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|
defmodule LSG.IRC.LinkPlugin do
@moduledoc """
# Link Previewer
An extensible link previewer for IRC.
To extend the supported sites, create a new handler implementing the callbacks.
See `link_plugin/` directory for examples. The first in list handler that returns true to the `match/2` callback will be used,
and if the handler returns `:error` or crashes, will fallback to the default preview.
Unsupported websites will use the default link preview method, which is for html document the title, otherwise it'll use
the mimetype and size.
## Configuration:
```
config :lsg, LSG.IRC.LinkPlugin,
handlers: [
LSG.IRC.LinkPlugin.Youtube: [
invidious: true
],
LSG.IRC.LinkPlugin.Twitter: [],
LSG.IRC.LinkPlugin.Imgur: [],
]
```
"""
@ircdoc """
# Link preview
Previews links (just post a link!).
Announces real URL after redirections and provides extended support for YouTube, Twitter and Imgur.
"""
def short_irc_doc, do: false
def irc_doc, do: @ircdoc
require Logger
def start_link() do
GenServer.start_link(__MODULE__, [])
end
@callback match(uri :: URI.t, options :: Keyword.t) :: {true, params :: Map.t} | false
@callback expand(uri :: URI.t, params :: Map.t, options :: Keyword.t) :: {:ok, lines :: [] | String.t} | :error
defstruct [:client]
def init([]) do
{:ok, _} = Registry.register(IRC.PubSub, "message", [])
Logger.info("Link handler started")
{:ok, %__MODULE__{}}
end
def handle_info({:irc, :text, message = %{text: text}}, state) do
String.split(text)
|> Enum.map(fn(word) ->
if String.starts_with?(word, "http://") || String.starts_with?(word, "https://") do
uri = URI.parse(word)
if uri.scheme && uri.host do
spawn(fn() ->
case expand_link([uri]) do
{:ok, uris, text} ->
text = case uris do
[uri] -> text
[uri | _] -> ["-> #{URI.to_string(uri)}", text]
end
message.replyfun.(text)
_ -> nil
end
end)
end
end
end)
{:noreply, state}
end
def handle_info(msg, state) do
{:noreply, state}
end
def terminate(_reason, state) do
:ok
end
# 1. Match the first valid handler
# 2. Try to run the handler
# 3. If :error or crash, default link.
# If :skip, nothing
# 4. ?
# Over five redirections: cancel.
def expand_link([_, _, _, _, _, _ | _]) do
:error
end
def expand_link(acc=[uri | _]) do
handlers = Keyword.get(Application.get_env(:lsg, __MODULE__, [handlers: []]), :handlers)
handler = Enum.reduce_while(handlers, nil, fn({module, opts}, acc) ->
module = Module.concat([module])
case module.match(uri, opts) do
{true, params} -> {:halt, {module, params, opts}}
false -> {:cont, acc}
end
end)
run_expand(acc, handler)
end
def run_expand(acc, nil) do
expand_default(acc)
end
def run_expand(acc=[uri|_], {module, params, opts}) do
case module.expand(uri, params, opts) do
{:ok, data} -> {:ok, acc, data}
:error -> expand_default(acc)
:skip -> nil
end
rescue
e ->
Logger.error(inspect(e))
expand_default(acc)
catch
e, b ->
Logger.error(inspect({b}))
expand_default(acc)
end
defp get(url, headers \\ [], options \\ []) do
get_req(:hackney.get(url, headers, <<>>, options))
end
defp get_req({:error, reason}) do
{:error, reason}
end
defp get_req({:ok, 200, headers, client}) do
headers = Enum.reduce(headers, %{}, fn({key, value}, acc) ->
Map.put(acc, String.downcase(key), value)
end)
content_type = Map.get(headers, "content-type", "application/octect-stream")
length = Map.get(headers, "content-length", "0")
{length, _} = Integer.parse(length)
cond do
String.starts_with?(content_type, "text/html") && length <= 30_000_000 ->
get_body(30_000_000, client, <<>>)
true ->
:hackney.close(client)
{:ok, "file: #{content_type}, size: #{length} bytes"}
end
end
defp get_req({:ok, redirect, headers, client}) when redirect in 300..399 do
headers = Enum.reduce(headers, %{}, fn({key, value}, acc) ->
Map.put(acc, String.downcase(key), value)
end)
location = Map.get(headers, "location")
:hackney.close(client)
{:redirect, location}
end
defp get_req({:ok, status, headers, client}) do
:hackney.close(client)
{:error, status, headers}
end
defp get_body(len, client, acc) when len >= byte_size(acc) do
case :hackney.stream_body(client) do
{:ok, data} ->
get_body(len, client, << acc::binary, data::binary >>)
:done ->
html = Floki.parse(acc)
title = case Floki.find(html, "title") do
[{"title", [], [title]} | _] ->
String.trim(title)
_ ->
nil
end
{:ok, title}
{:error, reason} ->
{:ok, "failed to fetch body: #{inspect reason}"}
end
end
defp get_body(len, client, _acc) do
:hackney.close(client)
{:ok, "mais il rentrera jamais en ram ce fichier !"}
end
def expand_default(acc = [uri = %URI{scheme: scheme} | _]) when scheme in ["http", "https"] do
headers = []
options = [follow_redirect: false, max_body_length: 30_000_000]
case get(URI.to_string(uri), headers, options) do
{:ok, text} ->
{:ok, acc, text}
{:redirect, link} ->
new_uri = URI.parse(link)
new_uri = %URI{new_uri | scheme: scheme, authority: uri.authority, host: uri.host, port: uri.port}
expand_link([new_uri | acc])
{:error, status, _headers} ->
{:ok, acc, "Error #{status}"}
{:error, reason} ->
{:ok, acc, "Error #{to_string(reason)}"}
end
end
# Unsupported scheme, came from a redirect.
def expand_default(acc = [uri | _]) do
{:ok, [uri], "-> #{URI.to_string(uri)}"}
end
end
|
