%%%-------------------------------------------------------------------
%%% @doc Accepted shares on a calendar + revoke / rights / self-mirror.
%%%
%%% GET/DELETE/PUT /v1/calendars/:id/shares[/:user_id]
%%% PUT /v1/user/shares/:calendar_id  body: {mirror_to_default}
%%% @end
%%%-------------------------------------------------------------------
-module(handler_calendar_shares).
-behaviour(cowboy_handler).

-export([init/2, trails/0]).

-include("records.hrl").

init(Req, Opts) ->
  handle(Req, Opts).

trails() ->
  IdParam = #{name => <<"id">>, in => <<"path">>, required => true,
    schema => #{type => string}},
  UserParam = #{name => <<"user_id">>, in => <<"path">>, required => true,
    schema => #{type => string}},
  CalParam = #{name => <<"calendar_id">>, in => <<"path">>, required => true,
    schema => #{type => string}},
  [
    #{path => <<"/v1/calendars/:id/shares">>, method => <<"GET">>,
      description => <<"List calendar shares">>, tags => [<<"Calendars">>],
      parameters => [IdParam], responses => #{200 => #{description => <<"OK">>}}},
    #{path => <<"/v1/calendars/:id/shares/:user_id">>, method => <<"DELETE">>,
      description => <<"Revoke share grant">>, tags => [<<"Calendars">>],
      parameters => [IdParam, UserParam], responses => #{200 => #{description => <<"OK">>}}},
    #{path => <<"/v1/calendars/:id/shares/:user_id">>, method => <<"PUT">>,
      description => <<"Update share rights">>, tags => [<<"Calendars">>],
      parameters => [IdParam, UserParam], responses => #{200 => #{description => <<"OK">>}}},
    #{path => <<"/v1/user/shares/:calendar_id">>, method => <<"PUT">>,
      description => <<"Update own mirror_to_default">>, tags => [<<"Users">>],
      parameters => [CalParam], responses => #{200 => #{description => <<"OK">>}}}
  ].

handle(Req, _Opts) ->
  Method = cowboy_req:method(Req),
  Path = cowboy_req:path(Req),
  case Path of
    <<"/v1/user/shares/", _/binary>> ->
      case Method of
        <<"PUT">> -> update_my_mirror(Req);
        _ -> handler_utils:send_error(Req, 405, <<"Method not allowed">>)
      end;
    _ ->
      UserId = cowboy_req:binding(user_id, Req),
      case {Method, UserId} of
        {<<"GET">>, undefined} -> list_shares(Req);
        {<<"DELETE">>, Id} when is_binary(Id) -> revoke_share(Req);
        {<<"PUT">>, Id} when is_binary(Id) -> update_rights(Req);
        _ -> handler_utils:send_error(Req, 405, <<"Method not allowed">>)
      end
  end.

list_shares(Req) ->
  case handler_utils:auth_user(Req) of
    {ok, ActorId, Req1} ->
      CalendarId = cowboy_req:binding(id, Req1),
      case logic_calendar_share:list(ActorId, CalendarId) of
        {ok, List} ->
          handler_utils:send_json(Req1, 200,
            [logic_calendar_share:to_json(S) || S <- List]);
        {error, not_found} ->
          handler_utils:send_error(Req1, 404, <<"Calendar not found">>);
        {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.

revoke_share(Req) ->
  case handler_utils:auth_user(Req) of
    {ok, ActorId, Req1} ->
      CalendarId = cowboy_req:binding(id, Req1),
      TargetUserId = cowboy_req:binding(user_id, Req1),
      case logic_calendar_share:revoke(ActorId, CalendarId, TargetUserId) of
        ok ->
          handler_utils:send_json(Req1, 200, #{ok => true});
        {error, not_found} ->
          handler_utils:send_error(Req1, 404, <<"Not found">>);
        {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.

update_rights(Req) ->
  case handler_utils:auth_user(Req) of
    {ok, ActorId, Req1} ->
      CalendarId = cowboy_req:binding(id, Req1),
      TargetUserId = cowboy_req:binding(user_id, Req1),
      {ok, Body, Req2} = cowboy_req:read_body(Req1),
      try jsx:decode(Body, [return_maps]) of
        #{<<"rights">> := RightsBin} when is_binary(RightsBin) ->
          case binary_to_existing_atom_safe(RightsBin) of
            invalid ->
              handler_utils:send_error(Req2, 400, <<"Bad request">>);
            Rights ->
              case logic_calendar_share:update_rights(ActorId, CalendarId, TargetUserId, Rights) of
                {ok, Share} ->
                  handler_utils:send_json(Req2, 200, logic_calendar_share:to_json(Share));
                {error, Reason} ->
                  map_share_error(Req2, Reason)
              end
          end;
        _ ->
          handler_utils:send_error(Req2, 400, <<"rights required">>)
      catch
        _:_ -> handler_utils:send_error(Req2, 400, <<"Invalid JSON">>)
      end;
    {error, Code, Message, Req1} ->
      handler_utils:send_error(Req1, Code, Message)
  end.

update_my_mirror(Req) ->
  case handler_utils:auth_user(Req) of
    {ok, UserId, Req1} ->
      CalendarId = cowboy_req:binding(calendar_id, Req1),
      {ok, Body, Req2} = cowboy_req:read_body(Req1),
      try jsx:decode(Body, [return_maps]) of
        #{<<"mirror_to_default">> := Mirror} when is_boolean(Mirror) ->
          case logic_calendar_share:update_my_mirror(UserId, CalendarId, Mirror) of
            {ok, Share} ->
              handler_utils:send_json(Req2, 200, logic_calendar_share:to_json(Share));
            {error, Reason} ->
              map_share_error(Req2, Reason)
          end;
        _ ->
          handler_utils:send_error(Req2, 400, <<"mirror_to_default required">>)
      catch
        _:_ -> handler_utils:send_error(Req2, 400, <<"Invalid JSON">>)
      end;
    {error, Code, Message, Req1} ->
      handler_utils:send_error(Req1, Code, Message)
  end.

binary_to_existing_atom_safe(<<"read">>) -> read;
binary_to_existing_atom_safe(<<"write">>) -> write;
binary_to_existing_atom_safe(<<"admin">>) -> admin;
binary_to_existing_atom_safe(_) -> invalid.

map_share_error(Req, not_found) ->
  handler_utils:send_error(Req, 404, <<"Not found">>);
map_share_error(Req, access_denied) ->
  handler_utils:send_error(Req, 403, <<"Access denied">>);
map_share_error(Req, bad_request) ->
  handler_utils:send_error(Req, 400, <<"Bad request">>);
map_share_error(Req, invalid) ->
  handler_utils:send_error(Req, 400, <<"Bad request">>);
map_share_error(Req, _) ->
  handler_utils:send_error(Req, 500, <<"Internal server error">>).