gtsocial-umbx

indexeditems.go (3389B)

---

 // 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 timeline
 
 import (
 	"container/list"
 	"context"
 
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
 )
 
 type indexedItems struct {
 	data       *list.List
 	skipInsert SkipInsertFunction
 }
 
 type indexedItemsEntry struct {
 	itemID           string
 	boostOfID        string
 	accountID        string
 	boostOfAccountID string
 	prepared         Preparable
 }
 
 // WARNING: ONLY CALL THIS FUNCTION IF YOU ALREADY HAVE
 // A LOCK ON THE TIMELINE CONTAINING THIS INDEXEDITEMS!
 func (i *indexedItems) insertIndexed(ctx context.Context, newEntry *indexedItemsEntry) (bool, error) {
 	// Lazily init indexed items.
 	if i.data == nil {
 		i.data = &list.List{}
 		i.data.Init()
 	}
 
 	if i.data.Len() == 0 {
 		// We have no entries yet, meaning this is both the
 		// newest + oldest entry, so just put it in the front.
 		i.data.PushFront(newEntry)
 		return true, nil
 	}
 
 	var (
 		insertMark      *list.Element
 		currentPosition int
 	)
 
 	// We need to iterate through the index to make sure we put
 	// this item in the appropriate place according to its id.
 	// We also need to make sure we're not inserting a duplicate
 	// item -- this can happen sometimes and it's sucky UX.
 	for e := i.data.Front(); e != nil; e = e.Next() {
 		currentPosition++
 
 		currentEntry := e.Value.(*indexedItemsEntry) //nolint:forcetypeassert
 
 		// Check if we need to skip inserting this item based on
 		// the current item.
 		//
 		// For example, if the new item is a boost, and the current
 		// item is the original, we may not want to insert the boost
 		// if it would appear very shortly after the original.
 		if skip, err := i.skipInsert(
 			ctx,
 			newEntry.itemID,
 			newEntry.accountID,
 			newEntry.boostOfID,
 			newEntry.boostOfAccountID,
 			currentEntry.itemID,
 			currentEntry.accountID,
 			currentEntry.boostOfID,
 			currentEntry.boostOfAccountID,
 			currentPosition,
 		); err != nil {
 			return false, gtserror.Newf("error calling skipInsert: %w", err)
 		} else if skip {
 			// We don't need to insert this at all,
 			// so we can safely bail.
 			return false, nil
 		}
 
 		if insertMark != nil {
 			// We already found our mark.
 			continue
 		}
 
 		if currentEntry.itemID > newEntry.itemID {
 			// We're still in items newer than
 			// the one we're trying to insert.
 			continue
 		}
 
 		// We found our spot!
 		insertMark = e
 	}
 
 	if insertMark == nil {
 		// We looked through the whole timeline and didn't find
 		// a mark, so the new item is the oldest item we've seen;
 		// insert it at the back.
 		i.data.PushBack(newEntry)
 		return true, nil
 	}
 
 	i.data.InsertBefore(newEntry, insertMark)
 	return true, nil
 }