gotosocial/internal/processing/account/rss.go
tobi ca5492b65f
[bugfix] Tidy up rss feed serving; don't error on empty feed (#1970)
* [bugfix] Tidy up rss feed serving; don't error on empty feed

* fall back to account creation time as rss feed update time

* return feed early when account has no eligible statuses
2023-07-10 17:05:59 +02:00

177 lines
6 KiB
Go

// 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 account
import (
"context"
"errors"
"fmt"
"time"
"github.com/gorilla/feeds"
"github.com/superseriousbusiness/gotosocial/internal/config"
"github.com/superseriousbusiness/gotosocial/internal/db"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
)
const (
rssFeedLength = 20
)
type GetRSSFeed func() (string, gtserror.WithCode)
// GetRSSFeedForUsername returns a function to return the RSS feed of a local account
// with the given username, and the last-modified time (time that the account last
// posted a status eligible to be included in the rss feed).
//
// To save db calls, callers to this function should only call the returned GetRSSFeed
// func if the last-modified time is newer than the last-modified time they have cached.
//
// If the account has not yet posted an RSS-eligible status, the returned last-modified
// time will be zero, and the GetRSSFeed func will return a valid RSS xml with no items.
func (p *Processor) GetRSSFeedForUsername(ctx context.Context, username string) (GetRSSFeed, time.Time, gtserror.WithCode) {
var (
never = time.Time{}
)
account, err := p.state.DB.GetAccountByUsernameDomain(ctx, username, "")
if err != nil {
if errors.Is(err, db.ErrNoEntries) {
// Simply no account with this username.
err = gtserror.New("account not found")
return nil, never, gtserror.NewErrorNotFound(err)
}
// Real db error.
err = gtserror.Newf("db error getting account %s: %w", username, err)
return nil, never, gtserror.NewErrorInternalError(err)
}
// Ensure account has rss feed enabled.
if !*account.EnableRSS {
err = gtserror.New("account RSS feed not enabled")
return nil, never, gtserror.NewErrorNotFound(err)
}
// LastModified time is needed by callers to check freshness for cacheing.
// This might be a zero time.Time if account has never posted a status that's
// eligible to appear in the RSS feed; that's fine.
lastPostAt, err := p.state.DB.GetAccountLastPosted(ctx, account.ID, true)
if err != nil && !errors.Is(err, db.ErrNoEntries) {
err = gtserror.Newf("db error getting account %s last posted: %w", username, err)
return nil, never, gtserror.NewErrorInternalError(err)
}
return func() (string, gtserror.WithCode) {
// Assemble author namestring once only.
author := "@" + account.Username + "@" + config.GetAccountDomain()
// Derive image/thumbnail for this account (may be nil).
image, errWithCode := p.rssImageForAccount(ctx, account, author)
if errWithCode != nil {
return "", errWithCode
}
feed := &feeds.Feed{
Title: "Posts from " + author,
Description: "Posts from " + author,
Link: &feeds.Link{Href: account.URL},
Image: image,
}
// If the account has never posted anything, just use
// account creation time as Updated value for the feed;
// we could use time.Now() here but this would likely
// mess up cacheing; we want something determinate.
//
// We can also return early rather than wasting a db call,
// since we already know there's no eligible statuses.
if lastPostAt.IsZero() {
feed.Updated = account.CreatedAt
return stringifyFeed(feed)
}
// Account has posted at least one status that's
// eligible to appear in the RSS feed.
//
// Reuse the lastPostAt value for feed.Updated.
feed.Updated = lastPostAt
// Retrieve latest statuses as they'd be shown on the web view of the account profile.
statuses, err := p.state.DB.GetAccountWebStatuses(ctx, account.ID, rssFeedLength, "")
if err != nil && !errors.Is(err, db.ErrNoEntries) {
err = fmt.Errorf("db error getting account web statuses: %w", err)
return "", gtserror.NewErrorInternalError(err)
}
// Add each status to the rss feed.
for _, status := range statuses {
item, err := p.tc.StatusToRSSItem(ctx, status)
if err != nil {
err = gtserror.Newf("error converting status to feed item: %w", err)
return "", gtserror.NewErrorInternalError(err)
}
feed.Add(item)
}
return stringifyFeed(feed)
}, lastPostAt, nil
}
func (p *Processor) rssImageForAccount(ctx context.Context, account *gtsmodel.Account, author string) (*feeds.Image, gtserror.WithCode) {
if account.AvatarMediaAttachmentID == "" {
// No image, no problem!
return nil, nil
}
// Ensure account avatar attachment populated.
if account.AvatarMediaAttachment == nil {
var err error
account.AvatarMediaAttachment, err = p.state.DB.GetAttachmentByID(ctx, account.AvatarMediaAttachmentID)
if err != nil {
if errors.Is(err, db.ErrNoEntries) {
// No attachment found with this ID (race condition?).
return nil, nil
}
// Real db error.
err = gtserror.Newf("db error fetching avatar media attachment: %w", err)
return nil, gtserror.NewErrorInternalError(err)
}
}
return &feeds.Image{
Url: account.AvatarMediaAttachment.Thumbnail.URL,
Title: "Avatar for " + author,
Link: account.URL,
}, nil
}
func stringifyFeed(feed *feeds.Feed) (string, gtserror.WithCode) {
// Stringify the feed. Even with no statuses,
// this will still produce valid rss xml.
rss, err := feed.ToRss()
if err != nil {
err := gtserror.Newf("error converting feed to rss string: %w", err)
return "", gtserror.NewErrorInternalError(err)
}
return rss, nil
}