[feature] Add admin media prune orphaned CLI command (#1146)

* add FilePath regex

* add `admin media prune orphaned` command

* add prune orphaned function to media manager

* don't mark flag as required

* document admin media prune orphaned cmd

* oh envparsing.sh you coy minx

internal/media/pruneorphaned.go

@@ -0,0 +1,127 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package media
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/regexes"
+)
+
+func (m *manager) PruneOrphaned(ctx context.Context, dry bool) (int, error) {
+	var totalPruned int
+
+	// keys in storage will look like the following:
+	// `[ACCOUNT_ID]/[MEDIA_TYPE]/[MEDIA_SIZE]/[FILE_NAME]`
+	// we can filter out keys we're not interested in by
+	// matching through a regex
+	var matchCount int
+	match := func(storageKey string) bool {
+		if regexes.FilePath.MatchString(storageKey) {
+			matchCount++
+			return true
+		}
+		return false
+	}
+
+	log.Info("checking storage keys for orphaned pruning candidates...")
+	iterator, err := m.storage.Iterator(ctx, match)
+	if err != nil {
+		return 0, fmt.Errorf("PruneOrphaned: error getting storage iterator: %s", err)
+	}
+
+	// make sure we have some keys, and also advance
+	// the iterator to the first non-empty key
+	if !iterator.Next() {
+		return 0, nil
+	}
+
+	// for each key in the iterator, check if entry is orphaned
+	log.Info("got %d orphaned pruning candidates, checking for orphaned status, please wait...")
+	var checkedKeys int
+	orphanedKeys := make([]string, 0, matchCount)
+	for key := iterator.Key(); iterator.Next(); key = iterator.Key() {
+		if m.orphaned(ctx, key) {
+			orphanedKeys = append(orphanedKeys, key)
+		}
+		checkedKeys++
+		if checkedKeys%50 == 0 {
+			log.Infof("checked %d of %d orphaned pruning candidates...", checkedKeys, matchCount)
+		}
+	}
+	iterator.Release()
+
+	if !dry {
+		// the real deal, we have to delete stuff
+		for _, key := range orphanedKeys {
+			log.Infof("key %s corresponds to orphaned media, will remove it now", key)
+			if err := m.storage.Delete(ctx, key); err != nil {
+				log.Errorf("error deleting item with key %s from storage: %s", key, err)
+				continue
+			}
+			totalPruned++
+		}
+	} else {
+		// just a dry run, don't delete anything
+		for _, key := range orphanedKeys {
+			log.Infof("DRY RUN: key %s corresponds to orphaned media which would be deleted", key)
+			totalPruned++
+		}
+	}
+
+	return totalPruned, nil
+}
+
+func (m *manager) orphaned(ctx context.Context, key string) bool {
+	pathParts := regexes.FilePath.FindStringSubmatch(key)
+	if len(pathParts) != 6 {
+		return false
+	}
+
+	mediaType := pathParts[2]
+	mediaID := pathParts[4]
+
+	var orphaned bool
+	switch Type(mediaType) {
+	case TypeAttachment, TypeHeader, TypeAvatar:
+		if _, err := m.db.GetAttachmentByID(ctx, mediaID); err != nil {
+			if errors.Is(err, db.ErrNoEntries) {
+				orphaned = true
+			} else {
+				log.Errorf("orphaned: error calling GetAttachmentByID: %s", err)
+			}
+		}
+	case TypeEmoji:
+		if _, err := m.db.GetEmojiByID(ctx, mediaID); err != nil {
+			if errors.Is(err, db.ErrNoEntries) {
+				orphaned = true
+			} else {
+				log.Errorf("orphaned: error calling GetEmojiByID: %s", err)
+			}
+		}
+	default:
+		orphaned = true
+	}
+
+	return orphaned
+}