[2/2] Erlang programming ex3_10

ex3_10.erl

-module(ex3_10).
-export([format_pretty/2]).

format_pretty(Text, Width) -> do_format(Text, Width, Width).

do_format([], _, _) -> ok;
do_format([H | T], Width, 0) -> display_long_word([H | T], Width, []);
do_format(Text, Width, Request) ->
    Len = length(Text),
    if
        Len < Width -> io:format("~p~n", [Text]);
    true ->
        Head = lists:sublist(Text, Request),
        Last = lists:last(Head),
        Remain = lists:sublist(Text, Request+1, Len-Request),
        Next = lists:nth(1, Remain),
        case [Last] of
            " " -> format_fixed(lists:sublist(Head, length(Head)-1), Width),
                   do_format(Remain, Width, Width);
            _ ->
                case [Next] of
                    " " -> format_fixed(Head, Width),
                           do_format(lists:sublist(Remain, 2, length(Remain)-1), Width, Width);
                    _ -> do_format(Text, Width, Request-1)
                end
        end
    end.
            
display_long_word([H | T], Width, R) when [H] /= " " -> 
    NewR = lists:append(R, [H]),
    display_long_word(T, Width, NewR);
display_long_word(List, Width, R) ->
    io:format("~p~n", [R]),
    do_format(lists:sublist(List, 2, length(List)-1), Width, Width).

format_fixed(List, Width) ->
    Len = length(List),
    Fills = Width - Len,
    if
        Fills > 0 ->
            NewList = add_blanks(List, Fills, []),
            io:format("~p~n", [NewList]);
    true ->
        io:format("~p~n", [List])
    end.

add_blanks(List, 0, Result) -> lists:append(Result, List);
add_blanks([], Fills, Result) when Fills > 0 -> add_blanks(Result, Fills, []);
add_blanks([H | T], Fills, Result) when [H] == " " ->
    R1 = lists:append(Result, [H]),
    R2 = lists:append(R1, [H]),
    add_blanks(T, Fills-1, R2);
add_blanks([H | T], Fills, Result) ->
    R1 = lists:append(Result, [H]),
    add_blanks(T, Fills, R1).