erlydtl/src/erlydtl_filters.erl

%%%-------------------------------------------------------------------
%%% File:      erlydtl_filters.erl
%%% @author    Roberto Saccon <rsaccon@gmail.com> [http://rsaccon.com]
%%% @author    Evan Miller <emmiller@gmail.com>
%%% @copyright 2008 Roberto Saccon, Evan Miller
%%% @doc
%%% Template filters
%%% @end 
%%%
%%% The MIT License
%%%
%%% Copyright (c) 2007 Roberto Saccon, Evan Miller
%%%
%%% Permission is hereby granted, free of charge, to any person obtaining a copy
%%% of this software and associated documentation files (the "Software"), to deal
%%% in the Software without restriction, including without limitation the rights
%%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
%%% copies of the Software, and to permit persons to whom the Software is
%%% furnished to do so, subject to the following conditions:
%%%
%%% The above copyright notice and this permission notice shall be included in
%%% all copies or substantial portions of the Software.
%%%
%%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
%%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
%%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
%%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
%%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
%%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
%%% THE SOFTWARE.
%%%
%%% @since 2007-11-11 by Roberto Saccon, Evan Miller
%%%-------------------------------------------------------------------
-module(erlydtl_filters).
-author('rsaccon@gmail.com').
-author('emmiller@gmail.com').
-author('drew dot gulino at google dot com').
 
-ifdef(TEST).
-undef(TEST).
-endif.
-define(TEST,"").
%-define(NOTEST,1).
-define(NODEBUG,1).
-include_lib("eunit/include/eunit.hrl").
 
-ifdef(TEST).
        -export([cast_to_float/1,cast_to_integer/1,stringformat_io/7,round/2,unjoin/2,addDefaultURI/1]).
-endif.
 
 
-export([add/2,
        addslashes/1,
        capfirst/1,
        center/2,
        cut/2,
        date/1,
        date/2,
        default/2,
        default_if_none/2,
        dictsort/2,
        dictsortreversed/2,
        divisibleby/2,
        %escape/, - implemented in erlydtl_compiler
        escapejs/1,
        filesizeformat/1,
        first/1,
        fix_ampersands/1,
        floatformat/1,
        floatformat/2,
        force_escape/1,
        format_integer/1,
        format_number/1,
        get_digit/2,
        iriencode/1,
        join/2,
        last/1,
        length/1,
        length_is/2,
        linebreaks/1,
        linebreaksbr/1,
        linenumbers/1,
        ljust/2,
        lower/1,
        make_list/1, 
        phone2numeric/1,
        pluralize/1,
        pluralize/2,
        pprint/1,
        random/1,
        random_num/1,
        random_range/1,
        removetags/2,
        rjust/2,
        %safe/, - implemented in erlydtl_compiler
        %safeseq/, - implemented in erlydtl_compiler
        slice/2,
        slugify/1,
        stringformat/2,
        striptags/1,
        time/1,
        time/2,
        timesince/1,
        timesince/2,
        timeuntil/1,
        timeuntil/2,
        title/1,
        truncatechars/2,
        truncatewords/2,
        truncatewords_html/2,
        unordered_list/1,
        upper/1,
        urlencode/1,
        urlencode/2,
        urlize/1,
        urlize/2,
        urlizetrunc/2,
        wordcount/1,
        wordwrap/2,
        yesno/2]).
 
-define(NO_ENCODE(C), ((C >= $a andalso C =< $z) orelse
        (C >= $A andalso C =< $Z) orelse
        (C >= $0 andalso C =< $9) orelse
        (C =:= $\. orelse C =:= $-
        orelse C =:= $~ orelse C =:= $_))).

-define(NO_IRI_ENCODE(C), (?NO_ENCODE(C) orelse (
            C =:= $/ orelse 
            C =:= $# orelse 
            C =:= $[ orelse
            C =:= $] orelse
            C =:= $= orelse
            C =:= $: orelse
            C =:= $; orelse
            C =:= $$ orelse
            C =:= $& orelse
            C =:= $( orelse
            C =:= $) orelse
            C =:= $+ orelse
            C =:= $, orelse
            C =:= $! orelse
            C =:= $? orelse
            C =:= $* orelse
            C =:= $@ orelse
            C =:= $' orelse
            C =:= $~))).
 
-define(KILOBYTE, 1024).
-define(MEGABYTE, (1024 * ?KILOBYTE)).
-define(GIGABYTE, (1024 * ?MEGABYTE)).

-define(SECONDS_PER_MINUTE, 60).
-define(SECONDS_PER_HOUR,  (60 * ?SECONDS_PER_MINUTE)).
-define(SECONDS_PER_DAY,   (24 * ?SECONDS_PER_HOUR)).
-define(SECONDS_PER_WEEK,   (7 * ?SECONDS_PER_DAY)).
-define(SECONDS_PER_MONTH, (30 * ?SECONDS_PER_DAY)).
-define(SECONDS_PER_YEAR, (365 * ?SECONDS_PER_DAY)).
 
%% @doc Adds to values
add(LHS, RHS) when is_number(LHS), is_number(RHS) ->
    LHS + RHS;
add(LHS, RHS) when is_binary(LHS) ->
    add(unicode:characters_to_list(LHS), RHS);
add(LHS, RHS) when is_binary(RHS) ->
    add(LHS, unicode:characters_to_list(RHS));
add(LHS, RHS) when is_list(LHS), is_list(RHS) ->
    case {to_numeric(LHS), to_numeric(RHS)} of
	{{number, LHSNum}, {number, RHSNum}} ->
	    LHSNum + RHSNum;
	_ ->
	    LHS ++ RHS
    end;
add(LHS, RHS) when is_list(LHS), is_number(RHS) ->
    case to_numeric(LHS) of
	{number, LHSNum} ->
	    LHSNum + RHS;
	_ ->
	    LHS ++ to_string(RHS)
    end;
add(LHS, RHS) when is_number(LHS), is_list(RHS) ->
    case to_numeric(RHS) of
	{number, RHSNum} ->
	    LHS + RHSNum;
	_ ->
	    to_string(LHS) ++ RHS
    end.

to_string(Num) when is_integer(Num) ->
    integer_to_list(Num);
to_string(Num) when is_float(Num) ->
    float_to_list(Num).

to_numeric(List) ->
    try
	{number, list_to_integer(List)}
    catch
	error:badarg ->
	    try
		{number, list_to_float(List)}
	    catch
		error:badarg ->
		    undefined
	    end
    end.
 
%% @doc Adds slashes before quotes.
addslashes(Input) when is_binary(Input) ->
    addslashes(unicode:characters_to_list(Input));
addslashes(Input) when is_list(Input) ->
    addslashes(Input, []).
 
%% @doc Capitalizes the first character of the value.
capfirst([H|T]) when H >= $a andalso H =< $z ->
    [H + $A - $a | T];
capfirst(Other) when is_list(Other) ->
    Other;
capfirst(<<Byte:8/integer, Binary/binary>>) when Byte >= $a andalso Byte =< $z ->
    [(Byte + $A - $a)|unicode:characters_to_list(Binary)];
capfirst(Other) when is_binary(Other) ->
    Other.
 
%% @doc Centers the value in a field of a given width.
center(Input, Number) when is_binary(Input) ->
    unicode:characters_to_binary(center(unicode:characters_to_list(Input), Number));
center(Input, Number) when is_list(Input) ->
    string:centre(Input, Number).
 
%% @doc Removes all values of arg from the given string.
cut(Input, Arg) when is_binary(Arg) ->
    cut(Input, unicode:characters_to_list(Arg));
cut(Input, Arg) when is_binary(Input) ->
    cut(unicode:characters_to_list(Input), Arg);
cut(Input, [Char]) when is_list(Input) ->
    cut(Input, Char, []).
 
%% @doc Formats a date according to the default format.
date(Input) ->
    date(Input, "F j, Y").

%% @doc Formats a date according to the given format.
date(Input, FormatStr)
  when is_tuple(Input)
       andalso (size(Input) == 2 orelse size(Input) == 3) ->
    erlydtl_dateformat:format(Input, FormatStr);
date(Input, _FormatStr) ->
    io:format("Unexpected date parameter: ~p~n", [Input]),
    "".

%% @doc If value evaluates to `false', use given default. Otherwise, use the value.
default(Input, Default) ->
    case erlydtl_runtime:is_false(Input) of
        true -> Default;
        false -> Input
    end.

%% @doc If (and only if) value is `undefined', use given default. Otherwise, use the value.
default_if_none(undefined, Default) ->
    Default;
default_if_none(Input, _) ->
    Input.

%% @doc Takes a list of dictionaries or proplists and returns that list sorted by the key given in the argument.
dictsort(DictList, Key) when is_binary(Key) ->
    dictsort(DictList, [binary_to_atom(B,latin1) ||
			   B <- binary:split(Key,<<".">>)]);
dictsort(DictList, Key) ->
    case lists:all(
	   fun(Dict) ->
		   erlydtl_runtime:find_deep_value(Key, Dict) /= undefined
	   end, DictList) of
        true ->
	    lists:sort(
	      fun(K1,K2) ->
		      erlydtl_runtime:find_deep_value(Key,K1) =<
			  erlydtl_runtime:find_deep_value(Key,K2)
	      end, DictList);
        false -> error
    end.

%% @doc Same as dictsort, but the list is reversed.
dictsortreversed(DictList, Key) ->
    lists:reverse(dictsort(DictList, Key)).

%% @doc Returns `true' if the value is divisible by the argument.
divisibleby(Input, Divisor) when is_binary(Input) ->
    divisibleby(unicode:characters_to_list(Input), Divisor);
divisibleby(Input, Divisor) when is_list(Input) ->
    divisibleby(list_to_integer(Input), Divisor);
divisibleby(Input, Divisor) when is_binary(Divisor) ->
    divisibleby(Input, unicode:characters_to_list(Divisor));
divisibleby(Input, Divisor) when is_list(Divisor) ->
    divisibleby(Input, list_to_integer(Divisor));
divisibleby(Input, Divisor) when is_integer(Input), is_integer(Divisor) ->
    Input rem Divisor =:= 0.

%% @doc Escapes characters for use in JavaScript strings.
escapejs(Input) when is_binary(Input) ->
    unicode:characters_to_binary(escapejs(unicode:characters_to_list(Input)));
escapejs(Input) when is_list(Input) ->
    escapejs(Input, []).

%% @doc Format the value like a human-readable file size.
filesizeformat(Input) when is_binary(Input) ->
    filesizeformat(unicode:characters_to_list(Input));
filesizeformat(Input) when is_list(Input) ->
    filesizeformat(list_to_integer(Input));
filesizeformat(Bytes) when is_integer(Bytes), Bytes >= ?GIGABYTE->
    filesizeformat(Bytes / ?GIGABYTE, "GB");
filesizeformat(Bytes) when is_integer(Bytes), Bytes >= ?MEGABYTE ->
    filesizeformat(Bytes / ?MEGABYTE, "MB");
filesizeformat(Bytes) when is_integer(Bytes), Bytes >= ?KILOBYTE ->
    filesizeformat(Bytes / ?KILOBYTE, "KB");
filesizeformat(Bytes) when is_integer(Bytes) ->
    integer_to_list(Bytes) ++ " bytes".

%% @doc Returns the first item in a list.
first([First|_Rest]) ->
    [First];
first(<<First, _/binary>>) ->
    <<First>>.

%% @doc Replaces ampersands with &amp; entities.
fix_ampersands(Input) when is_binary(Input) ->
    fix_ampersands(Input, 0);
fix_ampersands(Input) when is_list(Input) ->
    fix_ampersands(Input, []).

%% @doc When used without an argument, rounds a floating-point number to one decimal place
%% -- but only if there's a decimal part to be displayed
floatformat(Number) ->
    floatformat(Number, []).

floatformat(Number, Place)
  when is_number(Number); is_binary(Number); is_list(Number) ->
    floatformat_io(cast_to_float(Number), cast_to_integer(Place));
floatformat(_, _) -> "".

floatformat_io(Number, []) ->
    floatformat_io(Number, -1);
floatformat_io(Number, 0) ->
    hd(io_lib:format("~B", [erlang:round(Number)]));
floatformat_io(Number, Precision) when Precision > 0 ->
    hd(io_lib:format("~.*f",[Precision, Number]));
floatformat_io(Number, Precision) when Precision < 0 ->   
    Round = erlang:round(Number),
    RoundPrecision = round(Number, -Precision),
    if RoundPrecision == Round ->
            floatformat_io(Round, 0);
       true ->
            floatformat_io(RoundPrecision, -Precision)
    end.

round(Number, Precision) ->
    P = math:pow(10, Precision),
    erlang:round(Number * P) / P.

%% @doc Applies HTML escaping to a string.
force_escape(Input) when is_list(Input) ->
    escape(Input, []);
force_escape(Input) when is_binary(Input) ->
    escape(Input, 0);
force_escape(Input) ->
    Input.

format_integer(Input) when is_integer(Input) ->
    integer_to_list(Input);
format_integer(Input) ->
    Input.

format_number(Input) when is_integer(Input) ->
    integer_to_list(Input);
format_number(Input) when is_float(Input) ->
    io_lib:format("~p", [Input]);
format_number(Input) when is_function(Input, 0) ->
    format_number(Input());
format_number(Input) ->
    Input.

%% @doc Given a whole number, returns the requested digit, where 1 is the right-most digit.
get_digit(Input, Digit) when is_binary(Input) ->
    get_digit(unicode:characters_to_list(Input), Digit);
get_digit(Input, Digit) when is_integer(Input) ->
    get_digit(integer_to_list(Input), Digit);
get_digit(Input, Digit) when is_binary(Digit) ->
    get_digit(Input, unicode:characters_to_list(Digit));
get_digit(Input, Digit) when is_list(Digit) ->
    get_digit(Input, list_to_integer(Digit));
get_digit(Input, Digit) when Digit > erlang:length(Input) ->
    0;
get_digit(Input, Digit) when Digit > 0 ->
    lists:nth(Digit, lists:reverse(Input)) - $0;
get_digit(Input, _) ->
    Input.

iriencode(Input) ->
    iriencode(unicode:characters_to_list(Input), []).

%% @doc Joins a list with a given separator.
join(Input, Separator) when is_list(Input) ->
    join_io(Input, Separator).

%% @doc Returns the last item in a list.
last(Input) when is_binary(Input) ->
    case size(Input) of
        0 -> Input;
        N ->
            Offset = N - 1,
            <<_:Offset/binary, Byte/binary>> = Input,
            Byte
    end;
last(Input) when is_list(Input) ->
    [lists:last(Input)].

%% @doc Returns the length of the value.
length(Input) when is_list(Input) ->
    integer_to_list(erlang:length(Input));
length(Input) when is_binary(Input) ->
    integer_to_list(size(Input)).

%% @doc Returns True iff the value's length is the argument.
length_is(Input, Number) when is_list(Input), is_integer(Number) ->
    length_is(Input, integer_to_list(Number));
length_is(Input, Number) when is_list(Input), is_list(Number) ->
    ?MODULE:length(Input) =:= Number.

%% @doc Replaces line breaks in plain text with appropriate HTML
linebreaks(Input) when is_binary(Input) ->
    linebreaks(unicode:characters_to_list(Input),[]);
linebreaks(Input) ->
    linebreaks(Input,[]).

linebreaks([],Acc) ->
    "<p>" ++ lists:reverse(Acc) ++ "</p>";
linebreaks([$\n|T], ">p<"++_ = Acc) ->
    linebreaks(T, Acc);
linebreaks([$\r|T], ">p<"++_ = Acc) ->
    linebreaks(T, Acc);
linebreaks([$\n, $\n|T],Acc) ->
    linebreaks(T, lists:reverse("</p><p>", Acc));
linebreaks([$\r, $\n, $\r, $\n|T],Acc) ->
    linebreaks(T, lists:reverse("</p><p>", Acc));
linebreaks([$\r, $\n|T], Acc) ->
    linebreaks(T, lists:reverse("<br />", Acc));
linebreaks([$\n|T], Acc) ->
    linebreaks(T, lists:reverse("<br />", Acc));
linebreaks([C|T], Acc) ->
    linebreaks(T, [C|Acc]).

%% @doc Converts all newlines to HTML line breaks.
linebreaksbr(Input) when is_binary(Input) ->
    linebreaksbr(Input, 0);
linebreaksbr(Input) ->
    linebreaksbr(Input, []).

%% @doc Displays text with line numbers.
linenumbers(Input) when is_binary(Input) ->
    linenumbers(unicode:characters_to_list(Input));
linenumbers(Input) when is_list(Input) ->
    linenumbers_io(Input, [], 1).

linenumbers_io([], Acc, _) ->
    lists:reverse(Acc);
linenumbers_io(Input, [], LineNumber) ->
    linenumbers_io(Input, lists:reverse(integer_to_list(LineNumber)++". "), LineNumber + 1);
linenumbers_io("\n"++Rest, Acc, LineNumber) ->
    linenumbers_io(Rest, lists:reverse("\n" ++ integer_to_list(LineNumber) ++ ". ", Acc), LineNumber + 1);
linenumbers_io([H|T], Acc, LineNumber) ->
    linenumbers_io(T, [H|Acc], LineNumber).

%% @doc Left-aligns the value in a field of a given width.
ljust(Input, Number) when is_binary(Input) ->
    unicode:characters_to_binary(ljust(unicode:characters_to_list(Input), Number));
ljust(Input, Number) when is_list(Input) ->
    string:left(Input, Number).

%% @doc Converts a string into all lowercase.
lower(Input) when is_binary(Input) ->
    lower(Input, 0);
lower(Input) ->
    string:to_lower(Input).

%% @doc Returns the value turned into a list. For an integer, it's a list of digits. 
%% For a string, it's a list of characters.
%% Added this for DTL compatibility, but since strings are lists in Erlang, no need for this.
make_list(Input) when is_binary(Input) ->
    make_list(unicode:characters_to_list(Input));
make_list(Input) ->
    unjoin(Input,"").

%% @doc Converts a phone number (possibly containing letters) to its numerical equivalent.
phone2numeric(Input) when is_binary(Input) ->
    phone2numeric(unicode:characters_to_list(Input));
phone2numeric(Input) when is_list(Input) ->
    phone2numeric(Input, []).

%% @doc Returns a plural suffix if the value is not 1. By default, this suffix is 's'.
pluralize(Number, Suffix) when is_binary(Suffix) ->
    pluralize_io(Number, unicode:characters_to_list(Suffix) );
pluralize(Number, Suffix) when is_list(Suffix) ->
    pluralize_io(Number, Suffix).

pluralize(Number) ->
    pluralize(Number, "s").

pluralize_io(Number, Suffix) ->
    [Singular, Plural] =
        case string:tokens(Suffix,",") of
            [P] -> ["", P];
            [S, P|_] -> [S, P]
        end,
    if Number == 1; Number == "1"; Number == <<"1">> -> Singular;
       true -> Plural
    end.

%% @doc "pretty print" arbitrary data structures.  Used for debugging.
pprint(Input) ->
    io_lib:format("~p",[Input]).

%% @doc Returns a random item from the given list.
random(Input) when is_list(Input) ->
    lists:nth(random:uniform(erlang:length(Input)), Input);
random(_) ->
    "".

random_num(Value) ->
    random:seed(now()),
    random:uniform(Value).

%% random tags to be used when using erlydtl in testing
random_range(Range) ->
    [Start, End] = string:tokens(Range,","),
    %?debugFmt("Start, End: ~p,~p~n",[Start,End]),
    random_range(cast_to_integer(Start),cast_to_integer(End)).

random_range(Start, End) when End >= Start ->
    %?debugFmt("Input, Start, End: ~p,~p,~p~n",[Input,Start,End]),
    Range = End - Start,
    Rand = random:uniform(Range),
    Num = Rand + Start,
    lists:flatten(io_lib:format("~B",[Num])).

removetags(Input, Tags) when is_binary(Input) ->
    removetags(unicode:characters_to_list(Input), Tags);
removetags(Input, Tags) when is_binary(Tags) ->
    removetags(Input, unicode:characters_to_list(Tags));
removetags(Input, Tags) ->
    TagList = string:tokens(Tags," "),
    TagListString = string:join(TagList,"|"),
    Regex = lists:flatten(io_lib:format("</?(~s)( |\n)?>",[TagListString])),
    Result = re:replace(Input,Regex,"", [global,{return,list}]),
    Result.

%% @doc Right-aligns the value in a field of a given width.
rjust(Input, Number) when is_binary(Input) ->
    unicode:characters_to_binary(rjust(unicode:characters_to_list(Input), Number));
rjust(Input, Number) ->
    string:right(Input, Number).

%% @doc Returns a slice of the list.
slice(Input, Index) when is_binary(Input) ->
    erlydtl_slice:slice(unicode:characters_to_list(Input), Index);
slice(Input, Index) when is_list(Input) ->
    erlydtl_slice:slice(Input, Index).

%% regex  " ^([#0-\s+].)([0-9\*]+)(\.[0-9]+)([diouxXeEfFgGcrs]) " matches ALL of "-10.0f"
%% ([#0-\s+]?)([0-9\*]+)?(\.?)([0-9]?)([diouxXeEfFgGcrs])
%% @doc Returns a formatted string
stringformat(Input, Conversion) when is_binary(Input) ->
    stringformat(unicode:characters_to_list(Input), Conversion);
stringformat(Input, Conversion) when is_binary(Conversion) ->
    stringformat(Input, unicode:characters_to_list(Conversion));
stringformat(Input, Conversion) ->
    ParsedConversion = re:replace(Conversion, "([\-#\+ ]?)([0-9\*]+)?(\.?)([0-9]?)([diouxXeEfFgGcrs])", "\\1 ,\\2 ,\\3 ,\\4 ,\\5 ", [{return,list}]),
    ?debugFmt("ParsedConversion: ~p~n", [ParsedConversion]),
    ParsedConversion1 = lists:map(fun(X) -> string:strip(X) end, string:tokens(ParsedConversion, ",")),
    [ConversionFlag, MinFieldWidth, Precision, PrecisionLength, ConversionType] = ParsedConversion1,
    ?debugFmt("ConversionFlag, MinFieldWidth, Precision, PrecisionLength, ConversionType: ~p, ~p, ~p, ~p, ~p ~n", [ConversionFlag, cast_to_integer(MinFieldWidth), Precision, cast_to_integer(PrecisionLength), ConversionType]),
    [String] = stringformat_io(Input, Conversion, ConversionFlag, cast_to_integer(MinFieldWidth), Precision, cast_to_integer(PrecisionLength), ConversionType),
    lists:flatten(String).

%% @doc
%% A conversion specifier contains two or more characters and has the following components, which must occur in this order:
%% 
%%    1. The "%" character, which marks the start of the specifier.
%%    2. Mapping key (optional), consisting of a parenthesised sequence of characters (for example, (somename)).
%%    3. Conversion flags (optional), which affect the result of some conversion types.
%%    4. Minimum field width (optional). If specified as an "*" (asterisk), the actual width is read from the next element of the tuple in values, and the object to convert comes after the minimum field width and optional precision.
%%    5. Precision (optional), given as a "." (dot) followed by the precision. If specified as "*" (an asterisk), the actual width is read from the next element of the tuple in values, and the value to convert comes after the precision.
%%    6. Length modifier (optional).
%%    7. Conversion type.

stringformat_io(Input, _Conversion, _ConversionFlag, [],
    _Precision, _PrecisionLength, "s") when is_list(Input) ->
    Format = lists:flatten(io_lib:format("~~s", [])),
    io_lib:format(Format, [Input]);
stringformat_io(Input, _Conversion, ConversionFlag, MinFieldWidth,
    _Precision, _PrecisionLength, "s") when is_list(Input) ->
    %Conversion = [ConversionFlag, MinFieldWidth, Precision, PrecisionLength, ConversionType],
    InputLength = erlang:length(Input),
    case erlang:abs(MinFieldWidth) < InputLength of
        true ->
            MFW = InputLength;
        false ->
            MFW = MinFieldWidth
    end,
    Format = lists:flatten(io_lib:format("~~~s~ps", [ConversionFlag,MFW])),
    io_lib:format(Format, [Input]);
stringformat_io(Input, _Conversion, _ConversionFlag, MinFieldWidth,
    Precision, PrecisionLength, "f") when Precision == ".", MinFieldWidth == 0 ->
    Conversion1 = lists:concat(["","",Precision,PrecisionLength,"f"]),
    stringformat_io(Input, Conversion1, [], [], Precision, PrecisionLength, "f");
stringformat_io(Input, Conversion, ConversionFlag, MinFieldWidth,
    Precision, "", "f") when Precision == "." ->
    Format = re:replace(Conversion, "f", "d", [{return, list}] ),
    stringformat_io(Input, Format, ConversionFlag, MinFieldWidth,
        Precision, "", "d");
stringformat_io(Input, Conversion, _ConversionFlag, _MinFieldWidth,
    _Precision, _PrecisionLength, "f")->
    %Conversion = [ConversionFlag, MinFieldWidth, Precision, PrecisionLength, ConversionType],
    Format = "~" ++ Conversion,
    io_lib:format(Format, [cast_to_float(Input)]);
stringformat_io(Input, Conversion, _ConversionFlag, _MinFieldWidth,
    [], [], "d")->
    %?debugMsg("plain d"),
    %Conversion = [ConversionFlag, MinFieldWidth, Precision, PrecisionLength, ConversionType],
    Format = "~" ++ re:replace(Conversion, "d", "B", [{return, list}] ),
    io_lib:format(Format, [cast_to_integer(Input)]);
stringformat_io(Input, _Conversion, "-", MinFieldWidth,
    _Precision, PrecisionLength, "d") when MinFieldWidth > 0 ->
    %Format = "~" ++ re:replace(Conversion, "d", "B", [{return, list}] ),
    DecimalFormat = "~" ++ integer_to_list(PrecisionLength) ++ "..0B", 
    Decimal = lists:flatten( io_lib:format(DecimalFormat, [cast_to_integer(Input)]) ),
    SpaceFormat = "~" ++ integer_to_list(MinFieldWidth - erlang:length(Decimal)) ++ "s",
    Spaces = io_lib:format(SpaceFormat,[""]),
    ?debugFmt("Spaces: |~s|", [Spaces]),
    ?debugFmt("Decimal: ~s", [Decimal]),
    [lists:flatten(Decimal  ++ Spaces)];
stringformat_io(Input, _Conversion, _ConversionFlag, MinFieldWidth,
    _Precision, PrecisionLength, "d") when MinFieldWidth > 0 ->
    %Format = "~" ++ re:replace(Conversion, "d", "B", [{return, list}] ),
    DecimalFormat = "~" ++ integer_to_list(PrecisionLength) ++ "..0B", 
    Decimal = lists:flatten( io_lib:format(DecimalFormat, [cast_to_integer(Input)]) ),
    SpaceFormat = "~" ++ integer_to_list(MinFieldWidth - erlang:length(Decimal)) ++ "s",
    Spaces = io_lib:format(SpaceFormat,[""]),
    ?debugFmt("Spaces: |~s|", [Spaces]),
    ?debugFmt("Decimal: ~s", [Decimal]),
    [lists:flatten(Spaces ++ Decimal)];
stringformat_io(Input, _Conversion, _ConversionFlag, _MinFieldWidth,
    _Precision, PrecisionLength, "d") ->
    %Conversion = [ConversionFlag, MinFieldWidth, Precision, PrecisionLength, ConversionType],
    %Format = "~" ++ PrecisionLength ++ "..0" ++ re:replace(Conversion, "d", "B", [{return, list}] ),
    %?debugFmt("precision d, Conversion: ~p~n", [Conversion]),
    Format = lists:flatten("~" ++ io_lib:format("~B..0B",[PrecisionLength])), 
    ?debugFmt("Format: ~p~n",[Format]),
    io_lib:format(Format, [cast_to_integer(Input)]);
stringformat_io(Input, Conversion, _ConversionFlag, _MinFieldWidth,
    _Precision, _PrecisionLength, "i")->
    Format = "~" ++ re:replace(Conversion, "i", "B", [{return, list}] ),
    io_lib:format(Format, [cast_to_integer(Input)]);
stringformat_io(Input, Conversion, _ConversionFlag, _MinFieldWidth,
    _Precision, _PrecisionLength, "X")->
    Format = "~" ++ re:replace(Conversion, "X", ".16B", [{return, list}] ),
    io_lib:format(Format, [cast_to_integer(Input)]);
stringformat_io(Input, Conversion, _ConversionFlag, _MinFieldWidth,
    _Precision, _PrecisionLength, "x")->
    Format = "~" ++ re:replace(Conversion, "x", ".16b", [{return, list}] ),
    io_lib:format(Format, [cast_to_integer(Input)]);
stringformat_io(Input, Conversion, _ConversionFlag, _MinFieldWidth,
    _Precision, _PrecisionLength, "o")->
    Format = "~" ++ re:replace(Conversion, "o", ".8b", [{return, list}] ),
    io_lib:format(Format, [cast_to_integer(Input)]);
stringformat_io(Input, _Conversion, _ConversionFlag, _MinFieldWidth,
    Precision, PrecisionLength, "e") when is_integer(PrecisionLength), PrecisionLength >= 2->
    ?debugFmt("PrecisionLength ~p~n", [PrecisionLength]),
    Conversion1 = lists:concat(["","",Precision,PrecisionLength + 1,"e"]),
    Format = "~" ++ Conversion1,
    io_lib:format(Format, [cast_to_float(Input)]);
stringformat_io(Input, Conversion, ConversionFlag, MinFieldWidth,
    "", [], "e")->
    Format = "~" ++ re:replace(Conversion, "e", ".6e", [{return, list}] ),
    Raw = lists:flatten(stringformat_io(Input, Format, ConversionFlag, MinFieldWidth,
            ".", 6, "e")
    ),
    %io:format("Raw: ~p~n", [Raw]),
    Elocate = string:rstr(Raw,"e+"),
    %io:format("Elocate: ~p~n", [Elocate]),
    String = [string:substr(Raw,1,Elocate-1) ++ "e+" 
        ++ io_lib:format("~2..0B",[list_to_integer(string:substr(Raw,Elocate+2))])], %works till +99, then outputs "**"
    %io:format("String: ~p~n", [String]),
    String;
stringformat_io(Input, Conversion, ConversionFlag, MinFieldWidth,
    Precision, PrecisionLength, "E")->
    Format = re:replace(Conversion, "E", "e", [{return, list}] ),
    [Str] = stringformat_io(Input, Format, ConversionFlag, MinFieldWidth,
        Precision, PrecisionLength, "e"),
    [string:to_upper(Str)].

%% @doc Strips all [X]HTML tags.
striptags(Input) when is_binary(Input) ->
    striptags(unicode:characters_to_list(Input));
striptags(Input) ->
    Regex = "(<[^>]+>)",
    Result = re:replace(Input,Regex,"", [global,{return,list}]),
    Result.

cast_to_float([]) ->
    [];
cast_to_float(Input) when is_float(Input) ->
    Input;
cast_to_float(Input) when is_integer(Input) ->
    Input + 0.0;
cast_to_float(Input) when is_binary(Input) ->
    %% be compatible with releases prior to R16B
    case erlang:function_exported(erlang, binary_to_float, 1) of
        true ->
            try erlang:binary_to_float(Input)
            catch
                error:_Reason ->
                    erlang:binary_to_integer(Input) + 0.0
            end;
        false ->
            cast_to_float(binary_to_list(Input))
    end;
cast_to_float(Input) when is_list(Input) ->
    try list_to_float(Input)
    catch
        error:_Reason ->
            list_to_integer(Input) + 0.0
    end.

cast_to_integer([]) ->
    [];
cast_to_integer(Input) when is_integer(Input) ->
    Input;
cast_to_integer(Input) when is_float(Input) ->
    erlang:round(Input);
cast_to_integer(Input) when is_binary(Input) ->
    cast_to_integer(unicode:characters_to_list(Input));
cast_to_integer(Input) when is_list(Input)->
    case lists:member($., Input) of
        true ->
            erlang:round(erlang:list_to_float(Input));
        false ->       
            erlang:list_to_integer(Input)
    end.

cast_to_list(Input) when is_list(Input) -> Input;
cast_to_list(Input) when is_binary(Input) -> binary_to_list(Input);
cast_to_list(Input) when is_atom(Input) -> atom_to_list(Input);
cast_to_list(Input) -> hd(io_lib:format("~p", [Input])).

%% @doc Converts to lowercase, removes non-word characters (alphanumerics and underscores) and converts spaces to hyphens.
slugify(Input) when is_binary(Input) ->
    slugify(unicode:characters_to_list(Input));
slugify(Input) when is_list(Input) ->
    slugify(Input, []).

%% @doc Formats a time according to the given format.
time(Input) ->
    date(Input, "f a").

time(Input, FormatStr) ->
    date(Input, FormatStr).

timesince(Date) ->
    timesince(Date, calendar:local_time()).
%%algorithm taken from django code
timesince(Date,Comparison) ->
    Since = calendar:datetime_to_gregorian_seconds(Comparison) - calendar:datetime_to_gregorian_seconds(Date),
    timesince0(Since, [], 0).

timesince0(_, Acc, 2) ->
    string:join(lists:reverse(Acc), ", ");
timesince0(Seconds, Acc, Terms) when Seconds >= ?SECONDS_PER_YEAR ->
    Years = Seconds div ?SECONDS_PER_YEAR,
    timesince0(Seconds rem ?SECONDS_PER_YEAR,  [io_lib:format("~B ~s~s", [Years, "year", pluralize(Years)])|Acc], Terms+1);
timesince0(Seconds, Acc, Terms) when Seconds >= ?SECONDS_PER_MONTH ->
    Months = Seconds div ?SECONDS_PER_MONTH,
    timesince0(Seconds rem ?SECONDS_PER_MONTH, [io_lib:format("~B ~s~s", [Months, "month", pluralize(Months)])|Acc], Terms+1);
timesince0(Seconds, Acc, Terms) when Seconds >= ?SECONDS_PER_WEEK ->
    Weeks = Seconds div ?SECONDS_PER_WEEK,
    timesince0(Seconds rem ?SECONDS_PER_WEEK,  [io_lib:format("~B ~s~s", [Weeks, "week", pluralize(Weeks)])|Acc], Terms+1);
timesince0(Seconds, Acc, Terms) when Seconds >= ?SECONDS_PER_DAY ->
    Days = Seconds div ?SECONDS_PER_DAY,
    timesince0(Seconds rem ?SECONDS_PER_DAY,   [io_lib:format("~B ~s~s", [Days, "day", pluralize(Days)])|Acc], Terms+1);
timesince0(Seconds, Acc, Terms) when Seconds >= ?SECONDS_PER_HOUR ->
    Hours = Seconds div ?SECONDS_PER_HOUR,
    timesince0(Seconds rem ?SECONDS_PER_HOUR,  [io_lib:format("~B ~s~s", [Hours, "hour", pluralize(Hours)])|Acc], Terms+1);
timesince0(Seconds, Acc, Terms) when Seconds >= ?SECONDS_PER_MINUTE ->
    Minutes = Seconds div ?SECONDS_PER_MINUTE,
    timesince0(Seconds rem ?SECONDS_PER_MINUTE,[io_lib:format("~B ~s~s", [Minutes, "minute", pluralize(Minutes)])|Acc], Terms+1);
timesince0(Seconds, Acc, Terms) when Seconds >= 1 ->
    timesince0(0, [io_lib:format("~B ~s~s", [Seconds, "second", pluralize(Seconds)])|Acc], Terms+1);
timesince0(Seconds, [], 0) when Seconds =< 0 -> 
    timesince0(0, ["0 minutes"], 1);
timesince0(0, Acc, Terms) ->
    timesince0(0, Acc, Terms+1).

timeuntil(Date) ->
    timesince(calendar:local_time(),Date).

timeuntil(Date,Comparison) ->
    timesince(Comparison,Date).

%% @doc Converts a string into titlecase.
title(Input) when is_binary(Input) ->
    title(unicode:characters_to_list(Input));
title(Input) when is_list(Input) ->
    title(lower(Input), []).

%% @doc Truncates a string after a certain number of characters.
truncatechars(Input, Max) ->
    truncatechars_io(cast_to_list(Input), Max, []).

%% @doc Truncates a string after a certain number of words.
truncatewords(_Input, Max) when Max < 0 ->
    "";
truncatewords(Input, Max) when is_binary(Input) ->
    unicode:characters_to_binary(truncatewords(unicode:characters_to_list(Input), Max));
truncatewords(Input, Max) ->
    truncatewords_io(cast_to_list(Input), Max, []).

%% @doc Similar to truncatewords, except that it is aware of HTML tags.
truncatewords_html(_Input, Max) when Max < 0 ->
    "";
truncatewords_html(Input, Max) when is_binary(Input) ->
    unicode:characters_to_binary(truncatewords_html(unicode:characters_to_list(Input), Max));
truncatewords_html(Input, Max) ->
    truncatewords_html_io(cast_to_list(Input), Max, [], [], text).

%% @doc Recursively takes a self-nested list and returns an HTML unordered list -- WITHOUT opening and closing `<ul>' tags. 
unordered_list(List) ->
    String = lists:flatten(unordered_list(List, [])),
    string:substr(String, 5, erlang:length(String) - 9).
  
unordered_list([], Acc) ->
    ["<ul>", lists:reverse(Acc), "</ul>"];
unordered_list([First|_] = List, []) when is_integer(First) ->
    "<li>"++List;
unordered_list([First|Rest], Acc) when is_list(First), Rest == [] ->
    unordered_list(Rest, ["</li>"] ++ [unordered_list(First, []) |  Acc ])  ;
unordered_list([First|Rest], Acc) when is_list(First), is_integer(hd(hd(Rest))) ->
    unordered_list(Rest, [unordered_list(First, []) ++ "</li>" |Acc]);
unordered_list([First|Rest], Acc) when is_list(First) ->
    unordered_list(Rest, [unordered_list(First, [])|Acc]).

%% @doc Converts a string into all uppercase.
upper(Input) when is_binary(Input) ->
    unicode:characters_to_binary(upper(unicode:characters_to_list(Input)));
upper(Input) ->
    string:to_upper(Input).

%% @doc Escapes a value for use in a URL.
urlencode(Input) ->
    urlencode(Input, <<"/">>).

urlencode(Input, Safe) when is_binary(Input) ->
    urlencode_io(Input, Safe, 0);
urlencode(Input, Safe) when is_list(Input) ->
    urlencode_io(Input, Safe, []).

%% @doc Returns the number of words.
wordcount(Input) when is_binary(Input) ->
    wordcount(unicode:characters_to_list(Input));
wordcount(Input) when is_list(Input) ->
    wordcount(Input, 0).

%% @doc Wraps words at specified line length, uses `<BR/>' html tag to delimit lines
wordwrap(Input, Number) when is_binary(Input) ->
    wordwrap(unicode:characters_to_list(Input), Number);
wordwrap(Input, Number) when is_list(Input) ->
    wordwrap(Input, [], [], 0, Number).

%% @doc Given a string mapping values for true, false and (optionally) undefined, returns one of those strings according to the value.
yesno(Bool, Choices) when is_binary(Choices) ->
    yesno_io(Bool, Choices);
yesno(Bool, Choices) when is_list(Choices) ->
    yesno_io(Bool, unicode:characters_to_binary(Choices)).

% internal

addslashes([], Acc) ->
    lists:reverse(Acc);
addslashes([H|T], Acc) when H =:= $"; H =:= $' ->
addslashes(T, [H, $\\|Acc]);
addslashes([H|T], Acc) ->
    addslashes(T, [H|Acc]).

cut([], _, Acc) ->
    lists:reverse(Acc);
cut([H|T], H, Acc) ->
    cut(T, H, Acc);
cut([H|T], Char, Acc) ->
    cut(T, Char, [H|Acc]).

escape(Binary, Index) when is_binary(Binary) ->
    case Binary of
        <<Pre:Index/binary, $<, Post/binary>> ->
            process_binary_match(Pre, <<"&lt;">>, size(Post), escape(Post, 0));
        <<Pre:Index/binary, $>, Post/binary>> ->
            process_binary_match(Pre, <<"&gt;">>, size(Post), escape(Post, 0));
        <<Pre:Index/binary, $&, Post/binary>> ->
            process_binary_match(Pre, <<"&amp;">>, size(Post), escape(Post, 0));
        <<Pre:Index/binary, 34, Post/binary>> ->
            process_binary_match(Pre, <<"&quot;">>, size(Post), escape(Post, 0));
        <<Pre:Index/binary, 39, Post/binary>> ->
            process_binary_match(Pre, <<"&#039;">>, size(Post), escape(Post, 0));
        <<_:Index/binary, _, _/binary>> ->
            escape(Binary, Index + 1);
        Binary ->
            Binary
    end;
escape([], Acc) ->
    lists:reverse(Acc);
escape("<" ++ Rest, Acc) ->
    escape(Rest, lists:reverse("&lt;", Acc));
escape(">" ++ Rest, Acc) ->
    escape(Rest, lists:reverse("&gt;", Acc));
escape("&" ++ Rest, Acc) ->
    escape(Rest, lists:reverse("&amp;", Acc));
escape("\"" ++ Rest, Acc) ->
    escape(Rest, lists:reverse("&quot;", Acc));
escape("'" ++ Rest, Acc) ->
    escape(Rest, lists:reverse("&#039;", Acc));
escape([S | Rest], Acc) when is_list(S); is_binary(S)->
    escape(Rest, [force_escape(S) | Acc]);
escape([C | Rest], Acc) ->
    escape(Rest, [C | Acc]).


escapejs([], Acc) ->
    lists:reverse(Acc);
escapejs([C | Rest], Acc) when C < 32; C =:= $"; C =:= $'; C =:= $\\; C =:= $<;
C =:= $>; C =:= $&; C =:= $=; C =:= $-; C =:= $;;
C =:= 8232; C =:= 8233 -> % just following django here...
escapejs(Rest, lists:reverse(lists:flatten(io_lib:format("\\u~4.16.0B", [C])), Acc));
escapejs([C | Rest], Acc) ->
    escapejs(Rest, [C | Acc]).

filesizeformat(Bytes, UnitStr) ->
    lists:flatten(io_lib:format("~.1f ~s", [Bytes, UnitStr])).

fix_ampersands(Input, Index) when is_binary(Input) ->
    case Input of
        <<Pre:Index/binary, $&, Post/binary>> ->
            process_binary_match(Pre, <<"&amp;">>, size(Post), Post);
        <<_:Index/binary, _/binary>> ->
            fix_ampersands(Input, Index + 1);
        _ ->
            Input
    end;
fix_ampersands([], Acc) ->
    lists:reverse(Acc);
fix_ampersands("&" ++ Rest, Acc) ->
    fix_ampersands(Rest, lists:reverse("&amp;", Acc));
fix_ampersands([C | Rest], Acc) ->
    fix_ampersands(Rest, [C | Acc]).

iriencode([], Acc) ->
    lists:reverse(Acc);
iriencode([C | Rest], Acc) when ?NO_IRI_ENCODE(C) ->
    iriencode(Rest, [C | Acc]);
iriencode([$\s | Rest], Acc) ->
    iriencode(Rest, [$+ | Acc]);
iriencode([C | Rest], Acc) ->
    <<Hi:4, Lo:4>> = <<C>>,
    iriencode(Rest, [hexdigit(Lo), hexdigit(Hi), $\% | Acc]).

join_io([], _Sep) -> [];
join_io([_] = X, _Sep) -> X;
join_io([X|T], Sep) -> [X,Sep] ++ join_io(T, Sep).

linebreaksbr(Input, Index) when is_binary(Input) ->
    Break = <<"<br />">>,
    case Input of
        <<Pre:Index/binary, $\r, $\n, Post/binary>> ->
            process_binary_match(Pre, Break, size(Post), linebreaksbr(Post, 0));
        <<Pre:Index/binary, $\n, Post/binary>> ->
            process_binary_match(Pre, Break, size(Post), linebreaksbr(Post, 0));
        <<_:Index/binary, _/binary>> ->
            linebreaksbr(Input, Index + 1);
        _ ->
            Input
    end;
linebreaksbr([], Acc) ->
    lists:reverse(Acc);
linebreaksbr("\r\n" ++ Rest, Acc) ->
    linebreaksbr(Rest, lists:reverse("<br />", Acc));
linebreaksbr("\n" ++ Rest, Acc) ->
    linebreaksbr(Rest, lists:reverse("<br />", Acc));
linebreaksbr([C | Rest], Acc) ->
    linebreaksbr(Rest, [C | Acc]).

lower(Input, Index) ->
    case Input of
        <<Pre:Index/binary, Byte, Post/binary>> when Byte >= $A andalso Byte =< $Z ->
            process_binary_match(Pre, <<(Byte - $A + $a)>>, size(Post), lower(Post, 0));
        <<_:Index/binary, _/binary>> ->
            lower(Input, Index + 1);
        _ ->
            Input
    end.

phone2numeric([], Acc) ->
    lists:reverse(Acc);
phone2numeric([H|T], Acc) when H >= $a, H =< $c; H >= $A, H =< $C ->
    phone2numeric(T, [$2|Acc]);
phone2numeric([H|T], Acc) when H >= $d, H =< $f; H >= $D, H =< $F ->
    phone2numeric(T, [$3|Acc]);
phone2numeric([H|T], Acc) when H >= $g, H =< $i; H >= $G, H =< $I ->
    phone2numeric(T, [$4|Acc]);
phone2numeric([H|T], Acc) when H >= $j, H =< $l; H >= $J, H =< $L ->
    phone2numeric(T, [$5|Acc]);
phone2numeric([H|T], Acc) when H >= $m, H =< $o; H >= $M, H =< $O ->
    phone2numeric(T, [$6|Acc]);
phone2numeric([H|T], Acc) when H >= $p, H =< $s; H >= $P, H =< $S ->
    phone2numeric(T, [$7|Acc]);
phone2numeric([H|T], Acc) when H >= $t, H =< $v; H >= $T, H =< $V ->
    phone2numeric(T, [$8|Acc]);
phone2numeric([H|T], Acc) when H >= $w, H =< $z; H >= $W, H =< $Z ->
    phone2numeric(T, [$9|Acc]);
phone2numeric([H|T], Acc) ->
    phone2numeric(T, [H|Acc]).

slugify([], Acc) ->
    lists:reverse(Acc);
slugify([H|T], Acc) when H >= $A, H =< $Z ->
    slugify(T, [H-$A+$a|Acc]);
slugify([$\ |T], Acc) ->
    slugify(T, [$-|Acc]);
slugify([H|T], Acc) when H >= $a, H =< $z; H >= $0, H =< $9; H =:= $_ ->
    slugify(T, [H|Acc]);
slugify([_|T], Acc) ->
    slugify(T, Acc).

title([], Acc) ->
    lists:reverse(Acc);
title([Char | Rest], [] = Acc) when Char >= $a, Char =< $z ->
    title(Rest, [Char + ($A - $a) | Acc]);
title([Char | Rest], [Sep|[Sep2|_Other]] = Acc)
  when Char >= $a, Char =< $z,
       not (Sep >= $a andalso Sep =< $z),
       not (Sep >= $A andalso Sep =< $Z),
       not (Sep >= $0 andalso Sep =< $9),
       not (Sep =:= $' andalso (Sep2 >= $a andalso Sep2 =< $z)) ->
    title(Rest, [Char + ($A - $a) | Acc]);
title([Char | Rest], Acc) ->
    title(Rest, [Char | Acc]).

truncatechars_io([], _CharsLeft, Acc) ->
    lists:reverse(Acc);
truncatechars_io(_Input, 0, Acc) ->
    lists:reverse("..." ++ drop_chars(Acc, 3));
truncatechars_io([C|Rest], CharsLeft, Acc) when C >= 2#11111100 ->
    truncatechars_io(Rest, CharsLeft + 4, [C|Acc]);
truncatechars_io([C|Rest], CharsLeft, Acc) when C >= 2#11111000 ->
    truncatechars_io(Rest, CharsLeft + 3, [C|Acc]);
truncatechars_io([C|Rest], CharsLeft, Acc) when C >= 2#11110000 ->
    truncatechars_io(Rest, CharsLeft + 2, [C|Acc]);
truncatechars_io([C|Rest], CharsLeft, Acc) when C >= 2#11100000 ->
    truncatechars_io(Rest, CharsLeft + 1, [C|Acc]);
truncatechars_io([C|Rest], CharsLeft, Acc) when C >= 2#11000000 ->
    truncatechars_io(Rest, CharsLeft, [C|Acc]);
truncatechars_io([C|Rest], CharsLeft, Acc) ->
    truncatechars_io(Rest, CharsLeft - 1, [C|Acc]).

drop_chars([], _) -> [];
drop_chars(Cs, 0) -> Cs;
drop_chars([C|Cs], Count) when C >= 2#11111100 ->
    drop_chars(Cs, Count + 4);
drop_chars([C|Cs], Count) when C >= 2#11111000 ->
    drop_chars(Cs, Count + 3);
drop_chars([C|Cs], Count) when C >= 2#11110000 ->
    drop_chars(Cs, Count + 2);
drop_chars([C|Cs], Count) when C >= 2#11100000 ->
    drop_chars(Cs, Count + 1);
drop_chars([C|Cs], Count) when C >= 2#11000000 ->
    drop_chars(Cs, Count);
drop_chars([_|Cs], Count) ->
    drop_chars(Cs, Count - 1).


truncatewords_io([], _WordsLeft, Acc) ->
    lists:reverse(Acc);
truncatewords_io(_Input, 0, Acc) ->
    lists:reverse("... " ++ Acc);
truncatewords_io([C1, C2|Rest], WordsLeft, Acc) when C1 =/= $\s andalso C2 =:= $\s ->
    truncatewords_io([C2|Rest], WordsLeft - 1, [C1|Acc]);
truncatewords_io([C1|Rest], WordsLeft, Acc) ->
    truncatewords_io(Rest, WordsLeft, [C1|Acc]).

truncatewords_html_io([], _WordsLeft, Acc, [], _) ->
    lists:reverse(Acc);
truncatewords_html_io(_Input, 0, Acc, [], _) ->
    lists:reverse(Acc);
truncatewords_html_io(Input, 0, Acc, [Tag|RestOfTags], done) ->
    truncatewords_html_io(Input, 0, ">"++Tag++"/<" ++ Acc, RestOfTags, done);
truncatewords_html_io(Input, 0, Acc, [Tag|RestOfTags], _) ->
    truncatewords_html_io(Input, 0, "...>"++Tag++"/<" ++ Acc, RestOfTags, done);
truncatewords_html_io([], WordsLeft, Acc, [Tag|RestOfTags], _) ->
    truncatewords_html_io([], WordsLeft, ">"++Tag++"/<" ++ Acc, RestOfTags, text);
truncatewords_html_io([C|Rest], WordsLeft, Acc, Tags, text) when C =:= $< ->
    truncatewords_html_io(Rest, WordsLeft, [C|Acc], [""|Tags], tag);
truncatewords_html_io([C1, C2|Rest], WordsLeft, Acc, Tags, text) when C1 =/= $\ , C2 =:= $\ ; C1 =/= $\ , C2 =:= $< ->
    truncatewords_html_io([C2|Rest], WordsLeft - 1, [C1|Acc], Tags, text);
truncatewords_html_io([C|Rest], WordsLeft, Acc, Tags, text) ->
    truncatewords_html_io(Rest, WordsLeft, [C|Acc], Tags, text);
truncatewords_html_io([C|Rest], WordsLeft, Acc, [""|Tags], tag) when C =:= $/ ->
    truncatewords_html_io(Rest, WordsLeft, [C|Acc], Tags, close_tag);
truncatewords_html_io([C|Rest], WordsLeft, Acc, [Tag|RestOfTags], tag) when C >= $a, C =< $z; C >= $A, C =< $Z ->
    truncatewords_html_io(Rest, WordsLeft, [C|Acc], [[C|Tag]|RestOfTags], tag);
truncatewords_html_io([C|Rest], WordsLeft, Acc, Tags, tag) when C =:= $> ->
    truncatewords_html_io(Rest, WordsLeft, [C|Acc], Tags, text);
truncatewords_html_io([C|Rest], WordsLeft, Acc, Tags, tag) ->
    truncatewords_html_io(Rest, WordsLeft, [C|Acc], Tags, attrs);
truncatewords_html_io([C|Rest], WordsLeft, Acc, Tags, attrs) when C =:= $> ->
    truncatewords_html_io(Rest, WordsLeft, [C|Acc], Tags, text);
truncatewords_html_io([C|Rest], WordsLeft, Acc, [_Tag|RestOfTags], close_tag) when C =:= $> ->
    truncatewords_html_io(Rest, WordsLeft, [C|Acc], RestOfTags, text).

wordcount([], Count) ->
    Count;
wordcount([C1], Count) when C1 =/= $\  ->
    Count+1;
wordcount([C1, C2|Rest], Count) when C1 =/= $\  andalso C2 =:= $\  ->
    wordcount([C2|Rest], Count + 1);
wordcount([_|Rest], Count) ->
    wordcount(Rest, Count).

% No more input, we're done
wordwrap([], Acc, WordAcc, _LineLength, _WrapAt) ->
    lists:reverse(WordAcc ++ Acc);
% Premature newline
wordwrap([$\n | Rest], Acc, WordAcc, _LineLength, WrapAt) ->
    wordwrap(Rest, [$\n | WordAcc ++ Acc], [], 0, WrapAt);
% Hit the wrap length at a space character. Add a newline
wordwrap([$\  | Rest], Acc, WordAcc, WrapAt, WrapAt) ->
    wordwrap(Rest, [$\n | WordAcc ++ Acc], [], 0, WrapAt);
% Hit a space character before the wrap length. Keep going
wordwrap([$\  | Rest], Acc, WordAcc, LineLength, WrapAt) ->
    wordwrap(Rest, [$\  | WordAcc ++ Acc], [], LineLength + 1 + erlang:length(WordAcc), WrapAt);
% Overflowed the current line while building a word
wordwrap([C | Rest], Acc, WordAcc, 0, WrapAt) when erlang:length(WordAcc) > WrapAt ->
    wordwrap(Rest, Acc, [C | WordAcc], 0, WrapAt);
wordwrap([C | Rest], Acc, WordAcc, LineLength, WrapAt) when erlang:length(WordAcc) + LineLength > WrapAt ->
    wordwrap(Rest, [$\n | Acc], [C | WordAcc], 0, WrapAt);
% Just building a word...
wordwrap([C | Rest], Acc, WordAcc, LineLength, WrapAt) ->
    wordwrap(Rest, Acc, [C | WordAcc], LineLength, WrapAt).

urlencode_io(Input, Safe, Index) when is_binary(Input) ->
    case Input of
        <<_:Index/binary, Byte, _/binary>> when ?NO_ENCODE(Byte) ->
            urlencode_io(Input, Safe, Index + 1);
        <<Pre:Index/binary, C:1/binary, Post/binary>> ->
            process_binary_match(
              Pre, maybe_urlencode_char(C, Safe),
              size(Post), urlencode_io(Post, Safe, 0));
        Input ->
            Input
    end;
urlencode_io([], _Safe, Acc) ->
    lists:reverse(Acc);
urlencode_io([C | Rest], Safe, Acc) when ?NO_ENCODE(C) ->
    urlencode_io(Rest, Safe, [C | Acc]);
urlencode_io([C | Rest], Safe, Acc) ->
    urlencode_io(Rest, Safe, [maybe_urlencode_char(<<C>>, Safe) | Acc]).

maybe_urlencode_char(C, Safe) ->
    case binary:match(Safe, C) of
        nomatch ->
            <<Hi:4, Lo:4>> = C,
            HiDigit = hexdigit(Hi),
            LoDigit = hexdigit(Lo),
            <<$%, HiDigit, LoDigit>>;
        _ -> C
    end.

%% @doc Converts URLs in text into clickable links.
%%TODO: Autoescape not yet implemented
urlize(Input) when is_binary(Input) ->
    urlize(unicode:characters_to_list(Input),0);
urlize(Input) ->
    urlize(Input,0).

urlize(Input, Trunc) when is_binary(Input) ->
    urlize(unicode:characters_to_list(Input),Trunc);
urlize(Input, Trunc) ->
    {ok,RE} = re:compile("(([[:alpha:]]+://|www\.)[^<>[:space:]]+[[:alnum:]/])"),
    RegexResult = re:run(Input,RE,[global]),
    case RegexResult of
        {match, Matches} ->
            Indexes = lists:map(fun(Match) -> lists:nth(2,Match) end, Matches),
            Domains = lists:map(fun({Start, Length}) -> lists:sublist(Input, Start+1, Length) end, Indexes),
            URIDomains = lists:map(fun(Domain) -> addDefaultURI(Domain) end, Domains),
            case Trunc == 0 of
                true ->
                    DomainsTrunc = Domains;
                false ->
                    DomainsTrunc = lists:map(fun(Domain) -> string:concat( string:substr(Domain,1,Trunc-3), "...") end, Domains)
            end,
            ReplaceList = lists:zip(URIDomains,DomainsTrunc),
            ReplaceStrings = lists:map(fun({URIDomain,Domain}) -> lists:flatten(io_lib:format("<a href=\"~s\" rel=\"nofollow\">~s</a>",[URIDomain,Domain])) end, ReplaceList),
            Template = re:replace(Input,"(([[:alpha:]]+://|www\.)[^<>[:space:]]+[[:alnum:]/])", "~s", [global,{return,list}]),
            Result = lists:flatten(io_lib:format(Template,ReplaceStrings)),
            Result;
        nomatch ->
            Input
    end.

%% @doc Converts URLs into clickable links just like urlize, but truncates URLs longer than the given character limit.
urlizetrunc(Input, Trunc) ->
    urlize(Input, Trunc).

addDefaultURI(Domain) ->
    case string:str(Domain,"://") of
        0 ->
            Domain1 = string:concat("http://",Domain);
        _ ->
            Domain1 = Domain
    end,
    Domain1.

hexdigit(C) when C < 10 -> $0 + C;
hexdigit(C) when C < 16 -> $A + (C - 10).

process_binary_match(Pre, Insertion, SizePost, Post) ->
    case {size(Pre), SizePost} of
        {0, 0} -> Insertion;
        {0, _} -> [Insertion, Post];
        {_, 0} -> [Pre, Insertion];
        _ -> [Pre, Insertion, Post]
    end.

yesno_io(Val, Choices) ->
    {True, False, Undefined} =
        case binary:split(Choices, <<",">>, [global]) of
            [T, F, U] -> {T, F, U};
            [T, F] -> {T, F, F};
            _ -> throw({yesno, choices})
        end,
    if Val =:= false -> False;
       Val =:= undefined -> Undefined;
           is_list(Val); is_binary(Val) ->
                case iolist_size(Val) of
                    0 -> False;
                    _ -> True
                end;
       true -> True
    end.

%% unjoin == split in other languages; inverse of join
%%FROM: http://www.erlang.org/pipermail/erlang-questions/2008-October/038896.html
unjoin(String, []) ->
    unjoin0(String);
unjoin(String, [Sep]) when is_integer(Sep) ->
    unjoin1(String, Sep);
unjoin(String, [C1,C2|L]) when is_integer(C1), is_integer(C2) ->
    unjoin2(String, C1, C2, L).

%% Split a string at "", which is deemed to occur _between_
%% adjacent characters, but queerly, not at the beginning
%% or the end.

unjoin0([C|Cs]) ->
    [[C] | unjoin0(Cs)];
unjoin0([]) ->
    [].

%% Split a string at a single character separator.

unjoin1(String, Sep) ->
    unjoin1_loop(String, Sep, "").

unjoin1_loop([Sep|String], Sep, Rev) ->
    [lists:reverse(Rev) | unjoin1(String, Sep)];
unjoin1_loop([Chr|String], Sep, Rev) ->
    unjoin1_loop(String, Sep, [Chr|Rev]);
unjoin1_loop([], _, Rev) ->
    [lists:reverse(Rev)].

%% Split a string at a multi-character separator
%% [C1,C2|L].  These components are split out for
%% a fast match.

unjoin2(String, C1, C2, L) ->
    unjoin2_loop(String, C1, C2, L, "").

unjoin2_loop([C1|S = [C2|String]], C1, C2, L, Rev) ->
    case unjoin_prefix(L, String)
        of no   -> unjoin2_loop(S, C1, C2, L, [C1|Rev])
            ; Rest -> [lists:reverse(Rev) | unjoin2(Rest, C1, C2, L)]
    end;
unjoin2_loop([Chr|String], C1, C2, L, Rev) ->
    unjoin2_loop(String, C1, C2, L, [Chr|Rev]);
unjoin2_loop([], _, _, _, Rev) ->
    [lists:reverse(Rev)].

unjoin_prefix([C|L], [C|S]) -> unjoin_prefix(L, S);
unjoin_prefix([],    S)     -> S;
unjoin_prefix(_,     _)     -> no.