[core] Handle host announce messages from jtv user

Signed-off-by: Knut Ahlers <knut@ahlers.me>

irc.go

@@ -3,6 +3,7 @@ package main
 import (
 	"crypto/tls"
 	"fmt"
+	"regexp"
 	"strconv"
 	"strings"
 	"sync"
@@ -18,6 +19,8 @@ import (
 var (
 	rawMessageHandlers     []plugins.RawMessageHandlerFunc
 	rawMessageHandlersLock sync.Mutex
+
+	hostNotificationRegex = regexp.MustCompile(`^(?P<actor>\w+) is now(?: auto)? hosting you(?: for(?: up to)? (?P<amount>[0-9]+) viewers)?.$`)
 )
 
 func notifyRawMessageHandlers(m *irc.Message) error {
@@ -295,6 +298,28 @@ func (i ircHandler) handleTwitchPrivmsg(m *irc.Message) {
 		configLock.RUnlock()
 	}
 
+	// Handle the jtv host message for hosts
+	if m.User == "jtv" && hostNotificationRegex.MatchString(m.Trailing()) {
+		matches := hostNotificationRegex.FindStringSubmatch(m.Trailing())
+		if matches[2] == "" {
+			matches[2] = "0"
+		}
+
+		fields := plugins.FieldCollectionFromData(map[string]interface{}{
+			"from":        matches[1],
+			"viewerCount": 0,
+		})
+
+		if v, err := strconv.Atoi(matches[2]); err == nil {
+			fields.Set("viewerCount", v)
+		}
+
+		log.WithFields(log.Fields(fields.Data())).Info("Incoming Host (jtv announce)")
+
+		go handleMessage(i.c, m, eventTypeHost, fields)
+		return
+	}
+
 	if strings.HasPrefix(m.Trailing(), "!permit") {
 		i.handlePermit(m)
 		return