Add scripting (tengo) support for every incoming message (#731)

TengoModifyMessage allows you to specify the location of a tengo (https://github.com/d5/tengo/) script.
This script will receive every incoming message and can be used to modify the Username and the Text of that message.
The script will have the following global variables:
to modify: msgUsername and msgText
to read: msgChannel and msgAccount

The script is reloaded on every message, so you can modify the script on the fly.

Example script can be found in https://github.com/42wim/matterbridge/tree/master/gateway/bench.tengo
and https://github.com/42wim/matterbridge/tree/master/contrib/example.tengo

The example below will check if the text contains blah and if so, it'll replace the text and the username of that message.
text := import("text")
if text.re_match("blah",msgText) {
    msgText="replaced by this"
    msgUsername="fakeuser"
}

More information about tengo on: https://github.com/d5/tengo/blob/master/docs/tutorial.md and
https://github.com/d5/tengo/blob/master/docs/stdlib.md

1 files changed, 10 insertions, 0 deletions

diff --git a/gateway/gateway_test.go b/gateway/gateway_test.go
index 9621ab7d..677afde4 100644
--- a/gateway/gateway_test.go
+++ b/gateway/gateway_test.go
@@ -499,3 +499,13 @@ func TestIgnoreNicks(t *testing.T) {
 		assert.Equalf(t, testcase.output, output, "case '%s' failed", testname)
 	}
 }
+
+func BenchmarkTengo(b *testing.B) {
+	msg := &config.Message{Username: "user", Text: "blah testing", Account: "protocol.account", Channel: "mychannel"}
+	for n := 0; n < b.N; n++ {
+		err := modifyMessageTengo("bench.tengo", msg)
+		if err != nil {
+			return
+		}
+	}
+}