From bd8dfa1be5089d11e159cb664e476ddfec03b9d4 Mon Sep 17 00:00:00 2001
From: Fl_GUI <flor.guilini@hotmail.com>
Date: Thu, 9 May 2024 18:57:31 +0200
Subject: [PATCH] twitch core implementation

---
 twitch/core/auth.go                | 56 +++++++++++++++++++++++++++
 twitch/core/capabilities.go        | 40 +++++++++++++++++++
 twitch/core/commands/commands.go   | 30 +++++++++++++++
 twitch/core/connection.go          | 62 ++++++++++++++++++++++++++++++
 twitch/core/errors.go              | 24 ++++++++++++
 twitch/core/join.go                | 38 ++++++++++++++++++
 twitch/core/messages/acknak.go     | 15 ++++++++
 twitch/core/messages/auth.go       | 29 ++++++++++++++
 twitch/core/messages/capability.go | 17 ++++++++
 twitch/core/messages/join.go       | 42 ++++++++++++++++++++
 twitch/core/messages/messages.go   |  5 +++
 twitch/core/messages/notice.go     | 29 ++++++++++++++
 twitch/core/messages/ping.go       | 22 +++++++++++
 twitch/core/pingpong.go            | 18 +++++++++
 twitch/core/readerwritercloser.go  | 12 ++++++
 15 files changed, 439 insertions(+)
 create mode 100644 twitch/core/auth.go
 create mode 100644 twitch/core/capabilities.go
 create mode 100644 twitch/core/commands/commands.go
 create mode 100644 twitch/core/connection.go
 create mode 100644 twitch/core/errors.go
 create mode 100644 twitch/core/join.go
 create mode 100644 twitch/core/messages/acknak.go
 create mode 100644 twitch/core/messages/auth.go
 create mode 100644 twitch/core/messages/capability.go
 create mode 100644 twitch/core/messages/join.go
 create mode 100644 twitch/core/messages/messages.go
 create mode 100644 twitch/core/messages/notice.go
 create mode 100644 twitch/core/messages/ping.go
 create mode 100644 twitch/core/pingpong.go
 create mode 100644 twitch/core/readerwritercloser.go

diff --git a/twitch/core/auth.go b/twitch/core/auth.go
new file mode 100644
index 0000000..9f1b4ae
--- /dev/null
+++ b/twitch/core/auth.go
@@ -0,0 +1,56 @@
+package core
+
+import (
+	"errors"
+	"twitchchat/twitch/core/commands"
+	"twitchchat/twitch/core/messages"
+)
+
+// see https://dev.twitch.tv/docs/irc/authenticate-bot/#sending-the-pass-and-nick-messages.
+// The nickname should be the lowercase login name of the Twitch account used to get your access token
+func (c *Conn) Authenticate(nickname, access_token string, msgs <-chan messages.Message) (<-chan messages.Message, error) {
+	res := make(chan messages.Message)
+	authResp := make(chan messages.Message)
+
+	go func() {
+		for msg := range msgs {
+			switch msg.Command {
+			case "001":
+				fallthrough
+			case "002":
+				fallthrough
+			case "003":
+				fallthrough
+			case "004":
+				fallthrough
+			case "375":
+				fallthrough
+			case "372":
+				fallthrough
+			case "376":
+				authResp <- msg
+			case commands.Notice:
+				err := msg.ToNoticeError()
+				if errors.Is(err, messages.LoginFailedError) ||
+					errors.Is(err, messages.InvalidAuthError) {
+					authResp <- msg
+				} else {
+					res <- msg
+				}
+			default:
+				res <- msg
+			}
+		}
+	}()
+
+	c.WriteMessage(messages.Pass(access_token))
+	c.WriteMessage(messages.Nick(nickname))
+
+	for m := range authResp {
+		if messages.IsNotice(m) {
+			return res, m.ToNoticeError()
+		}
+	}
+
+	return res, nil
+}
diff --git a/twitch/core/capabilities.go b/twitch/core/capabilities.go
new file mode 100644
index 0000000..6b4dbb6
--- /dev/null
+++ b/twitch/core/capabilities.go
@@ -0,0 +1,40 @@
+package core
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+	"twitchchat/twitch/core/messages"
+)
+
+const (
+	CommandCapability    = "twitch.tv/commands"
+	MembershipCapability = "twitch.tv/membership"
+	// Unsupported by irc at the moment. Usage results in an error
+	TagsCapability = "twitch.tv/tags"
+)
+
+// See CommandCapability
+// See https://dev.twitch.tv/docs/irc/capabilities/
+func (c *Conn) WithCapability(msgs <-chan messages.Message, capabilities ...string) (<-chan messages.Message, error) {
+	caps := strings.Join(capabilities, " ")
+	if strings.Contains(caps, TagsCapability) {
+		return msgs, fmt.Errorf("TagsCapability is unavailable: %v", errors.ErrUnsupported)
+	}
+
+	c.WriteMessage(messages.Capability(caps))
+	msg := <-msgs
+
+	if messages.IsAck(msg) {
+		fmt.Fprintln(DebugLogger, "Capability request acknowledged")
+	} else if messages.IsNak(msg) {
+		badCaps := strings.Split(msg.Params.Trailing, " ")
+		return msgs, unsupportedCapabilities(badCaps)
+	} else {
+		// code error
+		fmt.Fprintf(DebugLogger, "Unexpected message after capability request: %v\n", msg)
+		return msgs, UnexpectedAnswerError
+	}
+
+	return msgs, nil
+}
diff --git a/twitch/core/commands/commands.go b/twitch/core/commands/commands.go
new file mode 100644
index 0000000..1f47e7d
--- /dev/null
+++ b/twitch/core/commands/commands.go
@@ -0,0 +1,30 @@
+package commands
+
+// see https://dev.twitch.tv/docs/irc/#supported-irc-messages
+const (
+	// supported common IRC messages
+	Join    = "JOIN"
+	Nick    = "NICK"
+	Notice  = "NOTICE"
+	Part    = "PART"
+	Pass    = "PASS"
+	Ping    = "PING"
+	Pong    = "PONG"
+	PrivMsg = "PRIVMSG"
+
+	// not documented on the main page
+	Cap = "CAP"
+	Ack = "ACK"
+	Nak = "NAK"
+
+	// twitch specific IRC messages. These are all receive only
+	ClearChat       = "CLEARCHAT"
+	ClearMsg        = "CLEARMSG"
+	GlobalUserStare = "GLOBALUSERSTATE"
+	HostTarget      = "HOSTTARGET"
+	Reconnect       = "RECONNECT"
+	RoomState       = "ROOMSTATE"
+	UserNotice      = "USERNOTICE"
+	UserState       = "USERSTATE"
+	Whisper         = "WHISPER"
+)
diff --git a/twitch/core/connection.go b/twitch/core/connection.go
new file mode 100644
index 0000000..aea4ea6
--- /dev/null
+++ b/twitch/core/connection.go
@@ -0,0 +1,62 @@
+package core
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"twitchchat/irc"
+	"twitchchat/twitch/core/messages"
+
+	"golang.org/x/net/websocket"
+)
+
+// This io.Writer is used to log incoming and outgoing messages.
+// Logs are written separated by newlines.
+// Assign a bytes.Buffer to this value, and read it using bufio.Scanner, optionally with bufio.ScanLines.
+var DebugLogger io.Writer = io.Discard
+
+// A twitch/core message is just a websocket connection. Any method is not guaranteed to be thread safe
+type Conn websocket.Conn
+
+func Dial(origin string) (*Conn, error) {
+	c, err := irc.Dial("wss://irc-ws.chat.twitch.tv:443", origin)
+	return (*Conn)(c), err
+}
+
+func DialNoSsl(origin string) (*Conn, error) {
+	c, err := irc.Dial("wss://irc-ws.chat.twitch.tv:80", origin)
+	return (*Conn)(c), err
+}
+
+func (w *Conn) WriteMessage(m messages.Message) error {
+	fmt.Fprintf(DebugLogger, "Writing %v\n", m)
+	if _, err := irc.Message(m).WriteTo(w); err != nil {
+		return err
+	}
+
+	// termination bytes
+	_, err := w.Write([]byte{'\r', '\n'})
+	return err
+}
+
+// Read all incoming messages on a connection.
+// Can only be called once per connection!
+// The channel is closed when the connection is closed
+func (w *Conn) ReadMessages() <-chan messages.Message {
+	res := make(chan messages.Message)
+	go func() {
+		scanner := bufio.NewScanner(w)
+		// no one will just put newlines in the body right?
+		scanner.Split(bufio.ScanLines)
+		for scanner.Scan() {
+			bytes := scanner.Bytes()
+			msg, err := irc.ParseBytes(bytes)
+			if err != nil {
+				fmt.Fprintf(DebugLogger, "Could not parse %#v\n", bytes)
+			}
+			res <- messages.Message(msg)
+		}
+		close(res)
+	}()
+	return res
+}
diff --git a/twitch/core/errors.go b/twitch/core/errors.go
new file mode 100644
index 0000000..0e25328
--- /dev/null
+++ b/twitch/core/errors.go
@@ -0,0 +1,24 @@
+package core
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+)
+
+type unsupportedCapabilities []string
+
+var UnexpectedAnswerError = errors.New("Unexpected result")
+var UnsupportedCapabilitiesError = errors.New("unsupported capabilities")
+
+func (u unsupportedCapabilities) Unwrap() error {
+	return UnsupportedCapabilitiesError
+}
+
+func (u unsupportedCapabilities) Error() string {
+	return fmt.Sprintf("cannot request capabilities %v: %v", strings.Join(u, ", "), UnsupportedCapabilitiesError)
+}
+
+func (u unsupportedCapabilities) Is(target error) bool {
+	return target == UnsupportedCapabilitiesError
+}
diff --git a/twitch/core/join.go b/twitch/core/join.go
new file mode 100644
index 0000000..88bd7d0
--- /dev/null
+++ b/twitch/core/join.go
@@ -0,0 +1,38 @@
+package core
+
+import "twitchchat/twitch/core/messages"
+
+type ChannelMembers map[string][]string
+
+func (w *Conn) Join(msgs <-chan messages.Message, channels ...string) (<-chan messages.Message, ChannelMembers, error) {
+
+	w.WriteMessage(messages.Join(channels...))
+
+	var channelMembers ChannelMembers
+	for _, c := range channels {
+		resp := <-msgs
+
+		if messages.IsNotice(resp) {
+			return msgs, channelMembers, resp.ToNoticeError()
+		} else if !messages.IsJoin(resp) {
+			return msgs, channelMembers, UnexpectedAnswerError
+		}
+
+		for !messages.IsEndOfJoin(resp) {
+			resp = <-msgs
+			if messages.IsMemberList(resp) {
+				members := resp.Members()
+				if _, ok := channelMembers[c]; !ok {
+					channelMembers[c] = members
+				} else {
+					// should be only the bot in the second message
+					for _, m := range members {
+						channelMembers[c] = append(channelMembers[c], m)
+					}
+				}
+			}
+		}
+	}
+
+	return msgs, channelMembers, nil
+}
diff --git a/twitch/core/messages/acknak.go b/twitch/core/messages/acknak.go
new file mode 100644
index 0000000..b30bf4b
--- /dev/null
+++ b/twitch/core/messages/acknak.go
@@ -0,0 +1,15 @@
+package messages
+
+import "twitchchat/twitch/core/commands"
+
+func IsAckNak(m Message) bool {
+	return IsAck(m) || IsNak(m)
+}
+
+func IsAck(m Message) bool {
+	return m.Command == commands.Ack
+}
+
+func IsNak(m Message) bool {
+	return m.Command == commands.Nak
+}
diff --git a/twitch/core/messages/auth.go b/twitch/core/messages/auth.go
new file mode 100644
index 0000000..ddab51c
--- /dev/null
+++ b/twitch/core/messages/auth.go
@@ -0,0 +1,29 @@
+package messages
+
+import (
+	"fmt"
+	"twitchchat/irc"
+	"twitchchat/twitch/core/commands"
+)
+
+func Pass(nickname string) Message {
+	return Message{
+		irc.Prefix{},
+		irc.Command(commands.Pass),
+		irc.Params{
+			[]string{fmt.Sprintf("oath:%s", nickname)},
+			"",
+		},
+	}
+}
+
+func Nick(nickname string) Message {
+	return Message{
+		irc.Prefix{},
+		irc.Command(commands.Nick),
+		irc.Params{
+			[]string{fmt.Sprintf("%s", nickname)},
+			"",
+		},
+	}
+}
diff --git a/twitch/core/messages/capability.go b/twitch/core/messages/capability.go
new file mode 100644
index 0000000..0a472e1
--- /dev/null
+++ b/twitch/core/messages/capability.go
@@ -0,0 +1,17 @@
+package messages
+
+import (
+	"twitchchat/irc"
+	"twitchchat/twitch/core/commands"
+)
+
+func Capability(capability string) Message {
+	return Message{
+		irc.Prefix{},
+		irc.Command(commands.Cap),
+		irc.Params{
+			[]string{},
+			capability,
+		},
+	}
+}
diff --git a/twitch/core/messages/join.go b/twitch/core/messages/join.go
new file mode 100644
index 0000000..0d5cc32
--- /dev/null
+++ b/twitch/core/messages/join.go
@@ -0,0 +1,42 @@
+package messages
+
+import (
+	"strings"
+	"twitchchat/irc"
+	"twitchchat/twitch/core/commands"
+)
+
+func Join(channels ...string) Message {
+	b := strings.Builder{}
+	for n, c := range channels {
+		if n != 0 {
+			b.WriteString(",")
+		}
+		b.WriteString("#")
+		b.WriteString(c)
+	}
+	return Message{
+		irc.Prefix{},
+		irc.Command(commands.Join),
+		irc.Params{
+			[]string{},
+			b.String(),
+		},
+	}
+}
+
+func IsJoin(m Message) bool {
+	return m.Command == commands.Join
+}
+
+func IsEndOfJoin(m Message) bool {
+	return m.Command == "366"
+}
+
+func IsMemberList(m Message) bool {
+	return m.Command == "353"
+}
+
+func (m Message) Members() []string {
+	return strings.Split(m.Params.Trailing, " ")
+}
diff --git a/twitch/core/messages/messages.go b/twitch/core/messages/messages.go
new file mode 100644
index 0000000..872f0b4
--- /dev/null
+++ b/twitch/core/messages/messages.go
@@ -0,0 +1,5 @@
+package messages
+
+import "twitchchat/irc"
+
+type Message irc.Message
diff --git a/twitch/core/messages/notice.go b/twitch/core/messages/notice.go
new file mode 100644
index 0000000..650a4e9
--- /dev/null
+++ b/twitch/core/messages/notice.go
@@ -0,0 +1,29 @@
+package messages
+
+import (
+	"errors"
+	"twitchchat/twitch/core/commands"
+)
+
+var LoginFailedError = errors.New("login authentication failed")
+var InvalidAuthError = errors.New("improperly formatted auth")
+
+func IsNotice(m Message) bool {
+	return m.Command == commands.Notice
+}
+
+func (m Message) ToNoticeError() error {
+	if !IsNotice(m) {
+		return nil
+	}
+
+	// known errors by string value
+	switch m.Params.Trailing {
+	case "Login authentication failed":
+		return LoginFailedError
+	case "Improperly formatted auth":
+		return InvalidAuthError
+	}
+
+	return errors.New(m.Params.Trailing)
+}
diff --git a/twitch/core/messages/ping.go b/twitch/core/messages/ping.go
new file mode 100644
index 0000000..220f95f
--- /dev/null
+++ b/twitch/core/messages/ping.go
@@ -0,0 +1,22 @@
+package messages
+
+import (
+	"twitchchat/irc"
+	"twitchchat/twitch/core/commands"
+)
+
+func IsPing(m Message) bool {
+	return m.Command == commands.Ping
+}
+
+func (p Message) Text() string {
+	return irc.Message(p).Params.Trailing
+}
+
+func (p Message) ToPong() Message {
+	return Message{
+		irc.Prefix{},
+		irc.Command(commands.Pong),
+		irc.Params{[]string{}, p.Text()},
+	}
+}
diff --git a/twitch/core/pingpong.go b/twitch/core/pingpong.go
new file mode 100644
index 0000000..3a4dde8
--- /dev/null
+++ b/twitch/core/pingpong.go
@@ -0,0 +1,18 @@
+package core
+
+import "twitchchat/twitch/core/messages"
+
+// Intercept received ping messages and respond to them with an appropriate pong
+func (c *Conn) PingPong(msgs <-chan messages.Message) <-chan messages.Message {
+	res := make(chan messages.Message)
+	go func() {
+		for msg := range msgs {
+			if messages.IsPing(msg) {
+				c.WriteMessage(msg.ToPong())
+			} else {
+				res <- msg
+			}
+		}
+	}()
+	return res
+}
diff --git a/twitch/core/readerwritercloser.go b/twitch/core/readerwritercloser.go
new file mode 100644
index 0000000..e6ed716
--- /dev/null
+++ b/twitch/core/readerwritercloser.go
@@ -0,0 +1,12 @@
+package core
+
+import "golang.org/x/net/websocket"
+
+// io.Writer
+func (w *Conn) Write(msg []byte) (n int, err error) { return (*websocket.Conn)(w).Write(msg) }
+
+// io.Reader
+func (w *Conn) Read(msg []byte) (n int, err error) { return (*websocket.Conn)(w).Read(msg) }
+
+// io.Closer
+func (w *Conn) Close() error { return (*websocket.Conn)(w).Close() }
-- 
2.47.1