Init V4 community edition (#2265)

* Init V4 community edition

* Init V4 community edition

pkg/filemanager/manager/viewer.go

@@ -0,0 +1,93 @@
+package manager
+
+import (
+	"context"
+	"encoding/gob"
+	"fmt"
+	"time"
+
+	"github.com/cloudreve/Cloudreve/v4/inventory/types"
+	"github.com/cloudreve/Cloudreve/v4/pkg/filemanager/fs"
+	"github.com/cloudreve/Cloudreve/v4/pkg/filemanager/fs/dbfs"
+	"github.com/cloudreve/Cloudreve/v4/pkg/setting"
+	"github.com/cloudreve/Cloudreve/v4/pkg/util"
+	"github.com/gofrs/uuid"
+)
+
+type (
+	ViewerSession struct {
+		ID          string  `json:"id"`
+		AccessToken string  `json:"access_token"`
+		Expires     int64   `json:"expires"`
+		File        fs.File `json:"-"`
+	}
+	ViewerSessionCache struct {
+		ID       string
+		Uri      string
+		UserID   int
+		FileID   int
+		ViewerID string
+		Version  string
+		Token    string
+	}
+	ViewerSessionCacheCtx struct{}
+	ViewerCtx             struct{}
+)
+
+const (
+	ViewerSessionCachePrefix = "viewer_session_"
+
+	sessionExpiresPadding = 10
+)
+
+func init() {
+	gob.Register(ViewerSessionCache{})
+}
+
+func (m *manager) CreateViewerSession(ctx context.Context, uri *fs.URI, version string, viewer *setting.Viewer) (*ViewerSession, error) {
+	file, err := m.fs.Get(ctx, uri, dbfs.WithFileEntities())
+	if err != nil {
+		return nil, err
+	}
+
+	versionType := types.EntityTypeVersion
+	found, desired := fs.FindDesiredEntity(file, version, m.hasher, &versionType)
+	if !found {
+		return nil, fs.ErrEntityNotExist
+	}
+
+	if desired.Size() > m.settings.MaxOnlineEditSize(ctx) {
+		return nil, fs.ErrFileSizeTooBig
+	}
+
+	sessionID := uuid.Must(uuid.NewV4()).String()
+	token := util.RandStringRunes(128)
+	sessionCache := &ViewerSessionCache{
+		ID:       sessionID,
+		Uri:      file.Uri(false).String(),
+		UserID:   m.user.ID,
+		ViewerID: viewer.ID,
+		FileID:   file.ID(),
+		Version:  version,
+		Token:    fmt.Sprintf("%s.%s", sessionID, token),
+	}
+	ttl := m.settings.ViewerSessionTTL(ctx)
+	if err := m.kv.Set(ViewerSessionCachePrefix+sessionID, *sessionCache, ttl); err != nil {
+		return nil, err
+	}
+
+	return &ViewerSession{
+		File:        file,
+		ID:          sessionID,
+		AccessToken: sessionCache.Token,
+		Expires:     time.Now().Add(time.Duration(ttl-sessionExpiresPadding) * time.Second).UnixMilli(),
+	}, nil
+}
+
+func ViewerSessionFromContext(ctx context.Context) *ViewerSessionCache {
+	return ctx.Value(ViewerSessionCacheCtx{}).(*ViewerSessionCache)
+}
+
+func ViewerFromContext(ctx context.Context) *setting.Viewer {
+	return ctx.Value(ViewerCtx{}).(*setting.Viewer)
+}