Switch to a library and move main to an example

src/device/mod.rs

@@ -0,0 +1,42 @@
+mod elm327;
+pub use elm327::Elm327;
+
+type Result<T> = std::result::Result<T, Error>;
+
+pub trait Obd2BaseDevice: Obd2Reader {
+    fn reset(&mut self) -> Result<()>;
+    fn flush(&mut self) -> Result<()>;
+    fn send_serial_cmd(&mut self, data: &str) -> Result<()>;
+    fn cmd(&mut self, cmd: &str) -> Result<Option<String>> {
+        self.send_serial_cmd(cmd)?;
+        self.get_until_prompt()
+            .map(|o| o.and_then(|resp| String::from_utf8(resp).ok()))
+    }
+}
+
+pub trait Obd2Reader {
+    fn get_line(&mut self) -> Result<Option<Vec<u8>>>;
+    fn get_until_prompt(&mut self) -> Result<Option<Vec<u8>>>;
+}
+
+#[derive(thiserror::Error, Debug)]
+pub enum Error {
+    #[error("FTDI error: `{0:?}`")]
+    Ftdi(ftdi::Error),
+    #[error("IO error: `{0:?}`")]
+    IO(std::io::Error),
+    #[error("Communication error: `{0}`")]
+    Communication(String),
+}
+
+impl From<ftdi::Error> for Error {
+    fn from(e: ftdi::Error) -> Self {
+        Error::Ftdi(e)
+    }
+}
+
+impl From<std::io::Error> for Error {
+    fn from(e: std::io::Error) -> Self {
+        Error::IO(e)
+    }
+}