* Add test

* Fix crash when encountering invalid account fields

If a status with a hashtag becomes very popular, it stands to
reason that the hashtag should have a chance at trending

Fix no stats being recorded for hashtags that are not allowed
to trend, and stop ignoring bots

Remove references to hashtags in profile directory from the code
and the admin UI

* Fix issues with POSIX::Spawn, Terrapin and Ruby 3.0

Also improve the Terrapin monkey-patch for the stderr/stdout issue.

* Fix keyword argument handling throughout the codebase

* Monkey-patch Paperclip to fix keyword arguments handling in validators

* Change validation_extensions to please CodeClimate

* Bump microformats from 4.2.1 to 4.3.1

* Allow Ruby 3.0

* Add Ruby 3.0 test target to CircleCI

* Add test for admin dashboard warnings

* Fix admin dashboard warnings on Ruby 3.0

Clicking the confirmation link multiple times currently leads to entering
account settings, which can be confusing. This commit changes that so that
it redirects to the root path, so it behaves the same way as clicking only
once in most cases.

* Add tests

* Ensure deleted statuses are marked as such

* Save some redis memory by not storing URIs in delete_upon_arrival values

* Avoid possible race condition when processing incoming Deletes

* Avoid potential duplicate Delete forwards

* Lower lock durations to reduce issues in case of hard crash of the Rails process

* Check for `lock.aquired?` and improve comment

* Refactor RedisLock usage in app/lib/activitypub

* Fix using incorrect or non-existent sender for relaying Deletes

Prevent new accounts from being created using the same underlying
e-mail as a suspended account using extensions and period
permutations. Stores e-mails as a SHA256 hash

Fix app scopes not being validated

With possible values `all`, `followed`, `follower`, and `none`,
control from whom notifications will generate a Web Push alert

Fix #15506

Raw SQL passed to `pluck` now has to be explicitly marked as SQL via
Arel.sql, see https://github.com/rails/rails/pull/27947

* Update devise-two-factor to unreleased fork for Rails 6 support

Update tests to match new `rotp` version.

* Update nsa gem to unreleased fork for Rails 6 support

* Update rails to 6.1.3 and rails-i18n to 6.0

* Update to unreleased fork of pluck_each for Ruby 6 support

* Run "rails app:update"

* Add missing ActiveStorage config file

* Use config.ssl_options instead of removed ApplicationController#force_ssl

Disabled force_ssl-related tests as they do not seem to be easily testable
anymore.

* Fix nonce directives by removing Rails 5 specific monkey-patching

* Fix fixture_file_upload deprecation warning

* Fix yield-based test failing with Rails 6

* Use Rails 6's index_with when possible

* Use ActiveRecord::Cache::Store#delete_multi from Rails 6

This will yield better performances when deleting an account

* Disable Rails 6.1's automatic preload link headers

Since Rails 6.1, ActionView adds preload links for javascript files
in the Links header per default.

In our case, that will bloat headers too much and potentially cause
issues with reverse proxies. Furhermore, we don't need those links,
as we already output them as HTML link tags.

* Switch to Rails 6.0 default config

* Switch to Rails 6.1 default config

* Do not include autoload paths in the load path

Fixes #5551

* Bypass MX validation for explicitly allowed domains

This spares some lookups and prevent issues in some edge cases with
local domains.

* Add tests

* Fix test

* Improve account counters handling

* Use ActiveRecord::Base::sanitize_sql to pass values instead of interpolating them

Keep using string interpolation for `key` as it is safe and using
“ActiveRecord::Base::sanitize_sql_hash_for_assignment” would require stitching
bits of SQL in a way that is not more easily checked for safety.

* Add migration hook to catch PostgreSQL versions earlier than 9.5

* Use ActiveRecord::Result#to_ary instead of deprecated to_hash

They do the same thing, and to_hash has been removed from Rails 6.1

* Explicitly name polymorphic indexes to workaround a bug in Rails 6.1

cf. https://github.com/rails/rails/issues/41693

* Fix incorrect usage of “foreign_key” in migration script

* Use `ActiveModel::Errors#delete` instead of deprecated clear method

* Fix link headers tests on Rails 6.1

Rails 6.1 adds values to the Link header by default, thus it is not a
LinkHeader object anymore. Fix the test to parse the Link header instead
of assuming it is a LinkHeader.

* Prepare Mastodon for zeitwerk autoloader (Rails 6)

Add inflections and rename/move a few classes.

In particular, app/lib/exceptions.rb and app/lib/sanitize_config.rb
were manually loaded while still in autoload paths.

* Add inflection for Url → URL

* Fix cache_collection crashing when given an empty collection

* Add tests

* Fix misuse of foreign_type

* Fix use of removed "add_template_helper"

* Use response.media_type instead of response.content_type in tests

* Fix CSV export controller test on Rails 6

Rails 6 sets a "filename*" field in the Content-Disposition header to
explicitly encode the filename as UTF-8.

This changes checks the first part of the Content-Disposition header so
it matches in both Rails 5 and Rails 6.

* Fix emoji formatting with Rails 6

* Make emoji output more idiomatic and robust

* Switch from redis-rails gem to built-in Rails redis cache storage

* Add tests

* Fix URL scanning in note length validator and preview card fetching

* Update twitter-text from 1.14 to 3.1.0

* Disable emoji parsing

* Properly depend on twitter-text for url detection

* Fix some URLs being wrongly detected client-side

* Add test for server-side validation of non-autolinkable URLs

* Fix server-side status length counting

* Change ResolveAccountService's handling of skip_webfinger

Change it so it never makes any webfinger query, as the name would imply.

* Add tests

* Change FollowService to not take an URI for target_account

* Restore domain-block check in FollowService

* Fix tests

* Fix URI of repeat follow requests not being recorded

In case we receive a “repeat” or “duplicate” follow request, we automatically
fast-forward the accept with the latest received Activity `id`, but we don't
record it.

In general, a “repeat” or “duplicate” follow request may happen if for some
reason (e.g. inconsistent handling of Block or Undo Accept activities, an
instance being brought back up from the dead, etc.) the local instance thought
the remote actor were following them while the remote actor thought otherwise.

In those cases, the remote instance does not know about the older Follow
activity `id`, so keeping that record serves no purpose, but knowing the most
recent one is useful if the remote implementation at some point refers to it
by `id` without inlining it.

* Add tests

* Atomically check for processing lock in Move handler

* Prevent race condition when creating account migrations

Fixes #15595

* Add tests

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

* Added .deepsource.toml

* Removed bad use of `alias`

* Fixed operand order in the binary expression

* Prefixed unused method arguments with an underscore

* Replaced the old OpenSSL algorithmic constants with the newer strings initializers.

* Removed unnecessary UTF-8 encoding comment

* Improved performance of notification preloading

* Remove Cacheable from Notification

* Fix test

* Use Rails' index_by where it makes sense

* Fix tests

Co-authored-by: Claire <claire.github-309c@sitedethib.com>