport(turn, "Terran")
+	updatedReport := sampleReport(turn, "Zenith")
+	wantOrder := sampleOrder()
+
+	saveReportDone := make(chan error, 1)
+	s.SaveReport(id, turn, initialReport, func(err error) {
+		saveReportDone <- err
+	})
+	if err := waitError(t, saveReportDone); err != nil {
+		t.Fatalf("save report: %v", err)
+	}
+
+	saveOrderDone := make(chan error, 1)
+	s.SaveOrder(id, turn, wantOrder, func(err error) {
+		saveOrderDone <- err
+	})
+	if err := waitError(t, saveOrderDone); err != nil {
+		t.Fatalf("save order: %v", err)
+	}
+
+	saveUpdatedReportDone := make(chan error, 1)
+	s.SaveReport(id, turn, updatedReport, func(err error) {
+		saveUpdatedReportDone <- err
+	})
+	if err := waitError(t, saveUpdatedReportDone); err != nil {
+		t.Fatalf("save updated report: %v", err)
+	}
+
+	loadReportDone := make(chan callbackResult[report.Report], 1)
+	s.LoadReport(id, turn, func(rep report.Report, err error) {
+		loadReportDone <- callbackResult[report.Report]{value: rep, err: err}
+	})
+	gotReport := waitResult(t, loadReportDone)
+	if gotReport.err != nil {
+		t.Fatalf("load report: %v", gotReport.err)
+	}
+	if !reflect.DeepEqual(gotReport.value, updatedReport) {
+		t.Fatalf("loaded report mismatch\nwant: %#v\ngot:  %#v", updatedReport, gotReport.value)
+	}
+
+	loadOrderDone := make(chan callbackResult[order.Order], 1)
+	s.LoadOrder(id, turn, func(got order.Order, err error) {
+		loadOrderDone <- callbackResult[order.Order]{value: got, err: err}
+	})
+	gotOrder := waitResult(t, loadOrderDone)
+	if gotOrder.err != nil {
+		t.Fatalf("load order: %v", gotOrder.err)
+	}
+	if !reflect.DeepEqual(gotOrder.value, wantOrder) {
+		t.Fatalf("loaded order mismatch\nwant: %#v\ngot:  %#v", wantOrder, gotOrder.value)
+	}
+}
+
+func TestSaveOrderBeforeReportReturnsNotExist(t *testing.T) {
+	s := newTestStorage(t)
+
+	done := make(chan error, 1)
+	s.SaveOrder("game-2", 3, sampleOrder(), func(err error) {
+		done <- err
+	})
+	err := waitError(t, done)
+	if !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("save order error = %v, want os.ErrNotExist", err)
+	}
+}
+
+func TestRawFileCRUDAndList(t *testing.T) {
+	s := newTestStorage(t)
+
+	if err := s.WriteFile("/nested/alpha.txt", []byte("alpha")); err != nil {
+		t.Fatalf("write alpha: %v", err)
+	}
+	if err := s.WriteFile("beta.txt", []byte("beta")); err != nil {
+		t.Fatalf("write beta: %v", err)
+	}
+
+	alphaExists, err := s.FileExists("nested/alpha.txt")
+	if err != nil {
+		t.Fatalf("file exists: %v", err)
+	}
+	if !alphaExists {
+		t.Fatal("nested/alpha.txt should exist")
+	}
+
+	alphaData, err := s.ReadFile("nested/alpha.txt")
+	if err != nil {
+		t.Fatalf("read alpha: %v", err)
+	}
+	if string(alphaData) != "alpha" {
+		t.Fatalf("read alpha = %q, want %q", alphaData, "alpha")
+	}
+
+	if err := os.WriteFile(filepath.Join(s.storageRoot, "skip.txt"+newFileSuffix), []byte("tmp"), 0o644); err != nil {
+		t.Fatalf("create stale .new file: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(s.storageRoot, "skip.txt"+oldFileSuffix), []byte("tmp"), 0o644); err != nil {
+		t.Fatalf("create stale .old file: %v", err)
+	}
+
+	files, err := s.ListFiles()
+	if err != nil {
+		t.Fatalf("list files: %v", err)
+	}
+	wantFiles := []string{
+		"beta.txt",
+		filepath.Join("nested", "alpha.txt"),
+	}
+	if !reflect.DeepEqual(files, wantFiles) {
+		t.Fatalf("listed files mismatch\nwant: %#v\ngot:  %#v", wantFiles, files)
+	}
+
+	if err := s.DeleteFile("beta.txt"); err != nil {
+		t.Fatalf("delete beta: %v", err)
+	}
+	if err := s.DeleteFile("beta.txt"); !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("delete missing beta error = %v, want os.ErrNotExist", err)
+	}
+}
+
+func TestPathTraversalRejected(t *testing.T) {
+	s := newTestStorage(t)
+
+	for _, path := range []string{"../escape.txt", "..\\escape.txt", ""} {
+		t.Run(path, func(t *testing.T) {
+			err := s.WriteFile(path, []byte("blocked"))
+			if err == nil {
+				t.Fatalf("write %q unexpectedly succeeded", path)
+			}
+		})
+	}
+}
+
+func TestAtomicWriteFirstAndOverwrite(t *testing.T) {
+	s := newTestStorage(t)
+	target := filepath.Join("turns", "12.bin")
+
+	if err := s.WriteFile(target, []byte("first")); err != nil {
+		t.Fatalf("first write: %v", err)
+	}
+	assertFileContent(t, s, target, "first")
+	assertNoTempArtifacts(t, s, target)
+
+	if err := s.WriteFile(target, []byte("second")); err != nil {
+		t.Fatalf("overwrite: %v", err)
+	}
+	assertFileContent(t, s, target, "second")
+	assertNoTempArtifacts(t, s, target)
+}
+
+func TestAtomicWriteStaleTempCollision(t *testing.T) {
+	t.Run("stale new file", func(t *testing.T) {
+		s := newTestStorage(t)
+		target := "collision-new.txt"
+		absTarget, err := s.resolvePath(target)
+		if err != nil {
+			t.Fatalf("resolve target: %v", err)
+		}
+		if err := os.MkdirAll(filepath.Dir(absTarget), os.ModePerm); err != nil {
+			t.Fatalf("create parent dir: %v", err)
+		}
+		if err := os.WriteFile(absTarget+newFileSuffix, []byte("stale"), 0o644); err != nil {
+			t.Fatalf("write stale new file: %v", err)
+		}
+
+		err = s.WriteFile(target, []byte("payload"))
+		if err == nil || !strings.Contains(err.Error(), "new file already exists") {
+			t.Fatalf("write error = %v, want stale new file error", err)
+		}
+	})
+
+	t.Run("stale old file", func(t *testing.T) {
+		s := newTestStorage(t)
+		target := "collision-old.txt"
+		absTarget, err := s.resolvePath(target)
+		if err != nil {
+			t.Fatalf("resolve target: %v", err)
+		}
+		if err := os.WriteFile(absTarget, []byte("current"), 0o644); err != nil {
+			t.Fatalf("write target: %v", err)
+		}
+		if err := os.WriteFile(absTarget+oldFileSuffix, []byte("stale"), 0o644); err != nil {
+			t.Fatalf("write stale old file: %v", err)
+		}
+
+		err = s.WriteFile(target, []byte("payload"))
+		if err == nil || !strings.Contains(err.Error(), "old file already exists") {
+			t.Fatalf("write error = %v, want stale old file error", err)
+		}
+	})
+}
+
+func TestAtomicWriteRollbackOnRenameFailure(t *testing.T) {
+	s := newTestStorage(t)
+	target := filepath.Join("rollback", "state.txt")
+	absTarget, err := s.resolvePath(target)
+	if err != nil {
+		t.Fatalf("resolve target: %v", err)
+	}
+
+	if err := s.WriteFile(target, []byte("original")); err != nil {
+		t.Fatalf("seed target file: %v", err)
+	}
+
+	origRename := s.renameFileFn
+	s.renameFileFn = func(oldPath, newPath string) error {
+		if oldPath == absTarget+newFileSuffix && newPath == absTarget {
+			return errors.New("forced rename failure")
+		}
+		return origRename(oldPath, newPath)
+	}
+
+	err = s.WriteFile(target, []byte("replacement"))
+	if err == nil || !strings.Contains(err.Error(), "forced rename failure") {
+		t.Fatalf("write error = %v, want forced rename failure", err)
+	}
+
+	assertFileContent(t, s, target, "original")
+	assertNoTempArtifacts(t, s, target)
+}
+
+func TestSamePathOperationsSerialize(t *testing.T) {
+	s := newTestStorage(t)
+	target := "shared.txt"
+	absTarget, err := s.resolvePath(target)
+	if err != nil {
+		t.Fatalf("resolve target: %v", err)
+	}
+
+	entered := make(chan struct{})
+	release := make(chan struct{})
+	origWrite := s.writeFileFn
+	var writes atomic.Int32
+	s.writeFileFn = func(path string, data []byte, perm os.FileMode) error {
+		if path == absTarget+newFileSuffix && writes.Add(1) == 1 {
+			close(entered)
+			<-release
+		}
+		return origWrite(path, data, perm)
+	}
+
+	firstDone := make(chan error, 1)
+	go func() {
+		firstDone <- s.WriteFile(target, []byte("one"))
+	}()
+	waitSignal(t, entered, "first write entered")
+
+	secondDone := make(chan error, 1)
+	go func() {
+		secondDone <- s.WriteFile(target, []byte("two"))
+	}()
+
+	select {
+	case err := <-secondDone:
+		t.Fatalf("second write finished before first released: %v", err)
+	case <-time.After(50 * time.Millisecond):
+	}
+	if writes.Load() != 1 {
+		t.Fatalf("same-path write reached file hook %d times before release, want 1", writes.Load())
+	}
+
+	close(release)
+	if err := waitError(t, firstDone); err != nil {
+		t.Fatalf("first write: %v", err)
+	}
+	if err := waitError(t, secondDone); err != nil {
+		t.Fatalf("second write: %v", err)
+	}
+}
+
+func TestDifferentPathOperationsDoNotBlockEachOther(t *testing.T) {
+	s := newTestStorage(t)
+	blockedTarget := "blocked.txt"
+	absTarget, err := s.resolvePath(blockedTarget)
+	if err != nil {
+		t.Fatalf("resolve blocked target: %v", err)
+	}
+
+	entered := make(chan struct{})
+	release := make(chan struct{})
+	origWrite := s.writeFileFn
+	s.writeFileFn = func(path string, data []byte, perm os.FileMode) error {
+		if path == absTarget+newFileSuffix {
+			close(entered)
+			<-release
+		}
+		return origWrite(path, data, perm)
+	}
+
+	blockedDone := make(chan error, 1)
+	go func() {
+		blockedDone <- s.WriteFile(blockedTarget, []byte("blocked"))
+	}()
+	waitSignal(t, entered, "blocked write entered")
+
+	freeDone := make(chan error, 1)
+	go func() {
+		freeDone <- s.WriteFile("free.txt", []byte("free"))
+	}()
+
+	select {
+	case err := <-freeDone:
+		if err != nil {
+			t.Fatalf("free write: %v", err)
+		}
+	case <-time.After(testTimeout):
+		t.Fatal("write for a different path should not block")
+	}
+
+	close(release)
+	if err := waitError(t, blockedDone); err != nil {
+		t.Fatalf("blocked write: %v", err)
+	}
+}
+
+func TestSaveStateIsNonBlockingAndCallbackBased(t *testing.T) {
+	s := newTestStorage(t)
+
+	entered := make(chan struct{})
+	release := make(chan struct{})
+	origWrite := s.writeFileFn
+	s.writeFileFn = func(path string, data []byte, perm os.FileMode) error {
+		close(entered)
+		<-release
+		return origWrite(path, data, perm)
+	}
+
+	callbacks := make(chan error, 2)
+	s.SaveState(sampleState(), func(err error) {
+		callbacks <- err
+	})
+
+	waitSignal(t, entered, "async save entered")
+
+	select {
+	case err := <-callbacks:
+		t.Fatalf("callback fired before storage write completed: %v", err)
+	default:
+	}
+
+	close(release)
+	if err := waitError(t, callbacks); err != nil {
+		t.Fatalf("callback error: %v", err)
+	}
+
+	select {
+	case err := <-callbacks:
+		t.Fatalf("callback fired more than once: %v", err)
+	case <-time.After(50 * time.Millisecond):
+	}
+}
+
+func newTestStorage(t *testing.T) *fsStorage {
+	t.Helper()
+
+	s, err := NewFS(t.TempDir())
+	if err != nil {
+		t.Fatalf("new test storage: %v", err)
+	}
+	return s
+}
+
+func sampleState() client.State {
+	return client.State{
+		GameState: []client.GameState{
+			{ID: client.GameID("game-1"), LastTurn: 12, ActiveTurn: 11},
+			{ID: client.GameID("game-2"), LastTurn: 4, ActiveTurn: 4},
+		},
+		ActiveGameID: client.GameID("game-2"),
+	}
+}
+
+func sampleReport(turn uint, race string) report.Report {
+	return report.Report{
+		Turn:        turn,
+		Width:       160,
+		Height:      90,
+		PlanetCount: 8,
+		Race:        race,
+		VoteFor:     "assembly",
+	}
+}
+
+func sampleOrder() order.Order {
+	return order.Order{
+		UpdatedAt: 1700,
+		Commands: []order.DecodableCommand{
+			&order.CommandPlanetRename{
+				CommandMeta: order.CommandMeta{
+					CmdType: order.CommandTypePlanetRename,
+					CmdID:   "rename-planet",
+				},
+				Number: 2,
+				Name:   "Nova Prime",
+			},
+			&order.CommandRaceVote{
+				CommandMeta: order.CommandMeta{
+					CmdType: order.CommandTypeRaceVote,
+					CmdID:   "vote-race",
+				},
+				Acceptor: "ZENITH",
+			},
+		},
+	}
+}
+
+func assertFileContent(t *testing.T, s *fsStorage, path, want string) {
+	t.Helper()
+
+	got, err := s.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read %q: %v", path, err)
+	}
+	if string(got) != want {
+		t.Fatalf("content for %q = %q, want %q", path, got, want)
+	}
+}
+
+func assertNoTempArtifacts(t *testing.T, s *fsStorage, path string) {
+	t.Helper()
+
+	absPath, err := s.resolvePath(path)
+	if err != nil {
+		t.Fatalf("resolve path %q: %v", path, err)
+	}
+	for _, tempPath := range []string{absPath + newFileSuffix, absPath + oldFileSuffix} {
+		if _, err := os.Stat(tempPath); !errors.Is(err, os.ErrNotExist) {
+			t.Fatalf("temp artifact %q should not exist, stat err = %v", tempPath, err)
+		}
+	}
+}
+
+func waitSignal(t *testing.T, ch <-chan struct{}, name string) {
+	t.Helper()
+
+	select {
+	case <-ch:
+	case <-time.After(testTimeout):
+		t.Fatalf("timeout waiting for %s", name)
+	}
+}
+
+func waitError(t *testing.T, ch <-chan error) error {
+	t.Helper()
+
+	select {
+	case err := <-ch:
+		return err
+	case <-time.After(testTimeout):
+		t.Fatal("timeout waiting for error callback")
+		return nil
+	}
+}
+
+func waitResult[T any](t *testing.T, ch <-chan callbackResult[T]) callbackResult[T] {
+	t.Helper()
+
+	select {
+	case result := <-ch:
+		return result
+	case <-time.After(testTimeout):
+		t.Fatal("timeout waiting for callback result")
+		return callbackResult[T]{}
+	}
+}