* Fix handling of malformed ActivityPub payloads when URIs are nil

* Gracefully handle JSON-LD canonicalization failures

Same URI passed between follow request and follow, since they are
the same thing in ActivityPub. Local URIs are generated during
creation using UUIDs and are passed to serializers.

* Revert "Fixes/do not override timestamps (#7331)"

This reverts commit 581a5c9d29.

* Document Snowflake ID corner-case a bit more

Snowflake IDs are used for two purposes: making object identifiers harder to
guess and ensuring they are in chronological order. For this reason, they
are based on the `created_at` attribute of the object.

Unfortunately, inserting items with older snowflakes IDs will break the
assumption of consumers of the paging APIs that new items will always have
a greater identifier than the last seen one.

* Add `override_timestamps` virtual attribute to not correlate snowflake ID with created_at

* Do not override timestamps for incoming toots

* Remove every reference to override_timestamps

Statuses are now created with the announced publishing date
and are only pushed to timelines if that date is at most
6 hours earlier than the time at which it is processed.

* Add equals_or_includes_any? helper in JsonLdHelper

* Support arrays in JSON-LD type fields for actors/tags/objects.

* Spec for resolving accounts with extension types

* Style tweaks for codeclimate

* Add bio fields

- Fix #3211
- Fix #232
- Fix #121

* Display bio fields in web UI

* Fix output of links and missing fields

* Federate bio fields over ActivityPub as PropertyValue

* Improve how the fields are stored, add to Edit profile form

* Add rel=me to links in fields

Fix #121

* Forward deletes on the same path as reply forwarding

* Remove trailing whitespace

* Support fetching objects of convertible types by URL (fixes #6924)

* Ignore invalid hashtags

That way, they are displayed in a list below the corresponding toot.

Fix #6821

* fix validation error (media only status)

* Incorporating review suggestions

* Reflect similar fix to OStatus side

* Fix not to include media in transaction

* Restore the limit of the number of media

* Fix not to return nil

* Federate pinned statuses over ActivityPub

* Display pinned toots in web UI

Fix #6117

* Fix migration

* Fix tests

* Update outbox_serializer.rb

* Update remove_serializer.rb

* Update add_serializer.rb

* Update fetch_featured_collection_service.rb

* Fix #2176: Federated reports

* UI for federated reports

* Add spec for ActivityPub Flag handler

* Add spec for ReportService

* Add focus param to media API, center thumbnails on focus point

* Add UI for setting a focal point

* Improve focal point icon on upload item

* Use focal point in upload preview

* Add focalPoint property to ActivityPub

* Don't show focal point button for non-image attachments

Time window of 6 hours

This may lead to out-of-order notifications, but this is better than not having
notifications at all.

* Skip ActivityPub Announces of non-public objects

* Skip OStatus reblogs of non-public statuses

This makes slightly more sense, and ensures that the author of a post is always referenced in the audience (which some servers might rely on). And the announce is POSTed to the author's inbox anyways.

* Fix actors accepting invalid URI schemes or different host between URI and URL

* Fix statuses accepting invalid URI scheme or different host to actor

* Adjust tests to new requirements

* Improve readability of mismatching_origin?/invalid_origin? methods

* Allow to dereference Follow object for ActivityPub

* Accept IRI as object representation for Accept activity

There's no reason for an Account record to persist after Delete->Actor is received. SuspendAccountService is necessary to make sure deleted toots get sent over streaming API properly and home feeds get cleaned up. By removing Account record, we can ensure that if in the future the account is restored remotely (or username reused), it can start with a clean slate.

* Add semi-support for Video/Image objects in ActivityPub

Video and Image objects will create corresponding status records
with manually crafted text contents (title + URL)

* Extract html-url-finding logic into JsonLdHelper

* Fallback to id when url missing, extract supported object types

* Avoid sending explicit Undo->Announce when original deleted

* Do not forward a reply back to the server that sent it

* Deduplicate inboxes of rebloggers' followers for delete forwarding

* Adjust test

* Fix wrong class, bad SQL, wrong variable, outdated comment

* Serialize moved accounts into REST and ActivityPub APIs

* Parse federated moved accounts from ActivityPub

* Add note about moved accounts to public profiles

* Add moved account message to web UI

* Fix code style issues

* Scrub text of html before detecting language.

* Detect language on statuses coming from activitypub.

* Fix rubocop comments.

* Remove custom emoji from text before language detection

This allows deletion of reblogs which delivered before with OStatus URI.

- Rename Mastodon::TimestampIds into Mastodon::Snowflake for clarity
- Skip for statuses coming from inbox, aka delivered in real-time
- Skip for statuses that claim to be from the future

* Encode custom emojis as resolveable objects in ActivityPub

* Improve code style

Additionally, ActivityPub::FetchRemoteStatusService no longer parses
activities.
OStatus::Activity::Creation no longer delegates to ActivityPub because
the provided ActivityPub representations are not signed while OStatus
representations are.

* Fix #117 - Add ability to specify alternative text for media attachments

- POST /api/v1/media accepts `description` straight away
- PUT /api/v1/media/:id to update `description` (only for unattached ones)
- Serialized as `name` of Document object in ActivityPub
- Uploads form adjusted for better performance and description input

* Add tests

* Change undo button blend mode to difference

* Define emoji context for ActivityPub

* Fix the emojo

* Use general Mastodon context instead

* Custom emoji

- In OStatus: `<link rel="emoji" name="coolcat" href="http://..." />`
- In ActivityPub: `{ type: "Emoji", name: ":coolcat:", href: "http://..." }`
- In REST API: Status object includes `emojis` array (`shortcode`, `url`)
- Domain blocks with reject media stop emojis
- Emoji file up to 50KB
- Web UI handles custom emojis
- Static pages render custom emojis as `<img />` tags

Side effects:

- Undo #4500 optimization, as I needed to modify it to restore
  shortcode handling in emojify()
- Formatter#plaintext should now make sure stripped out line-breaks
  and paragraphs are replaced with newlines

* Fix emoji at the start not being converted

Since reblogs are serialized as Announce activity, its published property can be used for the creation time of reblog.

We had returned `nil` for that case, but this raises an error instead, as a wrong usage of the method.
This method is currently only used in ActivitySerializer.

* Fix race condition when receiving an ActivityPub Create multiple times

* Use a RedisLock to avoid concurrent processing of a same Create activity

In before, the method uses stream_entry id as status id, so replied status was wrongly selected.

This PR uses StatusFinder which was introduced with `Api::Web::EmbedsController`.