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%% Feel free to use, reuse and abuse the code in this file.
%% @doc Pastebin handler.
-module(toppage_handler).
%% REST Callbacks
-export([init/3]).
-export([allowed_methods/2]).
-export([content_types_provided/2]).
-export([content_types_accepted/2]).
-export([resource_exists/2]).
-export([post_is_create/2]).
-export([create_path/2]).
%% Callback Callbacks
-export([create_paste/2]).
-export([paste_html/2]).
-export([paste_text/2]).
init(_Transport, _Req, []) ->
% For the random number generator:
{X, Y, Z} = now(),
random:seed(X, Y, Z),
{upgrade, protocol, cowboy_rest}.
allowed_methods(Req, State) ->
{[<<"GET">>, <<"POST">>], Req, State}.
content_types_provided(Req, State) ->
{[
{{<<"text">>, <<"plain">>, []}, paste_text},
{{<<"text">>, <<"html">>, []}, paste_html}
], Req, State}.
content_types_accepted(Req, State) ->
{[{{<<"application">>, <<"x-www-form-urlencoded">>, []}, create_paste}],
Req, State}.
resource_exists(Req, _State) ->
case cowboy_req:binding(paste_id, Req) of
{undefined, Req2} ->
{true, Req2, index};
{PasteID, Req2} ->
case valid_path(PasteID) and file_exists(PasteID) of
true -> {true, Req2, PasteID};
false -> {false, Req2, PasteID}
end
end.
post_is_create(Req, State) ->
{true, Req, State}.
create_path(Req, State) ->
{<<$/, (new_paste_id())/binary>>, Req, State}.
create_paste(Req, State) ->
{<<$/, PasteID/binary>>, Req2} = cowboy_req:meta(put_path, Req),
{ok, [{<<"paste">>, Paste}], Req3} = cowboy_req:body_qs(Req2),
ok = file:write_file(full_path(PasteID), Paste),
{true, Req3, State}.
paste_html(Req, index) ->
{read_file("index.html"), Req, index};
paste_html(Req, Paste) ->
{Style, Req2} = cowboy_req:qs_val(<<"lang">>, Req, plain),
{format_html(Paste, Style), Req2, Paste}.
paste_text(Req, index) ->
{read_file("index.txt"), Req, index};
paste_text(Req, Paste) ->
{Style, Req2} = cowboy_req:qs_val(<<"lang">>, Req, plain),
{format_text(Paste, Style), Req2, Paste}.
% Private
read_file(Name) ->
{ok, Binary} = file:read_file(full_path(Name)),
Binary.
full_path(Name) ->
{ok, Cwd} = file:get_cwd(),
filename:join([Cwd, "priv", Name]).
file_exists(Name) ->
case file:read_file_info(full_path(Name)) of
{ok, _Info} -> true;
{error, _Reason} -> false
end.
valid_path(<<>>) -> true;
valid_path(<<$., _T/binary>>) -> false;
valid_path(<<_Char, T/binary>>) -> valid_path(T).
new_paste_id() ->
Initial = random:uniform(62) - 1,
new_paste_id(<<Initial>>, 7).
new_paste_id(Bin, 0) ->
Chars = <<"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890">>,
<< <<(binary_part(Chars, B, 1))/binary>> || <<B>> <= Bin >>;
new_paste_id(Bin, Rem) ->
Next = random:uniform(62) - 1,
new_paste_id(<<Bin/binary, Next>>, Rem - 1).
format_html(Paste, plain) ->
Text = escape_html_chars(read_file(Paste)),
<<"<!DOCTYPE html><html>",
"<head><title>paste</title></head>",
"<body><pre><code>", Text/binary, "</code></pre></body></html>\n">>;
format_html(Paste, Lang) ->
highlight(full_path(Paste), Lang, "html").
format_text(Paste, plain) ->
read_file(Paste);
format_text(Paste, Lang) ->
highlight(full_path(Paste), Lang, "ansi").
highlight(Path, Lang, Type) ->
Path1 = binary_to_list(Path),
Lang1 = binary_to_list(Lang),
os:cmd(["highlight --syntax=", Lang1,
" --doc-title=paste ",
" --out-format=", Type,
" --include-style ", Path1]).
% Escape some HTML characters that might make a fuss
escape_html_chars(Bin) ->
<< <<(escape_html_char(B))/binary>> || <<B>> <= Bin >>.
escape_html_char($<) -> <<"<">>;
escape_html_char($>) -> <<">">>;
escape_html_char($&) -> <<"&">>;
escape_html_char(C) -> <<C>>.
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