%%%-------------------------------------------------------------------
%%% @doc Grants calendar_share: list / revoke / rights / mirror.
%%% @end
%%%-------------------------------------------------------------------
-module(logic_calendar_share).
-include("records.hrl").

-export([
  list/2,
  revoke/3,
  update_rights/4,
  update_my_mirror/3,
  get_rights/2,
  can_manage_shares/2,
  to_json/1
]).

-spec list(ActorId :: binary(), CalendarId :: binary()) ->
  {ok, [#calendar_share{}]} | {error, not_found | access_denied}.
list(ActorId, CalendarId) ->
  case require_can_view_shares(ActorId, CalendarId) of
    {ok, _} -> {ok, core_calendar_share:list_by_calendar(CalendarId)};
    Error -> Error
  end.

-spec revoke(ActorId :: binary(), CalendarId :: binary(), TargetUserId :: binary()) ->
  ok | {error, not_found | access_denied | term()}.
revoke(ActorId, CalendarId, TargetUserId) ->
  case require_can_manage(ActorId, CalendarId) of
    {ok, _} ->
      case core_calendar_share:delete(CalendarId, TargetUserId) of
        ok -> ok;
        {error, _} = E -> E
      end;
    Error -> Error
  end.

-spec update_rights(ActorId :: binary(), CalendarId :: binary(),
    TargetUserId :: binary(), Rights :: read | write | admin) ->
  {ok, #calendar_share{}} | {error, not_found | access_denied | bad_request | term()}.
update_rights(ActorId, CalendarId, TargetUserId, Rights) ->
  case valid_rights(Rights) of
    false -> {error, bad_request};
    true ->
      case require_can_manage(ActorId, CalendarId) of
        {ok, _} -> core_calendar_share:update_rights(CalendarId, TargetUserId, Rights);
        Error -> Error
      end
  end.

%% Invitee updates own mirror preference (personal shares only meaningful).
-spec update_my_mirror(UserId :: binary(), CalendarId :: binary(), Mirror :: boolean()) ->
  {ok, #calendar_share{}} | {error, not_found | access_denied | term()}.
update_my_mirror(UserId, CalendarId, Mirror) when is_boolean(Mirror) ->
  case core_calendar_share:get(CalendarId, UserId) of
    {ok, _} -> core_calendar_share:update_mirror(CalendarId, UserId, Mirror);
    {error, not_found} -> {error, not_found}
  end;
update_my_mirror(_, _, _) ->
  {error, bad_request}.

-spec get_rights(UserId :: binary(), CalendarId :: binary()) ->
  none | read | write | admin.
get_rights(UserId, CalendarId) ->
  case core_calendar_share:get(CalendarId, UserId) of
    {ok, #calendar_share{rights = R}} -> R;
    {error, not_found} -> none
  end.

-spec can_manage_shares(UserId :: binary(), #calendar{}) -> boolean().
can_manage_shares(UserId, #calendar{owner_id = UserId, status = active}) ->
  true;
can_manage_shares(UserId, #calendar{id = CalId, status = active}) ->
  get_rights(UserId, CalId) =:= admin;
can_manage_shares(_, _) ->
  false.

-spec to_json(#calendar_share{}) -> map().
to_json(S) ->
  #{
    id => S#calendar_share.id,
    calendar_id => S#calendar_share.calendar_id,
    user_id => S#calendar_share.user_id,
    rights => S#calendar_share.rights,
    mirror_to_default => S#calendar_share.mirror_to_default
  }.

%%%===================================================================
%%% Internal
%%%===================================================================

require_can_view_shares(ActorId, CalendarId) ->
  case core_calendar:get_by_id(CalendarId) of
    {ok, #calendar{status = active} = Cal} ->
      case can_manage_shares(ActorId, Cal)
            orelse Cal#calendar.owner_id =:= ActorId
            orelse get_rights(ActorId, CalendarId) =/= none of
        true -> {ok, Cal};
        false -> {error, access_denied}
      end;
    {ok, _} -> {error, not_found};
    Error -> Error
  end.

require_can_manage(ActorId, CalendarId) ->
  case core_calendar:get_by_id(CalendarId) of
    {ok, #calendar{status = active} = Cal} ->
      case can_manage_shares(ActorId, Cal) of
        true -> {ok, Cal};
        false -> {error, access_denied}
      end;
    {ok, _} -> {error, not_found};
    Error -> Error
  end.

valid_rights(read) -> true;
valid_rights(write) -> true;
valid_rights(admin) -> true;
valid_rights(_) -> false.