import { NextRequest, NextResponse } from "next/server";
import bcrypt from "bcryptjs";
import { prisma } from "@/lib/prisma";
import { signJWT } from "@/lib/auth";
import { findReferrerByCode } from "@/lib/referral";

const REFERRER_REWARD_FLH = 200;
const REFERRED_BONUS_FLH = 1000;

export async function POST(req: NextRequest) {
  try {
    const { email, name, password, referralCode } = await req.json();

    if (!email || !name || !password) {
      return NextResponse.json(
        { error: "Email, name, and password are required" },
        { status: 400 }
      );
    }

    const existing = await prisma.user.findUnique({ where: { email } });
    if (existing) {
      return NextResponse.json(
        { error: "An account with this email already exists" },
        { status: 409 }
      );
    }

    const passwordHash = await bcrypt.hash(password, 12);

    // Look up referrer if a referral code was provided
    let referrerId: string | null = null;
    if (referralCode && typeof referralCode === "string") {
      const users = await prisma.user.findMany({
        select: { id: true },
      });
      referrerId = await findReferrerByCode(users, referralCode);
    }

    // Calculate starting balance
    let startingBalance = 5000; // default sign-up bonus
    if (referrerId) {
      startingBalance += REFERRED_BONUS_FLH; // +1,000 FLH for using a referral code
    }

    const user = await prisma.user.create({
      data: {
        email,
        name,
        passwordHash,
        provider: "email",
        flhBalance: startingBalance,
        trialEndsAt: new Date(Date.now() + 7 * 24 * 60 * 60 * 1000),
      },
    });

    // If referral code was valid, create the referral record and credit the referrer
    if (referrerId) {
      await prisma.$transaction([
        // Create the referral record
        prisma.referral.create({
          data: {
            referrerId,
            referredId: user.id,
            status: "joined",
            rewardFlh: REFERRER_REWARD_FLH,
          },
        }),
        // Credit the referrer
        prisma.user.update({
          where: { id: referrerId },
          data: { flhBalance: { increment: REFERRER_REWARD_FLH } },
        }),
        // Notify the referrer
        prisma.notification.create({
          data: {
            userId: referrerId,
            type: "referral_bonus",
            title: "Referral Bonus Earned!",
            body: `${name} joined Falah using your referral code — you earned ${REFERRER_REWARD_FLH} FLH!`,
            data: JSON.stringify({
              referredUserId: user.id,
              referredName: name,
              rewardFlh: REFERRER_REWARD_FLH,
            }),
          },
        }),
      ]);
    }

    const token = await signJWT({
      userId: user.id,
      email: user.email,
      isPremium: user.isPremium,
      isPro: user.isPro,
    });

    return NextResponse.json({
      token,
      user: {
        id: user.id,
        email: user.email,
        name: user.name,
        isPremium: user.isPremium,
        isPro: user.isPro,
        flhBalance: user.flhBalance,
        dailyMsgCount: user.dailyMsgCount,
      },
      referralApplied: referrerId ? true : false,
      referralReward: referrerId ? REFERRED_BONUS_FLH : 0,
    });
  } catch (error) {
    console.error("Register error:", error);
    return NextResponse.json(
      { error: "Registration failed. Please try again." },
      { status: 500 }
    );
  }
}