Add a generate-registration command

config/bridge.go

@@ -0,0 +1,40 @@
+package config
+
+import (
+	"bytes"
+	"text/template"
+)
+
+type bridge struct {
+	UsernameTemplate string `yaml:"username_template"`
+
+	usernameTemplate *template.Template `yaml:"-"`
+}
+
+func (b *bridge) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type rawBridge bridge
+
+	raw := rawBridge{}
+
+	err := unmarshal(&raw)
+	if err != nil {
+		return err
+	}
+
+	raw.usernameTemplate, err = template.New("username").Parse(raw.UsernameTemplate)
+	if err != nil {
+		return err
+	}
+
+	*b = bridge(raw)
+
+	return nil
+}
+
+func (b bridge) FormatUsername(userid string) string {
+	var buffer bytes.Buffer
+
+	b.usernameTemplate.Execute(&buffer, userid)
+
+	return buffer.String()
+}