When doing a tag search, we have to be careful about which user we're
running the search as because the results depend on the current user.
Specifically, things like private favorites, private favorite groups,
post votes, saved searches, and flagger names depend on the user's
permissions, and whether non-safe or deleted posts are filtered out
depend on whether the user has safe mode on or the hide deleted posts
setting enabled.
* Refactor internal searches to explicitly state whether they're
running as the system user (DanbooruBot) or as the current user.
* Explicitly pass in the current user to PostQueryBuilder instead of
implicitly relying on the CurrentUser global.
* Get rid of CurrentUser.admin_mode? (used to ignore the hide deleted
post setting) and CurrentUser.without_safe_mode (used to ignore safe
mode).
* Change the /counts/posts.json endpoint to ignore safe mode and the
hide deleted posts settings when counting posts.
* Fix searches not correctly overriding the hide deleted posts setting
when multiple status: metatags were used (e.g. `status:banned status:active`)
* Fix fast_count not respecting the hide deleted posts setting when the
status:banned metatag was used.
Bug: in some cases searching for multiple metatags would cause one
metatag to be ignored. For example, a search for {{user:1 pool:2}} would
be treated as a search for {{pool:2}}.
Cause: we used `ActiveRecord::Relation#merge` to combine two relations,
which was wrong because `merge` doesn't combine `column IN (?)` clauses
correctly. If there are two `column IN (?)` clauses on the same column,
then `#merge` takes only the second clause and ignores the first.
Fix: write our own half-baked `#and` method to work around Rails'
broken-by-design `#merge` method.
ref: https://github.com/rails/rails/issues/33501.
* Fix not being able to use the status: metatag twice in the same search.
* Fix status:active excluding banned posts.
* Fix status:garbage returning all posts.
Support using the same numeric-valued metatag twice in the same search.
Numeric-valued metatags are those taking an integer, float, filesize, or
date argument. Previously using the same metatag twice would cause the
second metatag to overwrite the first metatag.
Examples:
* "id:>5 id:<10"
* "width:>500 width:<1000"
* "date:>2019-01-01 date:<2020-01-01"
Partial fix for #4389.
* Fix invalid username searches returning all posts instead of no posts.
* Fix "user:A user:B" returning results for user:B instead of no results.
* Fix "approver:A approver:B" returning results for approver:B instead of no results.
* Add support for negated -commenter, -noter, -noteupdater, -upvote, -downvote metatags.
* Add support for "any" and "none" values for all username metatags,
including negated metatags that didn't support "any" or "none" before.
* Change noter:any and commenter:any to include posts with deleted notes
or comments. Note that commenter:<username> already included deleted
comments before. This is so that commenter:any has the same behavior
as commenter:<username>
