"use client";

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

export default function RegisterPage() {
  const router = useRouter();
  const [username, setUsername] = useState("");
  const [email, setEmail] = useState("");
  const [password, setPassword] = useState("");
  const [error, setError] = useState("");
  const [loading, setLoading] = useState(false);

  // 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);
      if (res.user) {
        // 后端注册即签发登录态 cookie：直接进入社区，无需再手动登录
        router.push("/");
        router.refresh();
      } else if (res.id) {
        // 极端情况：注册成功但自动签发失败，引导去登录
        router.push("/login");
      } else {
        setError(res.error || "注册失败");
      }
    } finally {
      setLoading(false);
    }
  };

  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)" }}
        >
          <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)" }}>
          加入姜十三，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">邮箱（可选）</label>
          <input
            id="reg-email"
            type="email"
            value={email}
            onChange={(e) => setEmail(e.target.value)}
            autoComplete="email"
            className="field"
            placeholder="you@example.com"
          />
        </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>
  );
}