"use client";

import { useState, useEffect, useRef } from "react";
import { useRouter } from "next/navigation";
import Link from "next/link";
import { UserPlus } from "lucide-react";
import { apiRegister, apiMe, apiOperations } from "@/lib/api";
import { hasAuthCookieHint } from "@/lib/cookies";

/** 关闭注册时的说明页（提交失败切到关闭态时复用） */
export function RegisterClosedPanel({ notice }: { notice: string }) {
  return (
    <div className="max-w-md mx-auto pt-8 sm:pt-14">
      <div className="panel p-8 text-center">
        <h1 className="text-lg font-extrabold" style={{ color: "var(--ink)" }}>
          暂不开放注册
        </h1>
        <p className="meta mt-2 text-[13px]">
          {notice || "站点当前已关闭新用户注册，已有账号可直接登录。"}
        </p>
        <Link href="/login" className="btn btn-primary mt-6">
          去登录
        </Link>
      </div>
    </div>
  );
}

export default function RegisterClient({
  verifyEmail: initialVerifyEmail,
  registerNotice,
}: {
  verifyEmail: boolean;
  registerNotice: string;
}) {
  const router = useRouter();
  const [username, setUsername] = useState("");
  const [email, setEmail] = useState("");
  const [password, setPassword] = useState("");
  const [error, setError] = useState("");
  const [loading, setLoading] = useState(false);
  const [registerClosed, setRegisterClosed] = useState(false);
  const [code, setCode] = useState("");
  const [notice, setNotice] = useState(registerNotice);
  const [sending, setSending] = useState(false);
  const [sentMessage, setSentMessage] = useState("");
  // 重发倒计时（秒）；>0 期间按钮锁定不可点
  const [countdown, setCountdown] = useState(0);
  const countdownTimer = useRef<ReturnType<typeof setInterval> | null>(null);
  const verifyEmail = initialVerifyEmail;

  // 卸载时清理倒计时，避免泄漏
  useEffect(() => {
    return () => {
      if (countdownTimer.current) clearInterval(countdownTimer.current);
    };
  }, []);

  const startCountdown = () => {
    if (countdownTimer.current) clearInterval(countdownTimer.current);
    setCountdown(60);
    countdownTimer.current = setInterval(() => {
      setCountdown((c) => {
        if (c <= 1) {
          if (countdownTimer.current) clearInterval(countdownTimer.current);
          countdownTimer.current = null;
          return 0;
        }
        return c - 1;
      });
    }, 1000);
  };

  // 已登录用户不必再注册，直接回首页
  useEffect(() => {
    if (!hasAuthCookieHint()) return;
    apiMe()
      .then((res) => {
        if (res.user) router.replace("/");
      })
      .catch(() => {});
  }, [router]);

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    setError("");
    setLoading(true);
    try {
      const res = await apiRegister(username, email, password, code);
      if (res.user) {
        router.push("/");
        router.refresh();
      } else if (res.id) {
        router.push("/login");
      } else {
        const msg = res.error || "注册失败";
        if (msg.includes("关闭注册")) {
          // 热关闭：补拉提示文案后切关闭态
          try {
            const s = await apiOperations<{ register_notice: string }>("/api/site-state");
            setNotice(s.register_notice || notice);
          } catch {
            /* 沿用 SSR 提示 */
          }
          setRegisterClosed(true);
        }
        setError(msg);
      }
    } finally {
      setLoading(false);
    }
  };

  if (registerClosed) {
    return <RegisterClosedPanel notice={notice} />;
  }

  return (
    <div className="max-w-md mx-auto pt-8 sm:pt-14">
      <div className="mb-7 text-center">
        <span
          className="inline-flex w-14 h-14 rounded-2xl items-center justify-center mb-4"
          style={{ background: "var(--accent-soft)", color: "var(--accent)" }}
          aria-hidden
        >
          <UserPlus size={26} />
        </span>
        <h1 className="text-[28px] font-extrabold tracking-tight" style={{ color: "var(--ink)" }}>
          创建账号
        </h1>
        <p className="text-sm mt-2" style={{ color: "var(--ink-2)" }}>
          加入社区，开始你的第一帖
        </p>
      </div>

      <form onSubmit={handleSubmit} className="panel p-6 sm:p-7 space-y-4">
        {error && (
          <div className="alert-error" role="alert">
            {error}
          </div>
        )}
        <div>
          <label className="field-label" htmlFor="reg-username">
            用户名
          </label>
          <input
            id="reg-username"
            type="text"
            value={username}
            onChange={(e) => setUsername(e.target.value)}
            required
            minLength={3}
            maxLength={32}
            autoFocus
            autoComplete="username"
            className="field"
            placeholder="3–32 位"
          />
        </div>
        <div>
          <label className="field-label" htmlFor="reg-email">
            {verifyEmail ? "邮箱（必填）" : "邮箱（可选）"}
          </label>
          <input
            id="reg-email"
            required={verifyEmail}
            type="email"
            value={email}
            onChange={(e) => setEmail(e.target.value)}
            autoComplete="email"
            className="field"
            placeholder="you@example.com"
          />
        </div>
        {verifyEmail && (
          <div>
            <label className="field-label" htmlFor="reg-code">
              邮箱验证码
            </label>
            <div className="flex gap-2 items-stretch">
              <input
                id="reg-code"
                className="field min-w-0 flex-1"
                value={code}
                onChange={(e) => setCode(e.target.value)}
                required
                autoComplete="one-time-code"
                inputMode="numeric"
                placeholder="6 位验证码"
              />
              <button
                type="button"
                className="btn btn-line shrink-0"
                disabled={sending || countdown > 0 || !email}
                onClick={async () => {
                  // 点击即锁定，防止重复发送
                  setSending(true);
                  setError("");
                  try {
                    const r = await apiOperations<{ message: string }>("/api/auth/code", "POST", {
                      email,
                      purpose: "register",
                    });
                    setSentMessage(r.message);
                    startCountdown();
                  } catch (err) {
                    setError((err as Error).message);
                  } finally {
                    setSending(false);
                  }
                }}
              >
                {sending
                  ? "正在排队…"
                  : countdown > 0
                    ? `${countdown}s 后可重发`
                    : "发送验证码"}
              </button>
            </div>
            {sentMessage && (
              <p className="meta mt-2" role="status">
                {sentMessage}
              </p>
            )}
          </div>
        )}
        <div>
          <label className="field-label" htmlFor="reg-password">
            密码
          </label>
          <input
            id="reg-password"
            type="password"
            value={password}
            onChange={(e) => setPassword(e.target.value)}
            required
            minLength={6}
            autoComplete="new-password"
            className="field"
            placeholder="至少 6 位"
          />
        </div>
        <button type="submit" disabled={loading} className="btn btn-primary w-full justify-center mt-2">
          {loading ? "注册中..." : "注册"}
        </button>
      </form>

      <p className="meta text-center mt-5">
        已有账号？
        <Link href="/login" className="ml-1 font-semibold" style={{ color: "var(--accent)" }}>
          去登录
        </Link>
      </p>
    </div>
  );
}