feat: scraper system

src/state.rs

@@ -0,0 +1,48 @@
+//! Application state shared across components (bot, web, scheduler).
+
+use crate::banner::BannerApi;
+use crate::banner::Course;
+use anyhow::Result;
+use redis::AsyncCommands;
+use redis::Client;
+use std::sync::Arc;
+
+#[derive(Clone)]
+pub struct AppState {
+    pub banner_api: Arc<BannerApi>,
+    pub redis: Arc<Client>,
+}
+
+impl AppState {
+    pub fn new(
+        banner_api: Arc<BannerApi>,
+        redis_url: &str,
+    ) -> Result<Self, Box<dyn std::error::Error + Send + Sync>> {
+        let redis_client = Client::open(redis_url)?;
+
+        Ok(Self {
+            banner_api,
+            redis: Arc::new(redis_client),
+        })
+    }
+
+    /// Get a course by CRN with Redis cache fallback to Banner API
+    pub async fn get_course_or_fetch(&self, term: &str, crn: &str) -> Result<Course> {
+        let mut conn = self.redis.get_multiplexed_async_connection().await?;
+
+        let key = format!("class:{crn}");
+        if let Some(serialized) = conn.get::<_, Option<String>>(&key).await? {
+            let course: Course = serde_json::from_str(&serialized)?;
+            return Ok(course);
+        }
+
+        // Fallback: fetch from Banner API
+        if let Some(course) = self.banner_api.get_course_by_crn(term, crn).await? {
+            let serialized = serde_json::to_string(&course)?;
+            let _: () = conn.set(&key, serialized).await?;
+            return Ok(course);
+        }
+
+        Err(anyhow::anyhow!("Course not found for CRN {crn}"))
+    }
+}