feat(insights): committed/discretionary chart, recurring charge detection, fees & interest audit

src/app/api/analytics/fees/route.ts

@@ -0,0 +1,74 @@
+import { NextRequest, NextResponse } from "next/server";
+import { getCurrentUser } from "@/lib/auth";
+import { queryRaw } from "@/lib/db";
+
+export async function GET(req: NextRequest) {
+  const user = await getCurrentUser(req);
+  if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 403 });
+
+  // Statement-level fees and interest (aggregated by Gemini from the PDF)
+  const stmtRows = await queryRaw<{
+    bank_name: string;
+    fees: string;
+    interest: string;
+  }>(
+    `SELECT
+      bank_name,
+      SUM(COALESCE(fees_charged, 0))::numeric(12,2) AS fees,
+      SUM(COALESCE(interest_charged, 0))::numeric(12,2) AS interest
+    FROM statements
+    WHERE owner_id = $1
+    GROUP BY bank_name
+    HAVING SUM(COALESCE(fees_charged, 0)) + SUM(COALESCE(interest_charged, 0)) > 0
+    ORDER BY (SUM(COALESCE(fees_charged, 0)) + SUM(COALESCE(interest_charged, 0))) DESC`,
+    [user.id]
+  );
+
+  // Transaction-level fee and interest line items (split-adjusted)
+  const txnRows = await queryRaw<{
+    id: number;
+    transaction_date: string;
+    description: string;
+    merchant_name: string | null;
+    transaction_type: string;
+    my_amount: string;
+    bank_name: string;
+  }>(
+    `SELECT
+      t.id,
+      t.transaction_date,
+      t.description,
+      t.merchant_name,
+      t.transaction_type,
+      CASE
+        WHEN ts.share_percent IS NOT NULL THEN COALESCE(t.amount_aud, t.amount) * ts.share_percent / 100
+        ELSE COALESCE(t.amount_aud, t.amount)
+      END::numeric(12,2) AS my_amount,
+      s.bank_name
+    FROM transactions t
+    LEFT JOIN transaction_splits ts ON ts.transaction_id = t.id AND ts.participant_id = $1
+    JOIN statements s ON s.id = t.statement_id
+    WHERE s.owner_id = $1
+      AND t.transaction_type IN ('fee', 'interest')
+    ORDER BY t.transaction_date DESC`,
+    [user.id]
+  );
+
+  const by_bank = stmtRows.map((r) => ({
+    bank_name: r.bank_name,
+    fees: Number(r.fees),
+    interest: Number(r.interest),
+    total: Number(r.fees) + Number(r.interest),
+  }));
+
+  const transactions = txnRows.map((r) => ({
+    ...r,
+    my_amount: Number(r.my_amount),
+  }));
+
+  // Totals from statement-level data (more complete — Gemini reads the statement summary)
+  const total_fees = by_bank.reduce((s, r) => s + r.fees, 0);
+  const total_interest = by_bank.reduce((s, r) => s + r.interest, 0);
+
+  return NextResponse.json({ by_bank, transactions, total_fees, total_interest });
+}