distraction.party/lib/pleroma/user/search.ex

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# Pleroma: A lightweight social networking server
# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.User.Search do
alias Pleroma.Repo
alias Pleroma.User
import Ecto.Query
@similarity_threshold 0.25
@limit 20
def search(query_string, opts \\ []) do
resolve = Keyword.get(opts, :resolve, false)
following = Keyword.get(opts, :following, false)
result_limit = Keyword.get(opts, :limit, @limit)
offset = Keyword.get(opts, :offset, 0)
for_user = Keyword.get(opts, :for_user)
# Strip the beginning @ off if there is a query
query_string = String.trim_leading(query_string, "@")
maybe_resolve(resolve, for_user, query_string)
{:ok, results} =
Repo.transaction(fn ->
Ecto.Adapters.SQL.query(
Repo,
"select set_limit(#{@similarity_threshold})",
[]
)
query_string
|> search_query(for_user, following)
|> paginate(result_limit, offset)
|> Repo.all()
end)
results
end
defp search_query(query_string, for_user, following) do
for_user
|> base_query(following)
|> search_subqueries(query_string)
|> union_subqueries
|> distinct_query()
|> boost_search_rank_query(for_user)
|> subquery()
|> order_by(desc: :search_rank)
|> maybe_restrict_local(for_user)
end
defp base_query(_user, false), do: User
defp base_query(user, true), do: User.get_followers_query(user)
defp paginate(query, limit, offset) do
from(q in query, limit: ^limit, offset: ^offset)
end
defp union_subqueries({fts_subquery, trigram_subquery}) do
from(s in trigram_subquery, union_all: ^fts_subquery)
end
defp search_subqueries(base_query, query_string) do
{
fts_search_subquery(base_query, query_string),
trigram_search_subquery(base_query, query_string)
}
end
defp distinct_query(q) do
from(s in subquery(q), order_by: s.search_type, distinct: s.id)
end
defp maybe_resolve(true, user, query) do
case {limit(), user} do
{:all, _} -> :noop
{:unauthenticated, %User{}} -> User.get_or_fetch(query)
{:unauthenticated, _} -> :noop
{false, _} -> User.get_or_fetch(query)
end
end
defp maybe_resolve(_, _, _), do: :noop
defp maybe_restrict_local(q, user) do
case {limit(), user} do
{:all, _} -> restrict_local(q)
{:unauthenticated, %User{}} -> q
{:unauthenticated, _} -> restrict_local(q)
{false, _} -> q
end
end
defp limit, do: Pleroma.Config.get([:instance, :limit_to_local_content], :unauthenticated)
defp restrict_local(q), do: where(q, [u], u.local == true)
defp boost_search_rank_query(query, nil), do: query
defp boost_search_rank_query(query, for_user) do
friends_ids = User.get_friends_ids(for_user)
followers_ids = User.get_followers_ids(for_user)
from(u in subquery(query),
select_merge: %{
search_rank:
fragment(
"""
CASE WHEN (?) THEN 0.5 + (?) * 1.3
WHEN (?) THEN 0.5 + (?) * 1.2
WHEN (?) THEN (?) * 1.1
ELSE (?) END
""",
u.id in ^friends_ids and u.id in ^followers_ids,
u.search_rank,
u.id in ^friends_ids,
u.search_rank,
u.id in ^followers_ids,
u.search_rank,
u.search_rank
)
}
)
end
@spec fts_search_subquery(User.t() | Ecto.Query.t(), String.t()) :: Ecto.Query.t()
defp fts_search_subquery(query, term) do
processed_query =
term
|> String.replace(~r/\W+/, " ")
|> String.trim()
|> String.split()
|> Enum.map(&(&1 <> ":*"))
|> Enum.join(" | ")
from(
u in query,
select_merge: %{
search_type: ^0,
search_rank:
fragment(
"""
ts_rank_cd(
setweight(to_tsvector('simple', regexp_replace(?, '\\W', ' ', 'g')), 'A') ||
setweight(to_tsvector('simple', regexp_replace(coalesce(?, ''), '\\W', ' ', 'g')), 'B'),
to_tsquery('simple', ?),
32
)
""",
u.nickname,
u.name,
^processed_query
)
},
where:
fragment(
"""
(setweight(to_tsvector('simple', regexp_replace(?, '\\W', ' ', 'g')), 'A') ||
setweight(to_tsvector('simple', regexp_replace(coalesce(?, ''), '\\W', ' ', 'g')), 'B')) @@ to_tsquery('simple', ?)
""",
u.nickname,
u.name,
^processed_query
)
)
|> User.restrict_deactivated()
end
@spec trigram_search_subquery(User.t() | Ecto.Query.t(), String.t()) :: Ecto.Query.t()
defp trigram_search_subquery(query, term) do
from(
u in query,
select_merge: %{
# ^1 gives 'Postgrex expected a binary, got 1' for some weird reason
search_type: fragment("?", 1),
search_rank:
fragment(
"similarity(?, trim(? || ' ' || coalesce(?, '')))",
^term,
u.nickname,
u.name
)
},
where: fragment("trim(? || ' ' || coalesce(?, '')) % ?", u.nickname, u.name, ^term)
)
|> User.restrict_deactivated()
end
end