feat: user API голосования за отзывы (like/dislike). Refs EventHub/EventHubBack#47

src/core/core_review.erl

@@ -111,8 +111,15 @@ update(Id, Updates) ->
 delete(Id) ->
   F = fun() ->
     case mnesia:read(review, Id) of
-      []       -> {error, not_found};
-      [Review] -> mnesia:delete_object(Review), {ok, deleted}
+      [] ->
+        {error, not_found};
+      [Review] ->
+        Votes = mnesia:match_object(#review_vote{review_id = Id, _ = '_'}),
+        lists:foreach(fun(#review_vote{id = VoteId}) ->
+          mnesia:delete({review_vote, VoteId})
+                        end, Votes),
+        mnesia:delete_object(Review),
+        {ok, deleted}
     end
       end,
   case mnesia:transaction(F) of

src/core/core_review_vote.erl

@@ -0,0 +1,156 @@
+%%%-------------------------------------------------------------------
+%%% @doc Хранение голосов пользователей за отзывы (like/dislike).
+%%% Счётчики на #review{} обновляются в той же транзакции.
+%%% @end
+%%%-------------------------------------------------------------------
+-module(core_review_vote).
+-include("records.hrl").
+
+-export([upsert/3, delete/2, get_by_user_and_review/2, list_by_user/1,
+  list_by_review/1, delete_by_review/1]).
+
+%%%-------------------------------------------------------------------
+%%% @doc Поставить или сменить голос. Идемпотентно при том же value.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec upsert(ReviewId :: binary(), UserId :: binary(), Value :: like | dislike) ->
+  {ok, #review{}, like | dislike} | {error, term()}.
+upsert(ReviewId, UserId, Value) when Value =:= like; Value =:= dislike ->
+  Now = calendar:universal_time(),
+  F = fun() ->
+    case mnesia:read(review, ReviewId) of
+      [] ->
+        {error, not_found};
+      [#review{status = Status}] when Status =/= visible ->
+        {error, not_found};
+      [#review{user_id = AuthorId}] when AuthorId =:= UserId ->
+        {error, own_review};
+      [Review] ->
+        case find_vote(ReviewId, UserId) of
+          [] ->
+            Vote = #review_vote{
+              id         = infra_utils:generate_id(16),
+              review_id  = ReviewId,
+              user_id    = UserId,
+              value      = Value,
+              created_at = Now,
+              updated_at = Now
+            },
+            mnesia:write(Vote),
+            Updated = bump(Review, Value, 1),
+            mnesia:write(Updated),
+            {ok, Updated, Value};
+          [#review_vote{value = Value} = Vote] ->
+            %% тот же голос — идемпотентно
+            mnesia:write(Vote#review_vote{updated_at = Now}),
+            {ok, Review, Value};
+          [#review_vote{value = OldValue} = Vote] ->
+            UpdatedVote = Vote#review_vote{value = Value, updated_at = Now},
+            mnesia:write(UpdatedVote),
+            Updated0 = bump(Review, OldValue, -1),
+            Updated1 = bump(Updated0, Value, 1),
+            mnesia:write(Updated1),
+            {ok, Updated1, Value}
+        end
+    end
+      end,
+  case mnesia:transaction(F) of
+    {atomic, Result} -> Result;
+    {aborted, Reason} -> {error, Reason}
+  end.
+
+%%%-------------------------------------------------------------------
+%%% @doc Снять голос. Идемпотентно, если голоса нет.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec delete(ReviewId :: binary(), UserId :: binary()) ->
+  {ok, #review{}, null} | {error, term()}.
+delete(ReviewId, UserId) ->
+  F = fun() ->
+    case mnesia:read(review, ReviewId) of
+      [] ->
+        {error, not_found};
+      [#review{status = Status}] when Status =/= visible ->
+        {error, not_found};
+      [#review{user_id = AuthorId}] when AuthorId =:= UserId ->
+        {error, own_review};
+      [Review] ->
+        case find_vote(ReviewId, UserId) of
+          [] ->
+            {ok, Review, null};
+          [#review_vote{value = Value, id = VoteId}] ->
+            mnesia:delete({review_vote, VoteId}),
+            Updated = bump(Review, Value, -1),
+            mnesia:write(Updated),
+            {ok, Updated, null}
+        end
+    end
+      end,
+  case mnesia:transaction(F) of
+    {atomic, Result} -> Result;
+    {aborted, Reason} -> {error, Reason}
+  end.
+
+%%%-------------------------------------------------------------------
+%%% @doc Голос пользователя за конкретный отзыв.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec get_by_user_and_review(UserId :: binary(), ReviewId :: binary()) ->
+  {ok, #review_vote{}} | {error, not_found}.
+get_by_user_and_review(UserId, ReviewId) ->
+  case mnesia:dirty_match_object(
+         #review_vote{review_id = ReviewId, user_id = UserId, _ = '_'}) of
+    [] -> {error, not_found};
+    [Vote] -> {ok, Vote};
+    [Vote | _] -> {ok, Vote}
+  end.
+
+%%%-------------------------------------------------------------------
+%%% @doc Все голоса пользователя.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec list_by_user(UserId :: binary()) -> [#review_vote{}].
+list_by_user(UserId) ->
+  mnesia:dirty_match_object(#review_vote{user_id = UserId, _ = '_'}).
+
+%%%-------------------------------------------------------------------
+%%% @doc Все голоса за отзыв.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec list_by_review(ReviewId :: binary()) -> [#review_vote{}].
+list_by_review(ReviewId) ->
+  mnesia:dirty_match_object(#review_vote{review_id = ReviewId, _ = '_'}).
+
+%%%-------------------------------------------------------------------
+%%% @doc Удалить все голоса отзыва (при физическом удалении review).
+%%% Вызывать внутри транзакции или отдельно.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec delete_by_review(ReviewId :: binary()) -> ok.
+delete_by_review(ReviewId) ->
+  F = fun() ->
+    lists:foreach(fun(#review_vote{id = Id}) ->
+      mnesia:delete({review_vote, Id})
+                    end, list_by_review_tx(ReviewId)),
+    ok
+      end,
+  case mnesia:transaction(F) of
+    {atomic, ok} -> ok;
+    {aborted, Reason} -> error({delete_votes_failed, Reason})
+  end.
+
+%%%===================================================================
+%%% Внутренние
+%%%===================================================================
+
+find_vote(ReviewId, UserId) ->
+  mnesia:match_object(#review_vote{review_id = ReviewId, user_id = UserId, _ = '_'}).
+
+list_by_review_tx(ReviewId) ->
+  mnesia:match_object(#review_vote{review_id = ReviewId, _ = '_'}).
+
+-spec bump(#review{}, like | dislike, integer()) -> #review{}.
+bump(#review{likes = L} = R, like, Delta) ->
+  R#review{likes = max(0, L + Delta), updated_at = calendar:universal_time()};
+bump(#review{dislikes = D} = R, dislike, Delta) ->
+  R#review{dislikes = max(0, D + Delta), updated_at = calendar:universal_time()}.