perf: connection pooling, query consolidation, inline chart data, batch milestones

app/routes/dashboard.py

@@ -1,6 +1,8 @@
+from datetime import timezone
 from flask import Blueprint, render_template
 from app.auth import login_required, get_current_user
 from app.db import query, query_one
+from app.config import SYDNEY_TZ
 from app.utils import calculate_streak, calculate_weight_change
 
 bp = Blueprint("dashboard", __name__)
@@ -10,38 +12,53 @@ bp = Blueprint("dashboard", __name__)
 @login_required
 def index():
     user = get_current_user()
+    uid = user["id"]
 
-    # Get latest check-in
-    latest = query_one(
-        "SELECT * FROM checkins WHERE user_id = %s ORDER BY checked_in_at DESC LIMIT 1",
-        (user["id"],),
-    )
-
-    # Get check-in count
-    stats = query_one(
-        "SELECT COUNT(*) as total_checkins FROM checkins WHERE user_id = %s",
-        (user["id"],),
-    )
-
-    # Calculate weight change
-    first_checkin = query_one(
-        "SELECT weight_kg FROM checkins WHERE user_id = %s ORDER BY checked_in_at ASC LIMIT 1",
-        (user["id"],),
-    )
+    # --- Single query: latest, first, count via window functions ----------
+    summary = query_one("""
+        SELECT
+            total,
+            first_weight,
+            latest_weight,
+            latest_bmi,
+            latest_at
+        FROM (
+            SELECT
+                COUNT(*) OVER ()                                                   AS total,
+                FIRST_VALUE(weight_kg) OVER (ORDER BY checked_in_at ASC)           AS first_weight,
+                FIRST_VALUE(weight_kg) OVER (ORDER BY checked_in_at DESC)          AS latest_weight,
+                FIRST_VALUE(bmi)       OVER (ORDER BY checked_in_at DESC)          AS latest_bmi,
+                FIRST_VALUE(checked_in_at) OVER (ORDER BY checked_in_at DESC)     AS latest_at,
+                ROW_NUMBER()           OVER (ORDER BY checked_in_at DESC)          AS rn
+            FROM checkins
+            WHERE user_id = %s
+        ) sub
+        WHERE rn = 1
+    """, (uid,))
 
+    # Build lightweight "latest" dict for the template
+    latest = None
     weight_change = None
     weight_change_pct = None
-    if latest and first_checkin:
+    total_checkins = 0
+
+    if summary:
+        total_checkins = summary["total"]
+        latest = {
+            "weight_kg": summary["latest_weight"],
+            "bmi": summary["latest_bmi"],
+            "checked_in_at": summary["latest_at"],
+        }
         kg_lost, pct_lost = calculate_weight_change(
-            first_checkin["weight_kg"], latest["weight_kg"]
+            summary["first_weight"], summary["latest_weight"]
         )
-        weight_change = round(-kg_lost, 1)       # negative = gained, positive = lost
+        weight_change = round(-kg_lost, 1)
         weight_change_pct = round(-pct_lost, 1)
 
     # Recent check-ins (last 5)
     recent_checkins = query(
         "SELECT * FROM checkins WHERE user_id = %s ORDER BY checked_in_at DESC LIMIT 5",
-        (user["id"],),
+        (uid,),
     )
 
     # Activity feed (recent check-ins from all users)
@@ -52,26 +69,57 @@ def index():
         WHERE u.is_private = FALSE OR u.id = %s
         ORDER BY c.checked_in_at DESC
         LIMIT 10
-    """, (user["id"],))
+    """, (uid,))
 
     # Milestones
     milestones = query(
         "SELECT * FROM milestones WHERE user_id = %s ORDER BY achieved_at DESC",
-        (user["id"],),
+        (uid,),
     )
 
     # Streak
-    streak = calculate_streak(user["id"])
+    streak = calculate_streak(uid)
+
+    # --- Pre-compute chart data (eliminates 2 client-side fetches) --------
+    chart_checkins = query(
+        """SELECT weight_kg, bmi, checked_in_at
+           FROM checkins WHERE user_id = %s
+           ORDER BY checked_in_at ASC""",
+        (uid,),
+    )
+
+    chart_labels = []
+    chart_weights = []
+    weekly_labels = []
+    weekly_changes = []
+
+    for i, c in enumerate(chart_checkins):
+        dt = c["checked_in_at"]
+        if dt.tzinfo is None:
+            dt = dt.replace(tzinfo=timezone.utc)
+        label = dt.astimezone(SYDNEY_TZ).strftime("%d %b")
+        chart_labels.append(label)
+        chart_weights.append(float(c["weight_kg"]))
+
+        if i > 0:
+            prev_w = float(chart_checkins[i - 1]["weight_kg"])
+            curr_w = float(c["weight_kg"])
+            weekly_labels.append(label)
+            weekly_changes.append(round(curr_w - prev_w, 1))
 
     return render_template(
         "dashboard.html",
         user=user,
         latest=latest,
-        stats=stats,
+        stats={"total_checkins": total_checkins},
         weight_change=weight_change,
         weight_change_pct=weight_change_pct,
         recent_checkins=recent_checkins,
         activity=activity,
         milestones=milestones,
         streak=streak,
+        chart_labels=chart_labels,
+        chart_weights=chart_weights,
+        weekly_labels=weekly_labels,
+        weekly_changes=weekly_changes,
     )