From bbc6977e73eb5872c63bb4775560f461008c68c3 Mon Sep 17 00:00:00 2001
From: GW_MC <72297530+GWMCwing@users.noreply.github.com>
Date: Fri, 5 Dec 2025 14:05:09 +0800
Subject: [PATCH] Add health check routes and state management

---
 apps/api/src/routes/api.rs              |   3 +
 apps/api/src/routes/api/health.rs       |  12 +++
 apps/api/src/routes/api/health/info.rs  | 108 ++++++++++++++++++++++++
 apps/api/src/routes/api/health/state.rs |  23 +++++
 4 files changed, 146 insertions(+)
 create mode 100644 apps/api/src/routes/api/health.rs
 create mode 100644 apps/api/src/routes/api/health/info.rs
 create mode 100644 apps/api/src/routes/api/health/state.rs

diff --git a/apps/api/src/routes/api.rs b/apps/api/src/routes/api.rs
index 2924fe9..7f648a2 100644
--- a/apps/api/src/routes/api.rs
+++ b/apps/api/src/routes/api.rs
@@ -1,7 +1,10 @@
+mod health;
+
 use axum::{Router, response::IntoResponse, routing::any};
 
 pub fn get_api_router() -> Router {
     Router::new()
+        .nest("/health", health::get_health_router())
         // explicit fallback for unmatched API routes
         .route("/{*wildcard}", any(api_fallback_handler))
 }
diff --git a/apps/api/src/routes/api/health.rs b/apps/api/src/routes/api/health.rs
new file mode 100644
index 0000000..98f6b15
--- /dev/null
+++ b/apps/api/src/routes/api/health.rs
@@ -0,0 +1,12 @@
+mod info;
+mod state;
+
+use std::sync::Arc;
+
+use axum::{Router, routing::get};
+
+pub fn get_health_router() -> Router {
+    Router::new()
+        .route("/info", get(info::get_health_info))
+        .with_state(Arc::new(state::HealthState::default()))
+}
diff --git a/apps/api/src/routes/api/health/info.rs b/apps/api/src/routes/api/health/info.rs
new file mode 100644
index 0000000..6f38ac2
--- /dev/null
+++ b/apps/api/src/routes/api/health/info.rs
@@ -0,0 +1,108 @@
+use std::sync::Arc;
+
+use axum::{Json, extract::State, http::StatusCode};
+use chrono::{Duration, Utc};
+use serde::{Deserialize, Serialize};
+use tokio::time::Instant;
+
+use crate::routes::api::health::state::HealthState;
+
+const STATUS_HEALTHY: &str = "healthy";
+const STATUS_UNHEALTHY: &str = "unhealthy";
+
+#[derive(Serialize, Deserialize)]
+pub struct HealthInfo {
+    pub status: String,
+    pub version: String,
+    // timestamp in milliseconds when the service started
+    pub up_since: String,
+    pub errors: Option<Vec<String>>,
+}
+
+pub async fn get_health_info(
+    State(state): State<Arc<HealthState>>,
+) -> (StatusCode, Json<HealthInfo>) {
+    let mut errors = vec![];
+    let up_since = if *state.get_start_time() > Instant::now() {
+        errors.push("Invalid up time".into());
+        // Fall back to reporting 'now' as the up_since timestamp when invalid.
+        Utc::now()
+    } else {
+        let elapsed = state.get_start_time().elapsed();
+        Utc::now()
+            - Duration::from_std(elapsed).unwrap_or_else(|_| {
+                errors.push("Invalid up time".into());
+                Duration::zero()
+            })
+    };
+
+    (
+        StatusCode::OK,
+        Json(HealthInfo {
+            status: if errors.is_empty() {
+                STATUS_HEALTHY.into()
+            } else {
+                STATUS_UNHEALTHY.into()
+            },
+            version: env!("CARGO_PKG_VERSION").into(),
+            up_since: up_since.to_rfc3339(),
+            errors: if errors.is_empty() {
+                None
+            } else {
+                Some(errors)
+            },
+        }),
+    )
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use axum::body::to_bytes;
+    use axum::{
+        Router,
+        body::Body,
+        http::{Request, StatusCode},
+    };
+    use tower::ServiceExt;
+
+    #[tokio::test]
+    async fn test_get_health_info() {
+        let health_state = Arc::new(HealthState::default());
+        let app = Router::new()
+            .route("/info", axum::routing::get(get_health_info))
+            .with_state(health_state);
+
+        let response = app
+            .oneshot(Request::builder().uri("/info").body(Body::empty()).unwrap())
+            .await
+            .unwrap();
+
+        assert_eq!(response.status(), StatusCode::OK);
+        let body = to_bytes(response.into_body(), 1024 * 1024).await.unwrap(); // Set limit to 1 MB
+        let health_info: HealthInfo = serde_json::from_slice(&body).unwrap();
+        assert_eq!(health_info.status, STATUS_HEALTHY);
+        assert_eq!(health_info.version, env!("CARGO_PKG_VERSION"));
+        assert!(health_info.errors.is_none());
+    }
+
+    #[tokio::test]
+    async fn test_invalid_up_time() {
+        let health_state = Arc::new(HealthState::new(
+            tokio::time::Instant::now() + std::time::Duration::from_secs(60000),
+        ));
+        let app = Router::new()
+            .route("/info", axum::routing::get(get_health_info))
+            .with_state(health_state);
+        let response = app
+            .oneshot(Request::builder().uri("/info").body(Body::empty()).unwrap())
+            .await
+            .unwrap();
+        assert_eq!(response.status(), StatusCode::OK);
+        let body = to_bytes(response.into_body(), 1024 * 1024).await.unwrap(); // Set limit to 1 MB
+        let health_info: HealthInfo = serde_json::from_slice(&body).unwrap();
+        assert_eq!(health_info.status, STATUS_UNHEALTHY);
+        assert_eq!(health_info.version, env!("CARGO_PKG_VERSION"));
+        assert!(health_info.errors.as_ref().is_some_and(|e| !e.is_empty()));
+    }
+}
diff --git a/apps/api/src/routes/api/health/state.rs b/apps/api/src/routes/api/health/state.rs
new file mode 100644
index 0000000..ef81a99
--- /dev/null
+++ b/apps/api/src/routes/api/health/state.rs
@@ -0,0 +1,23 @@
+use tokio::time::Instant;
+
+pub struct HealthState {
+    start_time: Instant,
+}
+
+impl Default for HealthState {
+    fn default() -> Self {
+        Self {
+            start_time: Instant::now(),
+        }
+    }
+}
+
+impl HealthState {
+    pub fn new(start_time: Instant) -> Self {
+        Self { start_time }
+    }
+
+    pub fn get_start_time(&self) -> &Instant {
+        &self.start_time
+    }
+}