background worker

crates/application/src/event_handlers.rs

@@ -0,0 +1,62 @@
+use std::time::Duration;
+
+use async_trait::async_trait;
+use domain::ports::EventHandler;
+use domain::{errors::DomainError, events::DomainEvent};
+
+use crate::{commands::SyncPosterCommand, context::AppContext, use_cases::sync_poster};
+
+pub struct PosterSyncHandler {
+    ctx: AppContext,
+    max_retries: u32,
+}
+
+impl PosterSyncHandler {
+    pub fn new(ctx: AppContext, max_retries: u32) -> Self {
+        Self { ctx, max_retries }
+    }
+}
+
+#[async_trait]
+impl EventHandler for PosterSyncHandler {
+    async fn handle(&self, event: &DomainEvent) -> Result<(), DomainError> {
+        let (movie_id, external_metadata_id) = match event {
+            DomainEvent::MovieDiscovered {
+                movie_id,
+                external_metadata_id,
+            } => (movie_id.value(), external_metadata_id.value().to_owned()),
+            _ => return Ok(()),
+        };
+
+        let mut last_err: Option<DomainError> = None;
+        for attempt in 0..=self.max_retries {
+            let cmd = SyncPosterCommand {
+                movie_id,
+                external_metadata_id: external_metadata_id.clone(),
+            };
+            match sync_poster::execute(&self.ctx, cmd).await {
+                Ok(()) => return Ok(()),
+                Err(e) => {
+                    if attempt < self.max_retries {
+                        let delay = Duration::from_secs(2u64.pow(attempt));
+                        tracing::warn!(
+                            attempt = attempt + 1,
+                            max_attempts = self.max_retries + 1,
+                            delay_secs = delay.as_secs(),
+                            "poster sync failed, retrying: {e}"
+                        );
+                        tokio::time::sleep(delay).await;
+                    }
+                    last_err = Some(e);
+                }
+            }
+        }
+
+        let err = last_err.expect("loop runs at least once and always sets last_err on Err");
+        tracing::error!(
+            attempts = self.max_retries + 1,
+            "poster sync failed after all attempts: {err}"
+        );
+        Err(err)
+    }
+}