1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
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
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 HTTPoison.get(URI.to_string(uri), headers, options) do
{:ok, %HTTPoison.Response{status_code: 200, headers: headers, body: body}} ->
headers = Enum.reduce(headers, %{}, fn({key, value}, acc) ->
Map.put(acc, String.downcase(key), value)
end)
text = case Map.get(headers, "content-type") do
"text/html"<>_ ->
html = Floki.parse(body)
case Floki.find(html, "title") do
[{"title", [], [title]} | _] ->
title
_ ->
nil
end
other ->
"file: #{other}, size: #{Map.get(headers, "content-length", "?")} bytes"
end
{:ok, acc, text}
{:ok, resp = %HTTPoison.Response{headers: headers, status_code: redirect, body: body}} when redirect in 300..399 ->
headers = Enum.reduce(headers, %{}, fn({key, value}, acc) ->
Map.put(acc, String.downcase(key), value)
end)
link = Map.get(headers, "location")
new_uri = URI.parse(link)
expand_link([new_uri | acc])
{:ok, %HTTPoison.Response{status_code: code}} ->
{:ok, acc, "Error #{code}"}
{:error, %HTTPoison.Error{reason: reason}} ->
{:ok, acc, "Error #{to_string(reason)}"}
{:error, error} ->
{:ok, acc, "Error #{inspect(error)}"}
end
end
# Unsupported scheme, came from a redirect.
def expand_default(acc = [uri | _]) do
{:ok, [uri], "-> #{URI.to_string(uri)}"}
end
end
|
