"use client";

import { useEffect, useState } from "react";
import Link from "next/link";
import { useRouter } from "next/navigation";
import { trackEvent } from "@/lib/ebook/analytics";
import { getFeatures } from "@/lib/ebook/features";
import { useT } from "@/components/ebook/LocaleProvider";
import { useAuth } from "@/lib/auth";
import { api } from "@/lib/api";

/** Buy download edition via FastAPI /pay/create (pay_type=ebook). */
export function BuyEbook({ compact = false }: { compact?: boolean }) {
  const t = useT();
  const { token } = useAuth();
  const router = useRouter();
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState("");
  const [owned, setOwned] = useState(false);
  const features = getFeatures();
  const enabled = features.payment?.checkout?.enabled !== false;
  const productName = features.payment?.checkout?.productName || "Download Edition";
  const buttonText = features.payment?.checkout?.buttonText || "购买下载版";

  useEffect(() => {
    if (!token) return;
    api.ebookStatus(token).then((s) => setOwned(s.owned)).catch(() => {});
  }, [token]);

  if (!enabled) return null;

  const buy = async () => {
    setError("");
    if (!token) {
      router.push("/login?next=/book");
      return;
    }
    if (owned) {
      router.push("/book/thanks");
      return;
    }
    setBusy(true);
    trackEvent("buy_click", { from: compact ? "reader" : "cover" });
    try {
      const returnUrl = `${window.location.origin}/book/thanks`;
      const res = await api.createPayment(token, returnUrl, "ebook");
      if (res.order_id) {
        localStorage.setItem("nomadro-ebook-order", res.order_id);
      }
      // DEV_AUTO_PAY or already-paid: confirm then go to thanks
      if (res.status === "paid" && res.order_id) {
        await api.completePayment(token, res.order_id).catch(() => null);
        router.push(`/book/thanks?order_id=${encodeURIComponent(res.order_id)}`);
        return;
      }
      if (!res.redirect_url) {
        throw new Error(t("payment.checkoutFailed"));
      }
      window.location.href = res.redirect_url;
    } catch (err) {
      setError(err instanceof Error ? err.message : t("payment.checkoutFailed"));
      setBusy(false);
    }
  };

  return (
    <section className={`buy-ebook${compact ? " is-compact" : ""}`}>
      <h2 className="buy-ebook-title">{t("payment.buyGet", { name: productName })}</h2>
      <p className="buy-ebook-sub">{t("payment.buySub")}</p>
      <button type="button" className="buy-ebook-btn" disabled={busy} onClick={buy}>
        {busy ? t("payment.openingCheckout") : owned ? "已购买 · 去下载" : buttonText}
      </button>
      {error ? <p className="buy-ebook-error">{error}</p> : null}
      <p className="buy-ebook-hint">
        也可免费 <Link href="/book/read">在线阅读</Link>
      </p>
    </section>
  );
}