feat: calendar follow API (POST/DELETE follow, GET following). Refs EventHub/EventHubFront#9

include/records.hrl

@@ -103,6 +103,14 @@
   rights          :: read | write | admin
 }).
 
+%% Follow чужого календаря (не путать с платной subscription / calendar_share)
+-record(calendar_follow, {
+  id              :: binary(),
+  calendar_id     :: binary(),
+  user_id         :: binary(),
+  created_at      :: calendar:datetime()
+}).
+
 %% ------------------- Специалисты календаря ---------------------------
 -record(calendar_specialist, {
   calendar_id     :: binary(),

src/core/core_calendar_follow.erl

@@ -0,0 +1,111 @@
+%%%-------------------------------------------------------------------
+%%% @doc Хранение follow чужих календарей (уникальность calendar_id+user_id).
+%%% @end
+%%%-------------------------------------------------------------------
+-module(core_calendar_follow).
+-include("records.hrl").
+
+-export([follow/2, unfollow/2, is_following/2, list_by_user/1,
+  list_by_calendar/1, delete_by_calendar/1]).
+
+%%%-------------------------------------------------------------------
+%%% @doc Подписаться на календарь. Идемпотентно, если уже follow.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec follow(CalendarId :: binary(), UserId :: binary()) ->
+  {ok, #calendar_follow{}} | {error, term()}.
+follow(CalendarId, UserId) ->
+  Now = calendar:universal_time(),
+  F = fun() ->
+    case find(CalendarId, UserId) of
+      [#calendar_follow{} = Existing] ->
+        {ok, Existing};
+      [] ->
+        Rec = #calendar_follow{
+          id          = infra_utils:generate_id(16),
+          calendar_id = CalendarId,
+          user_id     = UserId,
+          created_at  = Now
+        },
+        mnesia:write(Rec),
+        {ok, Rec}
+    end
+      end,
+  case mnesia:transaction(F) of
+    {atomic, Result} -> Result;
+    {aborted, Reason} -> {error, Reason}
+  end.
+
+%%%-------------------------------------------------------------------
+%%% @doc Отписаться. Идемпотентно, если follow нет.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec unfollow(CalendarId :: binary(), UserId :: binary()) -> ok | {error, term()}.
+unfollow(CalendarId, UserId) ->
+  F = fun() ->
+    case find(CalendarId, UserId) of
+      [] ->
+        ok;
+      [#calendar_follow{id = Id}] ->
+        mnesia:delete({calendar_follow, Id}),
+        ok
+    end
+      end,
+  case mnesia:transaction(F) of
+    {atomic, ok} -> ok;
+    {aborted, Reason} -> {error, Reason}
+  end.
+
+%%%-------------------------------------------------------------------
+%%% @doc Есть ли follow у пользователя.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec is_following(UserId :: binary(), CalendarId :: binary()) -> boolean().
+is_following(UserId, CalendarId) ->
+  case mnesia:dirty_match_object(
+         #calendar_follow{calendar_id = CalendarId, user_id = UserId, _ = '_'}) of
+    [] -> false;
+    _ -> true
+  end.
+
+%%%-------------------------------------------------------------------
+%%% @doc Все follow пользователя.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec list_by_user(UserId :: binary()) -> [#calendar_follow{}].
+list_by_user(UserId) ->
+  mnesia:dirty_match_object(#calendar_follow{user_id = UserId, _ = '_'}).
+
+%%%-------------------------------------------------------------------
+%%% @doc Все follow календаря.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec list_by_calendar(CalendarId :: binary()) -> [#calendar_follow{}].
+list_by_calendar(CalendarId) ->
+  mnesia:dirty_match_object(#calendar_follow{calendar_id = CalendarId, _ = '_'}).
+
+%%%-------------------------------------------------------------------
+%%% @doc Удалить все follow календаря (при удалении calendar).
+%%% @end
+%%%-------------------------------------------------------------------
+-spec delete_by_calendar(CalendarId :: binary()) -> ok.
+delete_by_calendar(CalendarId) ->
+  F = fun() ->
+    lists:foreach(
+      fun(#calendar_follow{id = Id}) ->
+        mnesia:delete({calendar_follow, Id})
+      end,
+      mnesia:match_object(#calendar_follow{calendar_id = CalendarId, _ = '_'})),
+    ok
+      end,
+  case mnesia:transaction(F) of
+    {atomic, ok} -> ok;
+    {aborted, Reason} -> error({delete_follows_failed, Reason})
+  end.
+
+%%%===================================================================
+%%% Internal
+%%%===================================================================
+
+find(CalendarId, UserId) ->
+  mnesia:match_object(#calendar_follow{calendar_id = CalendarId, user_id = UserId, _ = '_'}).

src/eventhub_app.erl

@@ -90,9 +90,11 @@ start_http() ->
       {"/v1/user/me", handler_user_me, []},
       {"/v1/user/bookings", handler_user_bookings, []},
       {"/v1/user/reviews", handler_user_reviews, []},
+      {"/v1/user/following", handler_user_following, []},
       {"/v1/search", handler_search, []},
       {"/v1/calendars", handler_calendars, []},
       {"/v1/calendars/:id", handler_calendar_by_id, []},
+      {"/v1/calendars/:id/follow", handler_calendar_follow, []},
       {"/v1/calendars/:calendar_id/view", handler_calendar_view, []},
       {"/v1/calendars/:calendar_id/events", handler_events, []},
       {"/v1/events/:id", handler_event_by_id, []},

src/handlers/handler_calendar_by_id.erl

@@ -114,7 +114,9 @@ get_calendar(Req) ->
       CalendarId = cowboy_req:binding(id, Req1),
       case logic_calendar:get_calendar(UserId, CalendarId) of
         {ok, Calendar} ->
-          handler_utils:send_json(Req1, 200, handler_utils:calendar_to_json(Calendar));
+          Json0 = handler_utils:calendar_to_json(Calendar),
+          Following = logic_calendar_follow:is_following(UserId, CalendarId),
+          handler_utils:send_json(Req1, 200, Json0#{following => Following});
         {error, access_denied} ->
           handler_utils:send_error(Req1, 403, <<"Access denied">>);
         {error, not_found} ->

src/handlers/handler_calendar_follow.erl

@@ -0,0 +1,123 @@
+%%%-------------------------------------------------------------------
+%%% @doc Follow / unfollow чужого календаря.
+%%%
+%%% POST   /v1/calendars/:id/follow — подписаться
+%%% DELETE /v1/calendars/:id/follow — отписаться
+%%% @end
+%%%-------------------------------------------------------------------
+-module(handler_calendar_follow).
+-behaviour(cowboy_handler).
+
+-export([init/2]).
+-export([trails/0]).
+
+-include("records.hrl").
+
+-spec init(cowboy_req:req(), any()) -> {ok, cowboy_req:req(), any()}.
+init(Req, Opts) ->
+  handle(Req, Opts).
+
+-spec trails() -> [map()].
+trails() ->
+  BaseParams = [
+    #{
+      name        => <<"id">>,
+      in          => <<"path">>,
+      description => <<"Calendar ID">>,
+      required    => true,
+      schema      => #{type => string}
+    }
+  ],
+  FollowResponse = #{
+    type       => object,
+    properties => #{
+      calendar_id => #{type => string},
+      following   => #{type => boolean}
+    }
+  },
+  [
+    #{
+      path        => <<"/v1/calendars/:id/follow">>,
+      method      => <<"POST">>,
+      description => <<"Follow a calendar (not paid subscription)">>,
+      tags        => [<<"Calendars">>],
+      parameters  => BaseParams,
+      responses => #{
+        200 => #{
+          description => <<"Following">>,
+          content     => #{<<"application/json">> => #{schema => FollowResponse}}
+        },
+        401 => #{description => <<"Unauthorized">>},
+        403 => #{description => <<"Own calendar or access denied">>},
+        404 => #{description => <<"Calendar not found">>}
+      }
+    },
+    #{
+      path        => <<"/v1/calendars/:id/follow">>,
+      method      => <<"DELETE">>,
+      description => <<"Unfollow a calendar">>,
+      tags        => [<<"Calendars">>],
+      parameters  => BaseParams,
+      responses => #{
+        200 => #{
+          description => <<"Unfollowed">>,
+          content     => #{<<"application/json">> => #{schema => FollowResponse}}
+        },
+        401 => #{description => <<"Unauthorized">>},
+        403 => #{description => <<"Own calendar">>},
+        404 => #{description => <<"Calendar not found">>}
+      }
+    }
+  ].
+
+-spec handle(cowboy_req:req(), any()) -> {ok, cowboy_req:req(), any()}.
+handle(Req, _Opts) ->
+  case cowboy_req:method(Req) of
+    <<"POST">>   -> follow(Req);
+    <<"DELETE">> -> unfollow(Req);
+    _            -> handler_utils:send_error(Req, 405, <<"Method not allowed">>)
+  end.
+
+-spec follow(cowboy_req:req()) -> {ok, cowboy_req:req(), any()}.
+follow(Req) ->
+  case handler_utils:auth_user(Req) of
+    {ok, UserId, Req1} ->
+      CalendarId = cowboy_req:binding(id, Req1),
+      case logic_calendar_follow:follow(UserId, CalendarId) of
+        {ok, _} ->
+          handler_utils:send_json(Req1, 200, #{
+            calendar_id => CalendarId,
+            following   => true
+          });
+        {error, not_found} ->
+          handler_utils:send_error(Req1, 404, <<"Calendar not found">>);
+        {error, own_calendar} ->
+          handler_utils:send_error(Req1, 403, <<"Cannot follow own calendar">>);
+        {error, access_denied} ->
+          handler_utils:send_error(Req1, 403, <<"Access denied">>);
+        {error, _} ->
+          handler_utils:send_error(Req1, 500, <<"Internal server error">>)
+      end;
+    {error, Code, Message, Req1} ->
+      handler_utils:send_error(Req1, Code, Message)
+  end.
+
+-spec unfollow(cowboy_req:req()) -> {ok, cowboy_req:req(), any()}.
+unfollow(Req) ->
+  case handler_utils:auth_user(Req) of
+    {ok, UserId, Req1} ->
+      CalendarId = cowboy_req:binding(id, Req1),
+      case logic_calendar_follow:unfollow(UserId, CalendarId) of
+        ok ->
+          handler_utils:send_json(Req1, 200, #{
+            calendar_id => CalendarId,
+            following   => false
+          });
+        {error, own_calendar} ->
+          handler_utils:send_error(Req1, 403, <<"Cannot unfollow own calendar">>);
+        {error, _} ->
+          handler_utils:send_error(Req1, 500, <<"Internal server error">>)
+      end;
+    {error, Code, Message, Req1} ->
+      handler_utils:send_error(Req1, Code, Message)
+  end.

src/handlers/handler_user_following.erl

@@ -0,0 +1,55 @@
+%%%-------------------------------------------------------------------
+%%% @doc Список календарей, которые пользователь отслеживает (follow).
+%%%
+%%% GET /v1/user/following
+%%% @end
+%%%-------------------------------------------------------------------
+-module(handler_user_following).
+-behaviour(cowboy_handler).
+
+-export([init/2]).
+-export([trails/0]).
+
+-include("records.hrl").
+
+-spec init(cowboy_req:req(), any()) -> {ok, cowboy_req:req(), any()}.
+init(Req0, _State) ->
+  case cowboy_req:method(Req0) of
+    <<"GET">> -> list_following(Req0);
+    _         -> handler_utils:send_error(Req0, 405, <<"Method not allowed">>)
+  end.
+
+-spec trails() -> [map()].
+trails() ->
+  [
+    #{
+      path        => <<"/v1/user/following">>,
+      method      => <<"GET">>,
+      description => <<"List calendars the current user follows">>,
+      tags        => [<<"Calendars">>],
+      responses => #{
+        200 => #{
+          description => <<"Array of followed calendars">>,
+          content => #{<<"application/json">> => #{schema => #{
+            type  => array,
+            items => #{type => object}
+          }}}
+        },
+        401 => #{description => <<"Unauthorized">>}
+      }
+    }
+  ].
+
+-spec list_following(cowboy_req:req()) -> {ok, cowboy_req:req(), any()}.
+list_following(Req) ->
+  case handler_utils:auth_user(Req) of
+    {ok, UserId, Req1} ->
+      {ok, Calendars} = logic_calendar_follow:list_following_calendars(UserId),
+      Response = [
+        maps:put(following, true, handler_utils:calendar_to_json(C))
+        || C <- Calendars
+      ],
+      handler_utils:send_json(Req1, 200, Response);
+    {error, Code, Message, Req1} ->
+      handler_utils:send_error(Req1, Code, Message)
+  end.

src/infra/infra_mnesia.erl

@@ -14,7 +14,7 @@
 
 -define(TABLES, [
   user, session, verification, admin, admin_session, auth_session,
-  calendar, calendar_share, calendar_specialist,
+  calendar, calendar_share, calendar_follow, calendar_specialist,
   event, recurrence_exception,
   booking,
   review, review_vote, report, banned_word, automod_settings, automod_hit,
@@ -317,6 +317,7 @@ table_opts(user) -> [{disc_copies, [node()]}, {attributes, record_info(fields, u
 table_opts(admin) -> [{disc_copies, [node()]}, {attributes, record_info(fields, admin)}];
 table_opts(calendar) -> [{disc_copies, [node()]}, {attributes, record_info(fields, calendar)}];
 table_opts(calendar_share) -> [{disc_copies, [node()]}, {attributes, record_info(fields, calendar_share)}];
+table_opts(calendar_follow) -> [{disc_copies, [node()]}, {attributes, record_info(fields, calendar_follow)}];
 table_opts(calendar_specialist) -> [{disc_copies, [node()]}, {attributes, record_info(fields, calendar_specialist)}];
 table_opts(event) -> [{disc_copies, [node()]}, {attributes, record_info(fields, event)}];
 table_opts(recurrence_exception) -> [{disc_copies, [node()]}, {attributes, record_info(fields, recurrence_exception)}];

src/infra/migration_engine.erl

@@ -24,7 +24,8 @@
   '20260716230000_ticket_source_and_hash_index',
   '20260717180000_stats_counters',
   '20260717190000_admin_stats_indexes',
-  '20260719210000_review_vote'
+  '20260719210000_review_vote',
+  '20260720210000_calendar_follow'
 ]).
 
 %% ------------------------------

src/logic/logic_calendar_follow.erl

@@ -0,0 +1,84 @@
+%%%-------------------------------------------------------------------
+%%% @doc Бизнес-логика follow чужого календаря.
+%%% Follow не даёт право на отзыв (см. logic_review:can_review/3).
+%%% @end
+%%%-------------------------------------------------------------------
+-module(logic_calendar_follow).
+-include("records.hrl").
+
+-export([follow/2, unfollow/2, is_following/2, list_following_calendars/1]).
+
+%%%-------------------------------------------------------------------
+%%% @doc Follow доступного чужого календаря.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec follow(UserId :: binary(), CalendarId :: binary()) ->
+  {ok, #calendar_follow{}} | {error, term()}.
+follow(UserId, CalendarId) ->
+  case core_calendar:get_by_id(CalendarId) of
+    {error, not_found} ->
+      {error, not_found};
+    {ok, #calendar{owner_id = UserId}} ->
+      {error, own_calendar};
+    {ok, Calendar} ->
+      case logic_calendar:can_access(UserId, Calendar) of
+        false ->
+          {error, access_denied};
+        true ->
+          case Calendar#calendar.status of
+            active ->
+              core_calendar_follow:follow(CalendarId, UserId);
+            _ ->
+              {error, not_found}
+          end
+      end
+  end.
+
+%%%-------------------------------------------------------------------
+%%% @doc Unfollow. Идемпотентно.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec unfollow(UserId :: binary(), CalendarId :: binary()) -> ok | {error, term()}.
+unfollow(UserId, CalendarId) ->
+  case core_calendar:get_by_id(CalendarId) of
+    {error, not_found} ->
+      %% всё равно снимаем локальный follow, если был
+      core_calendar_follow:unfollow(CalendarId, UserId);
+    {ok, #calendar{owner_id = UserId}} ->
+      {error, own_calendar};
+    {ok, _} ->
+      core_calendar_follow:unfollow(CalendarId, UserId)
+  end.
+
+%%%-------------------------------------------------------------------
+%%% @doc Флаг following для текущего пользователя.
+%%% @end
+%%%-------------------------------------------------------------------
+-spec is_following(UserId :: binary(), CalendarId :: binary()) -> boolean().
+is_following(UserId, CalendarId) ->
+  core_calendar_follow:is_following(UserId, CalendarId).
+
+%%%-------------------------------------------------------------------
+%%% @doc Список календарей, на которые подписан пользователь (active, доступные).
+%%% @end
+%%%-------------------------------------------------------------------
+-spec list_following_calendars(UserId :: binary()) -> {ok, [#calendar{}]}.
+list_following_calendars(UserId) ->
+  Follows = core_calendar_follow:list_by_user(UserId),
+  Calendars = lists:filtermap(
+    fun(#calendar_follow{calendar_id = CalId}) ->
+      case core_calendar:get_by_id(CalId) of
+        {ok, #calendar{status = active} = Cal} ->
+          case logic_calendar:can_access(UserId, Cal) of
+            true -> {true, Cal};
+            false -> false
+          end;
+        _ ->
+          false
+      end
+    end,
+    Follows),
+  Sorted = lists:sort(
+    fun(#calendar{title = A}, #calendar{title = B}) -> A =< B end,
+    Calendars),
+  {ok, Sorted}.

src/migrations/20260720210000_calendar_follow.erl

@@ -0,0 +1,37 @@
+%% @doc Create calendar_follow table and indexes if missing.
+-module('20260720210000_calendar_follow').
+
+-export([up/0, down/0]).
+
+-include("records.hrl").
+
+up() ->
+  ensure_table(calendar_follow, record_info(fields, calendar_follow)),
+  ensure_index(calendar_follow, calendar_id),
+  ensure_index(calendar_follow, user_id),
+  ok.
+
+down() ->
+  _ = mnesia:delete_table(calendar_follow),
+  ok.
+
+ensure_table(Table, Attrs) ->
+  case lists:member(Table, mnesia:system_info(tables)) of
+    true ->
+      ok;
+    false ->
+      case mnesia:create_table(Table, [{disc_copies, [node()]}, {attributes, Attrs}]) of
+        {atomic, ok} -> ok;
+        {aborted, {already_exists, Table}} -> ok;
+        {aborted, Reason} -> error({create_table_failed, Table, Reason})
+      end
+  end.
+
+ensure_index(Table, Attr) ->
+  case mnesia:add_table_index(Table, Attr) of
+    {atomic, ok} -> ok;
+    {aborted, {already_exists, Table, _Pos}} -> ok;
+    {aborted, {already_exists, Table, Attr}} -> ok;
+    {aborted, {already_exists, _}} -> ok;
+    {aborted, Reason} -> error({add_index_failed, Table, Attr, Reason})
+  end.

src/swagger/eventhub_trails.erl

@@ -72,6 +72,7 @@ user() ->
     handler_booking_by_id,
     handler_bookings,
     handler_calendar_by_id,
+    handler_calendar_follow,
     handler_calendar_view,
     handler_calendars,
     handler_event_by_id,
@@ -86,6 +87,7 @@ user() ->
     handler_ticket_by_id,
     handler_tickets,
     handler_user_bookings,
+    handler_user_following,
     handler_user_me,
     handler_user_reviews
   ],

test/api/users/user_calendar_follow_tests.erl

@@ -0,0 +1,113 @@
+%%%-------------------------------------------------------------------
+%%% @doc Тесты follow / unfollow чужого календаря.
+%%%
+%%% POST   /v1/calendars/:id/follow
+%%% DELETE /v1/calendars/:id/follow
+%%% GET    /v1/user/following
+%%% GET    /v1/calendars/:id  (поле following)
+%%% @end
+%%%-------------------------------------------------------------------
+-module(user_calendar_follow_tests).
+-include_lib("eunit/include/eunit.hrl").
+
+-export([test/0]).
+
+-spec test() -> ok.
+test() ->
+  ct:pal("=== User Calendar Follow Tests ==="),
+  OwnerEmail = api_test_runner:unique_email(<<"flowner">>),
+  OwnerToken = api_test_runner:register_and_login(OwnerEmail, <<"pass">>),
+  FollowerEmail = api_test_runner:unique_email(<<"fluser">>),
+  FollowerToken = api_test_runner:register_and_login(FollowerEmail, <<"pass">>),
+
+  %% commercial calendar requires subscription
+  {ok, 201, _, _} = api_test_runner:client_request(
+    post, <<"/v1/subscription">>, OwnerToken,
+    jsx:encode(#{action => <<"start_trial">>})),
+  CalId = api_test_runner:create_calendar(OwnerToken, #{
+    title => <<"FollowMe">>,
+    type  => <<"commercial">>
+  }),
+  FollowPath = <<"/v1/calendars/", CalId/binary, "/follow">>,
+
+  test_follow(FollowerToken, FollowPath, CalId),
+  test_follow_idempotent(FollowerToken, FollowPath, CalId),
+  test_get_calendar_following(FollowerToken, CalId, true),
+  test_list_following(FollowerToken, CalId),
+  test_own_forbidden(OwnerToken, FollowPath),
+  test_unfollow(FollowerToken, FollowPath, CalId),
+  test_unfollow_idempotent(FollowerToken, FollowPath, CalId),
+  test_get_calendar_following(FollowerToken, CalId, false),
+  test_list_following_empty(FollowerToken),
+  test_unauthorized(FollowPath),
+
+  ct:pal("=== All user calendar follow tests passed ==="),
+  ok.
+
+%%%===================================================================
+%%% Cases
+%%%===================================================================
+
+test_follow(Token, Path, CalId) ->
+  ct:pal("  TEST: POST follow"),
+  {ok, 200, _, Body} = api_test_runner:client_request(post, Path, Token, <<"{}">>),
+  Resp = jsx:decode(list_to_binary(Body), [return_maps]),
+  ?assertEqual(CalId, maps:get(<<"calendar_id">>, Resp)),
+  ?assertEqual(true, maps:get(<<"following">>, Resp)),
+  ct:pal("    OK").
+
+test_follow_idempotent(Token, Path, CalId) ->
+  ct:pal("  TEST: POST follow idempotent"),
+  {ok, 200, _, Body} = api_test_runner:client_request(post, Path, Token, <<"{}">>),
+  Resp = jsx:decode(list_to_binary(Body), [return_maps]),
+  ?assertEqual(CalId, maps:get(<<"calendar_id">>, Resp)),
+  ?assertEqual(true, maps:get(<<"following">>, Resp)),
+  ct:pal("    OK").
+
+test_get_calendar_following(Token, CalId, Expected) ->
+  ct:pal("  TEST: GET calendar following=~p", [Expected]),
+  Cal = api_test_runner:client_get(<<"/v1/calendars/", CalId/binary>>, Token),
+  ?assertEqual(Expected, maps:get(<<"following">>, Cal)),
+  ct:pal("    OK").
+
+test_list_following(Token, CalId) ->
+  ct:pal("  TEST: GET /v1/user/following"),
+  List = api_test_runner:client_get(<<"/v1/user/following">>, Token),
+  ?assert(is_list(List)),
+  Match = [C || C <- List, maps:get(<<"id">>, C) =:= CalId],
+  ?assertMatch([_], Match),
+  [C] = Match,
+  ?assertEqual(true, maps:get(<<"following">>, C)),
+  ct:pal("    OK").
+
+test_own_forbidden(Token, Path) ->
+  ct:pal("  TEST: follow own calendar forbidden"),
+  Resp = api_test_runner:client_request(post, Path, Token, <<"{}">>),
+  ?assertMatch({ok, 403, _, _}, Resp),
+  ct:pal("    OK").
+
+test_unfollow(Token, Path, CalId) ->
+  ct:pal("  TEST: DELETE unfollow"),
+  Resp = api_test_runner:client_delete(Path, Token),
+  ?assertEqual(CalId, maps:get(<<"calendar_id">>, Resp)),
+  ?assertEqual(false, maps:get(<<"following">>, Resp)),
+  ct:pal("    OK").
+
+test_unfollow_idempotent(Token, Path, CalId) ->
+  ct:pal("  TEST: DELETE unfollow idempotent"),
+  Resp = api_test_runner:client_delete(Path, Token),
+  ?assertEqual(CalId, maps:get(<<"calendar_id">>, Resp)),
+  ?assertEqual(false, maps:get(<<"following">>, Resp)),
+  ct:pal("    OK").
+
+test_list_following_empty(Token) ->
+  ct:pal("  TEST: GET following empty"),
+  List = api_test_runner:client_get(<<"/v1/user/following">>, Token),
+  ?assertEqual([], List),
+  ct:pal("    OK").
+
+test_unauthorized(Path) ->
+  ct:pal("  TEST: unauthorized"),
+  Resp = api_test_runner:client_request(post, Path, <<>>, <<"{}">>),
+  ?assertMatch({ok, 401, _, _}, Resp),
+  ct:pal("    OK").

test/api_users_SUITE.erl

@@ -40,6 +40,7 @@ all() ->
     user_test_reviews,
     user_test_review_by_id,
     user_test_review_vote,
+    user_test_calendar_follow,
     user_test_my_reviews,
     user_test_search,
     user_test_refresh,
@@ -140,6 +141,9 @@ user_test_review_by_id(_Config) ->
 user_test_review_vote(_Config) ->
   user_review_vote_tests:test().
 
+user_test_calendar_follow(_Config) ->
+  user_calendar_follow_tests:test().
+
 user_test_my_reviews(_Config) ->
   user_my_reviews_tests:test().
 

test/unit/core_calendar_follow_tests.erl

@@ -0,0 +1,49 @@
+-module(core_calendar_follow_tests).
+-include_lib("eunit/include/eunit.hrl").
+-include("records.hrl").
+
+-define(TABLES, [calendar_follow]).
+
+setup() ->
+  eh_test_support:start_mnesia(),
+  eh_test_support:ensure_tables(?TABLES),
+  ok.
+
+cleanup(_) ->
+  eh_test_support:delete_tables(?TABLES),
+  eh_test_support:stop_mnesia(),
+  ok.
+
+core_calendar_follow_test_() ->
+  {foreach, fun setup/0, fun cleanup/1, [
+    {"follow and is_following", fun test_follow/0},
+    {"follow idempotent", fun test_follow_idempotent/0},
+    {"unfollow", fun test_unfollow/0},
+    {"list_by_user", fun test_list_by_user/0}
+  ]}.
+
+test_follow() ->
+  {ok, F} = core_calendar_follow:follow(<<"cal1">>, <<"u1">>),
+  ?assertEqual(<<"cal1">>, F#calendar_follow.calendar_id),
+  ?assertEqual(<<"u1">>, F#calendar_follow.user_id),
+  ?assert(core_calendar_follow:is_following(<<"u1">>, <<"cal1">>)),
+  ?assertNot(core_calendar_follow:is_following(<<"u2">>, <<"cal1">>)).
+
+test_follow_idempotent() ->
+  {ok, F1} = core_calendar_follow:follow(<<"cal1">>, <<"u1">>),
+  {ok, F2} = core_calendar_follow:follow(<<"cal1">>, <<"u1">>),
+  ?assertEqual(F1#calendar_follow.id, F2#calendar_follow.id),
+  ?assertEqual(1, length(core_calendar_follow:list_by_user(<<"u1">>))).
+
+test_unfollow() ->
+  {ok, _} = core_calendar_follow:follow(<<"cal1">>, <<"u1">>),
+  ok = core_calendar_follow:unfollow(<<"cal1">>, <<"u1">>),
+  ?assertNot(core_calendar_follow:is_following(<<"u1">>, <<"cal1">>)),
+  ok = core_calendar_follow:unfollow(<<"cal1">>, <<"u1">>).
+
+test_list_by_user() ->
+  {ok, _} = core_calendar_follow:follow(<<"cal1">>, <<"u1">>),
+  {ok, _} = core_calendar_follow:follow(<<"cal2">>, <<"u1">>),
+  {ok, _} = core_calendar_follow:follow(<<"cal1">>, <<"u2">>),
+  ?assertEqual(2, length(core_calendar_follow:list_by_user(<<"u1">>))),
+  ?assertEqual(2, length(core_calendar_follow:list_by_calendar(<<"cal1">>))).

test/unit/eh_test_support.erl

@@ -126,6 +126,8 @@ table_opts(calendar) ->
   [{ram_copies, [node()]}, {attributes, record_info(fields, calendar)}];
 table_opts(calendar_share) ->
   [{ram_copies, [node()]}, {attributes, record_info(fields, calendar_share)}];
+table_opts(calendar_follow) ->
+  [{ram_copies, [node()]}, {attributes, record_info(fields, calendar_follow)}];
 table_opts(calendar_specialist) ->
   [{ram_copies, [node()]}, {attributes, record_info(fields, calendar_specialist)}];
 table_opts(event) ->

test/unit/migration_engine_tests.erl

@@ -10,7 +10,8 @@
   "20260716230000_ticket_source_and_hash_index",
   "20260717180000_stats_counters",
   "20260717190000_admin_stats_indexes",
-  "20260719210000_review_vote"
+  "20260719210000_review_vote",
+  "20260720210000_calendar_follow"
 ]).
 
 setup() ->