import { type NextRequest, NextResponse } from "next/server";
import { z } from "zod";
import { auth } from "@/app/(auth)/auth";
import {
  getPaidPlanAmountFen,
  getPaidPlanById,
  getWechatPayConfig,
  isPaidBillingPlanId,
  type PaidBillingPlanId,
} from "@/lib/billing/plans";
import { createWechatNativeOrder, generateWechatOutTradeNo, WechatPayError } from "@/lib/billing/wechat";
import { upsertSystemSetting } from "@/lib/db/queries";

const schema = z.object({
  planId: z.string(),
});

function getBaseUrl(request: NextRequest) {
  return (
    process.env.AUTH_URL ??
    `${request.nextUrl.protocol}//${request.headers.get("host") ?? request.nextUrl.host}`
  );
}

export async function POST(request: NextRequest) {
  try {
    const session = await auth();

    if (!session?.user?.id || !session.user.email) {
      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
    }

    if (session.user.type === "guest") {
      return NextResponse.json({ error: "Guest user cannot checkout" }, { status: 403 });
    }

    const parsed = schema.safeParse(await request.json());
    if (!parsed.success || !isPaidBillingPlanId(parsed.data.planId)) {
      return NextResponse.json({ error: "Invalid plan ID" }, { status: 400 });
    }

    const config = getWechatPayConfig();
    if (!config) {
      return NextResponse.json({ error: "WeChat Pay is not configured" }, { status: 503 });
    }

    const planId = parsed.data.planId as PaidBillingPlanId;
    const plan = getPaidPlanById(planId);

    if (!plan) {
      return NextResponse.json({ error: "Plan not found" }, { status: 400 });
    }

    const outTradeNo = generateWechatOutTradeNo();
    const amountFen = getPaidPlanAmountFen(planId);
    const notifyUrl = config.notifyUrl || new URL("/api/billing/wechat/notify", getBaseUrl(request)).toString();

    const attachPayload = JSON.stringify({
      planId,
      userId: session.user.id,
      email: session.user.email,
    });

    const order = await createWechatNativeOrder({
      appId: config.appId,
      mchId: config.mchId,
      privateKey: config.privateKey,
      serialNo: config.serialNo,
      description: `Lovart ${plan.name} Subscription`,
      outTradeNo,
      notifyUrl,
      amountFen,
      attach: attachPayload,
    });

    await upsertSystemSetting({
      key: `wechat:pay:order:${outTradeNo}`,
      value: {
        outTradeNo,
        channel: "wechat",
        status: "created",
        planId,
        userId: session.user.id,
        email: session.user.email,
        codeUrl: order.code_url,
        amountFen,
        createdAt: new Date().toISOString(),
      },
      updatedBy: session.user.id,
    });

    const qrCodeImageUrl = `https://api.qrserver.com/v1/create-qr-code/?size=260x260&data=${encodeURIComponent(order.code_url)}`;

    return NextResponse.json({
      outTradeNo,
      codeUrl: order.code_url,
      qrCodeImageUrl,
    });
  } catch (error) {
    if (error instanceof WechatPayError) {
      return NextResponse.json({ error: error.message }, { status: error.status });
    }

    console.error("[Billing WeChat Checkout API] Error:", error);
    return NextResponse.json({ error: "Failed to create wechat pay order" }, { status: 500 });
  }
}