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

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.