From 353eb865db02540ed06ab49205132780566d9b9f Mon Sep 17 00:00:00 2001
From: Joey Hines <joey@ahines.net>
Date: Fri, 23 May 2025 17:32:13 -0600
Subject: [PATCH] Handle errors from the API more gracefully

---
 Cargo.lock           |  2 +-
 Cargo.toml           |  2 +-
 src/lib.rs           |  8 ++++++--
 src/models/eta.rs    |  9 ++++++++-
 src/models/follow.rs | 12 ++++++++++--
 src/models/mod.rs    | 18 ++++++++++++++++--
 src/models/route.rs  |  9 ++++++++-
 7 files changed, 50 insertions(+), 10 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 1f637bb..faad84a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -101,7 +101,7 @@ checksum = "773648b94d0e5d620f64f280777445740e61fe701025087ec8b57f45c791888b"
 
 [[package]]
 name = "cta-api"
-version = "0.2.0"
+version = "0.3.0"
 dependencies = [
  "reqwest",
  "serde",
diff --git a/Cargo.toml b/Cargo.toml
index 2e7249d..bd6702e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "cta-api"
-version = "0.2.0"
+version = "0.3.0"
 edition = "2024"
 description = "CTA API Client"
 authors = ["Joey Hines joey@ahines.net"]
diff --git a/src/lib.rs b/src/lib.rs
index 0618fcf..7ad8285 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,7 @@
-use crate::models::Response;
 use crate::models::eta::{EtaRequest, EtaResp};
 use crate::models::follow::{FollowRequest, FollowResp};
 use crate::models::route::{RouteRequest, RouteResp};
+use crate::models::{CTAResponse, Response};
 use reqwest::{Client, Url};
 use serde::{Deserialize, Serialize};
 use thiserror::Error;
@@ -18,6 +18,8 @@ pub enum Error {
     ReqwestFailure(#[from] reqwest::Error),
     #[error("URL parse failure: {0}")]
     UrlParseError(#[from] url::ParseError),
+    #[error("Got error number '{0}': {1}")]
+    CtaError(String, String),
 }
 
 pub struct CTAClient {
@@ -35,7 +37,7 @@ impl CTAClient {
         }
     }
 
-    pub async fn make_request<T: Serialize, V: for<'a> Deserialize<'a>>(
+    pub async fn make_request<T: Serialize, V: for<'a> Deserialize<'a> + CTAResponse>(
         &mut self,
         endpoint: &str,
         req: T,
@@ -53,6 +55,8 @@ impl CTAClient {
             .json()
             .await?;
 
+        resp.ctatt.check_error()?;
+
         Ok(resp.ctatt)
     }
 
diff --git a/src/models/eta.rs b/src/models/eta.rs
index b2d45a6..13e2abc 100644
--- a/src/models/eta.rs
+++ b/src/models/eta.rs
@@ -1,4 +1,4 @@
-use crate::models::Ctatt;
+use crate::models::{CTAResponse, Ctatt};
 use serde::{Deserialize, Serialize};
 
 #[derive(Serialize, Debug)]
@@ -13,9 +13,16 @@ pub struct EtaRequest {
 pub struct EtaResp {
     #[serde(flatten)]
     pub header: Ctatt,
+    #[serde(default)]
     pub eta: Vec<Eta>,
 }
 
+impl CTAResponse for EtaResp {
+    fn get_header(&self) -> Ctatt {
+        self.header.clone()
+    }
+}
+
 #[derive(Deserialize, Debug)]
 pub struct Eta {
     #[serde(rename = "staId")]
diff --git a/src/models/follow.rs b/src/models/follow.rs
index 6ccb696..beb2e99 100644
--- a/src/models/follow.rs
+++ b/src/models/follow.rs
@@ -1,4 +1,4 @@
-use crate::models::Ctatt;
+use crate::models::{CTAResponse, Ctatt};
 use serde::{Deserialize, Serialize};
 
 #[derive(Serialize, Debug)]
@@ -7,7 +7,7 @@ pub struct FollowRequest {
     pub run_number: u32,
 }
 
-#[derive(Deserialize, Debug)]
+#[derive(Deserialize, Debug, Default)]
 pub struct Position {
     pub lat: String,
     pub lon: String,
@@ -48,6 +48,14 @@ pub struct ScheduledStop {
 pub struct FollowResp {
     #[serde(flatten)]
     pub header: Ctatt,
+    #[serde(default)]
     pub position: Position,
+    #[serde(default)]
     pub eta: Vec<ScheduledStop>,
 }
+
+impl CTAResponse for FollowResp {
+    fn get_header(&self) -> Ctatt {
+        self.header.clone()
+    }
+}
diff --git a/src/models/mod.rs b/src/models/mod.rs
index ebf10b2..e8e81a1 100644
--- a/src/models/mod.rs
+++ b/src/models/mod.rs
@@ -3,9 +3,10 @@ pub mod follow;
 pub mod route;
 pub mod train;
 
+use crate::Error;
 use serde::Deserialize;
 
-#[derive(Debug, Deserialize)]
+#[derive(Debug, Deserialize, Clone)]
 pub struct Ctatt {
     pub tmst: String,
     #[serde(rename = "errCd")]
@@ -14,7 +15,20 @@ pub struct Ctatt {
     pub err_nm: Option<String>,
 }
 
+pub trait CTAResponse {
+    fn get_header(&self) -> Ctatt;
+    fn check_error(&self) -> Result<(), Error> {
+        let header = self.get_header();
+
+        if let Some(err_number) = header.err_nm {
+            Err(Error::CtaError(err_number, header.err_cd))
+        } else {
+            Ok(())
+        }
+    }
+}
+
 #[derive(Debug, Deserialize)]
-pub struct Response<T> {
+pub struct Response<T: CTAResponse> {
     pub ctatt: T,
 }
diff --git a/src/models/route.rs b/src/models/route.rs
index 3faa38e..c401ceb 100644
--- a/src/models/route.rs
+++ b/src/models/route.rs
@@ -1,5 +1,5 @@
-use crate::models::Ctatt;
 use crate::models::train::Train;
+use crate::models::{CTAResponse, Ctatt};
 use serde::{Deserialize, Serialize};
 
 #[derive(Serialize, Debug)]
@@ -18,5 +18,12 @@ pub struct Route {
 pub struct RouteResp {
     #[serde(flatten)]
     pub header: Ctatt,
+    #[serde(default)]
     pub route: Vec<Route>,
 }
+
+impl CTAResponse for RouteResp {
+    fn get_header(&self) -> Ctatt {
+        self.header.clone()
+    }
+}