1 files changed, 121 insertions, 0 deletions
diff --git a/internal/visibility/public_timeline.go b/internal/visibility/public_timeline.go
new file mode 100644
index 000000000..13ac07831
--- /dev/null
+++ b/internal/visibility/public_timeline.go
@@ -0,0 +1,121 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// 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 visibility
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/superseriousbusiness/gotosocial/internal/cache"
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
+)
+
+// StatusHomeTimelineable checks if given status should be included on requester's public timeline. Primarily relying on status visibility to requester and the AP visibility setting, and ignoring conversation threads.
+func (f *Filter) StatusPublicTimelineable(ctx context.Context, requester *gtsmodel.Account, status *gtsmodel.Status) (bool, error) {
+	// By default we assume no auth.
+	requesterID := noauth
+
+	if requester != nil {
+		// Use provided account ID.
+		requesterID = requester.ID
+	}
+
+	visibility, err := f.state.Caches.Visibility.Load("Type.RequesterID.ItemID", func() (*cache.CachedVisibility, error) {
+		// Visibility not yet cached, perform timeline visibility lookup.
+		visible, err := f.isStatusPublicTimelineable(ctx, requester, status)
+		if err != nil {
+			return nil, err
+		}
+
+		// Return visibility value.
+		return &cache.CachedVisibility{
+			ItemID:      status.ID,
+			RequesterID: requesterID,
+			Type:        cache.VisibilityTypePublic,
+			Value:       visible,
+		}, nil
+	}, "public", requesterID, status.ID)
+	if err != nil {
+		if err == cache.SentinelError {
+			// Filter-out our temporary
+			// race-condition error.
+			return false, nil
+		}
+
+		return false, err
+	}
+
+	return visibility.Value, nil
+}
+
+func (f *Filter) isStatusPublicTimelineable(ctx context.Context, requester *gtsmodel.Account, status *gtsmodel.Status) (bool, error) {
+	if status.CreatedAt.After(time.Now().Add(24 * time.Hour)) {
+		// Statuses made over 1 day in the future we don't show...
+		log.Warnf(ctx, "status >24hrs in the future: %+v", status)
+		return false, nil
+	}
+
+	// Don't show boosts on timeline.
+	if status.BoostOfID != "" {
+		return false, nil
+	}
+
+	// Check whether status is visible to requesting account.
+	visible, err := f.StatusVisible(ctx, requester, status)
+	if err != nil {
+		return false, err
+	}
+
+	if !visible {
+		log.Trace(ctx, "status not visible to timeline requester")
+		return false, nil
+	}
+
+	for parent := status; parent.InReplyToURI != ""; {
+		// Fetch next parent to lookup.
+		parentID := parent.InReplyToID
+		if parentID == "" {
+			log.Warnf(ctx, "status not yet deref'd: %s", parent.InReplyToURI)
+			return false, cache.SentinelError
+		}
+
+		// Get the next parent in the chain from DB.
+		parent, err = f.state.DB.GetStatusByID(
+			gtscontext.SetBarebones(ctx),
+			parentID,
+		)
+		if err != nil {
+			return false, fmt.Errorf("isStatusHomeTimelineable: error getting status parent %s: %w", parentID, err)
+		}
+
+		if parent.AccountID != status.AccountID {
+			// This is not a single author reply-chain-thread,
+			// instead is an actualy conversation. Don't timeline.
+			log.Trace(ctx, "ignoring multi-author reply-chain")
+			return false, nil
+		}
+	}
+
+	// This is either a visible status in a
+	// single-author thread, or a visible top
+	// level status. Show on public timeline.
+	return true, nil
+}