feat(admin): overview dashboard sections + system temperature/load sensors (0.85.0) (#11)

backend/src/api/admin/overview.rs

@@ -0,0 +1,81 @@
+//! Admin overview dashboard aggregates.
+//!
+//! One composed endpoint feeding the Overview tab's per-section summary
+//! cards (Users, Mangas, Analysis). Pure DB aggregates — no system
+//! sampling — so it's cheap enough to poll. The System and Crawler cards
+//! reuse their own existing endpoints (`/admin/system`, `/admin/crawler`),
+//! and the Settings strip reuses the settings endpoints; only these three
+//! sections needed new aggregation, so they live together here.
+//!
+//! Admin-only (`RequireAdmin`, cookie-only).
+
+use axum::extract::State;
+use axum::routing::get;
+use axum::{Json, Router};
+use chrono::{DateTime, Utc};
+use serde::Serialize;
+
+use crate::app::AppState;
+use crate::auth::extractor::RequireAdmin;
+use crate::error::AppResult;
+use crate::repo;
+
+pub fn routes() -> Router<AppState> {
+    Router::new().route("/admin/overview", get(overview))
+}
+
+#[derive(Debug, Serialize)]
+pub struct OverviewStats {
+    pub users: UsersOverview,
+    pub mangas: repo::admin_view::MangaStats,
+    pub analysis: AnalysisOverview,
+}
+
+#[derive(Debug, Serialize)]
+pub struct UsersOverview {
+    pub total: i64,
+    pub admins: i64,
+    pub newest_username: Option<String>,
+    pub newest_created_at: Option<DateTime<Utc>>,
+}
+
+#[derive(Debug, Serialize)]
+pub struct AnalysisOverview {
+    pub analyzed_pages: i64,
+    pub total_pages: i64,
+}
+
+async fn overview(
+    State(state): State<AppState>,
+    _admin: RequireAdmin,
+) -> AppResult<Json<OverviewStats>> {
+    // Independent reads — run concurrently so latency is the slowest
+    // query, not their sum (mirrors the storage handler).
+    let (user_counts, user_newest, mangas, coverage) = tokio::try_join!(
+        repo::user::counts(&state.db),
+        repo::user::newest(&state.db),
+        repo::admin_view::manga_stats(&state.db),
+        repo::page_analysis::library_coverage(&state.db),
+    )?;
+
+    let (total, admins) = user_counts;
+    let (newest_username, newest_created_at) = match user_newest {
+        Some((username, created_at)) => (Some(username), Some(created_at)),
+        None => (None, None),
+    };
+    let (analyzed_pages, total_pages) = coverage;
+
+    Ok(Json(OverviewStats {
+        users: UsersOverview {
+            total,
+            admins,
+            newest_username,
+            newest_created_at,
+        },
+        mangas,
+        analysis: AnalysisOverview {
+            analyzed_pages,
+            total_pages,
+        },
+    }))
+}