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, 149 insertions, 0 deletions

diff --git a/vendor/github.com/d5/tengo/script/variable.go b/vendor/github.com/d5/tengo/script/variable.go
new file mode 100644
index 00000000..c5e01bd9
--- /dev/null
+++ b/vendor/github.com/d5/tengo/script/variable.go
@@ -0,0 +1,149 @@
+package script
+
+import (
+	"errors"
+
+	"github.com/d5/tengo/objects"
+)
+
+// Variable is a user-defined variable for the script.
+type Variable struct {
+	name  string
+	value *objects.Object
+}
+
+// NewVariable creates a Variable.
+func NewVariable(name string, value interface{}) (*Variable, error) {
+	obj, err := objects.FromInterface(value)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Variable{
+		name:  name,
+		value: &obj,
+	}, nil
+}
+
+// Name returns the name of the variable.
+func (v *Variable) Name() string {
+	return v.name
+}
+
+// Value returns an empty interface of the variable value.
+func (v *Variable) Value() interface{} {
+	return objectToInterface(*v.value)
+}
+
+// ValueType returns the name of the value type.
+func (v *Variable) ValueType() string {
+	return (*v.value).TypeName()
+}
+
+// Int returns int value of the variable value.
+// It returns 0 if the value is not convertible to int.
+func (v *Variable) Int() int {
+	c, _ := objects.ToInt(*v.value)
+
+	return c
+}
+
+// Int64 returns int64 value of the variable value.
+// It returns 0 if the value is not convertible to int64.
+func (v *Variable) Int64() int64 {
+	c, _ := objects.ToInt64(*v.value)
+
+	return c
+}
+
+// Float returns float64 value of the variable value.
+// It returns 0.0 if the value is not convertible to float64.
+func (v *Variable) Float() float64 {
+	c, _ := objects.ToFloat64(*v.value)
+
+	return c
+}
+
+// Char returns rune value of the variable value.
+// It returns 0 if the value is not convertible to rune.
+func (v *Variable) Char() rune {
+	c, _ := objects.ToRune(*v.value)
+
+	return c
+}
+
+// Bool returns bool value of the variable value.
+// It returns 0 if the value is not convertible to bool.
+func (v *Variable) Bool() bool {
+	c, _ := objects.ToBool(*v.value)
+
+	return c
+}
+
+// Array returns []interface value of the variable value.
+// It returns 0 if the value is not convertible to []interface.
+func (v *Variable) Array() []interface{} {
+	switch val := (*v.value).(type) {
+	case *objects.Array:
+		var arr []interface{}
+		for _, e := range val.Value {
+			arr = append(arr, objectToInterface(e))
+		}
+		return arr
+	}
+
+	return nil
+}
+
+// Map returns map[string]interface{} value of the variable value.
+// It returns 0 if the value is not convertible to map[string]interface{}.
+func (v *Variable) Map() map[string]interface{} {
+	switch val := (*v.value).(type) {
+	case *objects.Map:
+		kv := make(map[string]interface{})
+		for mk, mv := range val.Value {
+			kv[mk] = objectToInterface(mv)
+		}
+		return kv
+	}
+
+	return nil
+}
+
+// String returns string value of the variable value.
+// It returns 0 if the value is not convertible to string.
+func (v *Variable) String() string {
+	c, _ := objects.ToString(*v.value)
+
+	return c
+}
+
+// Bytes returns a byte slice of the variable value.
+// It returns nil if the value is not convertible to byte slice.
+func (v *Variable) Bytes() []byte {
+	c, _ := objects.ToByteSlice(*v.value)
+
+	return c
+}
+
+// Error returns an error if the underlying value is error object.
+// If not, this returns nil.
+func (v *Variable) Error() error {
+	err, ok := (*v.value).(*objects.Error)
+	if ok {
+		return errors.New(err.String())
+	}
+
+	return nil
+}
+
+// Object returns an underlying Object of the variable value.
+// Note that returned Object is a copy of an actual Object used in the script.
+func (v *Variable) Object() objects.Object {
+	return *v.value
+}
+
+// IsUndefined returns true if the underlying value is undefined.
+func (v *Variable) IsUndefined() bool {
+	return *v.value == objects.UndefinedValue
+}