Refactor and simplify the templates hot-reload logic

crates/cli/src/util.rs

@@ -28,7 +28,7 @@ use sqlx::{
     postgres::{PgConnectOptions, PgPoolOptions},
     ConnectOptions, PgPool,
 };
-use tracing::log::LevelFilter;
+use tracing::{error, info, log::LevelFilter};
 
 pub async fn password_manager_from_config(
     config: &PasswordsConfig,
@@ -168,3 +168,61 @@ pub async fn database_from_config(config: &DatabaseConfig) -> Result<PgPool, any
         .await
         .context("could not connect to the database")
 }
+
+/// Watch for changes in the templates folders
+pub async fn watch_templates(templates: &Templates) -> anyhow::Result<()> {
+    use watchman_client::{prelude::*, SubscriptionData};
+
+    let client = Connector::new()
+        .connect()
+        .await
+        .context("could not connect to watchman")?;
+
+    let templates = templates.clone();
+
+    // Find which root we're supposed to watch
+    let root = templates.watch_root();
+
+    // Create a subscription on the root
+    let resolved = client
+        .resolve_root(CanonicalPath::canonicalize(root)?)
+        .await?;
+
+    // Only look for *.txt, *.html and *.subject files
+    let request = SubscribeRequest {
+        expression: Some(Expr::Suffix(vec![
+            "txt".into(),
+            "html".into(),
+            "subject".into(),
+        ])),
+        ..SubscribeRequest::default()
+    };
+
+    let (mut subscription, _) = client.subscribe::<NameOnly>(&resolved, request).await?;
+
+    tokio::spawn(async move {
+        loop {
+            let event = match subscription.next().await {
+                Ok(event) => event,
+                Err(error) => {
+                    error!(%error, "Stopped watching templates because of an error in the watchman subscription");
+                    break;
+                }
+            };
+
+            if let SubscriptionData::FilesChanged(QueryResult {
+                files: Some(files), ..
+            }) = event
+            {
+                let files: Vec<_> = files.into_iter().map(|f| f.name.into_inner()).collect();
+                info!(?files, "Files changed, reloading templates");
+
+                templates.clone().reload().await.unwrap_or_else(|err| {
+                    error!(?err, "Error while reloading templates");
+                });
+            }
+        }
+    });
+
+    Ok(())
+}