"use client";

import Link from "next/link";
import { FormEvent, useEffect, useState } from "react";
import { PreviewNotice } from "@/components/ui";

const apiBase = process.env.NEXT_PUBLIC_API_BASE_URL ?? "/api/v1";

export function AuthForm({ mode }: { mode: "login" | "register" }) {
  const isLogin = mode === "login";
  const [csrf, setCsrf] = useState("");
  const [email, setEmail] = useState("");
  const [phone, setPhone] = useState("");
  const [channel, setChannel] = useState<"email" | "phone">("email");
  const [password, setPassword] = useState("");
  const [confirmation, setConfirmation] = useState("");
  const [verificationId, setVerificationId] = useState("");
  const [verificationCode, setVerificationCode] = useState("");
  const [message, setMessage] = useState("");
  const [error, setError] = useState("");
  const [busy, setBusy] = useState(false);

  useEffect(() => {
    fetch(`${apiBase}/auth/csrf`, { credentials: "include" })
      .then((response) => response.json())
      .then((body) => setCsrf(body.csrf_token ?? ""))
      .catch(() => setError("暂时无法连接认证服务"));
  }, []);

  async function submit(event: FormEvent<HTMLFormElement>) {
    event.preventDefault();
    setError("");
    setMessage("");
    if (!isLogin && password !== confirmation) {
      setError("两次输入的密码不一致");
      return;
    }
    setBusy(true);
    try {
      const response = await fetch(`${apiBase}/auth/${isLogin ? "login" : "register"}`, {
        method: "POST",
        credentials: "include",
        headers: { "Content-Type": "application/json", ...(csrf ? { "X-CSRF-Token": csrf } : {}) },
        body: JSON.stringify(isLogin ? { identifier: email, password } : { email: channel === "email" ? email : email || null, phone: phone || null, verification_channel: channel, password }),
      });
      const body = await response.json().catch(() => ({}));
      if (!response.ok) throw new Error(body.error?.message ?? "请求失败，请稍后重试");
      if (isLogin) {
        window.location.assign("/account");
      } else {
        setVerificationId(body.challenge_id ?? "");
        setMessage(`注册成功，验证码已发送到你的${channel === "email" ? "邮箱" : "手机"}`);
      }
    } catch (submitError) {
      setError(submitError instanceof Error ? submitError.message : "请求失败，请稍后重试");
    } finally {
      setBusy(false);
    }
  }

  async function confirmVerification(event: FormEvent<HTMLFormElement>) {
    event.preventDefault();
    setError("");
    setBusy(true);
    try {
      const response = await fetch(`${apiBase}/auth/verification/confirm-registration`, {
        method: "POST", credentials: "include", headers: { "Content-Type": "application/json", ...(csrf ? { "X-CSRF-Token": csrf } : {}) },
        body: JSON.stringify({ challenge_id: verificationId, code: verificationCode }),
      });
      const body = await response.json().catch(() => ({}));
      if (!response.ok) throw new Error(body.error?.message ?? "验证码错误，请重试");
      setMessage("验证成功，请登录");
      window.setTimeout(() => window.location.assign("/login"), 500);
    } catch (confirmError) {
      setError(confirmError instanceof Error ? confirmError.message : "验证失败，请重试");
    } finally { setBusy(false); }
  }

  async function resendVerification() {
    setError("");
    setBusy(true);
    try {
      const response = await fetch(`${apiBase}/auth/verification/resend`, {
        method: "POST", credentials: "include", headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ challenge_id: verificationId }),
      });
      const body = await response.json().catch(() => ({}));
      if (!response.ok) throw new Error(body.error?.message ?? "验证码发送失败，请稍后重试");
      setMessage("新的验证码已发送");
    } catch (resendError) {
      setError(resendError instanceof Error ? resendError.message : "验证码发送失败，请稍后重试");
    } finally { setBusy(false); }
  }

  return (
    <div className="w-full max-w-md rounded-2xl border border-line bg-panel/70 p-6 sm:p-8">
      <PreviewNotice>支持邮箱或手机二选一验证。验证码只由服务端发送和校验。</PreviewNotice>
      {verificationId ? <form className="mt-8 space-y-5" onSubmit={confirmVerification}>
        <div><label className="field-label" htmlFor="verification-code">验证码</label><input className="field-input" id="verification-code" inputMode="numeric" maxLength={6} onChange={(event) => setVerificationCode(event.target.value)} placeholder="输入 6 位验证码" required value={verificationCode} /></div>
        {error ? <p className="rounded-lg border border-danger/30 bg-danger/10 px-3 py-2 text-sm leading-6 text-danger" role="alert">{error}</p> : null}
        <button className="button-primary w-full" disabled={busy || !csrf} type="submit">{busy ? "验证中…" : "验证邮箱"}</button>
        <button className="w-full text-sm text-muted hover:text-copy" disabled={busy} onClick={resendVerification} type="button">重新发送验证码</button>
      </form> : <form className="mt-8 space-y-5" onSubmit={submit}>
        {isLogin ? <div><label className="field-label" htmlFor="email">邮箱或手机号</label><input className="field-input" id="email" onChange={(event) => setEmail(event.target.value)} placeholder="name@example.com / 13800138000" required value={email} /></div> : <>
          <div className="grid grid-cols-2 gap-2 rounded-lg border border-line p-1"><button className={`rounded-md px-3 py-2 text-sm ${channel === "email" ? "bg-cyan text-slate-950" : "text-muted"}`} onClick={() => setChannel("email")} type="button">邮箱验证</button><button className={`rounded-md px-3 py-2 text-sm ${channel === "phone" ? "bg-cyan text-slate-950" : "text-muted"}`} onClick={() => setChannel("phone")} type="button">短信验证</button></div>
          <div><label className="field-label" htmlFor="email">邮箱{channel === "email" ? "（必填）" : "（可选）"}</label><input className="field-input" id="email" onChange={(event) => setEmail(event.target.value)} placeholder="name@example.com" required={channel === "email"} type="email" value={email} /></div>
          <div><label className="field-label" htmlFor="phone">手机号{channel === "phone" ? "（必填）" : "（可选）"}</label><input className="field-input" id="phone" onChange={(event) => setPhone(event.target.value)} placeholder="中国大陆手机号" required={channel === "phone"} type="tel" value={phone} /></div>
        </>}
        <div><label className="field-label" htmlFor="password">密码</label><input className="field-input" id="password" minLength={8} onChange={(event) => setPassword(event.target.value)} placeholder="至少 8 位字符" required type="password" value={password} /></div>
        {!isLogin ? <div><label className="field-label" htmlFor="password-confirm">确认密码</label><input className="field-input" id="password-confirm" minLength={8} onChange={(event) => setConfirmation(event.target.value)} placeholder="再次输入密码" required type="password" value={confirmation} /></div> : null}
        {error ? <p className="rounded-lg border border-danger/30 bg-danger/10 px-3 py-2 text-sm leading-6 text-danger" role="alert">{error}</p> : null}
        {message ? <p className="rounded-lg border border-success/30 bg-success/10 px-3 py-2 text-sm leading-6 text-success" role="status">{message}</p> : null}
        <button className="button-primary w-full" disabled={busy || !csrf} type="submit">{busy ? "处理中…" : isLogin ? "登录" : "注册"}</button>
      </form>}
      <p className="mt-6 text-center text-sm text-muted">{isLogin ? "还没有账户？" : "已有账户？"}{" "}<Link className="text-cyan hover:text-copy" href={isLogin ? "/register" : "/login"}>{isLogin ? "去注册" : "去登录"}</Link></p>
    </div>
  );
}