Add notifications API for vaccine reminders

- API endpoint /api/notifications returns due/overdue vaccines
- Checks child's birthDate to calculate due dates
- Returns notifications with type, status, days overdue

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/app/api/notifications/route.ts

@@ -0,0 +1,97 @@
+import { NextResponse } from "next/server";
+import { sql } from "@/db";
+
+// IAP Vaccination Schedule (weeks from birth)
+const IAP_SCHEDULE = [
+  { name: "BCG", weeks: 0 },
+  { name: "OPV-0", weeks: 0 },
+  { name: "HepB-1", weeks: 0 },
+  { name: "OPV-1", weeks: 6 },
+  { name: "Pentavalent-1", weeks: 6 },
+  { name: "PCV-1", weeks: 6 },
+  { name: "Rota-1", weeks: 6 },
+  { name: "OPV-2", weeks: 10 },
+  { name: "Pentavalent-2", weeks: 10 },
+  { name: "PCV-2", weeks: 10 },
+  { name: "Rota-2", weeks: 10 },
+  { name: "OPV-3", weeks: 14 },
+  { name: "Pentavalent-3", weeks: 14 },
+  { name: "PCV-3", weeks: 14 },
+  { name: "Rota-3", weeks: 14 },
+  { name: "MR-1", weeks: 48 },
+  { name: "JE-1", weeks: 48 },
+  { name: "Vitamin A-1", weeks: 48 },
+  { name: "OPV-4", weeks: 48 },
+  { name: "MR-2", weeks: 96 },
+  { name: "JE-2", weeks: 96 },
+  { name: "DPT-Booster-1", weeks: 96 },
+  { name: "Vitamin A-2", weeks: 96 },
+  { name: "OPV-5", weeks: 96 },
+  { name: "DPT-Booster-2", weeks: 208 },
+  { name: "Tetanus and adult diphtheria (Td)", weeks: 208 },
+];
+
+export async function GET(request: Request) {
+  try {
+    const { searchParams } = new URL(request.url);
+    const childId = searchParams.get("childId");
+
+    if (!childId) {
+      return NextResponse.json({ error: "childId required" }, { status: 400 });
+    }
+
+    // Get child's birth date
+    const children = await sql`
+      SELECT id, name, birth_date FROM children WHERE id = ${childId}
+    `;
+
+    if (!children || children.length === 0) {
+      return NextResponse.json({ notifications: [] });
+    }
+
+    const child = children[0];
+    const birthDate = new Date(child.birth_date);
+    const today = new Date();
+    today.setHours(0, 0, 0, 0);
+
+    // Get already given vaccines
+    const given = await sql`
+      SELECT vaccine_name, given_date FROM vaccinations
+      WHERE child_id = ${childId} AND status = 'given'
+    `;
+    const givenMap = new Set(given.map((v: any) => v.vaccine_name));
+
+    // Calculate upcoming vaccine notifications
+    const notifications = [];
+    for (const vaccine of IAP_SCHEDULE) {
+      if (givenMap.has(vaccine.name)) continue;
+
+      // Calculate due date
+      const dueDate = new Date(birthDate);
+      dueDate.setDate(dueDate.getDate() + vaccine.weeks * 7);
+      dueDate.setHours(0, 0, 0, 0);
+
+      const diffDays = Math.floor((dueDate.getTime() - today.getTime()) / (1000 * 60 * 60 * 24));
+
+      // Notify if due today or overdue
+      if (diffDays <= 0) {
+        notifications.push({
+          id: `vaccine-${vaccine.name}`,
+          type: "vaccine",
+          title: diffDays === 0 ? "Vaccine Due Today" : "Vaccine Overdue",
+          message: `${vaccine.name} is ${diffDays === 0 ? "due today" : `${Math.abs(diffDays)} days overdue`}`,
+          vaccineName: vaccine.name,
+          dueDate: dueDate.toISOString().split("T")[0],
+          status: diffDays === 0 ? "due_today" : "overdue",
+          childId,
+          childName: child.name,
+        });
+      }
+    }
+
+    return NextResponse.json({ notifications });
+  } catch (error) {
+    console.error("Notifications error:", error);
+    return NextResponse.json({ error: String(error) }, { status: 500 });
+  }
+}