existential types in rust are weird

… lots and lots of traits …

1 files changed, 76 insertions, 0 deletions

diff --git a/src/onboard/mod.rs b/src/onboard/mod.rs
new file mode 100644
index 0000000..56bd144
--- /dev/null
+++ b/src/onboard/mod.rs
@@ -0,0 +1,76 @@
+use crate::traits::IsStation;
+use crate::travelynx::TrainRef;
+use serde::de::DeserializeOwned;
+
+pub mod iceportal;
+pub mod zugportal;
+
+pub fn choose_api(name: &str) -> &dyn OnBoardAPI {
+  match name {
+    "iceportal" => &iceportal::Iceportal {} as &dyn OnBoardAPI,
+    "zugportal" => &zugportal::Zugportal {} as &dyn OnBoardAPI,
+    _ => panic!("no such API known")
+  }
+}
+
+pub trait OnBoardAPI {
+  fn apiurl(&self) -> &'static str;
+
+  fn request(
+    &self,
+    debug: bool
+  ) -> Result<Box<dyn OnBoardInfo>, serde_json::Error>;
+}
+
+pub fn request<Api, I>(
+  api: &Api,
+  debug: bool
+) -> Result<Box<dyn OnBoardInfo>, serde_json::Error>
+where
+  Api: OnBoardAPI,
+  I: OnBoardInfo + DeserializeOwned + 'static
+{
+  let url: &'static str = api.apiurl();
+  match get_request::<I>(url) {
+    Ok(resp) => Ok(Box::new(resp)),
+    Err((err, resp)) => {
+      if debug {
+        eprintln!("{:?}\n\nError was:{:?}", resp, err);
+      }
+      Err(err)
+    }
+  }
+}
+
+pub trait OnBoardInfo {
+  fn guess_last_station(&self) -> Option<&dyn IsStation>;
+
+  fn get_train_ref(&self) -> TrainRef;
+
+  fn stops<'a>(
+    &'a self
+  ) -> Box<dyn std::iter::Iterator<Item = &'a dyn IsStation> + 'a>;
+}
+
+fn get_request<R>(uri: &str) -> Result<R, (serde_json::Error, String)>
+where
+  R: serde::de::DeserializeOwned
+{
+  let resp: String = ureq::get(uri)
+    .call()
+    .unwrap_or_else(|err| exit_err(&err.to_string(), "get request failed"))
+    .into_string()
+    .unwrap_or_else(|err| {
+      exit_err(&err.to_string(), "get request response failed")
+    });
+
+  match serde_json::from_str::<R>(&resp) {
+    Ok(obj) => Ok(obj),
+    Err(err) => Err((err, resp))
+  }
+}
+
+fn exit_err(msg: &str, scope: &str) -> ! {
+  eprintln!("{}: {}", scope, msg);
+  std::process::exit(1)
+}