import { NextRequest, NextResponse } from "next/server";
import { prisma } from "@/lib/prisma";
import { requireAuth } from "@/lib/auth";

// Same encodeBase62 used in the code route
function encodeBase62(id: string): string {
  const chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
  let hash = 0;
  for (let i = 0; i < Math.min(id.length, 10); i++) {
    hash = (hash * 31 + id.charCodeAt(i)) >>> 0;
  }
  let code = "";
  while (code.length < 6) {
    code = chars[hash % 62] + code;
    hash = Math.floor(hash / 62);
    if (hash === 0 && code.length < 6) {
      hash = Math.floor(Math.random() * 62 ** (6 - code.length));
    }
  }
  return code;
}

export async function GET(req: NextRequest) {
  const jwtPayload = await requireAuth(req);
  if (!jwtPayload) {
    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
  }

  try {
    const userId = jwtPayload.userId;

    const [totalReferrals, upgradedCount, earnings] = await Promise.all([
      prisma.referral.count({
        where: { referrerId: userId },
      }),
      prisma.referral.count({
        where: { referrerId: userId, status: "upgraded" },
      }),
      prisma.referral.aggregate({
        where: { referrerId: userId },
        _sum: { rewardFlh: true },
      }),
    ]);

    const referralCode = encodeBase62(userId);

    return NextResponse.json({
      totalReferrals,
      upgradedCount,
      totalEarned: earnings._sum.rewardFlh || 0,
      referralCode,
      shareLink: `${process.env.NEXT_PUBLIC_APP_URL || "https://falah.app"}/join?ref=${referralCode}`,
    });
  } catch (error) {
    console.error("Referral stats error:", error);
    return NextResponse.json(
      { error: "Failed to get referral stats" },
      { status: 500 }
    );
  }
}