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mastodon/app/models/concerns/account_search.rb

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# frozen_string_literal: true
module AccountSearch
extend ActiveSupport::Concern
DISALLOWED_TSQUERY_CHARACTERS = /['?\\:]/
TEXT_SEARCH_RANKS = <<~SQL.squish
(
setweight(to_tsvector('simple', accounts.display_name), 'A') ||
setweight(to_tsvector('simple', accounts.username), 'B') ||
setweight(to_tsvector('simple', coalesce(accounts.domain, '')), 'C')
)
SQL
REPUTATION_SCORE_FUNCTION = <<~SQL.squish
(
greatest(0, coalesce(s.followers_count, 0)) / (
greatest(0, coalesce(s.following_count, 0)) + 1.0
)
)
SQL
FOLLOWERS_SCORE_FUNCTION = <<~SQL.squish
log(
greatest(0, coalesce(s.followers_count, 0)) + 2
)
SQL
TIME_DISTANCE_FUNCTION = <<~SQL.squish
(
case
when s.last_status_at is null then 0
else exp(
-1.0 * (
(
greatest(0, abs(extract(DAY FROM age(s.last_status_at))) - 30.0)^2) /#{' '}
(2.0 * ((-1.0 * 30^2) / (2.0 * ln(0.3)))
)
)
)
end
)
SQL
BOOST = <<~SQL.squish
(
(#{REPUTATION_SCORE_FUNCTION} + #{FOLLOWERS_SCORE_FUNCTION} + #{TIME_DISTANCE_FUNCTION}) / 3.0
)
SQL
BASIC_SEARCH_SQL = <<~SQL.squish
SELECT
accounts.*,
#{BOOST} * ts_rank_cd(#{TEXT_SEARCH_RANKS}, to_tsquery('simple', :tsquery), 32) AS rank
FROM accounts
LEFT JOIN users ON accounts.id = users.account_id
LEFT JOIN account_stats AS s ON accounts.id = s.account_id
WHERE to_tsquery('simple', :tsquery) @@ #{TEXT_SEARCH_RANKS}
AND accounts.suspended_at IS NULL
AND accounts.moved_to_account_id IS NULL
AND (accounts.domain IS NOT NULL OR (users.approved = TRUE AND users.confirmed_at IS NOT NULL))
ORDER BY rank DESC
LIMIT :limit OFFSET :offset
SQL
ADVANCED_SEARCH_WITH_FOLLOWING = <<~SQL.squish
WITH first_degree AS (
SELECT target_account_id
FROM follows
WHERE account_id = :id
UNION ALL
SELECT :id
)
SELECT
accounts.*,
(count(f.id) + 1) * #{BOOST} * ts_rank_cd(#{TEXT_SEARCH_RANKS}, to_tsquery('simple', :tsquery), 32) AS rank
FROM accounts
LEFT OUTER JOIN follows AS f ON (accounts.id = f.account_id AND f.target_account_id = :id)
LEFT JOIN account_stats AS s ON accounts.id = s.account_id
WHERE accounts.id IN (SELECT * FROM first_degree)
AND to_tsquery('simple', :tsquery) @@ #{TEXT_SEARCH_RANKS}
AND accounts.suspended_at IS NULL
AND accounts.moved_to_account_id IS NULL
GROUP BY accounts.id, s.id
ORDER BY rank DESC
LIMIT :limit OFFSET :offset
SQL
ADVANCED_SEARCH_WITHOUT_FOLLOWING = <<~SQL.squish
SELECT
accounts.*,
#{BOOST} * ts_rank_cd(#{TEXT_SEARCH_RANKS}, to_tsquery('simple', :tsquery), 32) AS rank,
count(f.id) AS followed
FROM accounts
LEFT OUTER JOIN follows AS f ON
(accounts.id = f.account_id AND f.target_account_id = :id) OR (accounts.id = f.target_account_id AND f.account_id = :id)
LEFT JOIN users ON accounts.id = users.account_id
LEFT JOIN account_stats AS s ON accounts.id = s.account_id
WHERE to_tsquery('simple', :tsquery) @@ #{TEXT_SEARCH_RANKS}
AND accounts.suspended_at IS NULL
AND accounts.moved_to_account_id IS NULL
AND (accounts.domain IS NOT NULL OR (users.approved = TRUE AND users.confirmed_at IS NOT NULL))
GROUP BY accounts.id, s.id
ORDER BY followed DESC, rank DESC
LIMIT :limit OFFSET :offset
SQL
class_methods do
def search_for(terms, limit: 10, offset: 0)
tsquery = generate_query_for_search(terms)
find_by_sql([BASIC_SEARCH_SQL, { limit: limit, offset: offset, tsquery: tsquery }]).tap do |records|
ActiveRecord::Associations::Preloader.new.preload(records, :account_stat)
end
end
def advanced_search_for(terms, account, limit: 10, following: false, offset: 0)
tsquery = generate_query_for_search(terms)
sql_template = following ? ADVANCED_SEARCH_WITH_FOLLOWING : ADVANCED_SEARCH_WITHOUT_FOLLOWING
find_by_sql([sql_template, { id: account.id, limit: limit, offset: offset, tsquery: tsquery }]).tap do |records|
ActiveRecord::Associations::Preloader.new.preload(records, :account_stat)
end
end
private
def generate_query_for_search(unsanitized_terms)
terms = unsanitized_terms.gsub(DISALLOWED_TSQUERY_CHARACTERS, ' ')
# The final ":*" is for prefix search.
# The trailing space does not seem to fit any purpose, but `to_tsquery`
# behaves differently with and without a leading space if the terms start
# with `./`, `../`, or `.. `. I don't understand why, so, in doubt, keep
# the same query.
"' #{terms} ':*"
end
end
end