1package plugins
 2
 3import (
 4	"errors"
 5	"fmt"
 6	"strings"
 7
 8	"gopkg.in/irc.v3"
 9)
10
11type Plugin interface {
12	Triggers() []string
13	Execute(m *irc.Message) (string, error)
14}
15
16var Plugins = make(map[string]Plugin)
17
18func Register(p Plugin) {
19	for _, t := range p.Triggers() {
20		Plugins[t] = p
21	}
22}
23
24// This Error is used to signal a NAK so other plugins
25// can attempt to parse the result
26// This is useful for broad prefix matching or future regexp
27// functions, other special errors may need defining
28// to determin priority or to "concatenate" output.
29var NoReply = errors.New("No Reply")
30
31// This error indicates we are sending a NOTICE instead of a PRIVMSG
32var IsNotice = errors.New("Is Notice")
33
34// This means the string(s) we are returning are raw IRC commands
35// that need to be written verbatim.
36var IsRaw = errors.New("Is Raw")
37
38// This error indicates that the message is a NOTICE, along with a
39// recepient.
40type IsPrivateNotice struct {
41	To string
42}
43
44func (e *IsPrivateNotice) Error() string {
45	return fmt.Sprintf("Is Private Notice: %s", e.To)
46}
47
48// Due to racey nature of the handler in main.go being invoked as a goroutine,
49// it's hard to have race free way of building correct state of the IRC world.
50// This is a temporary (lol) hack to check if the PRIVMSG target looks like a
51// IRC nickname. We assume that any IRC nickname target would be us, unless
52// the IRCd we are on is neurotic
53//
54// Normally one would use the ISUPPORT details to learn what prefixes are used
55// on the network's valid channel names.
56//
57// E.G. ISUPPORT ... CHANTYPES=# ... where # would be the only valid channel name
58// allowed on the IRCd.
59func unlikelyDirectMessage(target string) bool {
60	if len(target) < 1 {
61		panic("Conformity Error, IRCd sent us a PRIVMSG with an empty target and message.")
62	}
63
64	sym := target[0] // we only care about the byte (ASCII)
65	return likelyInvalidNickChr(sym)
66}
67
68func likelyInvalidNickChr(sym byte) bool {
69	// Is one of: !"#$%&'()*+,_./
70	// or one of: ;<=>?@
71	// If your IRCd uses symbols outside of this range,
72	// god help us.
73	//
74	// ALSO NOTE: RFC1459 defines a "nick" as
75	// <nick> ::= <letter> { <letter> | <number> | <special> }
76	// But I have seen some networks that allow special/number as the first letter.
77	return sym > 32 /* SPACE */ && sym < 48 /* 0 */ ||
78		sym > 58 /* : */ && sym < 65 /* A */ ||
79		sym == 126 /* ~ */
80}
81
82// Checks for triggers in a message and executes its
83// corresponding plugin, returning the response/error.
84func ProcessTrigger(m *irc.Message) (string, error) {
85	if !unlikelyDirectMessage(m.Params[0]) {
86		m.Params[0] = m.Name
87	}
88
89	for trigger, plugin := range Plugins {
90		if strings.HasPrefix(m.Trailing(), trigger) {
91			response, err := plugin.Execute(m)
92			if !errors.Is(err, NoReply) {
93				return response, err
94			}
95		}
96	}
97	return "", NoReply // No plugin matched, so we need to Ignore.
98}