From 376d9c1896d6e23970071a6e9da01f9f0842c0d0 Mon Sep 17 00:00:00 2001
From: Harald Eilertsen <haraldei@anduin.net>
Date: Sun, 24 Feb 2019 10:48:36 +0100
Subject: Let errors propagate out of main too.

Makes error messages from the program slightly nicer, but still a
bit cryptic for the casual user.
---
 src/error.rs | 20 ++++++++++++++++++++
 src/main.rs  | 17 +++++++++++------
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/src/error.rs b/src/error.rs
index ed17362..b0ab95d 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -27,6 +27,26 @@ pub enum Error {
     JsonError(serde_json::error::Error),
 }
 
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        match self {
+            Error::InvalidHeaderValue(e) => e.fmt(f),
+            Error::ReqwestError(e) => e.fmt(f),
+            Error::JsonError(e) => e.fmt(f),
+        }
+    }
+}
+
+impl std::error::Error for Error {
+    fn cause(&self) -> Option<&std::error::Error> {
+        match self {
+            Error::InvalidHeaderValue(e) => Some(e),
+            Error::ReqwestError(e) => Some(e),
+            Error::JsonError(e) => Some(e),
+        }
+    }
+}
+
 impl From<reqwest::header::InvalidHeaderValue> for Error {
     fn from(err: reqwest::header::InvalidHeaderValue) -> Error {
         Error::InvalidHeaderValue(err)
diff --git a/src/main.rs b/src/main.rs
index 014e8b2..5e18bac 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -18,14 +18,17 @@
 
 use dotenv;
 use oslobike;
+use std::error::Error;
+use std::result::Result;
 
-fn main() {
-    let api_key = dotenv::var("OSLOBIKE_APIKEY").expect("No API key defined!");
-    let api = oslobike::Api::new(api_key).unwrap();
-    let stations = api.stations().unwrap();
-    let station_availability = api.station_availability().unwrap();
+fn main() -> Result<(), Box<dyn Error>> {
+    let api_key = dotenv::var("OSLOBIKE_APIKEY")
+        .map_err(|_| "No API key defined.")?;
 
-    for station in api.stations().unwrap() {
+    let api = oslobike::Api::new(api_key)?;
+    let station_availability = api.station_availability()?;
+
+    for station in api.stations()? {
         let a = station_availability.iter().find(|s| s.id == station.id).unwrap();
         println!("{:>4} {:<32}: {:>2} bikes, {:>2} locks of {:>2} total",
             station.id,
@@ -34,4 +37,6 @@ fn main() {
             a.availability.locks,
             station.number_of_locks);
     }
+
+    Ok(())
 }
-- 
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