Improve error handling

Cargo.toml

@@ -6,6 +6,7 @@ license = "Apache-2.0"
 edition = "2021"
 
 [dependencies]
+anyhow = "1.0.71"
 csv = "1.2.1"
 itertools = "0.10.5"
 log = "0.4.17"

src/main.rs

@@ -1,3 +1,4 @@
+use anyhow::Context;
 use itertools::Itertools;
 use log::{error, info, LevelFilter};
 use reqwest::{
@@ -29,6 +30,13 @@ struct Config {
     listmonk_overwrite: bool,
 }
 
+#[derive(Debug)]
+struct Credentials {
+    square_api_token: String,
+    listmonk_username: String,
+    listmonk_password: String,
+}
+
 #[derive(Deserialize, Debug)]
 struct SquareCustomer {
     email_address: Option<String>,
@@ -81,8 +89,20 @@ async fn main() -> Result<(), Box<dyn Error>> {
         env!("CARGO_PKG_VERSION")
     );
 
-    let config_file = File::open("config.json")?;
-    let config: Config = serde_json::from_reader(config_file)?;
+    let config_file =
+        File::open("config.json").with_context(|| "Failed to open config.json! Does it exist?")?;
+    let config: Config = serde_json::from_reader(config_file).with_context(|| {
+        "Failed to deserialize config. Does it have syntax errors or missing fields?"
+    })?;
+
+    let creds = Credentials {
+        square_api_token: env::var("SQUARE_API_TOKEN")
+            .with_context(|| "Missing the SQUARE_API_TOKEN environment variable!")?,
+        listmonk_username: env::var("LISTMONK_USER")
+            .with_context(|| "Missing the LISTMONK_USER environment variable!")?,
+        listmonk_password: env::var("LISTMONK_PASSWORD")
+            .with_context(|| "Missing the LISTMONK_PASSWORD environment variable!")?,
+    };
 
     let forever = task::spawn(async move {
         let mut interval = time::interval(Duration::from_secs(config.run_every));
@@ -91,7 +111,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
         loop {
             interval.tick().await;
             info!("Syncing...");
-            if let Err(err) = run(&config).await {
+            if let Err(err) = run(&config, &creds).await {
                 error!("Failed to sync! {:?}", err);
             } else {
                 info!("Sync complete.")
@@ -102,8 +122,8 @@ async fn main() -> Result<(), Box<dyn Error>> {
     Ok(forever.await?)
 }
 
-async fn run(config: &Config) -> Result<(), Box<dyn Error>> {
-    let subscribers: Vec<ListmonkSubscriber> = get_square_customers()
+async fn run(config: &Config, creds: &Credentials) -> Result<(), Box<dyn Error>> {
+    let subscribers: Vec<ListmonkSubscriber> = get_square_customers(creds)
         .await?
         .into_iter()
         .filter(|c| c.email_address.is_some())
@@ -150,13 +170,13 @@ async fn run(config: &Config) -> Result<(), Box<dyn Error>> {
         let csv = generate_import_csv(&subs)?;
 
         info!("Uploading {} listmonk subscribers ({})", subs.len(), mode.0);
-        upload_subscribers(import, csv, &config.listmonk_domain).await?;
+        upload_subscribers(import, csv, &config.listmonk_domain, creds).await?;
     }
 
     Ok(())
 }
 
-async fn get_square_customers() -> Result<Vec<SquareCustomer>, Box<dyn Error>> {
+async fn get_square_customers(creds: &Credentials) -> Result<Vec<SquareCustomer>, Box<dyn Error>> {
     let mut cursor = String::new();
     let mut customers = vec![];
     let mut idx: u32 = 0;
@@ -167,7 +187,7 @@ async fn get_square_customers() -> Result<Vec<SquareCustomer>, Box<dyn Error>> {
             .get("https://connect.squareup.com/v2/customers")
             .header("Square-Version", SQUARE_VERSION)
             .query(&[("cursor", cursor)])
-            .bearer_auth(env::var("SQUARE_API_TOKEN")?)
+            .bearer_auth(&creds.square_api_token)
             .send()
             .await?
             .json::<SquareCustomersResponse>()
@@ -202,6 +222,7 @@ async fn upload_subscribers(
     import: ListmonkImport,
     csv: String,
     domain: &str,
+    creds: &Credentials,
 ) -> Result<Response, Box<dyn Error>> {
     let form = Form::new()
         .text("params", serde_json::to_string(&import)?)
@@ -214,10 +235,9 @@ async fn upload_subscribers(
     Ok(Client::new()
         .post(format!("https://{domain}/api/import/subscribers"))
         .multipart(form)
-        .basic_auth(
-            env::var("LISTMONK_USER")?,
-            Some(env::var("LISTMONK_PASSWORD")?),
-        )
+        .basic_auth(&creds.listmonk_username, Some(&creds.listmonk_password))
         .send()
-        .await?)
+        .await?
+        .error_for_status()
+        .with_context(|| "Failed to upload subscribers to listmonk")?)
 }