create version module

src/main.rs

@@ -6,6 +6,7 @@ mod config;
 mod database;
 mod event;
 mod ui;
+mod version;
 
 #[macro_use]
 mod log;

src/version.rs

@@ -0,0 +1,50 @@
+use std::{env, fmt};
+
+#[derive(Default)]
+pub struct Version {
+    major: u32,
+    minor: u32,
+    patch: u32,
+    pre: Option<String>,
+}
+
+impl Version {
+    /// read version at compile time from env variables
+    pub fn new() -> Self {
+        let mut res = Self::default();
+        let major_str = env!("CARGO_PKG_VERSION_MAJOR");
+        if let Ok(major) = major_str.parse::<u32>() {
+            res.major = major;
+        }
+        let minor_str = env!("CARGO_PKG_VERSION_MINOR");
+        if let Ok(minor) = minor_str.parse::<u32>() {
+            res.minor = minor;
+        }
+        let patch_str = env!("CARGO_PKG_VERSION_PATCH");
+        if let Ok(patch) = patch_str.parse::<u32>() {
+            res.patch = patch;
+        }
+        let pre_str = env!("CARGO_PKG_VERSION_PRE");
+        res.pre = if pre_str.is_empty() {
+            None
+        } else {
+            Some(pre_str.to_string())
+        };
+        res
+    }
+}
+
+impl fmt::Display for Version {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "v{}.{}.{}{}",
+            self.major,
+            self.minor,
+            self.patch,
+            self.pre
+                .as_ref()
+                .map_or(String::new(), |pre| format!("-{}", pre.to_string()))
+        )
+    }
+}