-module(fold_lines).
-export([count_lines/1, count_tbray_matches/1]).

int_fold_lines(Device, Kons, Result) ->
    case io:get_line(Device, "") of
        eof  -> file:close(Device), Result;
        Line -> NewResult = Kons(Line, Result),
                int_fold_lines(Device, Kons, NewResult)
    end.

fold_file_lines(FileName, Kons, Knil) ->
    {ok, Device} = file:open(FileName,[read]),
    int_fold_lines(Device, Kons, Knil).
    
count_lines(FileName) ->
    fold_file_lines(FileName, fun(_Line, Acc) -> Acc + 1 end, 0).

count_tbray_matches(FileName) ->
    fold_file_lines(FileName, fun(_Line, Acc) -> match_tbray_pattern(_Line, Acc) end, 0).

match_tbray_pattern(Line, Acc) ->
    Uri = list_to_binary(lists:nth(7, string:tokens(Line, " "))),
    case match_tbray_uri(Uri) of
        true -> Acc + 1;
        false -> Acc
    end.
    
match_tbray_uri(<< "/ongoing/When/", Trailer/binary >>) ->
    Last = binary_to_list(Trailer),
    lists:member($., Last);
    
match_tbray_uri(_) -> false.