create MessageInfo and MessageInfoBuilder

src/botscript.rs

@@ -1,5 +1,6 @@
 pub mod application;
 pub mod db;
+pub mod message_info;
 use std::collections::HashMap;
 use std::sync::{Arc, Mutex, PoisonError};
 use std::time::Duration;

src/botscript/message_info.rs

@@ -0,0 +1,27 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize, Default, Debug, Clone)]
+pub struct MessageInfo {
+    variant: Option<String>,
+}
+
+pub struct MessageInfoBuilder {
+    inner: MessageInfo,
+}
+
+impl MessageInfoBuilder {
+    pub fn new() -> Self {
+        Self {
+            inner: Default::default(),
+        }
+    }
+
+    pub fn set_variant(mut self, variant: Option<String>) -> Self {
+        self.inner.variant = variant;
+        self
+    }
+
+    pub fn build(self) -> MessageInfo {
+        self.inner
+    }
+}