%%%-------------------------------------------------------------------
%%% @doc Административный обработчик статистики по календарям.
%%% GET /v1/admin/calendars/stats
%%% @end
%%%-------------------------------------------------------------------
-module(admin_handler_calendar_stats).
-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) ->
  case cowboy_req:method(Req) of
    <<"GET">> -> get_calendar_stats(Req);
    _ -> handler_utils:send_error(Req, 405, <<"Method not allowed">>)
  end.

-spec trails() -> [map()].
trails() ->
  [ #{
    path => <<"/v1/admin/calendars/stats">>,
    method => <<"GET">>,
    description => <<"Calendar statistics">>,
    tags => [<<"Statistics">>],
    responses => #{
      200 => #{
        description => <<"Calendar statistics object">>,
        content => #{<<"application/json">> => #{schema => calendar_stats_schema()}}
      }
    }
  } ].

calendar_stats_schema() ->
  #{
    type => object,
    properties => #{
      <<"total_calendars">> => #{type => integer},
      <<"calendars_by_type">> => #{
        type => object,
        additionalProperties => #{type => integer}
      },
      <<"calendars_by_status">> => #{
        type => object,
        additionalProperties => #{type => integer}
      },
      <<"top_calendars_by_reviews">> => #{
        type => array,
        items => calendar_rank_schema()
      },
      <<"top_calendars_by_positive_reviews">> => #{
        type => array,
        items => calendar_rank_schema()
      },
      <<"top_calendars_by_negative_reviews">> => #{
        type => array,
        items => calendar_rank_schema()
      },
      <<"top_calendars_by_rating">> => #{
        type => array,
        items => calendar_rank_schema()
      }
    }
  }.

calendar_rank_schema() ->
  #{
    type => object,
    properties => #{
      <<"id">> => #{type => string},
      <<"title">> => #{type => string},
      <<"rating_avg">> => #{type => number, format => float},
      <<"review_count">> => #{type => integer}
    }
  }.

%%% Internal functions

get_calendar_stats(Req) ->
  case handler_utils:auth_admin(Req) of
    {ok, _AdminId, Req1} ->
      Total = core_calendar:count_calendars(),
      ByType = core_calendar:count_calendars_by_type(),
      ByStatus = core_calendar:count_calendars_by_status(),
      TopReviews = core_calendar:get_top_calendars_by_reviews(10),
      TopPositive = core_calendar:get_top_calendars_by_positive_reviews(10),
      TopNegative = core_calendar:get_top_calendars_by_negative_reviews(10),
      TopRating = core_calendar:get_top_calendars_by_rating(10),
      Stats = #{
        <<"total_calendars">> => Total,
        <<"calendars_by_type">> => maps:from_list([{atom_to_binary(T, utf8), C} || {T, C} <- ByType]),
        <<"calendars_by_status">> => maps:from_list([{atom_to_binary(S, utf8), C} || {S, C} <- ByStatus]),
        <<"top_calendars_by_reviews">> => format_calendar_list(TopReviews),
        <<"top_calendars_by_positive_reviews">> => format_calendar_list(TopPositive),
        <<"top_calendars_by_negative_reviews">> => format_calendar_list(TopNegative),
        <<"top_calendars_by_rating">> => format_calendar_list(TopRating)
      },
      handler_utils:send_json(Req1, 200, Stats);
    {error, Code, Msg, Req1} ->
      handler_utils:send_error(Req1, Code, Msg)
  end.

format_calendar_list(List) ->
  lists:map(fun(#calendar{id = Id, title = Title, rating_avg = RAvg}) ->
    #{<<"id">> => Id, <<"title">> => Title, <<"rating_avg">> => RAvg}
            end, List).