sheldon

%%% @doc HTML Adapter. *Note* This is not the final version of html_adapter, currently it only
%%% escapes tags and replace some special html characters.
%%%
%%% Copyright Erlang Solutions Ltd. 2017 <hello@inaka.net>
%%%
%%% Licensed under the Apache License, Version 2.0 (the "License");
%%% you may not use this file except in compliance with the License.
%%% You may obtain a copy of the License at
%%%
%%%     http://www.apache.org/licenses/LICENSE-2.0
%%%
%%% Unless required by applicable law or agreed to in writing, software
%%% distributed under the License is distributed on an "AS IS" BASIS,
%%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%%% See the License for the specific language governing permissions and
%%% limitations under the License.
%%% @end
%%% @copyright Erlang Solutions Ltd. <hello@inaka.net>
%%%
-module(html_adapter).
-author("Felipe Ripoll <felipe@inakanetworks.com>").

-behaviour(sheldon_adapter).

%% API
-export([adapt/1]).

%%%===================================================================
%%% API
%%%===================================================================

-spec adapt(binary()) -> iodata().
adapt(Line) ->
  Line1 = escape_tags(Line),
  replace_chars(Line1).

%%%===================================================================
%%% Internal Functions
%%%===================================================================

-spec replace_chars(binary()) -> iodata().
replace_chars(Line) ->
  Chars = chars_to_replace(),
  replace_chars(Line, Chars).

-spec replace_chars(iodata(), [{string(), string()}]) -> iodata().
replace_chars(Line, []) ->
  Line;
replace_chars(Line, [{Pattern, ReplaceBy} | Rest]) ->
  Result = re:replace(Line, Pattern, ReplaceBy, [global]),
  replace_chars(Result, Rest).

-spec escape_tags(iodata()) -> iodata().
escape_tags(Line) ->
  Pattern = "<[^>]*>",
  ReplaceBy = "",
  re:replace(Line, Pattern, ReplaceBy, [global]).

-spec chars_to_replace() -> [{string(), string()}].
chars_to_replace() ->
  [ {"&quot;", "\""}
  , {"&amp;", "\\&"}
  , {"&lt;", "<"}
  , {"&gt;", ">"}
  , {"&#39;", "'"}
  , {"&#[0-9]*;", ""}
  ].