GoToSocial/internal/timeline/prepareditems.go

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/*
GoToSocial
Copyright (C) 2021-2023 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 timeline
import (
"container/list"
"context"
"errors"
)
type preparedItems struct {
data *list.List
skipInsert SkipInsertFunction
}
type preparedItemsEntry struct {
itemID string
boostOfID string
accountID string
boostOfAccountID string
prepared Preparable
}
func (p *preparedItems) insertPrepared(ctx context.Context, newEntry *preparedItemsEntry) error {
if p.data == nil {
p.data = &list.List{}
}
// if we have no entries yet, this is both the newest and oldest entry, so just put it in the front
if p.data.Len() == 0 {
p.data.PushFront(newEntry)
return nil
}
var insertMark *list.Element
var position int
// We need to iterate through the index to make sure we put this entry in the appropriate place according to when it was created.
// We also need to make sure we're not inserting a duplicate entry -- this can happen sometimes and it's not nice UX (*shudder*).
for e := p.data.Front(); e != nil; e = e.Next() {
position++
entry, ok := e.Value.(*preparedItemsEntry)
if !ok {
return errors.New("insertPrepared: could not parse e as a preparedItemsEntry")
}
skip, err := p.skipInsert(ctx, newEntry.itemID, newEntry.accountID, newEntry.boostOfID, newEntry.boostOfAccountID, entry.itemID, entry.accountID, entry.boostOfID, entry.boostOfAccountID, position)
if err != nil {
return err
}
if skip {
return nil
}
// if the entry to index is newer than e, insert it before e in the list
if insertMark == nil {
if newEntry.itemID > entry.itemID {
insertMark = e
}
}
// make sure we don't insert a duplicate
if entry.itemID == newEntry.itemID {
return nil
}
}
if insertMark != nil {
p.data.InsertBefore(newEntry, insertMark)
return nil
}
// if we reach this point it's the oldest entry we've seen so put it at the back
p.data.PushBack(newEntry)
return nil
}