import { NextRequest, NextResponse } from "next/server";
import { queryRaw } from "@/lib/db";
import { getCurrentUser } from "@/lib/auth";

interface BalanceRow {
  participant_id: number;
  name: string;
  total_owed: number;
  transaction_count: number;
}

export async function GET(
  req: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  const user = await getCurrentUser(req);
  if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 403 });
  const { id } = await params;

  const rows = await queryRaw<BalanceRow>(
    `SELECT ts.participant_id, p.name,
       SUM(COALESCE(t.amount_aud, t.amount) * ts.share_percent / 100)::numeric(12,2) as total_owed,
       COUNT(*)::int as transaction_count
     FROM transaction_splits ts
     JOIN transactions t ON t.id = ts.transaction_id
     JOIN participants p ON p.id = ts.participant_id
     WHERE ts.participant_id = $1 AND ts.settled = false
     GROUP BY ts.participant_id, p.name`,
    [Number(id)]
  );

  return NextResponse.json(
    rows[0] ?? { participant_id: Number(id), total_owed: 0, transaction_count: 0 }
  );
}